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update for SPNG_FMT_PNG

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We can now decode PNG to g8/g16/ga8/ga16/rgb8/rgb16 etc.
This commit is contained in:
John Cupitt 2020-05-13 15:25:01 +01:00
parent df4f03863e
commit d78480c846
1 changed files with 51 additions and 11 deletions
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62
libvips/foreign/spngload.c
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@ -37,10 +37,10 @@
* no interlace == 0.
* an equivalent of png_sig_cmp() from libpng (is_a_png on a memory area)
*
* This always reads RGBA8 or RGBA16. Other formst G8/G16/GA8 etc. etc. are
* in the roadmap.
* test indexed decode
*
* Most metadata support (eg. XMP, ICC, etc. etc.) is missing.
* Most metadata support (eg. XMP, ICC, etc. etc.) is missing. We will need
* to set a chunk size limit with spng_set_chunks_limits().
*
* Load only, there's no save support for now.
*/
@ -211,6 +211,14 @@ vips_foreign_load_png_header( VipsForeignLoad *load )
*/
spng_set_crc_action( png->ctx, SPNG_CRC_USE, SPNG_CRC_USE );
/* Set limits to avoid decompression bombs. We should set
* spng_set_chunks_limits() as well, once that API goes in.
*
* No need to test the decoded image size -- the user can do that if
* they wish.
*/
spng_set_image_limits( png->ctx, VIPS_MAX_COORD, VIPS_MAX_COORD );
if( vips_source_rewind( png->source ) )
return( -1 );
spng_set_png_stream( png->ctx,
@ -230,23 +238,55 @@ vips_foreign_load_png_header( VipsForeignLoad *load )
png->ihdr.interlace_method );
*/
/* For now, libspng always outputs RGBA.
*/
png->interpretation = VIPS_INTERPRETATION_sRGB;
png->bands = 4;
switch( png->ihdr.color_type ) {
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;
png->interpretation = VIPS_INTERPRETATION_B_W;
png->fmt = SPNG_FMT_PNG;
break;
case SPNG_COLOR_TYPE_TRUECOLOR:
png->bands = 3;
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;
break;
default:
vips_error( class->nickname, "%s", _( "unknown color type" ) );
return( -1 );
}
if( png->ihdr.bit_depth == 16 ) {
png->fmt = SPNG_FMT_RGBA16;
png->format = VIPS_FORMAT_USHORT;
if( png->interpretation == VIPS_INTERPRETATION_B_W )
png->interpretation = VIPS_INTERPRETATION_GREY16;
if( png->interpretation == VIPS_INTERPRETATION_sRGB )
png->interpretation = VIPS_INTERPRETATION_RGB16;
}
else {
png->fmt = SPNG_FMT_RGBA8;
else
png->format = VIPS_FORMAT_UCHAR;
}
/* FIXME ... get resolution, profile, exif, xmp, etc. etc.
*/