c# - 如何在 WPF 中改变 Canvas 的位置？

Question

如何更改 Canvas 的运行时位置，我在其中动态添加了控件(标签、线条)？

我可以使用所有控件缩放 Canvas ，但我无法使用 MouseMove、MouseUp、MouseDown 移动到另一个位置。

<Canvas Name="canvas" Width="1000" Height="400"
            Margin="100 0 0 50"
            Background="White"
            VerticalAlignment="Bottom"
            HorizontalAlignment="Center"
            MouseWheel="Canvas_MouseWheel"
            MouseMove="Canvas_MouseMove"
            MouseUp="Canvas_MouseUp"
            MouseDown="Canvas_MouseDown">
        <Canvas.RenderTransform>
            <ScaleTransform x:Name="st" />
        </Canvas.RenderTransform>
    </Canvas>

我在网上找到这段代码，但对我来说不起作用

bool activated;
    Point point;

    private void Canvas_MouseDown(object sender, MouseButtonEventArgs e)
    {
        activated = true;
        point = Mouse.GetPosition(canvas);
        Mouse.Capture(canvas);
    }

    private void Canvas_MouseMove(object sender, MouseEventArgs e)
    {
        if (activated)
        {
            double top = Canvas.GetTop(canGraph) + Mouse.GetPosition(canvas).Y - point.Y;
            Canvas.SetTop(canvas, top);
            double left = Canvas.GetLeft(canvas) + Mouse.GetPosition(canvas).X - point.X;
            Canvas.SetLeft(canvas, left);
            point = Mouse.GetPosition(canvas);
        }
    }

    private void Canvas_MouseUp(object sender, MouseButtonEventArgs e)
    {
        activated = false;
        Mouse.Capture(null);
    }

Answer 1

编辑 - 如果没有更多代码，我提供的先前解决方案在元素第一次移动后将无法工作，所以这里有一个更好的解决方案

为了正确工作，canvas 元素必须与其父元素的坐标系对齐，这是我们将 canvas 放在左上角时实现的，如果你不把它放在那里，你必须计算与众不同。

代码隐藏

private void Canvas_MouseDown(object sender, MouseButtonEventArgs e)
    {
        canvas.CaptureMouse();
    }

    Stopwatch sw = new Stopwatch();
    private void Canvas_MouseMove(object sender, MouseEventArgs e)
    {
        if (canvas.IsMouseCaptured)
        {
            translate.X = e.GetPosition(container).X;
            translate.Y = e.GetPosition(container).Y;
        }
    }

    private void Canvas_MouseUp(object sender, MouseButtonEventArgs e)
    {
        canvas.ReleaseMouseCapture();
    }

XAML

<Grid Background="Green" x:Name="container">
    <Canvas Name="canvas" Width="100" Height="100"
        Margin="0 0 0 0"
        Background="Purple"
        VerticalAlignment="Top"
        HorizontalAlignment="Left"
        MouseMove="Canvas_MouseMove"

        MouseDown="Canvas_MouseDown">
        <StackPanel Background="White">

        <TextBlock >asdasda</TextBlock>
        <TextBlock >cccc</TextBlock>
        <TextBlock >aaaaa</TextBlock>
        <TextBlock >bbbb</TextBlock>
        </StackPanel>
    <Canvas.RenderTransform>
            <TransformGroup>
                <ScaleTransform x:Name="st" />
                <TranslateTransform x:Name="translate" />
            </TransformGroup>
        </Canvas.RenderTransform>
</Canvas>
</Grid>

---

原始答案

---

XAML

我会做这样的事情:

• 添加一个平移变换，为了保持之前的变换，将它放在一个组中

• 使用 translate transform 以根据鼠标事件的位置移动 Canvas

• 对于翻译的起点，您可以使用容器中的坐标

代码隐藏:

bool activated;
    Point point;

    private void Canvas_MouseDown(object sender, MouseButtonEventArgs e)
    {
        activated = true;
        point = e.GetPosition(container);
    }

    private void Canvas_MouseMove(object sender, MouseEventArgs e)
    {
        if (activated)
        {
            translate.X = e.GetPosition(container).X - point.X;
            translate.Y = e.GetPosition(container).Y - point.Y;
        }
    }

    private void Canvas_MouseUp(object sender, MouseButtonEventArgs e)
    {
        activated = false;
    }

XAML

<Canvas Name="canvas" Width="100" Height="100"
        Margin="0 0 0 0"
        Background="Purple"
        VerticalAlignment="Stretch"
        HorizontalAlignment="Stretch"
        MouseMove="Canvas_MouseMove"
        MouseUp="Canvas_MouseUp"
        MouseDown="Canvas_MouseDown">
    <Canvas.RenderTransform>
            <TransformGroup>
                <ScaleTransform x:Name="st" />
                <TranslateTransform x:Name="translate" />
            </TransformGroup>
        </Canvas.RenderTransform>
</Canvas>
</Grid>