WebPCompressor.h

/*  WebP Compressor Class:
    Handles alpha channels, ICC profiles and XMP metadata
 
    Copyright (C) 2022-2024 Ruven Pillay
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 3 of the License, or
    (at your option) any later version.
 
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software Foundation,
    Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
 
*/
 
 
#ifndef _WEBPCOMPRESSOR_H
#define _WEBPCOMPRESSOR_H
 
 
#include "Compressor.h"
#include <webp/encode.h>
#include <webp/mux.h>
 
 
 
class WebPCompressor : public Compressor {
 
 private:
 
  WebPConfig config;
  WebPPicture pic;
  WebPMemoryWriter writer;
  WebPMux* mux;
 
  RawTile tile;                   
  unsigned int chunk_size;        
  size_t current_chunk;           
 
 
  void writeICCProfile();
 
  void writeXMPMetadata();
 
  void writeExifMetadata();
 
 
 public:
 
 
  WebPCompressor( int compressionLevel ) : Compressor(compressionLevel) {
 
    // Initialize our configuration structure with default values
    WebPConfigInit( &config );
    config.method = 0;         // Fastest encoding
    config.thread_level = 1;   // Enable threading
 
    // Update our WebP config structure depending on whether lossless or lossy compression requested
    if( compressionLevel == -1 ){
      // -1 indicates lossless
      config.lossless = 1;
      config.quality = 0;      // Zero means fastest for lossless
    }
    // WebP's lossy quality range is 0-100
    else config.quality = this->Q;
 
    // Create our muxer object
    mux = WebPMuxNew();
 
  };
 
 
  ~WebPCompressor(){
    // Delete our muxer object
    WebPMuxDelete( mux );
  };
 
 
 
  void InitCompression( const RawTile& rawtile, unsigned int strip_height );
 
 
 
  unsigned int CompressStrip( unsigned char* source, unsigned char* output, unsigned int tile_height );
 
 
 
  unsigned int Finish( unsigned char* output );
 
 
 
  unsigned int Compress( RawTile& t );
 
 
  inline const char* getMimeType() const { return "image/webp"; }
 
  inline const char* getSuffix() const { return "webp"; }
 
  inline ImageEncoding getImageEncoding() const { return ImageEncoding::WEBP; };
 
 
 
  inline void setQuality( int quality ){
 
    // Flag that user has manually changed quality level
    default_quality = false;
 
    // WebP quality ranges from 0 (best compression - smallest size) to 100 (worst compression - largest size)
    this->Q = quality;
 
    // Limit to WebP quality range - negative values indicate lossless
    if( this->Q < 1 ) Q = -1;
    else if( Q > 100 ) Q = 100;
 
    // Update our WebP config structure depending on whether lossless or lossy compression requested
    if( this->Q == -1 ){
      // -1 indicates lossless
      config.lossless = 1;
      config.quality = 0;      // Zero means fastest for lossless
    }
    // WebP's lossy quality range is 0-100
    else config.quality = this->Q;
  }
 
 
 
  void injectMetadata( RawTile& r );
 
 
};
 
#endif