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Refactor GetColorPalette method.

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This was defined (slightly differently) at two places. Created a common
method and moved to utils/utils.[hc].

Change-Id: I19adc9c48f2a4e2ec9d995e78add6f25172774c2
This commit is contained in:
Urvang Joshi
2016-05-18 14:27:15 -07:00
parent e15afbce5d
commit 169004b1d5
4 changed files with 85 additions and 104 deletions
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60
src/mux/anim_encode.c
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@ -645,61 +645,6 @@ static int IsLossyBlendingPossible(const WebPPicture* const src,
return 1;
}
#define MIN_COLORS_LOSSY 31 // Don't try lossy below this threshold.
#define MAX_COLORS_LOSSLESS 194 // Don't try lossless above this threshold.
#define MAX_COLOR_COUNT 256 // Power of 2 greater than MAX_COLORS_LOSSLESS.
#define HASH_SIZE (MAX_COLOR_COUNT * 4)
#define HASH_RIGHT_SHIFT 22 // 32 - log2(HASH_SIZE).
// TODO(urvang): Also used in enc/vp8l.c. Move to utils.
// If the number of colors in the 'pic' is at least MAX_COLOR_COUNT, return
// MAX_COLOR_COUNT. Otherwise, return the exact number of colors in the 'pic'.
static int GetColorCount(const WebPPicture* const pic) {
int x, y;
int num_colors = 0;
uint8_t in_use[HASH_SIZE] = { 0 };
uint32_t colors[HASH_SIZE];
static const uint32_t kHashMul = 0x1e35a7bd;
const uint32_t* argb = pic->argb;
const int width = pic->width;
const int height = pic->height;
uint32_t last_pix = ~argb[0]; // so we're sure that last_pix != argb[0]
for (y = 0; y < height; ++y) {
for (x = 0; x < width; ++x) {
int key;
if (argb[x] == last_pix) {
continue;
}
last_pix = argb[x];
key = (kHashMul * last_pix) >> HASH_RIGHT_SHIFT;
while (1) {
if (!in_use[key]) {
colors[key] = last_pix;
in_use[key] = 1;
++num_colors;
if (num_colors >= MAX_COLOR_COUNT) {
return MAX_COLOR_COUNT; // Exact count not needed.
}
break;
} else if (colors[key] == last_pix) {
break; // The color is already there.
} else {
// Some other color sits here, so do linear conflict resolution.
++key;
key &= (HASH_SIZE - 1); // Key mask.
}
}
}
argb += pic->argb_stride;
}
return num_colors;
}
#undef MAX_COLOR_COUNT
#undef HASH_SIZE
#undef HASH_RIGHT_SHIFT
// For pixels in 'rect', replace those pixels in 'dst' that are same as 'src' by
// transparent pixels.
static void IncreaseTransparency(const WebPPicture* const src,
@ -856,6 +801,9 @@ enum {
CANDIDATE_COUNT
};
#define MIN_COLORS_LOSSY 31 // Don't try lossy below this threshold.
#define MAX_COLORS_LOSSLESS 194 // Don't try lossless above this threshold.
// Generates candidates for a given dispose method given pre-filled sub-frame
// 'params'.
static WebPEncodingError GenerateCandidates(
@ -890,7 +838,7 @@ static WebPEncodingError GenerateCandidates(
candidate_ll->evaluate_ = is_lossless;
candidate_lossy->evaluate_ = !is_lossless;
} else { // Use a heuristic for trying lossless and/or lossy compression.
const int num_colors = GetColorCount(&params->sub_frame_ll_);
const int num_colors = WebPGetColorPalette(&params->sub_frame_ll_, NULL);
candidate_ll->evaluate_ = (num_colors < MAX_COLORS_LOSSLESS);
candidate_lossy->evaluate_ = (num_colors >= MIN_COLORS_LOSSY);
}