Subversion Repositories planix.SVN

Rev

Blame | Last modification | View Log | RSS feed

#include        "u.h"
#include        "../port/lib.h"
#include        "mem.h"
#include        "dat.h"
#include        "fns.h"
#include        "../port/error.h"

#define Image   IMAGE
#include        <draw.h>
#include        <memdraw.h>
#include        <memlayer.h>
#include        <cursor.h>
#include        "screen.h"

enum
{
        Qtopdir         = 0,
        Qnew,
        Qwinname,
        Q3rd,
        Q2nd,
        Qcolormap,
        Qctl,
        Qdata,
        Qrefresh,
};

/*
 * Qid path is:
 *       4 bits of file type (qids above)
 *      24 bits of mux slot number +1; 0 means not attached to client
 */
#define QSHIFT  4       /* location in qid of client # */

#define QID(q)          ((((ulong)(q).path)&0x0000000F)>>0)
#define CLIENTPATH(q)   ((((ulong)q)&0x7FFFFFF0)>>QSHIFT)
#define CLIENT(q)       CLIENTPATH((q).path)

#define NHASH           (1<<5)
#define HASHMASK        (NHASH-1)
#define IOUNIT          (64*1024)

typedef struct Client Client;
typedef struct Draw Draw;
typedef struct DImage DImage;
typedef struct DScreen DScreen;
typedef struct CScreen CScreen;
typedef struct FChar FChar;
typedef struct Refresh Refresh;
typedef struct Refx Refx;
typedef struct DName DName;

ulong blanktime = 30;   /* in minutes; a half hour */

struct Draw
{
        int             clientid;
        int             nclient;
        Client**        client;
        int             nname;
        DName*          name;
        int             vers;
        int             softscreen;
        int             blanked;        /* screen turned off */
        ulong           blanktime;      /* time of last operation */
        ulong           savemap[3*256];
};

struct Client
{
        Ref             r;
        DImage*         dimage[NHASH];
        CScreen*        cscreen;
        Refresh*        refresh;
        Rendez          refrend;
        uchar*          readdata;
        int             nreaddata;
        int             busy;
        int             clientid;
        int             slot;
        int             refreshme;
        int             infoid;
        int             op;
};

struct Refresh
{
        DImage*         dimage;
        Rectangle       r;
        Refresh*        next;
};

struct Refx
{
        Client*         client;
        DImage*         dimage;
};

struct DName
{
        char            *name;
        Client          *client;
        DImage*         dimage;
        int             vers;
};

struct FChar
{
        int             minx;   /* left edge of bits */
        int             maxx;   /* right edge of bits */
        uchar           miny;   /* first non-zero scan-line */
        uchar           maxy;   /* last non-zero scan-line + 1 */
        schar           left;   /* offset of baseline */
        uchar           width;  /* width of baseline */
};

/*
 * Reference counts in DImages:
 *      one per open by original client
 *      one per screen image or fill
 *      one per image derived from this one by name
 */
struct DImage
{
        int             id;
        int             ref;
        char            *name;
        int             vers;
        Memimage*       image;
        int             ascent;
        int             nfchar;
        FChar*          fchar;
        DScreen*        dscreen;        /* 0 if not a window */
        DImage*         fromname;       /* image this one is derived from, by name */
        DImage*         next;
};

struct CScreen
{
        DScreen*        dscreen;
        CScreen*        next;
};

struct DScreen
{
        int             id;
        int             public;
        int             ref;
        DImage          *dimage;
        DImage          *dfill;
        Memscreen*      screen;
        Client*         owner;
        DScreen*        next;
};

static  Draw            sdraw;
        QLock   drawlock;

static  Memimage        *screenimage;
static  DImage* screendimage;
static  char    screenname[40];
static  int     screennameid;

static  Rectangle       flushrect;
static  int             waste;
static  DScreen*        dscreen;
extern  void            flushmemscreen(Rectangle);
        void            drawmesg(Client*, void*, int);
        void            drawuninstall(Client*, int);
        void            drawfreedimage(DImage*);
        Client*         drawclientofpath(ulong);
        DImage* allocdimage(Memimage*);

static  char Enodrawimage[] =   "unknown id for draw image";
static  char Enodrawscreen[] =  "unknown id for draw screen";
static  char Eshortdraw[] =     "short draw message";
static  char Eshortread[] =     "draw read too short";
static  char Eimageexists[] =   "image id in use";
static  char Escreenexists[] =  "screen id in use";
static  char Edrawmem[] =       "image memory allocation failed";
static  char Ereadoutside[] =   "readimage outside image";
static  char Ewriteoutside[] =  "writeimage outside image";
static  char Enotfont[] =       "image not a font";
static  char Eindex[] =         "character index out of range";
static  char Enoclient[] =      "no such draw client";
static  char Edepth[] =         "image has bad depth";
static  char Enameused[] =      "image name in use";
static  char Enoname[] =        "no image with that name";
static  char Eoldname[] =       "named image no longer valid";
static  char Enamed[] =         "image already has name";
static  char Ewrongname[] =     "wrong name for image";

static void
dlock(void)
{
        qlock(&drawlock);
}

static int
candlock(void)
{
        return canqlock(&drawlock);
}

static void
dunlock(void)
{
        qunlock(&drawlock);
}

static int
drawgen(Chan *c, char*, Dirtab*, int, int s, Dir *dp)
{
        int t;
        Qid q;
        ulong path;
        Client *cl;

        q.vers = 0;

        if(s == DEVDOTDOT){
                switch(QID(c->qid)){
                case Qtopdir:
                case Q2nd:
                        mkqid(&q, Qtopdir, 0, QTDIR);
                        devdir(c, q, "#i", 0, eve, 0500, dp);
                        break;
                case Q3rd:
                        cl = drawclientofpath(c->qid.path);
                        if(cl == nil)
                                strncpy(up->genbuf, "??", sizeof up->genbuf);
                        else
                                snprint(up->genbuf, sizeof up->genbuf,
                                        "%d", cl->clientid);
                        mkqid(&q, Q2nd, 0, QTDIR);
                        devdir(c, q, up->genbuf, 0, eve, 0500, dp);
                        break;
                default:
                        panic("drawwalk %llux", c->qid.path);
                }
                return 1;
        }

        /*
         * Top level directory contains the name of the device.
         */
        t = QID(c->qid);
        if(t == Qtopdir){
                switch(s){
                case 0:
                        mkqid(&q, Q2nd, 0, QTDIR);
                        devdir(c, q, "draw", 0, eve, 0555, dp);
                        break;
                case 1:
                        mkqid(&q, Qwinname, 0, QTFILE);
                        devdir(c, q, "winname", 0, eve, 0444, dp);
                        break;
                default:
                        return -1;
                }
                return 1;
        }

        if(t == Qwinname){
                mkqid(&q, Qwinname, 0, QTFILE);
                devdir(c, q, "winname", 0, eve, 0444, dp);
                return 1;
        }

        /*
         * Second level contains "new" plus all the clients.
         */
        if(t == Q2nd || t == Qnew){
                if(s == 0){
                        mkqid(&q, Qnew, 0, QTFILE);
                        devdir(c, q, "new", 0, eve, 0666, dp);
                }
                else if(s <= sdraw.nclient){
                        cl = sdraw.client[s-1];
                        if(cl == 0)
                                return 0;
                        snprint(up->genbuf, sizeof up->genbuf, "%d",
                                cl->clientid);
                        mkqid(&q, (s<<QSHIFT)|Q3rd, 0, QTDIR);
                        devdir(c, q, up->genbuf, 0, eve, 0555, dp);
                        return 1;
                }
                else
                        return -1;
                return 1;
        }

        /*
         * Third level.
         */
        path = c->qid.path&~((1<<QSHIFT)-1);    /* slot component */
        q.vers = c->qid.vers;
        q.type = QTFILE;
        switch(s){
        case 0:
                q.path = path|Qcolormap;
                devdir(c, q, "colormap", 0, eve, 0600, dp);
                break;
        case 1:
                q.path = path|Qctl;
                devdir(c, q, "ctl", 0, eve, 0600, dp);
                break;
        case 2:
                q.path = path|Qdata;
                devdir(c, q, "data", 0, eve, 0600, dp);
                break;
        case 3:
                q.path = path|Qrefresh;
                devdir(c, q, "refresh", 0, eve, 0400, dp);
                break;
        default:
                return -1;
        }
        return 1;
}

static
int
drawrefactive(void *a)
{
        Client *c;

        c = a;
        return c->refreshme || c->refresh!=0;
}

static
void
drawrefreshscreen(DImage *l, Client *client)
{
        while(l != nil && l->dscreen == nil)
                l = l->fromname;
        if(l != nil && l->dscreen->owner != client)
                l->dscreen->owner->refreshme = 1;
}

static
void
drawrefresh(Memimage*, Rectangle r, void *v)
{
        Refx *x;
        DImage *d;
        Client *c;
        Refresh *ref;

        if(v == 0)
                return;
        x = v;
        c = x->client;
        d = x->dimage;
        for(ref=c->refresh; ref; ref=ref->next)
                if(ref->dimage == d){
                        combinerect(&ref->r, r);
                        return;
                }
        ref = malloc(sizeof(Refresh));
        if(ref){
                ref->dimage = d;
                ref->r = r;
                ref->next = c->refresh;
                c->refresh = ref;
        }
}

static void
addflush(Rectangle r)
{
        int abb, ar, anbb;
        Rectangle nbb;

        if(sdraw.softscreen==0 || !rectclip(&r, screenimage->r))
                return;

        if(flushrect.min.x >= flushrect.max.x){
                flushrect = r;
                waste = 0;
                return;
        }
        nbb = flushrect;
        combinerect(&nbb, r);
        ar = Dx(r)*Dy(r);
        abb = Dx(flushrect)*Dy(flushrect);
        anbb = Dx(nbb)*Dy(nbb);
        /*
         * Area of new waste is area of new bb minus area of old bb,
         * less the area of the new segment, which we assume is not waste.
         * This could be negative, but that's OK.
         */
        waste += anbb-abb - ar;
        if(waste < 0)
                waste = 0;
        /*
         * absorb if:
         *      total area is small
         *      waste is less than half total area
         *      rectangles touch
         */
        if(anbb<=1024 || waste*2<anbb || rectXrect(flushrect, r)){
                flushrect = nbb;
                return;
        }
        /* emit current state */
        if(flushrect.min.x < flushrect.max.x)
                flushmemscreen(flushrect);
        flushrect = r;
        waste = 0;
}

static
void
dstflush(int dstid, Memimage *dst, Rectangle r)
{
        Memlayer *l;

        if(dstid == 0){
                combinerect(&flushrect, r);
                return;
        }
        /* how can this happen? -rsc, dec 12 2002 */
        if(dst == 0){
                print("nil dstflush\n");
                return;
        }
        l = dst->layer;
        if(l == nil)
                return;
        do{
                if(l->screen->image->data != screenimage->data)
                        return;
                r = rectaddpt(r, l->delta);
                l = l->screen->image->layer;
        }while(l);
        addflush(r);
}

void
drawflush(void)
{
        if(flushrect.min.x < flushrect.max.x)
                flushmemscreen(flushrect);
        flushrect = Rect(10000, 10000, -10000, -10000);
}

static
int
drawcmp(char *a, char *b, int n)
{
        if(strlen(a) != n)
                return 1;
        return memcmp(a, b, n);
}

DName*
drawlookupname(int n, char *str)
{
        DName *name, *ename;

        name = sdraw.name;
        ename = &name[sdraw.nname];
        for(; name<ename; name++)
                if(drawcmp(name->name, str, n) == 0)
                        return name;
        return 0;
}

int
drawgoodname(DImage *d)
{
        DName *n;

        /* if window, validate the screen's own images */
        if(d->dscreen)
                if(drawgoodname(d->dscreen->dimage) == 0
                || drawgoodname(d->dscreen->dfill) == 0)
                        return 0;
        if(d->name == nil)
                return 1;
        n = drawlookupname(strlen(d->name), d->name);
        if(n==nil || n->vers!=d->vers)
                return 0;
        return 1;
}

DImage*
drawlookup(Client *client, int id, int checkname)
{
        DImage *d;

        d = client->dimage[id&HASHMASK];
        while(d){
                if(d->id == id){
                        if(checkname && !drawgoodname(d))
                                error(Eoldname);
                        return d;
                }
                d = d->next;
        }
        return 0;
}

DScreen*
drawlookupdscreen(int id)
{
        DScreen *s;

        s = dscreen;
        while(s){
                if(s->id == id)
                        return s;
                s = s->next;
        }
        return 0;
}

DScreen*
drawlookupscreen(Client *client, int id, CScreen **cs)
{
        CScreen *s;

        s = client->cscreen;
        while(s){
                if(s->dscreen->id == id){
                        *cs = s;
                        return s->dscreen;
                }
                s = s->next;
        }
        error(Enodrawscreen);
        return 0;
}

DImage*
allocdimage(Memimage *i)
{
        DImage *d;

        d = malloc(sizeof(DImage));
        if(d == 0)
                return 0;
        d->ref = 1;
        d->name = 0;
        d->vers = 0;
        d->image = i;
        d->nfchar = 0;
        d->fchar = 0;
        d->fromname = 0;
        return d;
}

Memimage*
drawinstall(Client *client, int id, Memimage *i, DScreen *dscreen)
{
        DImage *d;

        d = allocdimage(i);
        if(d == 0)
                return 0;
        d->id = id;
        d->dscreen = dscreen;
        d->next = client->dimage[id&HASHMASK];
        client->dimage[id&HASHMASK] = d;
        return i;
}

Memscreen*
drawinstallscreen(Client *client, DScreen *d, int id, DImage *dimage, DImage *dfill, int public)
{
        Memscreen *s;
        CScreen *c;

        c = malloc(sizeof(CScreen));
        if(dimage && dimage->image && dimage->image->chan == 0)
                panic("bad image %p in drawinstallscreen", dimage->image);

        if(c == 0)
                return 0;
        if(d == 0){
                d = malloc(sizeof(DScreen));
                if(d == 0){
                        free(c);
                        return 0;
                }
                s = malloc(sizeof(Memscreen));
                if(s == 0){
                        free(c);
                        free(d);
                        return 0;
                }
                s->frontmost = 0;
                s->rearmost = 0;
                d->dimage = dimage;
                if(dimage){
                        s->image = dimage->image;
                        dimage->ref++;
                }
                d->dfill = dfill;
                if(dfill){
                        s->fill = dfill->image;
                        dfill->ref++;
                }
                d->ref = 0;
                d->id = id;
                d->screen = s;
                d->public = public;
                d->next = dscreen;
                d->owner = client;
                dscreen = d;
        }
        c->dscreen = d;
        d->ref++;
        c->next = client->cscreen;
        client->cscreen = c;
        return d->screen;
}

void
drawdelname(DName *name)
{
        int i;

        i = name-sdraw.name;
        memmove(name, name+1, (sdraw.nname-(i+1))*sizeof(DName));
        sdraw.nname--;
}

void
drawfreedscreen(DScreen *this)
{
        DScreen *ds, *next;

        this->ref--;
        if(this->ref < 0)
                print("negative ref in drawfreedscreen\n");
        if(this->ref > 0)
                return;
        ds = dscreen;
        if(ds == this){
                dscreen = this->next;
                goto Found;
        }
        while(next = ds->next){ /* assign = */
                if(next == this){
                        ds->next = this->next;
                        goto Found;
                }
                ds = next;
        }
        error(Enodrawimage);

    Found:
        if(this->dimage)
                drawfreedimage(this->dimage);
        if(this->dfill)
                drawfreedimage(this->dfill);
        free(this->screen);
        free(this);
}

void
drawfreedimage(DImage *dimage)
{
        int i;
        Memimage *l;
        DScreen *ds;

        dimage->ref--;
        if(dimage->ref < 0)
                print("negative ref in drawfreedimage\n");
        if(dimage->ref > 0)
                return;

        /* any names? */
        for(i=0; i<sdraw.nname; )
                if(sdraw.name[i].dimage == dimage)
                        drawdelname(sdraw.name+i);
                else
                        i++;
        if(dimage->fromname){   /* acquired by name; owned by someone else*/
                drawfreedimage(dimage->fromname);
                goto Return;
        }
//      if(dimage->image == screenimage)        /* don't free the display */
//              goto Return;
        ds = dimage->dscreen;
        if(ds){
                l = dimage->image;
                if(l->data == screenimage->data)
                        addflush(l->layer->screenr);
                if(l->layer->refreshfn == drawrefresh)  /* else true owner will clean up */
                        free(l->layer->refreshptr);
                l->layer->refreshptr = nil;
                if(drawgoodname(dimage))
                        memldelete(l);
                else
                        memlfree(l);
                drawfreedscreen(ds);
        }else
                freememimage(dimage->image);
    Return:
        free(dimage->fchar);
        free(dimage);
}

void
drawuninstallscreen(Client *client, CScreen *this)
{
        CScreen *cs, *next;

        cs = client->cscreen;
        if(cs == this){
                client->cscreen = this->next;
                drawfreedscreen(this->dscreen);
                free(this);
                return;
        }
        while(next = cs->next){ /* assign = */
                if(next == this){
                        cs->next = this->next;
                        drawfreedscreen(this->dscreen);
                        free(this);
                        return;
                }
                cs = next;
        }
}

void
drawuninstall(Client *client, int id)
{
        DImage *d, *next;

        d = client->dimage[id&HASHMASK];
        if(d == 0)
                error(Enodrawimage);
        if(d->id == id){
                client->dimage[id&HASHMASK] = d->next;
                drawfreedimage(d);
                return;
        }
        while(next = d->next){  /* assign = */
                if(next->id == id){
                        d->next = next->next;
                        drawfreedimage(next);
                        return;
                }
                d = next;
        }
        error(Enodrawimage);
}

void
drawaddname(Client *client, DImage *di, int n, char *str)
{
        DName *name, *ename, *new, *t;

        name = sdraw.name;
        ename = &name[sdraw.nname];
        for(; name<ename; name++)
                if(drawcmp(name->name, str, n) == 0)
                        error(Enameused);
        t = smalloc((sdraw.nname+1)*sizeof(DName));
        memmove(t, sdraw.name, sdraw.nname*sizeof(DName));
        free(sdraw.name);
        sdraw.name = t;
        new = &sdraw.name[sdraw.nname++];
        new->name = smalloc(n+1);
        memmove(new->name, str, n);
        new->name[n] = 0;
        new->dimage = di;
        new->client = client;
        new->vers = ++sdraw.vers;
}

Client*
drawnewclient(void)
{
        Client *cl, **cp;
        int i;

        for(i=0; i<sdraw.nclient; i++){
                cl = sdraw.client[i];
                if(cl == 0)
                        break;
        }
        if(i == sdraw.nclient){
                cp = malloc((sdraw.nclient+1)*sizeof(Client*));
                if(cp == 0)
                        return 0;
                memmove(cp, sdraw.client, sdraw.nclient*sizeof(Client*));
                free(sdraw.client);
                sdraw.client = cp;
                sdraw.nclient++;
                cp[i] = 0;
        }
        cl = malloc(sizeof(Client));
        if(cl == 0)
                return 0;
        memset(cl, 0, sizeof(Client));
        cl->slot = i;
        cl->clientid = ++sdraw.clientid;
        cl->op = SoverD;
        sdraw.client[i] = cl;
        return cl;
}

static int
drawclientop(Client *cl)
{
        int op;

        op = cl->op;
        cl->op = SoverD;
        return op;
}

int
drawhasclients(void)
{
        /*
         * if draw has ever been used, we can't resize the frame buffer,
         * even if all clients have exited (nclients is cumulative); it's too
         * hard to make work.
         */
        return sdraw.nclient != 0;
}

Client*
drawclientofpath(ulong path)
{
        Client *cl;
        int slot;

        slot = CLIENTPATH(path);
        if(slot == 0)
                return nil;
        cl = sdraw.client[slot-1];
        if(cl==0 || cl->clientid==0)
                return nil;
        return cl;
}


Client*
drawclient(Chan *c)
{
        Client *client;

        client = drawclientofpath(c->qid.path);
        if(client == nil)
                error(Enoclient);
        return client;
}

Memimage*
drawimage(Client *client, uchar *a)
{
        DImage *d;

        d = drawlookup(client, BGLONG(a), 1);
        if(d == nil)
                error(Enodrawimage);
        return d->image;
}

void
drawrectangle(Rectangle *r, uchar *a)
{
        r->min.x = BGLONG(a+0*4);
        r->min.y = BGLONG(a+1*4);
        r->max.x = BGLONG(a+2*4);
        r->max.y = BGLONG(a+3*4);
}

void
drawpoint(Point *p, uchar *a)
{
        p->x = BGLONG(a+0*4);
        p->y = BGLONG(a+1*4);
}

Point
drawchar(Memimage *dst, Memimage *rdst, Point p, Memimage *src, Point *sp, DImage *font, int index, int op)
{
        FChar *fc;
        Rectangle r;
        Point sp1;
        static Memimage *tmp;

        fc = &font->fchar[index];
        r.min.x = p.x+fc->left;
        r.min.y = p.y-(font->ascent-fc->miny);
        r.max.x = r.min.x+(fc->maxx-fc->minx);
        r.max.y = r.min.y+(fc->maxy-fc->miny);
        sp1.x = sp->x+fc->left;
        sp1.y = sp->y+fc->miny;

        /*
         * If we're drawing greyscale fonts onto a VGA screen,
         * it's very costly to read the screen memory to do the
         * alpha blending inside memdraw.  If this is really a stringbg,
         * then rdst is the bg image (in main memory) which we can
         * refer to for the underlying dst pixels instead of reading dst
         * directly.
         */
        if(ishwimage(dst) && !ishwimage(rdst) && font->image->depth > 1){
                if(tmp == nil || tmp->chan != dst->chan || Dx(tmp->r) < Dx(r) || Dy(tmp->r) < Dy(r)){
                        if(tmp)
                                freememimage(tmp);
                        tmp = allocmemimage(Rect(0,0,Dx(r),Dy(r)), dst->chan);
                        if(tmp == nil)
                                goto fallback;
                }
                memdraw(tmp, Rect(0,0,Dx(r),Dy(r)), rdst, r.min, memopaque, ZP, S);
                memdraw(tmp, Rect(0,0,Dx(r),Dy(r)), src, sp1, font->image, Pt(fc->minx, fc->miny), op);
                memdraw(dst, r, tmp, ZP, memopaque, ZP, S);
        }else{
        fallback:
                memdraw(dst, r, src, sp1, font->image, Pt(fc->minx, fc->miny), op);
        }

        p.x += fc->width;
        sp->x += fc->width;
        return p;
}

static DImage*
makescreenimage(void)
{
        int width, depth;
        ulong chan;
        DImage *di;
        Memdata *md;
        Memimage *i;
        Rectangle r;

        md = malloc(sizeof *md);
        if(md == nil)
                return nil;
        md->allocd = 1;
        md->base = nil;
        md->bdata = attachscreen(&r, &chan, &depth, &width, &sdraw.softscreen);
        if(md->bdata == nil){
                free(md);
                return nil;
        }
        md->ref = 1;
        i = allocmemimaged(r, chan, md);
        if(i == nil){
                free(md);
                return nil;
        }
        i->width = width;
        i->clipr = r;

        di = allocdimage(i);
        if(di == nil){
                freememimage(i);        /* frees md */
                return nil;
        }
        if(!waserror()){
                snprint(screenname, sizeof screenname, "noborder.screen.%d", ++screennameid);
                drawaddname(nil, di, strlen(screenname), screenname);
                poperror();
        }
        return di;
}

static int
initscreenimage(void)
{
        if(screenimage != nil)
                return 1;

        screendimage = makescreenimage();
        if(screendimage == nil)
                return 0;
        screenimage = screendimage->image;
// iprint("initscreenimage %p %p\n", screendimage, screenimage);
        mouseresize();
        return 1;
}

void
deletescreenimage(void)
{
        dlock();
        if(screenimage){
                /* will be freed via screendimage; disable */
                screenimage->clipr = ZR;
                screenimage = nil;
        }
        if(screendimage){
                drawfreedimage(screendimage);
                screendimage = nil;
        }
        dunlock();
}

void
resetscreenimage(void)
{
        dlock();
        initscreenimage();
        dunlock();
}

static Chan*
drawattach(char *spec)
{
        dlock();
        if(!initscreenimage()){
                dunlock();
                error("no frame buffer");
        }
        dunlock();
        return devattach('i', spec);
}

static Walkqid*
drawwalk(Chan *c, Chan *nc, char **name, int nname)
{
        if(screenimage == nil)
                error("no frame buffer");
        return devwalk(c, nc, name, nname, 0, 0, drawgen);
}

static int
drawstat(Chan *c, uchar *db, int n)
{
        return devstat(c, db, n, 0, 0, drawgen);
}

static Chan*
drawopen(Chan *c, int omode)
{
        Client *cl;
        DName *dn;
        DImage *di;

        if(c->qid.type & QTDIR){
                c = devopen(c, omode, 0, 0, drawgen);
                c->iounit = IOUNIT;
        }

        dlock();
        if(waserror()){
                dunlock();
                nexterror();
        }

        if(QID(c->qid) == Qnew){
                cl = drawnewclient();
                if(cl == 0)
                        error(Enodev);
                c->qid.path = Qctl|((cl->slot+1)<<QSHIFT);
        }

        switch(QID(c->qid)){
        case Qwinname:
                break;

        case Qnew:
                break;

        case Qctl:
                cl = drawclient(c);
                if(cl->busy)
                        error(Einuse);
                cl->busy = 1;
                flushrect = Rect(10000, 10000, -10000, -10000);
                dn = drawlookupname(strlen(screenname), screenname);
                if(dn == 0)
                        error("draw: cannot happen 2");
                if(drawinstall(cl, 0, dn->dimage->image, 0) == 0)
                        error(Edrawmem);
                di = drawlookup(cl, 0, 0);
                if(di == 0)
                        error("draw: cannot happen 1");
                di->vers = dn->vers;
                di->name = smalloc(strlen(screenname)+1);
                strcpy(di->name, screenname);
                di->fromname = dn->dimage;
                di->fromname->ref++;
                incref(&cl->r);
                break;

        case Qcolormap:
        case Qdata:
        case Qrefresh:
                cl = drawclient(c);
                incref(&cl->r);
                break;
        }
        dunlock();
        poperror();
        c->mode = openmode(omode);
        c->flag |= COPEN;
        c->offset = 0;
        c->iounit = IOUNIT;
        return c;
}

static void
drawclose(Chan *c)
{
        int i;
        DImage *d, **dp;
        Client *cl;
        Refresh *r;

        if(QID(c->qid) < Qcolormap)     /* Qtopdir, Qnew, Q3rd, Q2nd have no client */
                return;
        dlock();
        if(waserror()){
                dunlock();
                nexterror();
        }

        cl = drawclient(c);
        if(QID(c->qid) == Qctl)
                cl->busy = 0;
        if((c->flag&COPEN) && (decref(&cl->r)==0)){
                while(r = cl->refresh){ /* assign = */
                        cl->refresh = r->next;
                        free(r);
                }
                /* free names */
                for(i=0; i<sdraw.nname; )
                        if(sdraw.name[i].client == cl)
                                drawdelname(sdraw.name+i);
                        else
                                i++;
                while(cl->cscreen)
                        drawuninstallscreen(cl, cl->cscreen);
                /* all screens are freed, so now we can free images */
                dp = cl->dimage;
                for(i=0; i<NHASH; i++){
                        while((d = *dp) != nil){
                                *dp = d->next;
                                drawfreedimage(d);
                        }
                        dp++;
                }
                sdraw.client[cl->slot] = 0;
                drawflush();    /* to erase visible, now dead windows */
                free(cl);
        }
        dunlock();
        poperror();
}

long
drawread(Chan *c, void *a, long n, vlong off)
{
        int index, m;
        ulong red, green, blue;
        Client *cl;
        uchar *p;
        Refresh *r;
        DImage *di;
        Memimage *i;
        ulong offset = off;
        char buf[16];

        if(c->qid.type & QTDIR)
                return devdirread(c, a, n, 0, 0, drawgen);
        if(QID(c->qid) == Qwinname)
                return readstr(off, a, n, screenname);

        cl = drawclient(c);
        dlock();
        if(waserror()){
                dunlock();
                nexterror();
        }
        switch(QID(c->qid)){
        case Qctl:
                if(n < 12*12)
                        error(Eshortread);
                if(cl->infoid < 0)
                        error(Enodrawimage);
                if(cl->infoid == 0){
                        i = screenimage;
                        if(i == nil)
                                error(Enodrawimage);
                }else{
                        di = drawlookup(cl, cl->infoid, 1);
                        if(di == nil)
                                error(Enodrawimage);
                        i = di->image;
                }
                n = snprint(a, n,
                        "%11d %11d %11s %11d %11d %11d %11d %11d %11d %11d %11d %11d ",
                        cl->clientid, cl->infoid, chantostr(buf, i->chan),
                        (i->flags&Frepl)==Frepl,
                        i->r.min.x, i->r.min.y, i->r.max.x, i->r.max.y,
                        i->clipr.min.x, i->clipr.min.y, i->clipr.max.x,
                        i->clipr.max.y);
                cl->infoid = -1;
                break;

        case Qcolormap:
                drawactive(1);  /* to restore map from backup */
                p = malloc(4*12*256+1);
                if(p == 0)
                        error(Enomem);
                m = 0;
                for(index = 0; index < 256; index++){
                        getcolor(index, &red, &green, &blue);
                        m += snprint((char*)p+m, 4*12*256+1 - m,
                                "%11d %11lud %11lud %11lud\n", index,
                                red>>24, green>>24, blue>>24);
                }
                n = readstr(offset, a, n, (char*)p);
                free(p);
                break;

        case Qdata:
                if(cl->readdata == nil)
                        error("no draw data");
                if(n < cl->nreaddata)
                        error(Eshortread);
                n = cl->nreaddata;
                memmove(a, cl->readdata, cl->nreaddata);
                free(cl->readdata);
                cl->readdata = nil;
                break;

        case Qrefresh:
                if(n < 5*4)
                        error(Ebadarg);
                for(;;){
                        if(cl->refreshme || cl->refresh)
                                break;
                        dunlock();
                        if(waserror()){
                                dlock();        /* restore lock for waserror() above */
                                nexterror();
                        }
                        sleep(&cl->refrend, drawrefactive, cl);
                        poperror();
                        dlock();
                }
                p = a;
                while(cl->refresh && n>=5*4){
                        r = cl->refresh;
                        BPLONG(p+0*4, r->dimage->id);
                        BPLONG(p+1*4, r->r.min.x);
                        BPLONG(p+2*4, r->r.min.y);
                        BPLONG(p+3*4, r->r.max.x);
                        BPLONG(p+4*4, r->r.max.y);
                        cl->refresh = r->next;
                        free(r);
                        p += 5*4;
                        n -= 5*4;
                }
                cl->refreshme = 0;
                n = p-(uchar*)a;
                break;
        }
        dunlock();
        poperror();
        return n;
}

void
drawwakeall(void)
{
        Client *cl;
        int i;

        for(i=0; i<sdraw.nclient; i++){
                cl = sdraw.client[i];
                if(cl && (cl->refreshme || cl->refresh))
                        wakeup(&cl->refrend);
        }
}

static long
drawwrite(Chan *c, void *a, long n, vlong)
{
        char buf[128], *fields[4], *q;
        Client *cl;
        int i, m, red, green, blue, x;

        if(c->qid.type & QTDIR)
                error(Eisdir);
        cl = drawclient(c);
        dlock();
        if(waserror()){
                drawwakeall();
                dunlock();
                nexterror();
        }
        switch(QID(c->qid)){
        case Qctl:
                if(n != 4)
                        error("unknown draw control request");
                cl->infoid = BGLONG((uchar*)a);
                break;

        case Qcolormap:
                drawactive(1);  /* to restore map from backup */
                m = n;
                n = 0;
                while(m > 0){
                        x = m;
                        if(x > sizeof(buf)-1)
                                x = sizeof(buf)-1;
                        q = memccpy(buf, a, '\n', x);
                        if(q == 0)
                                break;
                        i = q-buf;
                        n += i;
                        a = (char*)a + i;
                        m -= i;
                        *q = 0;
                        if(tokenize(buf, fields, nelem(fields)) != 4)
                                error(Ebadarg);
                        i = strtoul(fields[0], 0, 0);
                        red = strtoul(fields[1], 0, 0);
                        green = strtoul(fields[2], 0, 0);
                        blue = strtoul(fields[3], &q, 0);
                        if(fields[3] == q)
                                error(Ebadarg);
                        if(red>255 || green>255 || blue>255 || i<0 || i>255)
                                error(Ebadarg);
                        red |= red<<8;
                        red |= red<<16;
                        green |= green<<8;
                        green |= green<<16;
                        blue |= blue<<8;
                        blue |= blue<<16;
                        setcolor(i, red, green, blue);
                }
                break;

        case Qdata:
                drawmesg(cl, a, n);
                drawwakeall();
                break;

        default:
                error(Ebadusefd);
        }
        dunlock();
        poperror();
        return n;
}

uchar*
drawcoord(uchar *p, uchar *maxp, int oldx, int *newx)
{
        int b, x;

        if(p >= maxp)
                error(Eshortdraw);
        b = *p++;
        x = b & 0x7F;
        if(b & 0x80){
                if(p+1 >= maxp)
                        error(Eshortdraw);
                x |= *p++ << 7;
                x |= *p++ << 15;
                if(x & (1<<22))
                        x |= ~0<<23;
        }else{
                if(b & 0x40)
                        x |= ~0<<7;
                x += oldx;
        }
        *newx = x;
        return p;
}

static void
printmesg(char *fmt, uchar *a, int plsprnt)
{
        char buf[256];
        char *p, *q;
        int s, left;

        if(1|| plsprnt==0){
                SET(s,q,p);
                USED(fmt, a, buf, p, q, s);
                return;
        }
        q = buf;
        *q++ = *a++;
        for(p=fmt; *p; p++){
                left = sizeof buf - 2 - (q - buf);      /* 2 for \n\0 */
                switch(*p){
                case 'l':
                        q += snprint(q, left, " %ld", (long)BGLONG(a));
                        a += 4;
                        break;
                case 'L':
                        q += snprint(q, left, " %.8lux", (ulong)BGLONG(a));
                        a += 4;
                        break;
                case 'R':
                        q += snprint(q, left, " [%d %d %d %d]", BGLONG(a),
                                BGLONG(a+4), BGLONG(a+8), BGLONG(a+12));
                        a += 16;
                        break;
                case 'P':
                        q += snprint(q, left, " [%d %d]", BGLONG(a), BGLONG(a+4));
                        a += 8;
                        break;
                case 'b':
                        q += snprint(q, left, " %d", *a++);
                        break;
                case 's':
                        q += snprint(q, left, " %d", BGSHORT(a));
                        a += 2;
                        break;
                case 'S':
                        q += snprint(q, left, " %.4ux", BGSHORT(a));
                        a += 2;
                        break;
                }
        }
        *q++ = '\n';
        *q = 0;
        iprint("%.*s", (int)(q-buf), buf);
}

void
drawmesg(Client *client, void *av, int n)
{
        int c, repl, m, y, dstid, scrnid, ni, ci, j, nw, e0, e1, op, ox, oy, oesize, esize, doflush;
        uchar *u, *a, refresh;
        char *fmt;
        ulong value, chan;
        Rectangle r, clipr;
        Point p, q, *pp, sp;
        Memimage *i, *bg, *dst, *src, *mask;
        Memimage *l, **lp;
        Memscreen *scrn;
        DImage *font, *ll, *di, *ddst, *dsrc;
        DName *dn;
        DScreen *dscrn;
        FChar *fc;
        Refx *refx;
        CScreen *cs;
        Refreshfn reffn;

        a = av;
        m = 0;
        fmt = nil;
        if(waserror()){
                if(fmt) printmesg(fmt, a, 1);
        /*      iprint("error: %s\n", up->errstr);      */
                nexterror();
        }
        while((n-=m) > 0){
                USED(fmt);
                a += m;
                switch(*a){
                default:
                        error("bad draw command");
                /* new allocate: 'b' id[4] screenid[4] refresh[1] chan[4] repl[1] R[4*4] clipR[4*4] rrggbbaa[4] */
                case 'b':
                        printmesg(fmt="LLbLbRRL", a, 0);
                        m = 1+4+4+1+4+1+4*4+4*4+4;
                        if(n < m)
                                error(Eshortdraw);
                        dstid = BGLONG(a+1);
                        scrnid = BGSHORT(a+5);
                        refresh = a[9];
                        chan = BGLONG(a+10);
                        repl = a[14];
                        drawrectangle(&r, a+15);
                        drawrectangle(&clipr, a+31);
                        value = BGLONG(a+47);
                        if(drawlookup(client, dstid, 0))
                                error(Eimageexists);
                        if(scrnid){
                                dscrn = drawlookupscreen(client, scrnid, &cs);
                                scrn = dscrn->screen;
                                if(repl || chan!=scrn->image->chan)
                                        error("image parameters incompatible with screen");
                                reffn = nil;
                                switch(refresh){
                                case Refbackup:
                                        break;
                                case Refnone:
                                        reffn = memlnorefresh;
                                        break;
                                case Refmesg:
                                        reffn = drawrefresh;
                                        break;
                                default:
                                        error("unknown refresh method");
                                }
                                l = memlalloc(scrn, r, reffn, 0, value);
                                if(l == 0)
                                        error(Edrawmem);
                                addflush(l->layer->screenr);
                                l->clipr = clipr;
                                rectclip(&l->clipr, r);
                                if(drawinstall(client, dstid, l, dscrn) == 0){
                                        memldelete(l);
                                        error(Edrawmem);
                                }
                                dscrn->ref++;
                                if(reffn){
                                        refx = nil;
                                        if(reffn == drawrefresh){
                                                refx = malloc(sizeof(Refx));
                                                if(refx == 0){
                                                        drawuninstall(client, dstid);
                                                        error(Edrawmem);
                                                }
                                                refx->client = client;
                                                refx->dimage = drawlookup(client, dstid, 1);
                                        }
                                        memlsetrefresh(l, reffn, refx);
                                }
                                continue;
                        }
                        i = allocmemimage(r, chan);
                        if(i == 0)
                                error(Edrawmem);
                        if(repl)
                                i->flags |= Frepl;
                        i->clipr = clipr;
                        if(!repl)
                                rectclip(&i->clipr, r);
                        if(drawinstall(client, dstid, i, 0) == 0){
                                freememimage(i);
                                error(Edrawmem);
                        }
                        memfillcolor(i, value);
                        continue;

                /* allocate screen: 'A' id[4] imageid[4] fillid[4] public[1] */
                case 'A':
                        printmesg(fmt="LLLb", a, 1);
                        m = 1+4+4+4+1;
                        if(n < m)
                                error(Eshortdraw);
                        dstid = BGLONG(a+1);
                        if(dstid == 0)
                                error(Ebadarg);
                        if(drawlookupdscreen(dstid))
                                error(Escreenexists);
                        ddst = drawlookup(client, BGLONG(a+5), 1);
                        dsrc = drawlookup(client, BGLONG(a+9), 1);
                        if(ddst==0 || dsrc==0)
                                error(Enodrawimage);
                        if(drawinstallscreen(client, 0, dstid, ddst, dsrc, a[13]) == 0)
                                error(Edrawmem);
                        continue;

                /* set repl and clip: 'c' dstid[4] repl[1] clipR[4*4] */
                case 'c':
                        printmesg(fmt="LbR", a, 0);
                        m = 1+4+1+4*4;
                        if(n < m)
                                error(Eshortdraw);
                        ddst = drawlookup(client, BGLONG(a+1), 1);
                        if(ddst == nil)
                                error(Enodrawimage);
                        if(ddst->name)
                                error("cannot change repl/clipr of shared image");
                        dst = ddst->image;
                        if(a[5])
                                dst->flags |= Frepl;
                        drawrectangle(&dst->clipr, a+6);
                        continue;

                /* draw: 'd' dstid[4] srcid[4] maskid[4] R[4*4] P[2*4] P[2*4] */
                case 'd':
                        printmesg(fmt="LLLRPP", a, 0);
                        m = 1+4+4+4+4*4+2*4+2*4;
                        if(n < m)
                                error(Eshortdraw);
                        dst = drawimage(client, a+1);
                        dstid = BGLONG(a+1);
                        src = drawimage(client, a+5);
                        mask = drawimage(client, a+9);
                        drawrectangle(&r, a+13);
                        drawpoint(&p, a+29);
                        drawpoint(&q, a+37);
                        op = drawclientop(client);
                        memdraw(dst, r, src, p, mask, q, op);
                        dstflush(dstid, dst, r);
                        continue;

                /* toggle debugging: 'D' val[1] */
                case 'D':
                        printmesg(fmt="b", a, 0);
                        m = 1+1;
                        if(n < m)
                                error(Eshortdraw);
                        drawdebug = a[1];
                        continue;

                /* ellipse: 'e' dstid[4] srcid[4] center[2*4] a[4] b[4] thick[4] sp[2*4] alpha[4] phi[4]*/
                case 'e':
                case 'E':
                        printmesg(fmt="LLPlllPll", a, 0);
                        m = 1+4+4+2*4+4+4+4+2*4+2*4;
                        if(n < m)
                                error(Eshortdraw);
                        dst = drawimage(client, a+1);
                        dstid = BGLONG(a+1);
                        src = drawimage(client, a+5);
                        drawpoint(&p, a+9);
                        e0 = BGLONG(a+17);
                        e1 = BGLONG(a+21);
                        if(e0<0 || e1<0)
                                error("invalid ellipse semidiameter");
                        j = BGLONG(a+25);
                        if(j < 0)
                                error("negative ellipse thickness");
                        drawpoint(&sp, a+29);
                        c = j;
                        if(*a == 'E')
                                c = -1;
                        ox = BGLONG(a+37);
                        oy = BGLONG(a+41);
                        op = drawclientop(client);
                        /* high bit indicates arc angles are present */
                        if(ox & (1<<31)){
                                if((ox & (1<<30)) == 0)
                                        ox &= ~(1<<31);
                                memarc(dst, p, e0, e1, c, src, sp, ox, oy, op);
                        }else
                                memellipse(dst, p, e0, e1, c, src, sp, op);
                        dstflush(dstid, dst, Rect(p.x-e0-j, p.y-e1-j, p.x+e0+j+1, p.y+e1+j+1));
                        continue;

                /* free: 'f' id[4] */
                case 'f':
                        printmesg(fmt="L", a, 1);
                        m = 1+4;
                        if(n < m)
                                error(Eshortdraw);
                        ll = drawlookup(client, BGLONG(a+1), 0);
                        if(ll && ll->dscreen && ll->dscreen->owner != client)
                                ll->dscreen->owner->refreshme = 1;
                        drawuninstall(client, BGLONG(a+1));
                        continue;

                /* free screen: 'F' id[4] */
                case 'F':
                        printmesg(fmt="L", a, 1);
                        m = 1+4;
                        if(n < m)
                                error(Eshortdraw);
                        drawlookupscreen(client, BGLONG(a+1), &cs);
                        drawuninstallscreen(client, cs);
                        continue;

                /* initialize font: 'i' fontid[4] nchars[4] ascent[1] */
                case 'i':
                        printmesg(fmt="Llb", a, 1);
                        m = 1+4+4+1;
                        if(n < m)
                                error(Eshortdraw);
                        dstid = BGLONG(a+1);
                        if(dstid == 0)
                                error("cannot use display as font");
                        font = drawlookup(client, dstid, 1);
                        if(font == 0)
                                error(Enodrawimage);
                        if(font->image->layer)
                                error("cannot use window as font");
                        ni = BGLONG(a+5);
                        if(ni<=0 || ni>4096)
                                error("bad font size (4096 chars max)");
                        free(font->fchar);      /* should we complain if non-zero? */
                        font->fchar = malloc(ni*sizeof(FChar));
                        if(font->fchar == 0)
                                error("no memory for font");
                        memset(font->fchar, 0, ni*sizeof(FChar));
                        font->nfchar = ni;
                        font->ascent = a[9];
                        continue;

                /* load character: 'l' fontid[4] srcid[4] index[2] R[4*4] P[2*4] left[1] width[1] */
                case 'l':
                        printmesg(fmt="LLSRPbb", a, 0);
                        m = 1+4+4+2+4*4+2*4+1+1;
                        if(n < m)
                                error(Eshortdraw);
                        font = drawlookup(client, BGLONG(a+1), 1);
                        if(font == 0)
                                error(Enodrawimage);
                        if(font->nfchar == 0)
                                error(Enotfont);
                        src = drawimage(client, a+5);
                        ci = BGSHORT(a+9);
                        if(ci >= font->nfchar)
                                error(Eindex);
                        drawrectangle(&r, a+11);
                        drawpoint(&p, a+27);
                        memdraw(font->image, r, src, p, memopaque, p, S);
                        fc = &font->fchar[ci];
                        fc->minx = r.min.x;
                        fc->maxx = r.max.x;
                        fc->miny = r.min.y;
                        fc->maxy = r.max.y;
                        fc->left = a[35];
                        fc->width = a[36];
                        continue;

                /* draw line: 'L' dstid[4] p0[2*4] p1[2*4] end0[4] end1[4] radius[4] srcid[4] sp[2*4] */
                case 'L':
                        printmesg(fmt="LPPlllLP", a, 0);
                        m = 1+4+2*4+2*4+4+4+4+4+2*4;
                        if(n < m)
                                error(Eshortdraw);
                        dst = drawimage(client, a+1);
                        dstid = BGLONG(a+1);
                        drawpoint(&p, a+5);
                        drawpoint(&q, a+13);
                        e0 = BGLONG(a+21);
                        e1 = BGLONG(a+25);
                        j = BGLONG(a+29);
                        if(j < 0)
                                error("negative line width");
                        src = drawimage(client, a+33);
                        drawpoint(&sp, a+37);
                        op = drawclientop(client);
                        memline(dst, p, q, e0, e1, j, src, sp, op);
                        /* avoid memlinebbox if possible */
                        if(dstid==0 || dst->layer!=nil){
                                /* BUG: this is terribly inefficient: update maximal containing rect*/
                                r = memlinebbox(p, q, e0, e1, j);
                                dstflush(dstid, dst, insetrect(r, -(1+1+j)));
                        }
                        continue;

                /* create image mask: 'm' newid[4] id[4] */
/*
 *
                case 'm':
                        printmesg("LL", a, 0);
                        m = 4+4;
                        if(n < m)
                                error(Eshortdraw);
                        break;
 *
 */

                /* attach to a named image: 'n' dstid[4] j[1] name[j] */
                case 'n':
                        printmesg(fmt="Lz", a, 0);
                        m = 1+4+1;
                        if(n < m)
                                error(Eshortdraw);
                        j = a[5];
                        if(j == 0)      /* give me a non-empty name please */
                                error(Eshortdraw);
                        m += j;
                        if(n < m)
                                error(Eshortdraw);
                        dstid = BGLONG(a+1);
                        if(drawlookup(client, dstid, 0))
                                error(Eimageexists);
                        dn = drawlookupname(j, (char*)a+6);
                        if(dn == nil)
                                error(Enoname);
                        if(drawinstall(client, dstid, dn->dimage->image, 0) == 0)
                                error(Edrawmem);
                        di = drawlookup(client, dstid, 0);
                        if(di == 0)
                                error("draw: cannot happen");
                        di->vers = dn->vers;
                        di->name = smalloc(j+1);
                        di->fromname = dn->dimage;
                        di->fromname->ref++;
                        memmove(di->name, a+6, j);
                        di->name[j] = 0;
                        client->infoid = dstid;
                        continue;

                /* name an image: 'N' dstid[4] in[1] j[1] name[j] */
                case 'N':
                        printmesg(fmt="Lbz", a, 0);
                        m = 1+4+1+1;
                        if(n < m)
                                error(Eshortdraw);
                        c = a[5];
                        j = a[6];
                        if(j == 0)      /* give me a non-empty name please */
                                error(Eshortdraw);
                        m += j;
                        if(n < m)
                                error(Eshortdraw);
                        di = drawlookup(client, BGLONG(a+1), 0);
                        if(di == 0)
                                error(Enodrawimage);
                        if(di->name)
                                error(Enamed);
                        if(c)
                                drawaddname(client, di, j, (char*)a+7);
                        else{
                                dn = drawlookupname(j, (char*)a+7);
                                if(dn == nil)
                                        error(Enoname);
                                if(dn->dimage != di)
                                        error(Ewrongname);
                                drawdelname(dn);
                        }
                        continue;

                /* position window: 'o' id[4] r.min [2*4] screenr.min [2*4] */
                case 'o':
                        printmesg(fmt="LPP", a, 0);
                        m = 1+4+2*4+2*4;
                        if(n < m)
                                error(Eshortdraw);
                        dst = drawimage(client, a+1);
                        if(dst->layer){
                                drawpoint(&p, a+5);
                                drawpoint(&q, a+13);
                                r = dst->layer->screenr;
                                ni = memlorigin(dst, p, q);
                                if(ni < 0)
                                        error("image origin failed");
                                if(ni > 0){
                                        addflush(r);
                                        addflush(dst->layer->screenr);
                                        ll = drawlookup(client, BGLONG(a+1), 1);
                                        drawrefreshscreen(ll, client);
                                }
                        }
                        continue;

                /* set compositing operator for next draw operation: 'O' op */
                case 'O':
                        printmesg(fmt="b", a, 0);
                        m = 1+1;
                        if(n < m)
                                error(Eshortdraw);
                        client->op = a[1];
                        continue;

                /* filled polygon: 'P' dstid[4] n[2] wind[4] ignore[2*4] srcid[4] sp[2*4] p0[2*4] dp[2*2*n] */
                /* polygon: 'p' dstid[4] n[2] end0[4] end1[4] radius[4] srcid[4] sp[2*4] p0[2*4] dp[2*2*n] */
                case 'p':
                case 'P':
                        printmesg(fmt="LslllLPP", a, 0);
                        m = 1+4+2+4+4+4+4+2*4;
                        if(n < m)
                                error(Eshortdraw);
                        dstid = BGLONG(a+1);
                        dst = drawimage(client, a+1);
                        ni = BGSHORT(a+5);
                        if(ni < 0)
                                error("negative count in polygon");
                        e0 = BGLONG(a+7);
                        e1 = BGLONG(a+11);
                        j = 0;
                        if(*a == 'p'){
                                j = BGLONG(a+15);
                                if(j < 0)
                                        error("negative polygon line width");
                        }
                        src = drawimage(client, a+19);
                        drawpoint(&sp, a+23);
                        drawpoint(&p, a+31);
                        ni++;
                        pp = malloc(ni*sizeof(Point));
                        if(pp == nil)
                                error(Enomem);
                        doflush = 0;
                        if(dstid==0 || (dst->layer && dst->layer->screen->image->data == screenimage->data))
                                doflush = 1;    /* simplify test in loop */
                        ox = oy = 0;
                        esize = 0;
                        u = a+m;
                        for(y=0; y<ni; y++){
                                q = p;
                                oesize = esize;
                                u = drawcoord(u, a+n, ox, &p.x);
                                u = drawcoord(u, a+n, oy, &p.y);
                                ox = p.x;
                                oy = p.y;
                                if(doflush){
                                        esize = j;
                                        if(*a == 'p'){
                                                if(y == 0){
                                                        c = memlineendsize(e0);
                                                        if(c > esize)
                                                                esize = c;
                                                }
                                                if(y == ni-1){
                                                        c = memlineendsize(e1);
                                                        if(c > esize)
                                                                esize = c;
                                                }
                                        }
                                        if(*a=='P' && e0!=1 && e0 !=~0)
                                                r = dst->clipr;
                                        else if(y > 0){
                                                r = Rect(q.x-oesize, q.y-oesize, q.x+oesize+1, q.y+oesize+1);
                                                combinerect(&r, Rect(p.x-esize, p.y-esize, p.x+esize+1, p.y+esize+1));
                                        }
                                        if(rectclip(&r, dst->clipr))            /* should perhaps be an arg to dstflush */
                                                dstflush(dstid, dst, r);
                                }
                                pp[y] = p;
                        }
                        if(y == 1)
                                dstflush(dstid, dst, Rect(p.x-esize, p.y-esize, p.x+esize+1, p.y+esize+1));
                        op = drawclientop(client);
                        if(*a == 'p')
                                mempoly(dst, pp, ni, e0, e1, j, src, sp, op);
                        else
                                memfillpoly(dst, pp, ni, e0, src, sp, op);
                        free(pp);
                        m = u-a;
                        continue;

                /* read: 'r' id[4] R[4*4] */
                case 'r':
                        printmesg(fmt="LR", a, 0);
                        m = 1+4+4*4;
                        if(n < m)
                                error(Eshortdraw);
                        i = drawimage(client, a+1);
                        drawrectangle(&r, a+5);
                        if(!rectinrect(r, i->r))
                                error(Ereadoutside);
                        c = bytesperline(r, i->depth);
                        c *= Dy(r);
                        free(client->readdata);
                        client->readdata = mallocz(c, 0);
                        if(client->readdata == nil)
                                error("readimage malloc failed");
                        client->nreaddata = memunload(i, r, client->readdata, c);
                        if(client->nreaddata < 0){
                                free(client->readdata);
                                client->readdata = nil;
                                error("bad readimage call");
                        }
                        continue;

                /* string: 's' dstid[4] srcid[4] fontid[4] P[2*4] clipr[4*4] sp[2*4] ni[2] ni*(index[2]) */
                /* stringbg: 'x' dstid[4] srcid[4] fontid[4] P[2*4] clipr[4*4] sp[2*4] ni[2] bgid[4] bgpt[2*4] ni*(index[2]) */
                case 's':
                case 'x':
                        printmesg(fmt="LLLPRPs", a, 0);
                        m = 1+4+4+4+2*4+4*4+2*4+2;
                        if(*a == 'x')
                                m += 4+2*4;
                        if(n < m)
                                error(Eshortdraw);

                        dst = drawimage(client, a+1);
                        dstid = BGLONG(a+1);
                        src = drawimage(client, a+5);
                        font = drawlookup(client, BGLONG(a+9), 1);
                        if(font == 0)
                                error(Enodrawimage);
                        if(font->nfchar == 0)
                                error(Enotfont);
                        drawpoint(&p, a+13);
                        drawrectangle(&r, a+21);
                        drawpoint(&sp, a+37);
                        ni = BGSHORT(a+45);
                        u = a+m;
                        m += ni*2;
                        if(n < m)
                                error(Eshortdraw);
                        clipr = dst->clipr;
                        dst->clipr = r;
                        op = drawclientop(client);
                        bg = dst;
                        if(*a == 'x'){
                                /* paint background */
                                bg = drawimage(client, a+47);
                                drawpoint(&q, a+51);
                                r.min.x = p.x;
                                r.min.y = p.y-font->ascent;
                                r.max.x = p.x;
                                r.max.y = r.min.y+Dy(font->image->r);
                                j = ni;
                                while(--j >= 0){
                                        ci = BGSHORT(u);
                                        if(ci<0 || ci>=font->nfchar){
                                                dst->clipr = clipr;
                                                error(Eindex);
                                        }
                                        r.max.x += font->fchar[ci].width;
                                        u += 2;
                                }
                                memdraw(dst, r, bg, q, memopaque, ZP, op);
                                u -= 2*ni;
                        }
                        q = p;
                        while(--ni >= 0){
                                ci = BGSHORT(u);
                                if(ci<0 || ci>=font->nfchar){
                                        dst->clipr = clipr;
                                        error(Eindex);
                                }
                                q = drawchar(dst, bg, q, src, &sp, font, ci, op);
                                u += 2;
                        }
                        dst->clipr = clipr;
                        p.y -= font->ascent;
                        dstflush(dstid, dst, Rect(p.x, p.y, q.x, p.y+Dy(font->image->r)));
                        continue;

                /* use public screen: 'S' id[4] chan[4] */
                case 'S':
                        printmesg(fmt="Ll", a, 0);
                        m = 1+4+4;
                        if(n < m)
                                error(Eshortdraw);
                        dstid = BGLONG(a+1);
                        if(dstid == 0)
                                error(Ebadarg);
                        dscrn = drawlookupdscreen(dstid);
                        if(dscrn==0 || (dscrn->public==0 && dscrn->owner!=client))
                                error(Enodrawscreen);
                        if(dscrn->screen->image->chan != BGLONG(a+5))
                                error("inconsistent chan");
                        if(drawinstallscreen(client, dscrn, 0, 0, 0, 0) == 0)
                                error(Edrawmem);
                        continue;

                /* top or bottom windows: 't' top[1] nw[2] n*id[4] */
                case 't':
                        printmesg(fmt="bsL", a, 0);
                        m = 1+1+2;
                        if(n < m)
                                error(Eshortdraw);
                        nw = BGSHORT(a+2);
                        if(nw < 0)
                                error(Ebadarg);
                        if(nw == 0)
                                continue;
                        m += nw*4;
                        if(n < m)
                                error(Eshortdraw);
                        lp = malloc(nw*sizeof(Memimage*));
                        if(lp == 0)
                                error(Enomem);
                        if(waserror()){
                                free(lp);
                                nexterror();
                        }
                        for(j=0; j<nw; j++)
                                lp[j] = drawimage(client, a+1+1+2+j*4);
                        if(lp[0]->layer == 0)
                                error("images are not windows");
                        for(j=1; j<nw; j++)
                                if(lp[j]->layer->screen != lp[0]->layer->screen)
                                        error("images not on same screen");
                        if(a[1])
                                memltofrontn(lp, nw);
                        else
                                memltorearn(lp, nw);
                        if(lp[0]->layer->screen->image->data == screenimage->data)
                                for(j=0; j<nw; j++)
                                        addflush(lp[j]->layer->screenr);
                        ll = drawlookup(client, BGLONG(a+1+1+2), 1);
                        drawrefreshscreen(ll, client);
                        poperror();
                        free(lp);
                        continue;

                /* visible: 'v' */
                case 'v':
                        printmesg(fmt="", a, 0);
                        m = 1;
                        drawflush();
                        continue;

                /* write: 'y' id[4] R[4*4] data[x*1] */
                /* write from compressed data: 'Y' id[4] R[4*4] data[x*1] */
                case 'y':
                case 'Y':
                        printmesg(fmt="LR", a, 0);
                //      iprint("load %c\n", *a);
                        m = 1+4+4*4;
                        if(n < m)
                                error(Eshortdraw);
                        dstid = BGLONG(a+1);
                        dst = drawimage(client, a+1);
                        drawrectangle(&r, a+5);
                        if(!rectinrect(r, dst->r))
                                error(Ewriteoutside);
                        y = memload(dst, r, a+m, n-m, *a=='Y');
                        if(y < 0)
                                error("bad writeimage call");
                        dstflush(dstid, dst, r);
                        m += y;
                        continue;
                }
        }
        poperror();
}

Dev drawdevtab = {
        'i',
        "draw",

        devreset,
        devinit,
        devshutdown,
        drawattach,
        drawwalk,
        drawstat,
        drawopen,
        devcreate,
        drawclose,
        drawread,
        devbread,
        drawwrite,
        devbwrite,
        devremove,
        devwstat,
};

/*
 * On 8 bit displays, load the default color map
 */
void
drawcmap(void)
{
        int r, g, b, cr, cg, cb, v;
        int num, den;
        int i, j;

        drawactive(1);  /* to restore map from backup */
        for(r=0,i=0; r!=4; r++)
            for(v=0; v!=4; v++,i+=16){
                for(g=0,j=v-r; g!=4; g++)
                    for(b=0;b!=4;b++,j++){
                        den = r;
                        if(g > den)
                                den = g;
                        if(b > den)
                                den = b;
                        if(den == 0)    /* divide check -- pick grey shades */
                                cr = cg = cb = v*17;
                        else{
                                num = 17*(4*den+v);
                                cr = r*num/den;
                                cg = g*num/den;
                                cb = b*num/den;
                        }
                        setcolor(i+(j&15),
                                cr*0x01010101, cg*0x01010101, cb*0x01010101);
                    }
        }
}

void
drawblankscreen(int blank)
{
        int i, nc;
        ulong *p;

        if(blank == sdraw.blanked)
                return;
        if(!candlock())
                return;
        if(screenimage == nil){
                dunlock();
                return;
        }
        p = sdraw.savemap;
        nc = screenimage->depth > 8 ? 256 : 1<<screenimage->depth;

        /*
         * blankscreen uses the hardware to blank the screen
         * when possible.  to help in cases when it is not possible,
         * we set the color map to be all black.
         */
        if(blank == 0){ /* turn screen on */
                for(i=0; i<nc; i++, p+=3)
                        setcolor(i, p[0], p[1], p[2]);
                blankscreen(0);
        }else{  /* turn screen off */
                blankscreen(1);
                for(i=0; i<nc; i++, p+=3){
                        getcolor(i, &p[0], &p[1], &p[2]);
                        setcolor(i, 0, 0, 0);
                }
        }
        sdraw.blanked = blank;
        dunlock();
}

/*
 * record activity on screen, changing blanking as appropriate
 */
void
drawactive(int active)
{
        if(active){
                drawblankscreen(0);
                sdraw.blanktime = MACHP(0)->ticks;
        }else{
                if(blanktime && sdraw.blanktime && TK2SEC(MACHP(0)->ticks - sdraw.blanktime)/60 >= blanktime)
                        drawblankscreen(1);
        }
}

int
drawidletime(void)
{
        return TK2SEC(MACHP(0)->ticks - sdraw.blanktime)/60;
}