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gifdec.h (4008B)

      1 // Copyright 2014 Google Inc. All Rights Reserved.
      2 //
      3 // Use of this source code is governed by a BSD-style license
      4 // that can be found in the COPYING file in the root of the source
      5 // tree. An additional intellectual property rights grant can be found
      6 // in the file PATENTS. All contributing project authors may
      7 // be found in the AUTHORS file in the root of the source tree.
      8 // -----------------------------------------------------------------------------
      9 //
     10 // GIF decode.
     11 
     12 #ifndef WEBP_EXAMPLES_GIFDEC_H_
     13 #define WEBP_EXAMPLES_GIFDEC_H_
     14 
     15 #include <stdio.h>
     16 
     17 #include "webp/types.h"
     18 
     19 #ifdef HAVE_CONFIG_H
     20 #include "webp/config.h"
     21 #endif
     22 
     23 #ifdef WEBP_HAVE_GIF
     24 #include <gif_lib.h>
     25 #endif
     26 
     27 #ifdef __cplusplus
     28 extern "C" {
     29 #endif
     30 
     31 // GIFLIB_MAJOR is only defined in libgif >= 4.2.0.
     32 #if defined(GIFLIB_MAJOR) && defined(GIFLIB_MINOR)
     33 # define LOCAL_GIF_VERSION ((GIFLIB_MAJOR << 8) | GIFLIB_MINOR)
     34 # define LOCAL_GIF_PREREQ(maj, min) \
     35     (LOCAL_GIF_VERSION >= (((maj) << 8) | (min)))
     36 #else
     37 # define LOCAL_GIF_VERSION 0
     38 # define LOCAL_GIF_PREREQ(maj, min) 0
     39 #endif
     40 
     41 #define GIF_INDEX_INVALID (-1)
     42 
     43 typedef enum GIFDisposeMethod {
     44   GIF_DISPOSE_NONE,
     45   GIF_DISPOSE_BACKGROUND,
     46   GIF_DISPOSE_RESTORE_PREVIOUS
     47 } GIFDisposeMethod;
     48 
     49 typedef struct {
     50   int x_offset, y_offset, width, height;
     51 } GIFFrameRect;
     52 
     53 struct WebPData;
     54 struct WebPPicture;
     55 
     56 #ifndef WEBP_HAVE_GIF
     57 struct ColorMapObject;
     58 struct GifFileType;
     59 typedef unsigned char GifByteType;
     60 #endif
     61 
     62 // Given the index of background color and transparent color, returns the
     63 // corresponding background color (in BGRA format) in 'bgcolor'.
     64 void GIFGetBackgroundColor(const struct ColorMapObject* const color_map,
     65                            int bgcolor_index, int transparent_index,
     66                            uint32_t* const bgcolor);
     67 
     68 // Parses the given graphics extension data to get frame duration (in 1ms
     69 // units), dispose method and transparent color index.
     70 // Returns true on success.
     71 int GIFReadGraphicsExtension(const GifByteType* const buf, int* const duration,
     72                              GIFDisposeMethod* const dispose,
     73                              int* const transparent_index);
     74 
     75 // Reads the next GIF frame from 'gif' into 'picture'. Also, returns the GIF
     76 // frame dimensions and offsets in 'rect'.
     77 // Returns true on success.
     78 int GIFReadFrame(struct GifFileType* const gif, int transparent_index,
     79                  GIFFrameRect* const gif_rect,
     80                  struct WebPPicture* const picture);
     81 
     82 // Parses loop count from the given Netscape extension data.
     83 int GIFReadLoopCount(struct GifFileType* const gif, GifByteType** const buf,
     84                      int* const loop_count);
     85 
     86 // Parses the given ICC or XMP extension data and stores it into 'metadata'.
     87 // Returns true on success.
     88 int GIFReadMetadata(struct GifFileType* const gif, GifByteType** const buf,
     89                     struct WebPData* const metadata);
     90 
     91 // Dispose the pixels within 'rect' of 'curr_canvas' based on 'dispose' method
     92 // and 'prev_canvas'.
     93 void GIFDisposeFrame(GIFDisposeMethod dispose, const GIFFrameRect* const rect,
     94                      const struct WebPPicture* const prev_canvas,
     95                      struct WebPPicture* const curr_canvas);
     96 
     97 // Given 'src' picture and its frame rectangle 'rect', blend it into 'dst'.
     98 void GIFBlendFrames(const struct WebPPicture* const src,
     99                     const GIFFrameRect* const rect,
    100                     struct WebPPicture* const dst);
    101 
    102 // Prints an error string based on 'gif_error'.
    103 void GIFDisplayError(const struct GifFileType* const gif, int gif_error);
    104 
    105 // In the given 'pic', clear the pixels in 'rect' to transparent color.
    106 void GIFClearPic(struct WebPPicture* const pic, const GIFFrameRect* const rect);
    107 
    108 // Copy pixels from 'src' to 'dst' honoring strides. 'src' and 'dst' are assumed
    109 // to be already allocated.
    110 void GIFCopyPixels(const struct WebPPicture* const src,
    111                    struct WebPPicture* const dst);
    112 
    113 #ifdef __cplusplus
    114 }    // extern "C"
    115 #endif
    116 
    117 #endif  // WEBP_EXAMPLES_GIFDEC_H_