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extras: add WebPUnmultiplyARGB() convenience function

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This is useful for converting associated to unassociated.

Change-Id: I0e6d16ec63cb5514a0f945c14a54e0d01e1fab0a
This commit is contained in:
Skal 2019-10-24 21:20:03 +02:00 committed by James Zern
parent 22cbae33e5
commit 47178dbd45
3 changed files with 27 additions and 2 deletions
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4
CMakeLists.txt
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@ -525,7 +525,9 @@ if(WEBP_BUILD_EXTRAS)
# webp_quality
add_executable(webp_quality ${WEBP_QUALITY_SRCS} ${WEBP_EXTRAS_SRCS})
target_link_libraries(webp_quality exampleutil imagedec)
target_include_directories(webp_quality PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
target_include_directories(webp_quality
PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}
${CMAKE_CURRENT_BINARY_DIR})
install(TARGETS webp_quality RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
# vwebp_sdl

16
extras/extras.c
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@ -12,6 +12,7 @@
#include "extras/extras.h"
#include "webp/format_constants.h"
#include "src/dsp/dsp.h"
#include <assert.h>
#include <string.h>
@ -144,3 +145,18 @@ int WebPImportColorMappedARGB(const uint8_t* indexed, int indexed_stride,
}
//------------------------------------------------------------------------------
int WebPUnmultiplyARGB(WebPPicture* pic) {
int y;
uint32_t* dst;
if (pic == NULL || pic->use_argb != 1 || pic->argb == NULL) return 0;
WebPInitAlphaProcessing();
dst = pic->argb;
for (y = 0; y < pic->height; ++y) {
WebPMultARGBRow(dst, pic->width, /*inverse=*/1);
dst += pic->argb_stride;
}
return 1;
}
//------------------------------------------------------------------------------

9
extras/extras.h
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@ -19,7 +19,7 @@ extern "C" {
#include "webp/encode.h"
#define WEBP_EXTRAS_ABI_VERSION 0x0001 // MAJOR(8b) + MINOR(8b)
#define WEBP_EXTRAS_ABI_VERSION 0x0002 // MAJOR(8b) + MINOR(8b)
//------------------------------------------------------------------------------
@ -51,6 +51,13 @@ WebPImportColorMappedARGB(const uint8_t* indexed, int indexed_stride,
const uint32_t palette[], int palette_size,
WebPPicture* pic);
// Convert the ARGB content of 'pic' from associated to unassociated.
// 'pic' can be for instance the result of calling of some WebPPictureImportXXX
// functions, with pic->use_argb set to 'true'. It is assumed (and not checked)
// that the pre-multiplied r/g/b values as less or equal than the alpha value.
// Return false in case of error (invalid parameter, ...).
WEBP_EXTERN int WebPUnmultiplyARGB(WebPPicture* pic);
//------------------------------------------------------------------------------
// Parse a bitstream, search for VP8 (lossy) header and report a