Merge pull request #42 from MCLoebl/add_test_with_more_colors

add a test with more than 256 colors in one frame

tests/meson.build

@@ -18,6 +18,7 @@ tests = [
   'max_color_table_test',
   'min_color_table_test',
   'min_size',
+  'more_than_256_colors',
   'noise256',
   'noise6',
   'one_full_block',

tests/more_than_256_colors.c

@@ -0,0 +1,97 @@
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <stdio.h>
+
+#include "cgif.h"
+
+#define WIDTH  255
+#define HEIGHT 255 
+
+/* This code is an example of how a GIF with frames including more than 256 colors can be created by reusing colors from a previous frame.
+   The general restriction of GIF that only 256 new colors can be introduced in one frame remains of course */
+int main(void) {
+  CGIF*          pGIF;
+  CGIF_Config     gConfig;
+  CGIF_FrameConfig   fConfig;
+  uint8_t*      pImageData;
+  uint16_t      numColorsLocal = 255;
+  uint8_t       aLocalPalette[3*numColorsLocal]; // local palette
+  uint8_t       aPalette[3*numColorsLocal]; // global palette (only used for 1st frame here)
+  cgif_result r;
+
+  memset(&gConfig, 0, sizeof(CGIF_Config));
+  memset(&fConfig, 0, sizeof(CGIF_FrameConfig));
+  gConfig.attrFlags               = CGIF_ATTR_IS_ANIMATED;
+  gConfig.width                   = WIDTH;
+  gConfig.height                  = HEIGHT;
+  gConfig.pGlobalPalette          = aPalette;
+  gConfig.numGlobalPaletteEntries = numColorsLocal;
+  gConfig.path                    = "more_than_256_colors.gif";
+
+  // define the global color palette
+  for(int i=0; i<numColorsLocal; i++){
+    aPalette[3*i+0] = i; // set color palette to red gradient
+    aPalette[3*i+1] = 0;
+    aPalette[3*i+2] = 0;
+  }
+
+  // create new GIF
+  pGIF = cgif_newgif(&gConfig);
+  if(pGIF == NULL) {
+    fputs("failed to create new GIF via cgif_newgif()\n", stderr);
+    return 1;
+  }
+
+  pImageData = malloc(WIDTH * HEIGHT);
+  fConfig.pImageData = pImageData;
+  fConfig.delay      = 200;
+
+  // 1st frame (uses global palette, but could use local palette, too)
+  for (int i = 0; i < (WIDTH * HEIGHT); ++i) {
+    pImageData[i] = i % WIDTH;
+  }
+  cgif_addframe(pGIF, &fConfig);
+
+  // set configs for the folowing frames
+  fConfig.numLocalPaletteEntries = numColorsLocal;
+  fConfig.pLocalPalette = aLocalPalette;
+  fConfig.transIndex = numColorsLocal;
+  fConfig.attrFlags = CGIF_FRAME_ATTR_USE_LOCAL_TABLE | CGIF_FRAME_ATTR_HAS_SET_TRANS; // use local palettes, transparency set by user
+
+  // 2nd frame
+  for(int i=0; i<numColorsLocal; i++){
+    aLocalPalette[3*i+0] = 0;
+    aLocalPalette[3*i+1] = i; // set color palette to green gradient
+    aLocalPalette[3*i+2] = 0;
+  }
+  memset(pImageData, numColorsLocal, WIDTH * HEIGHT); // set everything to transparent (frame from before shines through)
+  for (int i = WIDTH/3 * HEIGHT; i < (WIDTH * HEIGHT); ++i) {
+    pImageData[i] = i % WIDTH;  // set part of the image to new colors
+  }
+  r = cgif_addframe(pGIF, &fConfig);
+
+  // 3rd frame
+  for(int i=0; i<numColorsLocal; i++){
+    aLocalPalette[3*i+0] = 0;
+    aLocalPalette[3*i+1] = 0;
+    aLocalPalette[3*i+2] = i; // set color palette to blue gradient
+  }
+  memset(pImageData, numColorsLocal, WIDTH * HEIGHT); // set everything to transparent (frame from before shines through)
+  for (int i = WIDTH/3*2 * HEIGHT; i < (WIDTH * HEIGHT); ++i) {
+    pImageData[i] = i % WIDTH;  // set part of the image to new colors
+  }
+  r = cgif_addframe(pGIF, &fConfig);
+
+  free(pImageData);
+
+  // write GIF to file
+  r = cgif_close(pGIF);
+
+  // check for errors
+  if(r != CGIF_OK) {
+    fprintf(stderr, "failed to create GIF. error code: %d\n", r);
+    return 2;
+  }
+  return 0;
+}

tests/tests.md5

@@ -15,6 +15,7 @@ b702bac8f8ded19ec1f58c1f80ee9208  local_transp.gif
 # too large for CI: dd8cb01f5b02c16cc346b51d1faadc63  max_size.gif
 30ab701c8e56bc8b09c824305002de5a  min_color_table_test.gif
 f2bfeb47a7ecc834ae21140f02c60297  min_size.gif
+bcf6674e99f31e67da5bc17ad93cb7a7  more_than_256_colors.gif
 c6a8e6f6d6d0c969cb300ea7eb18391d  noise256.gif
 7de24bdbff1dec81aab1840bcf69b19f  noise6.gif
 3337de21095a6b19effb40c518af96e5  one_full_block.gif