VC++ UpdateLayeredWindowIndirect

最新推荐文章于 2024-12-24 17:28:40 发布

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#vc++ #structure #function #animation #windows #performance

本文介绍了UpdateLayeredWindowIndirect函数，该函数用于更新图层窗口的位置、大小、形状、内容及透明度。通过使用UPDATELAYEREDWINDOWINFO结构传递参数，可以更简洁地控制图层窗口的更新。此外，文章还提到了无缝动画效果实现及最佳性能实践。

UpdateLayeredWindowIndirect Function

Updates the position, size, shape, content, and translucency of a layered window.

Syntax

BOOL UpdateLayeredWindowIndirect(      
    HWND hwnd,
    const UPDATELAYEREDWINDOWINFO *pULWInfo
);

Parameters

hwnd
[in] Handle to a layered window. A layered window is created by specifying WS_EX_LAYERED when creating the window with the CreateWindowEx function.
pULWInfo
[in] Pointer to an UPDATELAYEREDWINDOWINFO structure that contains the information for the window.

Return Value

If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero. To get extended error information, call GetLastError.

Remarks

UpdateLayeredWindowIndirect is similar to UpdateLayeredWindow but uses an UPDATELAYEREDWINDOWINFO structure to contain much of the information that is provided to UpdateLayeredWindow through its parameters.

The UpdateLayeredWindowIndirect function maintains the window's appearance on the screen. The windows underneath a layered window do not need to be repainted when they are uncovered due to a call to UpdateLayeredWindowIndirect, because the system will automatically repaint them. This permits seamless animation of the layered window.

UpdateLayeredWindowIndirect always updates the entire window. To update part of a window, use the traditional WM_PAINT and set the blend value using SetLayeredWindowAttributes.

For best drawing performance by the layered window and any underlying windows, the layered window should be as small as possible. An application should also process the message and re-create its layered windows when the display's color depth changes.

For more information, see Layered Windows.