Adds WebP read support to kimgio

Signed-off-by: Alex Kent Hajnal <software@alephnull.net>
(cherry picked from commit 347a546d9dfb3210bcf907c3c622d6843d2ae9ce)

1 files changed, 148 insertions, 0 deletions

diff --git a/kimgio/webp.cpp b/kimgio/webp.cpp
new file mode 100644
index 000000000..ea50ee3b6
--- /dev/null
+++ b/kimgio/webp.cpp
@@ -0,0 +1,148 @@
+// 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