如何从 IntPtr 句柄创建 WPF 光标 [英] How to create a WPF Cursor from an IntPtr handle

问题描述

假设我有一个游标句柄，并且我想使用该句柄创建一个 WPF Cursor 实例.

Assuming I have handle of a cursor and I'd like to create an instance of WPF Cursor using that handle.

在 Windows 窗体中，System.Windows.Forms.Cursor 类有一个接受 IntPtr 的构造函数，但 WPF System.Windows.Input.Cursor 没有有一个接受 IntPtr 的构造函数.知道如何解决这个问题并从 IntPtr 句柄创建 WPF 光标吗?

In Windows Forms, System.Windows.Forms.Cursor class has a constructor which accepts IntPtr, but WPF System.Windows.Input.Cursor doesn't have a constructor that accepts IntPtr. Any idea how to get around this and create a WPF Cursor from IntPtr handle?

例如，以下代码段(从这篇文章中借用)适用于 Windows 窗体，但我会喜欢在 WPF 中编写等价物:

For example, the following piece of code (borrowed from this post)works in Windows Forms, but I'd like to write the equivalent in WPF:

[DllImport("kernel32.dll")]
private static extern IntPtr LoadLibrary(string dllToLoad);

[DllImport("user32.dll")]
private static extern IntPtr LoadCursor(IntPtr hInstance, UInt16 lpCursorName);

private void button1_Click(object sender, EventArgs e)
{
    var l = LoadLibrary("ole32.dll");
    var h = LoadCursor(l, 6);
    this.Cursor = new Cursor(h);
}

推荐答案

您需要使用 CursorInteropHelper.Create(SafeHandle) 接受 SafeHandle,然后你可以像这样使用它:

You need to use CursorInteropHelper.Create(SafeHandle) which accepts a SafeHandle, then you can use it like this:

CursorInteropHelper.Create(theSafeHandle);

因此您需要使用 IntPtr 创建一个 SafeHandle 实例.但是，现在的问题是 SafeHandle 类是抽象的！由于 Microsoft.Win32.SafeHandles 命名空间 用于游标句柄，您可以通过从 SafeHandleZeroOrMinusOneIsInvalid 类:

So you need to create an instance of SafeHandle using an IntPtr. But, now the problem is the SafeHandle class is abstract! Since there's no implementation available in Microsoft.Win32.SafeHandles namespace for cursor handle, you can create one by deriving from SafeHandleZeroOrMinusOneIsInvalid class:

using Microsoft.Win32.SafeHandles;
using System;
using System.Runtime.InteropServices;
public sealed class SafeCursorHandle : SafeHandleZeroOrMinusOneIsInvalid
{
    [DllImport("user32.dll")]
    private static extern bool DestroyCursor(IntPtr handle);

    public SafeCursorHandle() : base(true) { }
    public SafeCursorHandle(IntPtr handle) : base(true)
    {
        SetHandle(handle);
    }
    protected override bool ReleaseHandle()
    {
        return DestroyCursor(handle);
    }
}

最后，将所有内容放在一个 WPF 示例中，该示例与 Windows 窗体示例执行相同的操作:

Finally, to put everything in a WPF example which does the same thing as the Windows Forms example:

//using System;
//using System.Runtime.InteropServices;
//using System.Windows;
//using System.Windows.Interop;

[DllImport("kernel32.dll")]
private static extern IntPtr LoadLibrary(string dllToLoad);

[DllImport("user32.dll")]
private static extern IntPtr LoadCursor(IntPtr hInstance, UInt16 lpCursorName);

private void Button_Click(object sender, RoutedEventArgs e)
{
    var l = LoadLibrary("ole32.dll");
    var h = LoadCursor(l, 6);
    this.Cursor = CursorInteropHelper.Create(new SafeCursorHandle(h));
}

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