preview window flipped

src/preview/PreviewWindowThread.cpp

@@ -4,6 +4,7 @@
 #include "../logging/Logger.h"
 
 #include <algorithm>
+#include <cstring>
 
 namespace RenderCadenceCompositor
 {
@@ -209,6 +210,8 @@ void PreviewWindowThread::Paint(HWND window)
 		frame.width > 0 &&
 		frame.height > 0;
 	if (canPaintFrame)
+	{
+		if (CopyPreviewOrientedBgra8Frame(frame))
 		{
 			const int previousStretchMode = SetStretchBltMode(dc, HALFTONE);
 			POINT previousBrushOrigin = {};
@@ -232,7 +235,7 @@ void PreviewWindowThread::Paint(HWND window)
 				0,
 				static_cast<int>(frame.width),
 				static_cast<int>(frame.height),
-			frame.bytes,
+				mPaintPixels.data(),
 				&bitmapInfo,
 				DIB_RGB_COLORS,
 				SRCCOPY);
@@ -242,6 +245,16 @@ void PreviewWindowThread::Paint(HWND window)
 			SetBrushOrgEx(dc, previousBrushOrigin.x, previousBrushOrigin.y, nullptr);
 		}
 		else
+		{
+			if (!mLoggedPaintCopyFailure)
+			{
+				TryLog(LogLevel::Warning, "preview", "Preview frame could not be copied for mirrored presentation.");
+				mLoggedPaintCopyFailure = true;
+			}
+			FillRect(dc, &client, reinterpret_cast<HBRUSH>(GetStockObject(BLACK_BRUSH)));
+		}
+	}
+	else
 	{
 		FillRect(dc, &client, reinterpret_cast<HBRUSH>(GetStockObject(BLACK_BRUSH)));
 	}
@@ -251,4 +264,34 @@ void PreviewWindowThread::Paint(HWND window)
 
 	EndPaint(window, &paint);
 }
+
+bool PreviewWindowThread::CopyPreviewOrientedBgra8Frame(const SystemFrame& frame)
+{
+	constexpr std::size_t kBgraBytesPerPixel = 4;
+	if (frame.bytes == nullptr || frame.width == 0 || frame.height == 0 || frame.rowBytes <= 0)
+		return false;
+
+	const std::size_t width = static_cast<std::size_t>(frame.width);
+	const std::size_t height = static_cast<std::size_t>(frame.height);
+	const std::size_t sourceRowBytes = static_cast<std::size_t>(frame.rowBytes);
+	const std::size_t destinationRowBytes = width * kBgraBytesPerPixel;
+	if (sourceRowBytes < destinationRowBytes)
+		return false;
+
+	mPaintPixels.resize(destinationRowBytes * height);
+	const unsigned char* sourceBytes = static_cast<const unsigned char*>(frame.bytes);
+	for (std::size_t y = 0; y < height; ++y)
+	{
+		const unsigned char* sourceRow = sourceBytes + (height - 1u - y) * sourceRowBytes;
+		unsigned char* destinationRow = mPaintPixels.data() + y * destinationRowBytes;
+		for (std::size_t x = 0; x < width; ++x)
+		{
+			const unsigned char* sourcePixel = sourceRow + x * kBgraBytesPerPixel;
+			unsigned char* destinationPixel = destinationRow + x * kBgraBytesPerPixel;
+			std::memcpy(destinationPixel, sourcePixel, kBgraBytesPerPixel);
+		}
+	}
+
+	return true;
+}
 }

src/preview/PreviewWindowThread.h

@@ -6,6 +6,7 @@
 
 #include <atomic>
 #include <thread>
+#include <vector>
 
 #ifndef NOMINMAX
 #define NOMINMAX
@@ -35,9 +36,12 @@ private:
 	void ThreadMain();
 	bool CreatePreviewWindow(std::string& error);
 	void Paint(HWND window);
+	bool CopyPreviewOrientedBgra8Frame(const SystemFrame& frame);
 
 	SystemFrameExchange* mExchange = nullptr;
 	PreviewWindowConfig mConfig;
+	std::vector<unsigned char> mPaintPixels;
+	bool mLoggedPaintCopyFailure = false;
 	std::thread mThread;
 	std::atomic<bool> mStopRequested{ false };
 	std::atomic<bool> mRunning{ false };