static int
vips_shrink_gen( VipsRegion *or, void *vseq, void *a, void *b, gboolean *stop )
{
VipsShrinkSequence *seq = (VipsShrinkSequence *) vseq;
VipsShrink *shrink = (VipsShrink *) b;
VipsRegion *ir = seq->ir;
VipsRect *r = &or->valid;
/* How do we chunk up the image? We don't want to prepare the whole of
* the input region corresponding to *r since it could be huge.
*
* Each pixel of *r will depend on roughly mw x mh
* pixels, so we walk *r in chunks which map to the tile size.
*
* Make sure we can't ask for a zero step.
*
* We don't chunk horizontally. We want "vips shrink x.jpg b.jpg 100
* 100" to run sequentially. If we chunk horizontally, we will fetch
* 100x100 lines from the top of the image, then 100x100 100 lines
* down, etc. for each thread, then when they've finished, fetch
* 100x100, 100 pixels across from the top of the image. This will
* break sequentiality.
*/
int ystep = shrink->mh > VIPS__TILE_HEIGHT ?
1 : VIPS__TILE_HEIGHT / shrink->mh;
int y;
#ifdef DEBUG
printf( "vips_shrink_gen: generating %d x %d at %d x %d\n",
r->width, r->height, r->left, r->top );
#endif /*DEBUG*/
for( y = 0; y < r->height; y += ystep ) {
/* Clip the this rect against the demand size.
*/
int height = VIPS_MIN( ystep, r->height - y );
VipsRect s;
s.left = r->left * shrink->xshrink;
s.top = (r->top + y) * shrink->yshrink;
s.width = ceil( r->width * shrink->xshrink );
s.height = ceil( height * shrink->yshrink );
#ifdef DEBUG
printf( "shrink_gen: requesting %d x %d at %d x %d\n",
s.width, s.height, s.left, s.top );
#endif /*DEBUG*/
if( vips_region_prepare( ir, &s ) )
return( -1 );
vips_shrink_gen2( shrink, seq,
or, ir,
r->left, r->top + y, r->width, height );
}
return( 0 );
}
static int
vips_shrink_gen( VipsRegion *or, void *vseq, void *a, void *b, gboolean *stop )
{
VipsShrinkSequence *seq = (VipsShrinkSequence *) vseq;
VipsShrink *shrink = (VipsShrink *) b;
VipsRegion *ir = seq->ir;
VipsRect *r = &or->valid;
/* How do we chunk up the image? We don't want to prepare the whole of
* the input region corresponding to *r since it could be huge.
*
* Each pixel of *r will depend on roughly mw x mh
* pixels, so we walk *r in chunks which map to the tile size.
*
* Make sure we can't ask for a zero step.
*/
int xstep = shrink->mw > VIPS__TILE_WIDTH ?
1 : VIPS__TILE_WIDTH / shrink->mw;
int ystep = shrink->mh > VIPS__TILE_HEIGHT ?
1 : VIPS__TILE_HEIGHT / shrink->mh;
int x, y;
#ifdef DEBUG
printf( "vips_shrink_gen: generating %d x %d at %d x %d\n",
r->width, r->height, r->left, r->top );
#endif /*DEBUG*/
for( y = 0; y < r->height; y += ystep )
for( x = 0; x < r->width; x += xstep ) {
/* Clip the this rect against the demand size.
*/
int width = VIPS_MIN( xstep, r->width - x );
int height = VIPS_MIN( ystep, r->height - y );
VipsRect s;
s.left = (r->left + x) * shrink->xshrink;
s.top = (r->top + y) * shrink->yshrink;
s.width = ceil( width * shrink->xshrink );
s.height = ceil( height * shrink->yshrink );
#ifdef DEBUG
printf( "shrink_gen: requesting %d x %d at %d x %d\n",
s.width, s.height, s.left, s.top );
#endif /*DEBUG*/
if( vips_region_prepare( ir, &s ) )
return( -1 );
vips_shrink_gen2( shrink, seq,
or, ir,
r->left + x, r->top + y, width, height );
}
return( 0 );
}
