Question

感谢您之前的答案，这些答案使我能够完成在鼠标坐标中显示大红十字的基本工具，以便更加明显。红十字是透明背景的透明图像。问题是你不能点击，因为它的最顶层和窗体的中心实际上是鼠标xy。是否有任何方法可以使这个可用，以便交叉仍然显示在光标上，但“可点击”通过？

Answer 1

您可以使用SetWindowLong设置WS_EX_TRANSPARENT窗口样式：

如果分层窗口具有WS_EX_TRANSPARENT扩展窗口样式，则将忽略分层窗口的形状，并将鼠标事件传递给分层窗口下的其他窗口。

CodeProject有this文章详细介绍了该技术。虽然它在VB.NET中，但转换为C＃应该很容易。

我过去使用过以下代码：

public enum GWL
{
    ExStyle = -20
}

public enum WS_EX
{
    Transparent = 0x20,
    Layered = 0x80000
}

public enum LWA
{
    ColorKey = 0x1,
    Alpha = 0x2
}

[DllImport("user32.dll", EntryPoint = "GetWindowLong")]
public static extern int GetWindowLong(IntPtr hWnd, GWL nIndex);

[DllImport("user32.dll", EntryPoint = "SetWindowLong")]
public static extern int SetWindowLong(IntPtr hWnd, GWL nIndex, int dwNewLong);

[DllImport("user32.dll", EntryPoint = "SetLayeredWindowAttributes")]
public static extern bool SetLayeredWindowAttributes(IntPtr hWnd, int crKey, byte alpha, LWA dwFlags);

protected override void OnShown(EventArgs e)
{
    base.OnShown(e);
    int wl = GetWindowLong(this.Handle, GWL.ExStyle);
    wl = wl | 0x80000 | 0x20;
    SetWindowLong(this.Handle, GWL.ExStyle, wl);
    SetLayeredWindowAttributes(this.Handle, 0, 128, LWA.Alpha);
}

但它也是从其他地方复制的。这里的重要部分是OnShown方法。虽然我不得不承认这一行

wl = wl | 0x80000 | 0x20;

有点神秘，设置了WS_EX_LAYERED和WS_EX_TRANSPARENT扩展样式。

您也可以将其设置为

wl = wl | WS_EX.Layered | WS_EX.Transparent;

Answer 2

提供更详细/评论的版本，它也使用TransparencyKey作为透明度键（不是上面版本的黑色），并且可以根据需要设置_alpha。

        /// <summary>
        /// 0: the window is completely transparent ... 255: the window is opaque
        /// </summary>
        private byte _alpha;

        private enum GetWindowLong
        {
            /// <summary>
            /// Sets a new extended window style.
            /// </summary>
            GWL_EXSTYLE = -20
        }

        private enum ExtendedWindowStyles
        {
            /// <summary>
            /// Transparent window.
            /// </summary>
            WS_EX_TRANSPARENT = 0x20,
            /// <summary>
            /// Layered window. http://msdn.microsoft.com/en-us/library/windows/desktop/ms632599%28v=vs.85%29.aspx#layered
            /// </summary>
            WS_EX_LAYERED = 0x80000
        }

        private enum LayeredWindowAttributes
        {
            /// <summary>
            /// Use bAlpha to determine the opacity of the layered window.
            /// </summary>
            LWA_COLORKEY = 0x1,
            /// <summary>
            /// Use crKey as the transparency color.
            /// </summary>
            LWA_ALPHA = 0x2
        }

        [DllImport("user32.dll", EntryPoint = "GetWindowLong")]
        private static extern int User32_GetWindowLong(IntPtr hWnd, GetWindowLong nIndex);

        [DllImport("user32.dll", EntryPoint = "SetWindowLong")]
        private static extern int User32_SetWindowLong(IntPtr hWnd, GetWindowLong nIndex, int dwNewLong);

        [DllImport("user32.dll", EntryPoint = "SetLayeredWindowAttributes")]
        private static extern bool User32_SetLayeredWindowAttributes(IntPtr hWnd, int crKey, byte bAlpha, LayeredWindowAttributes dwFlags);

        protected override void OnShown(EventArgs e)
        {
            base.OnShown(e);
            //Click through
            int wl = User32_GetWindowLong(this.Handle, GetWindowLong.GWL_EXSTYLE);
            User32_SetWindowLong(this.Handle, GetWindowLong.GWL_EXSTYLE, wl | (int)ExtendedWindowStyles.WS_EX_LAYERED | (int)ExtendedWindowStyles.WS_EX_TRANSPARENT);
            //Change alpha
            User32_SetLayeredWindowAttributes(this.Handle, (TransparencyKey.B << 16) + (TransparencyKey.G << 8) + TransparencyKey.R, _alpha, LayeredWindowAttributes.LWA_COLORKEY | LayeredWindowAttributes.LWA_ALPHA);
        }

最顶层的形式，点击“通过”可能吗？

2 个答案: