如何在透明窗口中绘制透明DirectX内容？

问题描述

我想绘制DirectX内容，以便它似乎漂浮在桌面和任何其他正在运行的应用程序之上。我还需要能够使DirectX内容半透明，这样其他东西才能显示出来。有办法吗？

I want to draw DirectX content so that it appears to be floating over top of the desktop and any other applications that are running. I also need to be able to make the directx content semi-transparent, so other things show through. Is there a way of doing this?

我在C＃中使用托管DX。

I am using Managed DX with C#.

推荐答案

从OregonGhost提供的链接开始，我找到了一种适用于Vista的解决方案。这是使用C＃语法的基本过程。此代码位于从Form继承的类中。如果在UserControl中，它似乎不起作用：

I found a solution which works on Vista, starting from the link provided by OregonGhost. This is the basic process, in C# syntax. This code is in a class inheriting from Form. It doesn't seem to work if in a UserControl:

//this will allow you to import the necessary functions from the .dll
using System.Runtime.InteropServices;

//this imports the function used to extend the transparent window border.
[DllImport("dwmapi.dll")]
static extern void DwmExtendFrameIntoClientArea(IntPtr hWnd, ref Margins pMargins);

//this is used to specify the boundaries of the transparent area
internal struct Margins {
    public int Left, Right, Top, Bottom;
}
private Margins marg;

//Do this every time the form is resized. It causes the window to be made transparent.
marg.Left = 0;
marg.Top = 0;
marg.Right = this.Width;
marg.Bottom = this.Height;
DwmExtendFrameIntoClientArea(this.Handle, ref marg);

//This initializes the DirectX device. It needs to be done once.
//The alpha channel in the backbuffer is critical.
PresentParameters presentParameters = new PresentParameters();
presentParameters.Windowed = true;
presentParameters.SwapEffect = SwapEffect.Discard;
presentParameters.BackBufferFormat = Format.A8R8G8B8;

Device device = new Device(0, DeviceType.Hardware, this.Handle,
CreateFlags.HardwareVertexProcessing, presentParameters);

//the OnPaint functions maked the background transparent by drawing black on it.
//For whatever reason this results in transparency.
protected override void OnPaint(PaintEventArgs e) {
    Graphics g = e.Graphics;

    // black brush for Alpha transparency
    SolidBrush blackBrush = new SolidBrush(Color.Black);
    g.FillRectangle(blackBrush, 0, 0, Width, Height);
    blackBrush.Dispose();

    //call your DirectX rendering function here
}

//this is the dx rendering function. The Argb clearing function is important,
//as it makes the directx background transparent.
protected void dxrendering() {
    device.Clear(ClearFlags.Target, Color.FromArgb(0, 0, 0, 0), 1.0f, 0);

    device.BeginScene();
    //draw stuff here.
    device.EndScene();
    device.Present();
}

最后，具有默认设置的窗体将具有玻璃状看起来部分透明的背景。将FormBorderStyle设置为 none，它将是100％透明的，只有您的内容浮在所有内容之上。

Lastly, a Form with default setting will have a glassy looking partially transparent background. Set the FormBorderStyle to "none" and it will be 100% transparent with only your content floating above everything.

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