WPF 窗體中的 Canvas 限定範圍拖動 鼠標滾軸改變大小

xaml代碼:

 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#代碼：

  1 #region 拖動選區,滾軸改變大小  2 //鼠標相對於被拖動的Canvas控件mov的座標  3 Point childPoint = new Point();  4 //鼠標相對於做爲容器的Canvas控件movBg的座標  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