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note PNG background colour in metadata 

see https://github.com/libvips/libvips/issues/2111
This commit is contained in:
John Cupitt 2021-02-19 16:51:46 +00:00
parent acf010c2b7
commit d6201fc32d
3 changed files with 95 additions and 1 deletions
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1
ChangeLog
View File

@ -18,6 +18,7 @@
- fix ref leaks in mosaicing package
- run libvips leak test in CI
- add vips_fitsload_source()m vips_niftiload_source()
- png load notes background colour as metadata [781545872]
22/12/20 start 8.10.6
- don't seek on bad file descriptors [kleisauke]

45
libvips/foreign/spngload.c
View File

@ -2,6 +2,8 @@
*
* 1/5/20
* - from pngload.c
* 19/2/21 781545872
* - read out background, if we can
*/
/*
@ -199,6 +201,7 @@ vips_foreign_load_png_set_header( VipsForeignLoadPng *png, VipsImage *image )
struct spng_iccp iccp;
struct spng_exif exif;
struct spng_phys phys;
struct spng_bkgd bkgd;
guint32 n_text;
/* Get resolution. Default to 72 pixels per inch.
@ -267,6 +270,47 @@ vips_foreign_load_png_set_header( VipsForeignLoadPng *png, VipsImage *image )
*/
if( png->ihdr.interlace_method != SPNG_INTERLACE_NONE )
vips_image_set_int( image, "interlaced", 1 );
if( !spng_get_bkgd( png->ctx, &bkgd ) ) {
const int scale = image->BandFmt ==
VIPS_FORMAT_UCHAR ? 1 : 256;
double array[3];
int n;
switch( png->ihdr.color_type ) {
case SPNG_COLOR_TYPE_GRAYSCALE:
case SPNG_COLOR_TYPE_GRAYSCALE_ALPHA:
array[0] = bkgd.gray / scale;
n = 1;
break;
case SPNG_COLOR_TYPE_TRUECOLOR:
case SPNG_COLOR_TYPE_TRUECOLOR_ALPHA:
array[0] = bkgd.red / scale;
array[1] = bkgd.green / scale;
array[2] = bkgd.blue / scale;
n = 3;
break;
case SPNG_COLOR_TYPE_INDEXED:
default:
/* Not sure what to do here. I suppose we should read
* the palette.
*/
n = 0;
break;
}
if( n > 0 ) {
GValue value = { 0 };
g_value_init( &value, VIPS_TYPE_ARRAY_DOUBLE );
vips_value_set_array_double( &value, array, n );
vips_image_set( image, "background", &value );
g_value_unset( &value );
}
}
}
static int
@ -308,7 +352,6 @@ vips_foreign_load_png_header( VipsForeignLoad *load )
return( -1 );
}
#ifdef DEBUG
printf( "width: %d\nheight: %d\nbit depth: %d\ncolor type: %d\n",
png->ihdr.width, png->ihdr.height,

50
libvips/foreign/vipspng.c
View File

@ -79,6 +79,8 @@
* - revise for connection IO
* 11/5/20
* - only warn for saving bad profiles, don't fail
* 19/2/21 781545872
* - read out background, if we can
*/
/*
@ -559,6 +561,54 @@ png2vips_header( Read *read, VipsImage *out )
if( color_type == PNG_COLOR_TYPE_PALETTE )
vips_image_set_int( out, "palette-bit-depth", bitdepth );
/* Note the PNG background colour, if any.
*/
#ifdef PNG_bKGD_SUPPORTED
{
png_color_16 *background;
if( png_get_bKGD( read->pPng, read->pInfo, &background ) ) {
const int scale = out->BandFmt == VIPS_FORMAT_UCHAR ? 1 : 256;
double array[3];
int n;
switch( color_type ) {
case PNG_COLOR_TYPE_GRAY:
case PNG_COLOR_TYPE_GRAY_ALPHA:
array[0] = background->gray / scale;
n = 1;
break;
case PNG_COLOR_TYPE_RGB:
case PNG_COLOR_TYPE_RGB_ALPHA:
array[0] = background->red / scale;
array[1] = background->green / scale;
array[2] = background->blue / scale;
n = 3;
break;
case PNG_COLOR_TYPE_PALETTE:
default:
/* Not sure what to do here. I suppose we should read
* the palette.
*/
n = 0;
break;
}
if( n > 0 ) {
GValue value = { 0 };
g_value_init( &value, VIPS_TYPE_ARRAY_DOUBLE );
vips_value_set_array_double( &value, array, n );
vips_image_set( out, "background", &value );
g_value_unset( &value );
}
}
}
#endif
return( 0 );
}