在客户端窗口win32 c ++中捕获图像答案

【问题标题】：Capturing image in client window win32 c++在客户端窗口win32 c ++中捕获图像
【发布时间】：2012-02-01 20:53:40
【问题描述】：

此代码试图在光标周围最大 100x100 的框中捕获绘制在窗口上的图像。 BitBlt 在这里的任何一个位置都没有返回 0，我很确定问题出在 BitBlt 的第一个函数调用上，我试图将图像从窗口的背景复制到 meta，这是一个全局声明的 HDC .除了尝试完全在内存中创建 HDC 之外，我还尝试创建并加载空白位图并将新图像捕获到与之关联的句柄中，但所做的只是像橡皮擦一样画一个白框移动时围绕光标。相关代码如下，mouseRect 和 clientRect 分别是与光标周围的框和客户矩形相关的全局变量。任何帮助表示赞赏，谢谢！

    case WM_CREATE:
    hInstance = ((LPCREATESTRUCT) lParam)->hInstance;
    GetClientRect(hWnd, &clientRect);
    hdc = GetDC(hWnd);
    meta = CreateCompatibleDC(hdc);
    return 0;


case WM_MOUSEMOVE:    
    x = LOWORD(lParam);
    y = HIWORD(lParam);
    hdc = GetDC(hWnd);
    BitBlt(hdc, mouseRect.left, mouseRect.top, mouseRect.right-mouseRect.left, mouseRect.bottom-mouseRect.top, meta, 0, 0, SRCCOPY);
    ReleaseDC(hWnd, meta);
    meta = CreateCompatibleDC(hdc);
    if(y<50)
        mouseRect.top = 0;
    else
        mouseRect.top = y-50;
    if(x<50)
        mouseRect.left = 0;
    else
        mouseRect.left = x-50;
    if(clientRect.right-x<50)
        mouseRect.right = clientRect.right;
    else
        mouseRect.right = x+50;
    if(clientRect.bottom-y<50)
        mouseRect.bottom = clientRect.bottom;
    else
        mouseRect.bottom = y+50;
    BitBlt(meta, 0,  0, mouseRect.right-mouseRect.left, mouseRect.bottom-mouseRect.top, hdc, mouseRect.left, mouseRect.top, SRCCOPY);
    ReleaseDC(hWnd, hdc);
    return 0;

【问题讨论】：

标签： c++ winapi bitblt

【解决方案1】：

修正了代码，这里是更正后的 WM_MOUSEMOVE 代码

case WM_MOUSEMOVE:    
x = LOWORD(lParam);
y = HIWORD(lParam);
hdc = GetDC(hWnd);
BitBlt(hdc, mouseRect.left, mouseRect.top, mouseRect.right-mouseRect.left, mouseRect.bottom-mouseRect.top, hdcMemDC, 0, 0, SRCCOPY);
ReleaseDC(hWnd, hdcMemDC);
if(y<50)
    mouseRect.top = 0;
else
    mouseRect.top = y-50;
if(x<50)
    mouseRect.left = 0;
else
    mouseRect.left = x-50;
if(clientRect.right-x<50)
    mouseRect.right = clientRect.right;
else
    mouseRect.right = x+50;
if(clientRect.bottom-y<50)
    mouseRect.bottom = clientRect.bottom;
else
    mouseRect.bottom = y+50;
hdcMemDC = CreateCompatibleDC(hdc);
hbmScreen = CreateCompatibleBitmap(hdc, mouseRect.right-mouseRect.left, mouseRect.bottom-mouseRect.top);
SelectObject(hdcMemDC,hbmScreen);    
if(!BitBlt(hdcMemDC, 0, 0, mouseRect.right-mouseRect.left, mouseRect.bottom-mouseRect.top, hdc, mouseRect.left, mouseRect.top, SRCCOPY))
{
    MessageBox(hWnd, "BitBlt has failed", "Failed", MB_OK);
}
ReleaseDC(hWnd, hdc);
return 0;

【讨论】：