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我正在尝试在透明窗口上使用 GDIplus 进行绘制并遇到很多闪烁。我已经阅读了很多建议实现双缓冲或渲染到屏幕外表面的线程会有所帮助，我已经这样做了，但无济于事。

知道我做错了什么以及如何解决吗？谢谢。

#include <Windows.h>
#include <stdio.h>
#include <time.h>
#include <GdiPlus.h>

#pragma comment(lib, "GdiPlus.lib")

HWND hWnd = NULL;
WNDCLASSEX wcex;
HDC hdc = NULL;
PAINTSTRUCT ps;
HGDIOBJ hfDefault;
MSG msg;
COLORREF transKey = RGB(37,14,103);
ULONG_PTR m_gdiplusToken;

char window_title[9] = "testings";
char window_class[9] = "testings";

int window_width = GetSystemMetrics(SM_CXSCREEN);
int window_height = GetSystemMetrics(SM_CYSCREEN);

DWORD MainThread(LPVOID lpArgs)
{
    while(1)
    {
        RECT rc = {0,0,window_width,window_height};
        InvalidateRect(hWnd, &rc, false);
        UpdateWindow(hWnd);
        Sleep(50);
    }
}

LRESULT CALLBACK WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    if(msg == WM_CREATE)
    {
        hfDefault = (HFONT)GetStockObject(DEFAULT_GUI_FONT);

        Gdiplus::GdiplusStartupInput gdiplusStartupInput;
        Gdiplus::GdiplusStartup(&m_gdiplusToken, &gdiplusStartupInput, NULL);

        SetLayeredWindowAttributes(hWnd, transKey, 128, LWA_COLORKEY);
    }
    else if(msg == WM_PAINT)
    {
        hdc = BeginPaint(hWnd, &ps);

        Gdiplus::Graphics g(hdc);

        g.Clear(Gdiplus::Color(37,14,103));

        Gdiplus::Bitmap* curBitmap = new Gdiplus::Bitmap(window_width, window_height);
        Gdiplus::Graphics* g1 = g.FromImage(curBitmap);

        static int x=1,y=1;
        // x += 3;
        y += 2;

        Gdiplus::Pen pen(Gdiplus::Color(255, 255, 0, 255));

        g1->DrawLine(&pen, x, y, window_width/2, window_height/2);

        g.DrawImage(curBitmap, 0, 0);

        EndPaint(hWnd, &ps);
    }
    else if(msg == WM_CLOSE)
    {
        DestroyWindow(hWnd);
    }
    else if(msg == WM_DESTROY)
    {
        PostQuitMessage(0);
    }
    else
    {
        return DefWindowProc(hWnd, msg, wParam, lParam);
    }

    return 0;
}

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
    HBRUSH hbrBackground = CreateSolidBrush(transKey);

    wcex.cbSize        = sizeof(WNDCLASSEX);
    wcex.style         = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc   = WndProc;
    wcex.cbClsExtra    = 0;
    wcex.cbWndExtra    = 0;
    wcex.hInstance     = hInstance;
    wcex.hIcon         = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_APPLICATION));
    wcex.hCursor       = LoadCursor(NULL, IDC_ARROW);
    wcex.hbrBackground = hbrBackground;
    wcex.lpszMenuName  = NULL;
    wcex.lpszClassName = window_class;
    wcex.hIconSm       = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_APPLICATION));

    if(!RegisterClassEx(&wcex))
        return 1;

    hWnd = CreateWindowEx(
        WS_EX_LAYERED | WS_EX_TRANSPARENT | WS_EX_TOPMOST,
        window_class,
        window_title,
        WS_POPUP,
        0,
        0,
        window_width,
        window_height,
        NULL,
        NULL,
        hInstance,
        NULL
    );

    if(!hWnd)
        return 1;

    ShowWindow(hWnd, nCmdShow);
    UpdateWindow(hWnd);

    CreateThread(NULL, NULL, (LPTHREAD_START_ROUTINE)MainThread, NULL, NULL, NULL);

    while(GetMessage(&msg, NULL, 0, 0) > 0)
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    Gdiplus::GdiplusShutdown(m_gdiplusToken);
    return msg.wParam;
}
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1 回答 1

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您的窗口上有该WS_EX_TRANSPARENT属性，这会导致其下方的窗口在每次您的窗口无效时重新绘制。尝试删除它。

的意思WS_EX_TRANSPARENT是告诉 Windows 你不会在整个窗口表面上绘图（即保持部分透明），因此它需要确保首先渲染下面的所有内容，以便它可以显示出来。

于 2013-01-04T19:04:11.200 回答