使用SetLayeredWindowAttributes无法使子窗口半透明 [英] Can't make child window semi-transparent with SetLayeredWindowAttributes

问题描述

尝试使子窗口透明。 无论向SetLayeredWindowAttributes提供什么值，向子窗口提供 WS_EX_LAYERED 都会使其不可见。 然后我将以下MSDN代码
复制并粘贴到孩子的WM_CREATE处理程序中：

Trying to make a child window transparent.  Providing WS_EX_LAYERED to the child window renders it invisible no matter what values are provided to SetLayeredWindowAttributes.  Then I copied and pasted the following MSDN code to the child's WM_CREATE handler:

// Set WS_EX_LAYERED on this window 
SetWindowLong(hwnd, 
              GWL_EXSTYLE, 
              GetWindowLong(hwnd, GWL_EXSTYLE) | WS_EX_LAYERED);

// Make this window 70% alpha
SetLayeredWindowAttributes(hwnd, 0, (255 * 70) / 100, LWA_ALPHA);

因为孩子的窗口背景为白色，我也尝试将该功能的第二个参数从0（零）更改为RGB（255,255,255），但它不起作用。 有没有人有一个简单的代码示例，可以让孩子的窗口半透明？



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Since child's window background is white, I also tried to change 2nd parameter of that function from 0(zero) to RGB(255,255,255) but it didn't work.  Does anyone have a simple code sample that can make a child window semi-transparent?

推荐答案

以下是一些代码：

Here is some code:

HWND hWnd2=CreateWindowEx(WS_EX_LAYERED,lpWcx2.lpszClassName,TEXT("window name2"),WS_CHILD|WS_VISIBLE,0,0,100,100,hWnd,NULL,NULL,NULL);

case WM_CREATE:
{
  // Make this window 70% alpha
  SetLayeredWindowAttributes(hWnd, 0, (255 * 70) / 100, LWA_ALPHA);
  return 0;
}

适用于顶级窗口，但不适用于子窗口。 我在Windows 8系统上，所以该功能可以设置子窗口。出于某种原因，不是我的情况。

Works with top level window but not with child window.  I'm on Windows 8 system so the function can set child windows alike. For some reason not in my case.

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