应用程序窗口截屏有空白输出 [英] Application window screen capture has blank output

问题描述

我正在尝试屏幕捕获应用程序窗口的内容，类似于Alt-PrintScreen键盘快捷键。



对于大多数应用程序窗口，它工作正常。但是，对于某些应用程序，结果为空白输出。



相关代码：

 const int height = 1000; 
 const int width = 1000; 
 
 const wchar_t * windowTitle = L" MEmu 2.8.6-MEmu" ;; 
 HWND hwndSrc = FindWindowEx（0,0,0，windowTitle）; 
 HDC hdcSrc = GetWindowDC（hwndSrc）; 
 
 
 PAINTSTRUCT ps; 
 HDC hdc = BeginPaint（hWnd，& ps）; 
 BitBlt（hdc，0,0，width，height，hdcSrc，0,0，SRCCOPY）; 
 EndPaint（hWnd，& ps）; 

预期产量：

i.imgur.com/23bcC0Z.png



实际输出：

i.imgur.com/chYb9g2.png



$
为什么它不能用于某些窗口？

解决方案

尝试组合标志： SRCCOPY | CAPTUREBLT 。还要考虑替代方案，例如
PrintWindow 函数，Direct3d等：
https://blogs.msdn.microsoft.com/dsui_team/2013/03/25/ways-to-capture-the-screen

I am trying to screen capture an application window's contents, similar to the Alt-PrintScreen keyboard shortcut.

For most application windows, it works fine. However, for some applications, the result has blank output.

Relevant code:

const int height = 1000;
const int width = 1000;

const wchar_t *windowTitle = L"MEmu 2.8.6 - MEmu";
HWND hwndSrc = FindWindowEx(0, 0, 0, windowTitle);
HDC hdcSrc = GetWindowDC(hwndSrc);


PAINTSTRUCT ps;
HDC hdc = BeginPaint(hWnd, &ps);
BitBlt(hdc, 0, 0, width, height, hdcSrc, 0, 0, SRCCOPY);
EndPaint(hWnd, &ps);

Expected output:
i.imgur.com/23bcC0Z.png

Actual output:
i.imgur.com/chYb9g2.png


Why is it not working for some windows?

解决方案

Try a combination of flags: SRCCOPY | CAPTUREBLT. Also consider the alternatives, such as the PrintWindow function, Direct3d, etc.: https://blogs.msdn.microsoft.com/dsui_team/2013/03/25/ways-to-capture-the-screen.

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