动态切换光标类型
自定义光标
系统有很多光标类型 ：Cursors 类 (System.Windows.Input) | Microsoft Docs
本章介绍如何自定义光标、并动态切换光标类型。
动态切换光标类型以白板书写为例：鼠标操作时,Cursor为红点；触摸时，Cursor为空；
public MainWindow()
{
InitializeComponent();
MouseEnter += (s, e) =>
{
ShowMouseCursor(e);
};
MouseMove += (s, e) =>
{
ShowMouseCursor(e);
};
StylusMove += (s, e) =>
{
ShowNoneCursor();
};
}
设置光标显示：
private void ShowNoneCursor()
{
if (Cursor == Cursors.None)
{
return;
}
Cursor = Cursors.None;
Mouse.UpdateCursor();
}
private void ShowMouseCursor(MouseEventArgs e)
{
if (e.StylusDevice != null && e.StylusDevice.Id > -1)
{
return;
}
if (Cursor == GetFillCursor())
{
return;
}
Cursor = GetFillCursor();
Mouse.UpdateCursor();
}
private Cursor _fillCursor = null;
private Cursor GetFillCursor()
{
return _fillCursor ?? (_fillCursor = CursorHelper.CreateFillCursor());
}
触摸书写时，会有个默认光标，所以此处把触摸时的光标置空Cursors.None。
Mouse.UpdateCursor()能强制更新光标。当然，不调用这个更新方法肉眼其实也看不出啥。。。
光标切换效果如上，前面一段是用鼠标书写，后面是触摸书写，光标类型有切换。红点光标自定义方案见下方。
自定义光标自定义一个纯色的圆形光标：
public static Cursor CreateFillCursor(int size = 24, Brush fillBrush = null)
{
int unitSize = size / 4;
var bmp = new Bitmap(size, size);
using (Graphics g = Graphics.FromImage(bmp))
{
g.Clip = new Region(new Rectangle(0, 0, size, size));
g.SmoothingMode = SmoothingMode.HighQuality;
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
using (var pen = new Pen(fillBrush ?? Brushes.Red, unitSize))
{
g.DrawEllipse(pen, new Rectangle(unitSize, unitSize, unitSize, unitSize));
}
}
return BitmapCursor.CreateBmpCursor(bmp);
}
也可以通过图片资源BitmapSource来生成光标：
public static Cursor CreateFromBitmapSource(BitmapSource source)
{
var bitmap = BitmapSourceToBitmap(source);
return BitmapCursor.CreateBmpCursor(bitmap);
}
private static Bitmap BitmapSourceToBitmap(BitmapSource source)
{
using (var stream = new MemoryStream())
{
var e = new BmpBitmapEncoder();
e.Frames.Add(BitmapFrame.Create(source));
e.Save(stream);
var bmp = new Bitmap(stream);
return bmp;
}
}
BitmapCursor:
internal class BitmapCursor : SafeHandle
{
public override bool IsInvalid => handle == (IntPtr)(-1);
public static Cursor CreateBmpCursor(Bitmap cursorBitmap)
{
var c = new BitmapCursor(cursorBitmap);
return CursorInteropHelper.Create(c);
}
protected BitmapCursor(Bitmap cursorBitmap)
: base((IntPtr)(-1), true)
{
handle = cursorBitmap.GetHicon();
}
protected override bool ReleaseHandle()
{
bool result = DestroyIcon(handle);
handle = (IntPtr)(-1);
return result;
}
[DllImport("user32")]
private static extern bool DestroyIcon(IntPtr hIcon);
}
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