58 lines
1.5 KiB
C++
58 lines
1.5 KiB
C++
#include <easy2d/graphics/alpha_mask.h>
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namespace easy2d {
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AlphaMask::AlphaMask(int width, int height)
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: width_(width)
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, height_(height)
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, data_(width * height, 255) {
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}
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AlphaMask AlphaMask::createFromPixels(const uint8_t* pixels, int width, int height, int channels) {
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AlphaMask mask(width, height);
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if (!pixels || width <= 0 || height <= 0) {
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return mask;
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}
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// 根据通道数提取Alpha值
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for (int y = 0; y < height; ++y) {
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for (int x = 0; x < width; ++x) {
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int pixelIndex = (y * width + x) * channels;
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uint8_t alpha = 255;
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if (channels == 4) {
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// RGBA格式，Alpha在第四个通道
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alpha = pixels[pixelIndex + 3];
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} else if (channels == 1) {
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// 灰度图，直接作为Alpha
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alpha = pixels[pixelIndex];
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} else if (channels == 3) {
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// RGB格式，没有Alpha通道，视为不透明
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alpha = 255;
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}
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mask.data_[y * width + x] = alpha;
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}
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}
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return mask;
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}
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uint8_t AlphaMask::getAlpha(int x, int y) const {
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if (!isValid(x, y)) {
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return 0;
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}
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return data_[y * width_ + x];
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}
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bool AlphaMask::isOpaque(int x, int y, uint8_t threshold) const {
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return getAlpha(x, y) >= threshold;
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}
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bool AlphaMask::isValid(int x, int y) const {
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return x >= 0 && x < width_ && y >= 0 && y < height_;
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}
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} // namespace easy2d
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