WPF 窗体中的 Canvas 限定范围拖动 鼠标滚轴改变大小

xaml代码:

 1 <Canvas Name="movBg">
 2             <Canvas.Background>
 3                 <LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
 4                     <GradientStop Color="White" Offset="0" />
 5                     <GradientStop Color="#FFF5FF00" Offset="1" />
 6                 </LinearGradientBrush>
 7             </Canvas.Background>
 8             <Canvas Canvas.Top="50" Canvas.Left="50"  Height="100" HorizontalAlignment="Left" Name="mov" VerticalAlignment="Top" Width="200" MouseLeftButtonDown="mov_MouseLeftButtonDown" MouseLeftButtonUp="mov_MouseLeftButtonUp" MouseMove="mov_MouseMove" MouseWheel="mov_MouseWheel" MaxWidth="300" MaxHeight="300">
 9                 <Border BorderThickness="1" BorderBrush="Black" Width="{Binding ElementName=mov,Path=Width}" Height="{Binding ElementName=mov,Path=Height}" MaxWidth="{Binding ElementName=mov,Path=MaxWidth}" MaxHeight="{Binding ElementName=mov,Path=MaxHeight}"></Border>
10                 <Canvas.Background>
11                     <LinearGradientBrush EndPoint="1,0.5" StartPoint="0,0.5">
12                         <GradientStop Color="White" Offset="0" />
13                         <GradientStop Color="#FFD679F2" Offset="1" />
14                     </LinearGradientBrush>
15                 </Canvas.Background>
16             </Canvas>
17 </Canvas>  

C#代码：

  1 #region 拖动选区,滚轴改变大小
  2         //鼠标相对于被拖动的Canvas控件mov的坐标
  3         Point childPoint = new Point();
  4         //鼠标相对于作为容器的Canvas控件movBg的坐标
  5         Point prevPoint = new Point();
  6
  7         private void mov_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
  8         {
  9             childPoint = e.GetPosition(mov);
 10         }
 11
 12         private void mov_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
 13         {
 14             Canvas c = sender as Canvas;
 15             Rect rc = new Rect(1, 1, movBg.ActualWidth, movBg.ActualHeight);
 16             Rect childRc = new Rect(Canvas.GetLeft(c), Canvas.GetTop(c), c.ActualWidth, c.ActualHeight);
 17             if (!rc.Contains(childRc))
 18             {
 19                 childRc = AutoResize(rc, childRc);
 20                 c.SetValue(Canvas.LeftProperty, childRc.Left);
 21                 c.SetValue(Canvas.TopProperty, childRc.Top);
 22                 c.Width = childRc.Width;
 23                 c.Height = childRc.Height;
 24             }
 25             c.ReleaseMouseCapture();
 26         }
 27
 28         private void mov_MouseMove(object sender, MouseEventArgs e)
 29         {
 30             if (e.LeftButton == MouseButtonState.Pressed)
 31             {
 32                 Canvas c = sender as Canvas;
 33
 34                 prevPoint = e.GetPosition(movBg);
 35                 double x = prevPoint.X - childPoint.X;
 36                 double y = prevPoint.Y - childPoint.Y;
 37
 38                 Rect rc = new Rect(1, 1, movBg.ActualWidth, movBg.ActualHeight);
 39                 Rect childRc = new Rect(Canvas.GetLeft(c), Canvas.GetTop(c), c.ActualWidth, c.ActualHeight);
 40                 if (!rc.Contains(childRc))
 41                 {
 42                     childRc = AutoResize(rc, childRc);
 43                     c.SetValue(Canvas.LeftProperty, childRc.Left);
 44                     c.SetValue(Canvas.TopProperty, childRc.Top);
 45                     c.Width = childRc.Width;
 46                     c.Height = childRc.Height;
 47                     c.ReleaseMouseCapture();
 48                 }
 49                 else
 50                 {
 51                     c.SetValue(Canvas.LeftProperty, prevPoint.X - childPoint.X);
 52                     c.SetValue(Canvas.TopProperty, prevPoint.Y - childPoint.Y);
 53                     c.CaptureMouse();
 54                 }
 55             }
 56         }
 57
 58         private Rect AutoResize(Rect outerRc, Rect innerRc)
 59         {
 60             double with = innerRc.Width;
 61             double height = innerRc.Height;
 62
 63             if (innerRc.Left < outerRc.Left)
 64             {
 65                 innerRc.X = outerRc.Left + 1;
 66                 innerRc.Width = with;
 67             }
 68             if (innerRc.Right > outerRc.Right)
 69             {
 70                 innerRc.X = outerRc.Right - with - 1;
 71                 innerRc.Width = with;
 72             }
 73             if (innerRc.Top < outerRc.Top)
 74             {
 75                 innerRc.Y = outerRc.Top + 1;
 76                 innerRc.Height = height;
 77             }
 78             if (innerRc.Bottom > outerRc.Bottom)
 79             {
 80                 innerRc.Y = outerRc.Bottom - height - 1;
 81                 innerRc.Height = height;
 82             }
 83             return innerRc;
 84         }
 85
 86         private void mov_MouseWheel(object sender, MouseWheelEventArgs e)
 87         {
 88             double val = e.Delta * 0.001;
 89             double wl = mov.Width * (val / 0.12) * 0.02;
 90             double hl = mov.Height * (val / 0.12) * 0.02;
 91
 92             if ((Canvas.GetLeft(mov) - wl/2.0) > 0 && (Canvas.GetLeft(mov) + wl + mov.Width) <= movBg.ActualWidth &&
 93                 (Canvas.GetTop(mov) - hl/2.0) > 0 && (Canvas.GetTop(mov) + hl + mov.Height) <= movBg.ActualHeight &&
 94                 (mov.Width + wl) < mov.MaxWidth && (mov.Height + hl) < mov.MaxHeight)
 95             {
 96                 mov.SetValue(Canvas.LeftProperty, Canvas.GetLeft(mov) - wl / 2.0);
 97                 mov.SetValue(Canvas.TopProperty, Canvas.GetTop(mov) - hl / 2.0);
 98                 mov.Width += wl;
 99                 mov.Height += hl;
100
101             }
102             return;
103         }
104         #endregion