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cgifsave: avoid size issue (#2628)

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* cgifsave: avoid size issue

avoid size issue by restoring the original transparency setting after quantization/dithering

* switch to per-frame alpha channel

* add option for lossy transparency

* switch lossy transparency off by default

* switch to g_malloc instead of g_malloc0

no need to 0 initialize at this point

* adapt to libvips coding conventions

* cgifsave: avoid size issue

avoid size issue by restoring the original transparency setting after quantization/dithering

* switch to per-frame alpha channel

* add option for lossy transparency

* switch lossy transparency off by default

* switch to g_malloc instead of g_malloc0

no need to 0 initialize at this point

* adapt to libvips coding conventions

* switch to official Homebrew sources for installing cgif

* bump required cgif version to v0.2.0
This commit is contained in:
Daniel Löbl 2022-02-28 17:19:13 +01:00 committed by GitHub
parent c02b69eaba
commit b0f993eec8
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GPG Key ID: 4AEE18F83AFDEB23
4 changed files with 90 additions and 15 deletions
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4
.github/workflows/ci.yml vendored
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@ -82,9 +82,7 @@ jobs:
if: runner.os == 'macOS'
run: |
brew install meson ninja fftw fontconfig glib libexif libgsf little-cms2 orc pango
brew install cfitsio libheif libimagequant libjpeg-turbo libmatio librsvg libspng libtiff openexr openjpeg openslide poppler webp
brew tap lovell/cgif-packaging https://github.com/lovell/cgif-packaging.git
brew install --build-bottle lovell/cgif-packaging/cgif
brew install cfitsio libheif libimagequant libjpeg-turbo libmatio librsvg libspng libtiff openexr openjpeg openslide poppler webp cgif
- name: Install Clang 13
if: runner.os == 'Linux' && matrix.build.cc == 'clang-13'

4
configure.ac
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@ -1493,8 +1493,8 @@ AC_ARG_WITH([cgif],
AS_HELP_STRING([--without-cgif], [build without cgif (default: test)]))
if test x"$quantisation_package" != x"" && test x"$with_cgif" != x"no"; then
PKG_CHECK_MODULES(CGIF, cgif,
[AC_DEFINE(HAVE_CGIF,1,[define if you have cgif installed.])
PKG_CHECK_MODULES(CGIF, cgif >= 0.2.0,
[AC_DEFINE(HAVE_CGIF,1,[define if you have cgif >= 0.2.0 installed.])
with_cgif=yes
PACKAGES_USED="$PACKAGES_USED cgif"
],

95
libvips/foreign/cgifsave.c
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@ -45,6 +45,7 @@
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <vips/vips.h>
@ -61,6 +62,7 @@ typedef struct _VipsForeignSaveCgif {
double dither;
int effort;
int bitdepth;
double maxerror;
VipsTarget *target;
/* Derived write params.
@ -100,6 +102,10 @@ typedef struct _VipsForeignSaveCgif {
*/
VipsPel *index;
/* frame_bytes head (needed for transparency trick).
*/
VipsPel *frame_bytes_head;
/* The frame as written by libcgif.
*/
CGIF *cgif_context;
@ -138,6 +144,7 @@ vips_foreign_save_cgif_dispose( GObject *gobject )
VIPS_FREE( cgif->palette_rgb );
VIPS_FREE( cgif->index );
VIPS_FREE( cgif->frame_bytes_head );
VIPS_FREEF( cgif_close, cgif->cgif_context );
@ -153,6 +160,25 @@ static int vips__cgif_write( void *target, const uint8_t *buffer,
(const void *) buffer, (size_t) length );
}
/* Compare pixels in a lossy way (allow a slight colour difference).
In combination with the GIF transparency optimization this leads to
less difference between frames and therefore improves the compression ratio.
*/
static gboolean
cgif_pixels_are_equal(const VipsPel *cur, const VipsPel *bef, double maxerror)
{
if( bef[3] != 0xFF )
/* Done. Cannot compare with alpha channel in frame before.
*/
return FALSE;
/* Test Euclidean distance between the two points.
*/
const int dR = cur[0] - bef[0];
const int dG = cur[1] - bef[1];
const int dB = cur[2] - bef[2];
return( sqrt( dR * dR + dG * dG + dB * dB ) <= maxerror );
}
/* We have a complete frame --- write!
*/
static int
@ -274,8 +300,6 @@ vips_foreign_save_cgif_write_frame( VipsForeignSaveCgif *cgif )
if( !cgif->cgif_context ) {
cgif->cgif_config.pGlobalPalette = cgif->palette_rgb;
cgif->cgif_config.attrFlags = CGIF_ATTR_IS_ANIMATED;
cgif->cgif_config.attrFlags |=
cgif->has_transparency ? CGIF_ATTR_HAS_TRANSPARENCY : 0;
cgif->cgif_config.width = frame_rect->width;
cgif->cgif_config.height = frame_rect->height;
cgif->cgif_config.numGlobalPaletteEntries = cgif->lp->count;
@ -286,12 +310,6 @@ vips_foreign_save_cgif_write_frame( VipsForeignSaveCgif *cgif )
cgif->cgif_context = cgif_newgif( &cgif->cgif_config );
}
/* Reset global transparency flag.
*/
cgif->cgif_config.attrFlags =
(cgif->cgif_config.attrFlags & ~CGIF_ATTR_HAS_TRANSPARENCY) |
(cgif->has_transparency ? CGIF_ATTR_HAS_TRANSPARENCY : 0);
/* Write frame to cgif.
*/
memset( &frame_config, 0, sizeof( CGIF_FrameConfig ) );
@ -303,6 +321,50 @@ vips_foreign_save_cgif_write_frame( VipsForeignSaveCgif *cgif )
frame_config.genFlags =
CGIF_FRAME_GEN_USE_TRANSPARENCY |
CGIF_FRAME_GEN_USE_DIFF_WINDOW;
frame_config.attrFlags = 0;
/* Switch per-frame alpha channel on.
* Index 0 is used for pixels with alpha channel.
*/
if( cgif->has_transparency ) {
frame_config.attrFlags |= CGIF_FRAME_ATTR_HAS_ALPHA;
frame_config.transIndex = 0;
}
/* Do the transparency trick (only possible when no alpha channel present)
*/
if( cgif->frame_bytes_head ) {
VipsPel *cur, *bef;
cur = frame_bytes;
bef = cgif->frame_bytes_head;
if( !cgif->has_transparency ) {
const uint8_t trans_index = cgif->lp->count;
const double maxerror = cgif->maxerror;
int i;
for( i = 0; i < n_pels; i++ ) {
if( cgif_pixels_are_equal( cur, bef, maxerror ) )
cgif->index[i] = trans_index;
else {
bef[0] = cur[0];
bef[1] = cur[1];
bef[2] = cur[2];
bef[3] = cur[3];
}
cur += 4;
bef += 4;
}
frame_config.attrFlags |= CGIF_FRAME_ATTR_HAS_SET_TRANS;
frame_config.transIndex = trans_index;
} else {
/* Transparency trick not possible (alpha channel present).
* Update head.
*/
memcpy( bef, cur, 4 * n_pels);
}
}
if( cgif->delay &&
page_index < cgif->delay_length )
@ -312,13 +374,21 @@ vips_foreign_save_cgif_write_frame( VipsForeignSaveCgif *cgif )
/* Attach a local palette, if we need one.
*/
if( cgif->cgif_config.attrFlags & CGIF_ATTR_NO_GLOBAL_TABLE ) {
frame_config.attrFlags = CGIF_FRAME_ATTR_USE_LOCAL_TABLE;
frame_config.attrFlags |= CGIF_FRAME_ATTR_USE_LOCAL_TABLE;
frame_config.pLocalPalette = cgif->palette_rgb;
frame_config.numLocalPaletteEntries = cgif->lp->count;
}
cgif_addframe( cgif->cgif_context, &frame_config );
if( !cgif->frame_bytes_head ) {
/* Keep head frame_bytes in memory for transparency trick
* which avoids the size explosion (#2576).
*/
cgif->frame_bytes_head = g_malloc( 4 * n_pels );
memcpy( cgif->frame_bytes_head, frame_bytes, 4 * n_pels );
}
return( 0 );
}
@ -529,6 +599,12 @@ vips_foreign_save_cgif_class_init( VipsForeignSaveCgifClass *class )
G_STRUCT_OFFSET( VipsForeignSaveCgif, bitdepth ),
1, 8, 8 );
VIPS_ARG_DOUBLE( class, "maxerror", 13,
_( "Max. error for lossy transparency setting"),
_( "Maximum pixel error to allow when identifying areas as identical (inter frame)" ),
VIPS_ARGUMENT_OPTIONAL_INPUT,
G_STRUCT_OFFSET( VipsForeignSaveCgif, maxerror ),
0, 32, 0.0 );
}
static void
@ -537,6 +613,7 @@ vips_foreign_save_cgif_init( VipsForeignSaveCgif *gif )
gif->dither = 1.0;
gif->effort = 7;
gif->bitdepth = 8;
gif->maxerror = 0.0;
}
typedef struct _VipsForeignSaveCgifTarget {

2
meson.build
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@ -234,7 +234,7 @@ endif
cgif_dep = disabler()
if quantisation_package.found()
cgif_dep = dependency('cgif', required: get_option('cgif'))
cgif_dep = dependency('cgif', version: '>=0.2.0', required: get_option('cgif'))
if cgif_dep.found()
libvips_deps += cgif_dep
cfg_var.set('HAVE_CGIF', '1')