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https://github.com/thorvg/thorvg.git
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4cdf648e14
Previously, translucent png images are not displayed properly due to alpha channels premultiplication. This patch implements that missing part to support it properly by introducing the Surface data between canvas engine & rasterizer @Issue: https://github.com/Samsung/thorvg/issues/655
122 lines
3.3 KiB
C++
122 lines
3.3 KiB
C++
/*
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* Copyright (c) 2020-2021 Samsung Electronics Co., Ltd. All rights reserved.
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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#include "tvgLoader.h"
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#include "tvgPngLoader.h"
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static inline uint32_t ALPHA_BLEND(uint32_t c, uint32_t a)
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{
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return (((((c >> 8) & 0x00ff00ff) * a + 0x00ff00ff) & 0xff00ff00) +
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((((c & 0x00ff00ff) * a + 0x00ff00ff) >> 8) & 0x00ff00ff));
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}
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static void _premultiply(uint32_t* data, uint32_t w, uint32_t h)
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{
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auto buffer = data;
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for (uint32_t y = 0; y < h; ++y, buffer += w) {
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auto src = buffer;
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for (uint32_t x = 0; x < w; ++x, ++src) {
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*src = ALPHA_BLEND(*src, (*src >> 24));
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}
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}
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}
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PngLoader::PngLoader()
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{
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image = static_cast<png_imagep>(calloc(1, sizeof(png_image)));
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image->version = PNG_IMAGE_VERSION;
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image->opaque = NULL;
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}
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PngLoader::~PngLoader()
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{
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if (content) {
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free((void*)content);
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content = nullptr;
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}
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free(image);
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}
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bool PngLoader::open(const string& path)
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{
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image->opaque = NULL;
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if (!png_image_begin_read_from_file(image, path.c_str())) return false;
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w = (float)image->width;
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h = (float)image->height;
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return true;
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}
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bool PngLoader::open(const char* data, uint32_t size, bool copy)
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{
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image->opaque = NULL;
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if (!png_image_begin_read_from_memory(image, data, size)) return false;
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w = (float)image->width;
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h = (float)image->height;
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return true;
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}
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bool PngLoader::read()
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{
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png_bytep buffer;
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image->format = PNG_FORMAT_BGRA;
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buffer = static_cast<png_bytep>(malloc(PNG_IMAGE_SIZE((*image))));
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if (!buffer) {
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//out of memory, only time when libpng doesnt free its data
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png_image_free(image);
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return false;
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}
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if (!png_image_finish_read(image, NULL, buffer, 0, NULL)) return false;
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content = reinterpret_cast<uint32_t*>(buffer);
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_premultiply(reinterpret_cast<uint32_t*>(buffer), image->width, image->height);
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return true;
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}
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bool PngLoader::close()
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{
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png_image_free(image);
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return true;
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}
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unique_ptr<Surface> PngLoader::bitmap()
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{
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if (!content) return nullptr;
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auto surface = static_cast<Surface*>(malloc(sizeof(Surface)));
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surface->buffer = (uint32_t*)(content);
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surface->stride = w;
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surface->w = w;
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surface->h = h;
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surface->cs = SwCanvas::ARGB8888;
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return unique_ptr<Surface>(surface);
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}
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