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