#include "paint.h"

static uchar *tmp;
static int tmpsz;

static int
alloc(int sz)
{
	if(sz > tmpsz) {
		if(tmp != nil)
			free(tmp);
		tmpsz = 0;
		if((tmp = malloc(sz)) == nil)
			return -1;
		tmpsz = sz;
	}
	return 0;
}

int
syncimg(Image *img, Memimage *mem, Rectangle r)
{
	int n;

	if(alloc(Dy(r) * Dx(r) * chantodepth(mem->chan)) < 0)
		return -1;

	if((n = unloadmemimage(mem, r, tmp, tmpsz)) < 0) {
		werrstr("unload");
		return -1;
	}

	if(loadimage(img, r, tmp, n) < 0) {
		werrstr("load");
		return -1;
	}

	return 0;
}

int
magsyncimg(Image *img, Memimage *mem, Rectangle imgr, Point pos, int mag)
{
	int nch, xfract, y, x, ch;
	uchar *dst, *src;

	nch = chantodepth(mem->chan) / 8;
	if(alloc(Dy(imgr) * Dx(imgr) * nch) < 0)
		return -1;

	xfract = (pos.x + imgr.min.x) % mag;
	for(y = 0; y < Dy(imgr); y++) {
		dst = tmp + y*Dx(imgr)*nch;
		src = byteaddr(mem, divpt(addpt(addpt(imgr.min, pos), Pt(0, y)), mag));
		for(x = 0; x < Dx(imgr); x++) {
			for(ch = 0; ch < nch; ch++)
				dst[x*nch + ch] = src[((x + xfract)/mag)*nch + ch];
		}
	}

	if(loadimage(img, imgr, tmp, Dy(imgr)*Dx(imgr)*nch) < 0) {
		werrstr("load");
		return -1;
	}

	return 0;
}

int
synccanvasmem(Canvas *c, Rectangle memr)
{
	Rectangle imgr;	/* the area of the Image which will be overwritten */

	imgr = rectsubpt(scalerect(memr, c->mag), c->pos);
	if(rectclip(&imgr, c->img->r) == 0)
		return 0;
	return synccanvasimg(c, imgr);
}

int
synccanvasimg(Canvas *c, Rectangle imgr)
{
	return magsyncimg(c->img, c->s->mem, imgr, c->pos, c->mag);
}