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improve transparency support

This commit is contained in:
John Cupitt 2020-06-07 17:27:24 +01:00
parent 6705ff85b5
commit 20c9a7f7cc
1 changed files with 18 additions and 21 deletions
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39
libvips/foreign/spngload.c
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@ -41,12 +41,11 @@
* set a chunk size limit with spng_set_chunks_limits() when that API is done
*
* load only, there's no save support for now
*
*/
/*
#define DEBUG
*/
#define DEBUG
#ifdef HAVE_CONFIG_H
#include <config.h>
@ -316,37 +315,28 @@ vips_foreign_load_png_header( VipsForeignLoad *load )
switch( png->ihdr.color_type ) {
case SPNG_COLOR_TYPE_GRAYSCALE_ALPHA:
case SPNG_COLOR_TYPE_GRAYSCALE:
png->bands = 1;
png->interpretation = VIPS_INTERPRETATION_B_W;
png->fmt = SPNG_FMT_PNG;
break;
case SPNG_COLOR_TYPE_GRAYSCALE_ALPHA:
png->bands = 2;
if( !spng_get_trns( png->ctx ) )
png->bands += 1;
png->interpretation = VIPS_INTERPRETATION_B_W;
png->fmt = SPNG_FMT_PNG;
break;
case SPNG_COLOR_TYPE_TRUECOLOR:
case SPNG_COLOR_TYPE_TRUECOLOR_ALPHA:
png->bands = 3;
if( !spng_get_trns( png->ctx ) )
png->bands += 1;
png->interpretation = VIPS_INTERPRETATION_sRGB;
png->fmt = SPNG_FMT_PNG;
break;
case SPNG_COLOR_TYPE_INDEXED:
png->bands = 3;
png->interpretation = VIPS_INTERPRETATION_sRGB;
/* Expand indexed images to RGB8.
*/
png->fmt = SPNG_FMT_RGB8;
break;
case SPNG_COLOR_TYPE_TRUECOLOR_ALPHA:
png->bands = 4;
png->interpretation = VIPS_INTERPRETATION_sRGB;
png->fmt = SPNG_FMT_PNG;
png->fmt = SPNG_FMT_RGBA8;
break;
default:
@ -457,10 +447,15 @@ vips_foreign_load_png_load( VipsForeignLoad *load )
vips_object_local_array( VIPS_OBJECT( load ), 3 );
int error;
enum spng_decode_flags;
if( vips_source_decode( png->source ) )
return( -1 );
/* We want the alpha, if present.
*/
flags = SPNG_DECODE_TRNS;
if( png->ihdr.interlace_method != SPNG_INTERLACE_NONE ) {
/* Arg awful interlaced image. We have to load to a huge mem
* buffer, then copy to out.
@ -473,7 +468,7 @@ vips_foreign_load_png_load( VipsForeignLoad *load )
if( (error = spng_decode_image( png->ctx,
VIPS_IMAGE_ADDR( t[0], 0, 0 ),
VIPS_IMAGE_SIZEOF_IMAGE( t[0] ),
png->fmt, 0 )) ) {
png->fmt, flags )) ) {
vips_error( class->nickname,
"%s", spng_strerror( error ) );
return( -1 );
@ -486,10 +481,12 @@ vips_foreign_load_png_load( VipsForeignLoad *load )
t[0] = vips_image_new();
vips_foreign_load_png_set_header( png, t[0] );
/* Initialize for progressive decoding.
/* We can decode regular PNGs progressively.
*/
flags |= SPNG_DECODE_PROGRESSIVE;
if( (error = spng_decode_image( png->ctx, NULL, 0,
png->fmt, SPNG_DECODE_PROGRESSIVE )) ) {
png->fmt, flags )) ) {
vips_error( class->nickname,
"%s", spng_strerror( error ) );
return( -1 );