【WPF】对Image元素进行缩放平移等操作

元素布局

        <Border Grid.Row="1" Name="border" ClipToBounds="True" Margin="10,10,10,10"><Image Name="image" Visibility="Visible" Margin="3,3,3,3" Grid.Column="1" Source="{Binding SourceImage}" HorizontalAlignment="Center" VerticalAlignment="Center"></Image></Border>

1.平移

1.1 定义私有变量记录相关初始位置

        /// <summary>/// 图片的起始偏移位置/// </summary>private Point origin;  /// <summary>/// 鼠标相对Border的起始位置/// </summary>private Point start; 

1.2 绑定 鼠标左键按下、鼠标左键抬起、鼠标移动事件

        public DialogImageWindow(){InitializeComponent();image.MouseLeftButtonDown += image_MouseLeftButtonDown;image.MouseLeftButtonUp += image_MouseLeftButtonUp;image.MouseMove += image_MouseMove;}

1.3 鼠标左键按下

1. 通过CaptureMouse将鼠标捕获到指定的元素image
2. 通过GetPosition获取鼠标相对border位置
3. 记录image当前偏移位置

        private void image_MouseLeftButtonDown(object sender, MouseButtonEventArgs e){if (image.IsMouseCaptured) return;image.CaptureMouse();start = e.GetPosition(border);origin.X = image.RenderTransform.Value.OffsetX;origin.Y = image.RenderTransform.Value.OffsetY;}

1.4 鼠标移动

1. 通过GetPosition获取当前鼠标相对border位置
2. 计算鼠标相对初始位置移动的像素差值
3. 将像素差值累计到初始偏移量上

 private void image_MouseMove(object sender, MouseEventArgs e){if (!image.IsMouseCaptured) return;Point p = e.MouseDevice.GetPosition(border);Matrix m = image.RenderTransform.Value;m.OffsetX = origin.X + (p.X - start.X);m.OffsetY = origin.Y + (p.Y - start.Y);image.RenderTransform = new MatrixTransform(m);}

1.5 鼠标左键抬起

1. 通过ReleaseMouseCapture释放鼠标捕获

private void image_MouseLeftButtonUp(object sender, MouseButtonEventArgs e){if (image.IsMouseCaptured){image.ReleaseMouseCapture();}}

2. 缩放

2.1 绑定 鼠标滚轮事件

        public DialogImageWindow(){InitializeComponent();MouseWheel += MainWindow_MouseWheel;}

2.1

1. 通过GetPosition获取鼠标相对image的位置，该位置作为缩放中心点
2. 根据Delta参数来决定是在当前放大系数上放大(1.1倍)还是缩小(1.1倍).

 private void MainWindow_MouseWheel(object sender, MouseWheelEventArgs e){Point p = e.MouseDevice.GetPosition(image);Matrix m = image.RenderTransform.Value;if (e.Delta > 0)m.ScaleAtPrepend(1.1, 1.1, p.X, p.Y);elsem.ScaleAtPrepend(1 / 1.1, 1 / 1.1, p.X, p.Y);image.RenderTransform = new MatrixTransform(m);}

3. 还原

private void b1_Click(object sender, RoutedEventArgs e){image.RenderTransform = new ScaleTransform(1.0,1.0);image.RenderTransform = new TranslateTransform(0,0);}