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-rw-r--r--thirdparty/libwebp/enc/picture_tools.c226
1 files changed, 226 insertions, 0 deletions
diff --git a/thirdparty/libwebp/enc/picture_tools.c b/thirdparty/libwebp/enc/picture_tools.c
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+++ b/thirdparty/libwebp/enc/picture_tools.c
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+// Copyright 2014 Google Inc. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS. All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+// -----------------------------------------------------------------------------
+//
+// WebPPicture tools: alpha handling, etc.
+//
+// Author: Skal (pascal.massimino@gmail.com)
+
+#include <assert.h>
+
+#include "./vp8enci.h"
+#include "../dsp/yuv.h"
+
+static WEBP_INLINE uint32_t MakeARGB32(int r, int g, int b) {
+ return (0xff000000u | (r << 16) | (g << 8) | b);
+}
+
+//------------------------------------------------------------------------------
+// Helper: clean up fully transparent area to help compressibility.
+
+#define SIZE 8
+#define SIZE2 (SIZE / 2)
+static int is_transparent_area(const uint8_t* ptr, int stride, int size) {
+ int y, x;
+ for (y = 0; y < size; ++y) {
+ for (x = 0; x < size; ++x) {
+ if (ptr[x]) {
+ return 0;
+ }
+ }
+ ptr += stride;
+ }
+ return 1;
+}
+
+static int is_transparent_argb_area(const uint32_t* ptr, int stride, int size) {
+ int y, x;
+ for (y = 0; y < size; ++y) {
+ for (x = 0; x < size; ++x) {
+ if (ptr[x] & 0xff000000u) {
+ return 0;
+ }
+ }
+ ptr += stride;
+ }
+ return 1;
+}
+
+static void flatten(uint8_t* ptr, int v, int stride, int size) {
+ int y;
+ for (y = 0; y < size; ++y) {
+ memset(ptr, v, size);
+ ptr += stride;
+ }
+}
+
+static void flatten_argb(uint32_t* ptr, uint32_t v, int stride, int size) {
+ int x, y;
+ for (y = 0; y < size; ++y) {
+ for (x = 0; x < size; ++x) ptr[x] = v;
+ ptr += stride;
+ }
+}
+
+void WebPCleanupTransparentArea(WebPPicture* pic) {
+ int x, y, w, h;
+ if (pic == NULL) return;
+ w = pic->width / SIZE;
+ h = pic->height / SIZE;
+
+ // note: we ignore the left-overs on right/bottom
+ if (pic->use_argb) {
+ uint32_t argb_value = 0;
+ for (y = 0; y < h; ++y) {
+ int need_reset = 1;
+ for (x = 0; x < w; ++x) {
+ const int off = (y * pic->argb_stride + x) * SIZE;
+ if (is_transparent_argb_area(pic->argb + off, pic->argb_stride, SIZE)) {
+ if (need_reset) {
+ argb_value = pic->argb[off];
+ need_reset = 0;
+ }
+ flatten_argb(pic->argb + off, argb_value, pic->argb_stride, SIZE);
+ } else {
+ need_reset = 1;
+ }
+ }
+ }
+ } else {
+ const uint8_t* const a_ptr = pic->a;
+ int values[3] = { 0 };
+ if (a_ptr == NULL) return; // nothing to do
+ for (y = 0; y < h; ++y) {
+ int need_reset = 1;
+ for (x = 0; x < w; ++x) {
+ const int off_a = (y * pic->a_stride + x) * SIZE;
+ const int off_y = (y * pic->y_stride + x) * SIZE;
+ const int off_uv = (y * pic->uv_stride + x) * SIZE2;
+ if (is_transparent_area(a_ptr + off_a, pic->a_stride, SIZE)) {
+ if (need_reset) {
+ values[0] = pic->y[off_y];
+ values[1] = pic->u[off_uv];
+ values[2] = pic->v[off_uv];
+ need_reset = 0;
+ }
+ flatten(pic->y + off_y, values[0], pic->y_stride, SIZE);
+ flatten(pic->u + off_uv, values[1], pic->uv_stride, SIZE2);
+ flatten(pic->v + off_uv, values[2], pic->uv_stride, SIZE2);
+ } else {
+ need_reset = 1;
+ }
+ }
+ }
+ }
+}
+
+#undef SIZE
+#undef SIZE2
+
+void WebPCleanupTransparentAreaLossless(WebPPicture* const pic) {
+ int x, y, w, h;
+ uint32_t* argb;
+ assert(pic != NULL && pic->use_argb);
+ w = pic->width;
+ h = pic->height;
+ argb = pic->argb;
+
+ for (y = 0; y < h; ++y) {
+ for (x = 0; x < w; ++x) {
+ if ((argb[x] & 0xff000000) == 0) {
+ argb[x] = 0x00000000;
+ }
+ }
+ argb += pic->argb_stride;
+ }
+}
+
+//------------------------------------------------------------------------------
+// Blend color and remove transparency info
+
+#define BLEND(V0, V1, ALPHA) \
+ ((((V0) * (255 - (ALPHA)) + (V1) * (ALPHA)) * 0x101) >> 16)
+#define BLEND_10BIT(V0, V1, ALPHA) \
+ ((((V0) * (1020 - (ALPHA)) + (V1) * (ALPHA)) * 0x101) >> 18)
+
+void WebPBlendAlpha(WebPPicture* pic, uint32_t background_rgb) {
+ const int red = (background_rgb >> 16) & 0xff;
+ const int green = (background_rgb >> 8) & 0xff;
+ const int blue = (background_rgb >> 0) & 0xff;
+ int x, y;
+ if (pic == NULL) return;
+ if (!pic->use_argb) {
+ const int uv_width = (pic->width >> 1); // omit last pixel during u/v loop
+ const int Y0 = VP8RGBToY(red, green, blue, YUV_HALF);
+ // VP8RGBToU/V expects the u/v values summed over four pixels
+ const int U0 = VP8RGBToU(4 * red, 4 * green, 4 * blue, 4 * YUV_HALF);
+ const int V0 = VP8RGBToV(4 * red, 4 * green, 4 * blue, 4 * YUV_HALF);
+ const int has_alpha = pic->colorspace & WEBP_CSP_ALPHA_BIT;
+ if (!has_alpha || pic->a == NULL) return; // nothing to do
+ for (y = 0; y < pic->height; ++y) {
+ // Luma blending
+ uint8_t* const y_ptr = pic->y + y * pic->y_stride;
+ uint8_t* const a_ptr = pic->a + y * pic->a_stride;
+ for (x = 0; x < pic->width; ++x) {
+ const int alpha = a_ptr[x];
+ if (alpha < 0xff) {
+ y_ptr[x] = BLEND(Y0, y_ptr[x], a_ptr[x]);
+ }
+ }
+ // Chroma blending every even line
+ if ((y & 1) == 0) {
+ uint8_t* const u = pic->u + (y >> 1) * pic->uv_stride;
+ uint8_t* const v = pic->v + (y >> 1) * pic->uv_stride;
+ uint8_t* const a_ptr2 =
+ (y + 1 == pic->height) ? a_ptr : a_ptr + pic->a_stride;
+ for (x = 0; x < uv_width; ++x) {
+ // Average four alpha values into a single blending weight.
+ // TODO(skal): might lead to visible contouring. Can we do better?
+ const int alpha =
+ a_ptr[2 * x + 0] + a_ptr[2 * x + 1] +
+ a_ptr2[2 * x + 0] + a_ptr2[2 * x + 1];
+ u[x] = BLEND_10BIT(U0, u[x], alpha);
+ v[x] = BLEND_10BIT(V0, v[x], alpha);
+ }
+ if (pic->width & 1) { // rightmost pixel
+ const int alpha = 2 * (a_ptr[2 * x + 0] + a_ptr2[2 * x + 0]);
+ u[x] = BLEND_10BIT(U0, u[x], alpha);
+ v[x] = BLEND_10BIT(V0, v[x], alpha);
+ }
+ }
+ memset(a_ptr, 0xff, pic->width);
+ }
+ } else {
+ uint32_t* argb = pic->argb;
+ const uint32_t background = MakeARGB32(red, green, blue);
+ for (y = 0; y < pic->height; ++y) {
+ for (x = 0; x < pic->width; ++x) {
+ const int alpha = (argb[x] >> 24) & 0xff;
+ if (alpha != 0xff) {
+ if (alpha > 0) {
+ int r = (argb[x] >> 16) & 0xff;
+ int g = (argb[x] >> 8) & 0xff;
+ int b = (argb[x] >> 0) & 0xff;
+ r = BLEND(red, r, alpha);
+ g = BLEND(green, g, alpha);
+ b = BLEND(blue, b, alpha);
+ argb[x] = MakeARGB32(r, g, b);
+ } else {
+ argb[x] = background;
+ }
+ }
+ }
+ argb += pic->argb_stride;
+ }
+ }
+}
+
+#undef BLEND
+#undef BLEND_10BIT
+
+//------------------------------------------------------------------------------
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