绘制矩形使用WPF MVVM当鼠标拖(Draw rectangle when mouse dragg

下面是我的XAML。我有一个画布中的图像。我想，当拖动鼠标在图像上绘制图像的矩形。我在WPF做到了成功。但现在我想这样做的MVVM。而不必在代码中的事件处理程序的背后我想有他们在我的视图模型。我使用MVVM基金会执行MVVM。下面是MVVM基金会的链接。 http://mvvmfoundation.codeplex.com/

任何帮助，高度赞赏。

XAML

<Canvas Name="cnvImage">
        <Image Height="348" HorizontalAlignment="Left" Margin="12,39,0,0" Name="imgPreview" 
               Stretch="Fill" VerticalAlignment="Top" Width="443" 
               Source="/Images/CapturedImage.png" 
                MouseDown="imgCamera_MouseDown" MouseMove="imgCamera_MouseMove" MouseUp="imgCamera_MouseUp" />
    </Canvas>

代码写在后面的代码

// This is the rectangle to be shown when mouse is dragged on camera image.
private Point startPoint;
private Rectangle rectSelectArea;


/// <summary>
/// 
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void imgCamera_MouseDown(object sender, MouseButtonEventArgs e)
{
    startPoint = e.GetPosition(cnvImage);

    // Remove the drawn rectanglke if any.
    // At a time only one rectangle should be there
    if (rectSelectArea != null)
        cnvImage.Children.Remove(rectSelectArea);

    // Initialize the rectangle.
    // Set border color and width
    rectSelectArea = new Rectangle
    {
        Stroke = Brushes.LightBlue,
        StrokeThickness = 2
    };

    Canvas.SetLeft(rectSelectArea, startPoint.X);
    Canvas.SetTop(rectSelectArea, startPoint.X);
    cnvImage.Children.Add(rectSelectArea);
}

/// <summary>
/// 
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void imgCamera_MouseMove(object sender, MouseEventArgs e)
{
    if (e.LeftButton == MouseButtonState.Released || rectSelectArea == null)
        return;

    var pos = e.GetPosition(cnvImage);

    // Set the position of rectangle
    var x = Math.Min(pos.X, startPoint.X);
    var y = Math.Min(pos.Y, startPoint.Y);

    // Set the dimenssion of the rectangle
    var w = Math.Max(pos.X, startPoint.X) - x;
    var h = Math.Max(pos.Y, startPoint.Y) - y;

    rectSelectArea.Width = w;
    rectSelectArea.Height = h;

    Canvas.SetLeft(rectSelectArea, x);
    Canvas.SetTop(rectSelectArea, y);
}

/// <summary>
/// 
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void imgCamera_MouseUp(object sender, MouseButtonEventArgs e)
{
    rectSelectArea = null;
}

我需要知道我需要什么，在我的视图模型编写，并相应地在XAML需要什么样的变化。

提前致谢。

Answer 1:

实现调整大小的一个非常简洁的方式中可以找到这篇文章/项目。如果使用实施那里DesignerItemStyle，您可以添加像这样绑定的支持：

<Rectangle Style="{StaticResource DesignerItemStyle}"
           Canvas.Left="{Binding Path=Leftoffset, Mode=TwoWay}"
           Canvas.Top="{Binding Path=Topoffset, Mode=TwoWay}"
           Width="{Binding Path=Width, Mode=TwoWay}"
           Height="{Binding Path=Height, Mode=TwoWay}">

这使得该阻力在纯XAML来调整的东西，并使用标准的WPF手段得到的值到底层的ViewModels。

Answer 2:

只是请参考下访问代码项目提供的链接！

http://www.codeproject.com/Articles/148503/Simple-Drag-Selection-in-WPF ？