47 lines
1.6 KiB
C++
47 lines
1.6 KiB
C++
#pragma once
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#include "gdiplus_helpers.h"
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// Presumes prior #include of webp/decode.h
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static bool IsImageWebP(const void * ptr, size_t bytes) {
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if (bytes < 12) return false;
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return memcmp(ptr, "RIFF", 4) == 0 && memcmp((const char*)ptr + 8, "WEBP", 4) == 0;
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}
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// WebP-aware GdiplusImageFromMem
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static Gdiplus::Image * GdiplusImageFromMem2(const void * ptr, size_t bytes) {
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GdiplusErrorHandler EH;
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using namespace Gdiplus;
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if (IsImageWebP(ptr, bytes)) {
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WebPBitstreamFeatures bs;
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if (WebPGetFeatures((const uint8_t*)ptr, bytes, &bs) != VP8_STATUS_OK) {
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throw std::runtime_error("WebP decoding failure");
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}
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const Gdiplus::PixelFormat pf = bs.has_alpha ? PixelFormat32bppARGB : PixelFormat32bppRGB;
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const int pfBytes = 4; // Gdiplus RGB is 4 bytes
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int w = 0, h = 0;
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// ALWAYS decode BGRA, Gdiplus will disregard alpha if was not originally present
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uint8_t * decodedData = WebPDecodeBGRA((const uint8_t*)ptr, bytes, &w, &h);
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pfc::onLeaving scope([decodedData] {WebPFree(decodedData); });
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if (decodedData == nullptr || w <= 0 || h <= 0) throw std::runtime_error("WebP decoding failure");
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pfc::ptrholder_t<Bitmap> ret = new Gdiplus::Bitmap(w, h, pf);
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EH << ret->GetLastStatus();
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Rect rc(0, 0, w, h);
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Gdiplus::BitmapData bitmapData;
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EH << ret->LockBits(&rc, 0, pf, &bitmapData);
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uint8_t * target = (uint8_t*)bitmapData.Scan0;
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const uint8_t * source = decodedData;
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for (int y = 0; y < h; ++y) {
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memcpy(target, source, w * pfBytes);
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target += bitmapData.Stride;
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source += pfBytes * w;
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}
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EH << ret->UnlockBits(&bitmapData);
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return ret.detach();
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}
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return GdiplusImageFromMem(ptr, bytes);
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}
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