Question

我使用下面的代码渲染透明图标：

    private void button1_Click(object sender, EventArgs e)
    {
        // using LoadCursorFromFile from user32.dll
        var cursor = NativeMethods.LoadCustomCursor(@"d:\Temp\Cursors\Cursors\aero_busy.ani");

        // cursor -> bitmap
        Bitmap bitmap = new Bitmap(48, 48, PixelFormat.Format32bppArgb);
        Graphics gBitmap = Graphics.FromImage(bitmap);
        cursor.DrawStretched(gBitmap, new Rectangle(0, 0, 32, 32));

        // 1. Draw bitmap on a form canvas
        Graphics gForm = Graphics.FromHwnd(this.Handle);
        gForm.DrawImage(bitmap, 50, 50);

        // 2. Draw cursor directly to a form canvas
        cursor.Draw(gForm, new Rectangle(100, 50, 32, 32));

        cursor.Dispose();
    }

不幸的是我无法将透明光标渲染到位图！当我将Cursor直接绘制到窗体画布时，它可以工作，但是当我将Cursor绘制到位图时会出现问题。任何建议都非常感谢。

alt text

Answer 1

您现在拥有的解决方案并不完全适用于托管代码。你自己的评论说你是来自user32.dll的P / Invoking LoadCursorFromFile。无论如何，使用Win32 API实际上并不是你应该害怕的。

正如我在评论中提到的，您尝试做的事情通常是使用GDI +绘图函数存在问题，就像.NET Framework提供的大多数函数一样。使用GDI可以更轻松地完成任务。 您可以使用以下代码从光标（或图标，它们基本上可以互换）创建一个符合Alpha通道的位图：

[StructLayout(LayoutKind.Sequential)]    
private struct ICONINFO
{
    public bool fIcon;
    public int xHotspot;
    public int yHotspot;
    public IntPtr hbmMask;
    public IntPtr hbmColor;
}

[DllImport("user32")]
private static extern bool GetIconInfo(IntPtr hIcon, out ICONINFO pIconInfo);

[DllImport("user32.dll")]
private static extern IntPtr LoadCursorFromFile(string lpFileName);

[DllImport("gdi32.dll", SetLastError = true)]
private static extern bool DeleteObject(IntPtr hObject);

private Bitmap BitmapFromCursor(Cursor cur)
{
    ICONINFO ii;
    GetIconInfo(cur.Handle, out ii);

    Bitmap bmp = Bitmap.FromHbitmap(ii.hbmColor);
    DeleteObject(ii.hbmColor);
    DeleteObject(ii.hbmMask);

    BitmapData bmData = bmp.LockBits(new Rectangle(0, 0, bmp.Width, bmp.Height), ImageLockMode.ReadOnly, bmp.PixelFormat);
    Bitmap dstBitmap = new Bitmap(bmData.Width, bmData.Height, bmData.Stride, PixelFormat.Format32bppArgb, bmData.Scan0);
    bmp.UnlockBits(bmData);

    return new Bitmap(dstBitmap);
}

private void Form1_Paint(object sender, System.Windows.Forms.PaintEventArgs e)
{
    //Using LoadCursorFromFile from user32.dll, get a handle to the icon
    IntPtr hCursor = LoadCursorFromFile("C:\\Windows\\Cursors\\Windows Aero\\aero_busy.ani");

    //Create a Cursor object from that handle
    Cursor cursor = new Cursor(hCursor);

    //Convert that cursor into a bitmap
    using (Bitmap cursorBitmap = BitmapFromCursor(cursor))
    {
        //Draw that cursor bitmap directly to the form canvas
        e.Graphics.DrawImage(cursorBitmap, 50, 50);
    }
}

如果此代码无法编译，请确保您为using，System.Drawing和System.Drawing.Imaging添加了System.Runtime.InteropServices条语句。另请记得将Form1_Paint方法连接为表单Paint事件的处理程序。

经过测试可行：

cursor, drawn from bitmap complete with alpha channel

Answer 2

@Cody Gray，这不适用于颜色位低的游标。

另一种方法是使用Icon.ExtractAssociatedIcon代替：

System.Drawing.Icon i = System.Drawing.Icon.ExtractAssociatedIcon(@"C:\Windows\Cursors\arrow_rl.cur");
System.Drawing.Bitmap b = i.ToBitmap();

希望有人帮助......

如何渲染透明光标到位图保留alpha通道？

2 个答案: