c - InvalidateRect() 是否向子控件发送 WM_PAINT 消息？

Question

如果我在父窗口上调用 InvalidateRect()，例如:

InvalidateRect(hWnd, NULL, TRUE);

将会发生的是，在 WM_PAINT 处理程序中，BeginPaint() 将发送一条 WM_ERASEBKGND 消息，该消息将删除背景，并且因此所有子控件都会消失。

但是当我调用 InvalidateRect() 时，子控件仍然保留，这是否意味着 InvalidateRect() 也会向子控件发送 WM_PAINT 消息还可以控制吗？

Answer 1

Does InvalidateRect() sends WM_PAINT messages to the child controls?

是的(大部分)，这里描述得很清楚:

https://msdn.microsoft.com/en-us/library/windows/desktop/dd183426(v=vs.85).aspx

The system sets the update region for a child window whenever part of the parent window's update region includes a portion of the child window. In such cases, the system first sends a WM_PAINT message to the parent window and then sends a message to the child window, allowing the child to restore any portions of the window that the parent may have drawn over.

但有异常(exception):

an application cannot generate a WM_PAINT message for the child by invalidating a portion of the parent's client area that lies entirely under the child window. In such cases, neither window receives a WM_PAINT message.

这实际上很有趣

您可以通过将 WS_CLIPCHILDREN 设置为父窗口来防止子窗口重绘，或者通过使用带有 RDW_NOCHILDREN 标志的 RedrawWindow 函数使重绘无效。