Subversion Repositories planix.SVN

#include <u.h>
#include <libc.h>
#include <draw.h>
#include <cursor.h>
#include <event.h>
#include <bio.h>
#include <plumb.h>
#include <ctype.h>
#include <keyboard.h>
#include "page.h"

typedef struct Cached Cached;
struct Cached
{
        Document *doc;
        int page;
        int angle;
        Image *im;
};

static Cached cache[5];

static Image*
questionmark(void)
{
        static Image *im;

        if(im)
                return im;      
        im = xallocimage(display, Rect(0,0,50,50), GREY1, 1, DBlack);
        if(im == nil)
                return nil;
        string(im, ZP, display->white, ZP, display->defaultfont, "?");
        return im;
}

void
cacheflush(void)
{
        int i;
        Cached *c;

        for(i=0; i<nelem(cache); i++){
                c = &cache[i];
                if(c->im)
                        freeimage(c->im);
                c->im = nil;
                c->doc = nil;
        }
}

static Image*
_cachedpage(Document *doc, int angle, int page, char *ra)
{
        int i;
        Cached *c, old;
        Image *im, *tmp;
        static int lastpage = -1;

        if((page < 0 || page >= doc->npage) && !doc->fwdonly)
                return nil;

Again:
        for(i=0; i<nelem(cache); i++){
                c = &cache[i];
                if(c->doc == doc && c->angle == angle && c->page == page){
                        if(chatty) fprint(2, "cache%s hit %d\n", ra, page);
                        goto Found;
                }
                if(c->doc == nil)
                        break;
        }

        if(i >= nelem(cache))
                i = nelem(cache)-1;
        c = &cache[i];
        if(c->im)
                freeimage(c->im);
        c->im = nil;
        c->doc = nil;
        c->page = -1;

        if(chatty) fprint(2, "cache%s load %d\n", ra, page);
        im = doc->drawpage(doc, page);
        if(im == nil){
                if(doc->fwdonly)        /* end of file */
                        wexits(0);
                im = questionmark();
                if(im == nil){
                Flush:
                        if(i > 0){
                                cacheflush();
                                goto Again;
                        }
                        fprint(2, "out of memory: %r\n");
                        wexits("memory");
                }
                return im;
        }

        if(im->r.min.x != 0 || im->r.min.y != 0){
                /* translate to 0,0 */
                tmp = xallocimage(display, Rect(0, 0, Dx(im->r), Dy(im->r)), im->chan, 0, DNofill);
                if(tmp == nil){
                        freeimage(im);
                        goto Flush;
                }
                drawop(tmp, tmp->r, im, nil, im->r.min, S);
                freeimage(im);
                im = tmp;
        }

        switch(angle){
        case 90:
                im = rot90(im);
                break;
        case 180:
                rot180(im);
                break;
        case 270:
                im = rot270(im);
                break;
        }
        if(im == nil)
                goto Flush;

        c->doc = doc;
        c->page = page;
        c->angle = angle;
        c->im = im;

Found:
        if(chatty) fprint(2, "cache%s mtf %d @%d:", ra, c->page, i);
        old = *c;
        memmove(cache+1, cache, (c-cache)*sizeof cache[0]);
        cache[0] = old;
        if(chatty){
                for(i=0; i<nelem(cache); i++)
                        fprint(2, " %d", cache[i].page);
                fprint(2, "\n");
        }
        if(chatty) fprint(2, "cache%s return %d %p\n", ra, old.page, old.im);
        return old.im;
}

Image*
cachedpage(Document *doc, int angle, int page)
{
        static int lastpage = -1;
        static int rabusy;
        Image *im;
        int ra;
        
        if(doc->npage < 1)
                return display->white;

        im = _cachedpage(doc, angle, page, "");
        if(im == nil)
                return nil;

        /* readahead */
        ra = -1;
        if(!rabusy){
                if(page == lastpage+1)
                        ra = page+1;
                else if(page == lastpage-1)
                        ra = page-1;
        }
        lastpage = page;
        if(ra >= 0){
                rabusy = 1;
                switch(rfork(RFPROC|RFMEM|RFNOWAIT)){
                case -1:
                        rabusy = 0;
                        break;
                case 0:
                        lockdisplay(display);
                        _cachedpage(doc, angle, ra, "-ra");
                        rabusy = 0;
                        unlockdisplay(display);
                        _exits(nil);
                default:
                        break;
                }
        }
        return im;
}