Attachment 58775 Details for Bug 47601 – Buggy alpha blending under win32 demo

Buggy alpha blending under win32 demo

cairo_win32_alpha_blending_bug.cpp (text/plain), 2.25 KB, created by Szuromi Gábor on 2012-03-20 11:23:40 UTC

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Creator: Szuromi Gábor

Created: 2012-03-20 11:23:40 UTC

Size: 2.25 KB

patch

obsolete

>#define WIN32_LEAN_AND_MEAN
>#include <windows.h>
>#include <tchar.h>
>
>#include <cairo/cairo-win32.h>
>
>const wchar_t *windowClass = L"cairo_window";
>
>const double alpha = 1.0;
>
>void cairoPaint(HDC hdc) {
>    cairo_surface_t *paintSurface = cairo_win32_surface_create(hdc);
>    cairo_t *cr = cairo_create(paintSurface);
>
>    cairo_set_source_rgba(cr,
>        0.0, 0.0, 0.0,
>        alpha);
>    cairo_rectangle(cr,
>        10.0, 10.0,
>        50.0, 50.0);
>    cairo_fill(cr);
>
>    cairo_destroy(cr);
>    cairo_surface_destroy(paintSurface);
>}
>
>LRESULT CALLBACK windowProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam) {
>    PAINTSTRUCT ps;
>    HDC hdc;
>
>	switch (message) {
>        case WM_PAINT:
>	        hdc = BeginPaint(hWnd, &ps);
>	        cairoPaint(hdc);
>	        EndPaint(hWnd, &ps);
>	        break;
>
>        case WM_DESTROY:
>	        PostQuitMessage(0);
>	        break;
>
>        default:
>	        return DefWindowProc(hWnd, message, wParam, lParam);
>	}
>
>	return 0;
>}
>
>void registerWindowClass(HINSTANCE hInstance) {
>	WNDCLASSEX wcex;
>
>	wcex.cbSize = sizeof(WNDCLASSEX);
>
>	wcex.style			= CS_HREDRAW | CS_VREDRAW;
>	wcex.lpfnWndProc	= windowProc;
>	wcex.cbClsExtra		= 0;
>	wcex.cbWndExtra		= 0;
>	wcex.hInstance		= hInstance;
>	wcex.hIcon			= NULL;
>	wcex.hCursor		= LoadCursor(NULL, IDC_ARROW);
>	wcex.hbrBackground	= (HBRUSH)(COLOR_WINDOW+1);
>	wcex.lpszMenuName	= NULL;
>	wcex.lpszClassName	= windowClass;
>	wcex.hIconSm		= NULL;
>
>	RegisterClassEx(&wcex);
>}
>
>BOOL initInstance(HINSTANCE hInstance, int nCmdShow) {
>   HWND hWnd = CreateWindow(
>       windowClass,
>       L"Cairo Window",
>       WS_OVERLAPPEDWINDOW,
>       CW_USEDEFAULT,
>       0,
>       400,
>       200,
>       NULL,
>       NULL,
>       hInstance,
>       NULL);
>
>   if (!hWnd)
>      return FALSE;
>
>   ShowWindow(hWnd, nCmdShow);
>   UpdateWindow(hWnd);
>
>   return TRUE;
>}
>
>int APIENTRY _tWinMain(
>    HINSTANCE hInstance,
>    HINSTANCE hPrevInstance,
>    LPTSTR lpCmdLine,
>    int nCmdShow) {
>
>	registerWindowClass(hInstance);
>
>	if (!initInstance(hInstance, nCmdShow))
>	    return FALSE;
>
>    MSG msg;
>	while (GetMessage(&msg, NULL, 0, 0)) {
>	    TranslateMessage(&msg);
>		DispatchMessage(&msg);
>	}
>
>	return (int) msg.wParam;
>}

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