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tdelibs/kimgio/webp.cpp

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3.6 KiB

// WebP read support
// © 2024 Alexander Hajnal
// Based loosely on jp2.cpp
//
// If implementing write support it's suggested to use lossless mode with exact
// mode enabled when the quality setting is 100 and for other qualities to use
// lossy mode with the default settings.
//
// This library is distributed under the conditions of the GNU LGPL.
#include "config.h"
#include <tdetempfile.h>
#include <tqfile.h>
#include <tqimage.h>
#include <webp/decode.h>
#include <cstdlib>
#ifdef __cplusplus
extern "C" {
#endif
TDE_EXPORT void kimgio_webp_read( TQImageIO* io )
{
int width, height;
FILE* in;
// === Read the source file ===
// Based on code in jp2.cpp
// for QIODevice's other than TQFile, a temp. file is used.
KTempFile* tempf = 0;
TQFile* qf = 0;
if( ( qf = dynamic_cast<TQFile*>( io->ioDevice() ) ) ) {
// great, it's a TQFile. Let's just take the filename.
in = fopen( TQFile::encodeName( qf->name() ), "rb" );
} else {
// not a TQFile. Copy the whole data to a temp. file.
tempf = new KTempFile();
if( tempf->status() != 0 ) {
delete tempf;
return;
} // if
tempf->setAutoDelete( true );
TQFile* out = tempf->file();
// 4096 (=4k) is a common page size.
TQByteArray b( 4096 );
TQ_LONG size;
// 0 or -1 is EOF / error
while( ( size = io->ioDevice()->readBlock( b.data(), 4096 ) ) > 0 ) {
// in case of a write error, still give the decoder a try
if( ( out->writeBlock( b.data(), size ) ) == -1 ) break;
} // while
// flush everything out to disk
out->flush();
in = fopen( TQFile::encodeName( tempf->name() ), "rb" );
} // else
if( ! in ) {
delete tempf;
return;
} // if
// File is now open
// === Load compressed data ===
// Find file's size
fseek(in, 0L, SEEK_END); // Seek to end of file
long size = ftell(in); // Get position (i.e. the file size)
fseek(in, 0L, SEEK_SET); // Seek back to start of file
// Sanity check
if ( size > SIZE_MAX ) {
// File size is larger than a size_t can hold
fclose( in );
delete tempf;
return;
}
// Allocate a buffer for the compressed data
uint8_t* compressed_image = (uint8_t*)malloc(size);
if( ! compressed_image ) {
// malloc failed
fclose( in );
delete tempf;
return;
} // if
// Read compressed image into buffer
size_t bytes_read = fread( compressed_image, sizeof(uint8_t), size, in );
// Close the compressed image file
fclose( in );
delete tempf;
if ( bytes_read < size ) {
// Read failed
free( compressed_image );
return;
}
// === Decompress image ===
// Get image dimensions
if ( ! WebPGetInfo( compressed_image, size, &width, &height ) ) {
// Error
free( compressed_image );
return;
}
// Create an appropriately sized image
TQImage image;
if( ! image.create( width, height, 32 ) ) {
// Error
free( compressed_image );
return;
}
// Enable alpha channel
image.setAlphaBuffer(true);
// Get the image buffer
uint32_t* data = (uint32_t*)image.bits();
// Decompress the image
#ifdef WORDS_BIGENDIAN
if ( ! WebPDecodeARGBInto( compressed_image, size, (uint8_t*)data, width*height*4, width*4) ) {
#else
if ( ! WebPDecodeBGRAInto( compressed_image, size, (uint8_t*)data, width*height*4, width*4) ) {
#endif
// Error
free( compressed_image );
return;
}
// Free the compressed image buffer
free( compressed_image );
// Finalize load
io->setImage( image );
io->setStatus( 0 );
} // kimgio_webp_read
#ifdef __cplusplus
}
#endif