C#WPF – 拖动图像

发布时间：2020-12-16 00:23:19 所属栏目：百科来源：网络整理

导读：我试图获得一些简单的功能,从文件中获取图像,将其添加到Canvas,然后允许用户左键单击(并保持)图像,然后将其拖动到Canvas(即更新图像的地点) 这是我到目前为止,我应该添加什么？ private void btnAddImage_Click(object sender,RoutedEventArgs e) { try { Sy

我试图获得一些简单的功能,从文件中获取图像,将其添加到Canvas,然后允许用户左键单击(并保持)图像,然后将其拖动到Canvas(即更新图像的地点)

这是我到目前为止,我应该添加什么？

private void btnAddImage_Click(object sender,RoutedEventArgs e) {
    try {
        System.Windows.Forms.OpenFileDialog open = new System.Windows.Forms.OpenFileDialog();
        open.Filter = "Image Files(*.jpg; *.jpeg; *.gif; *.bmp)|*.jpg; *.jpeg; *.gif; *.bmp";
        if (open.ShowDialog() == System.Windows.Forms.DialogResult.OK) {
            PictureBox PictureBox1 = new PictureBox();
            PictureBox1.Image = new Bitmap(open.FileName);
            myCanvas.children.add(PictureBox1);
        }
    }
    catch (Exception) { throw new ApplicationException("Failed loading image"); }
}

解决方法

您可以向Canvas添加一个 Image控件,并在鼠标输入上修改其Left和Top属性.

XAML：

<Grid>
    <Grid.RowDefinitions>
        <RowDefinition/>
        <RowDefinition Height="Auto"/>
    </Grid.RowDefinitions>
    <Canvas x:Name="canvas"
            MouseLeftButtonDown="CanvasMouseLeftButtonDown"
            MouseLeftButtonUp="CanvasMouseLeftButtonUp"
            MouseMove="CanvasMouseMove"/>
    <Button Grid.Row="1" Content="Add Image" Click="AddButtonClick"/>
</Grid>

代码背后：

private void AddButtonClick(object sender,RoutedEventArgs e)
{
    var dialog = new Microsoft.Win32.OpenFileDialog();
    dialog.Filter =
        "Image Files (*.jpg; *.jpeg; *.gif; *.bmp)|*.jpg; *.jpeg; *.gif; *.bmp";

    if ((bool)dialog.ShowDialog())
    {
        var bitmap = new BitmapImage(new Uri(dialog.FileName));
        var image = new Image { Source = bitmap };
        Canvas.SetLeft(image,0);
        Canvas.SetTop(image,0);
        canvas.Children.Add(image);
    }
}

private Image draggedImage;
private Point mousePosition;

private void CanvasMouseLeftButtonDown(object sender,MouseButtonEventArgs e)
{
    var image = e.Source as Image;

    if (image != null && canvas.CaptureMouse())
    {
        mousePosition = e.GetPosition(canvas);
        draggedImage = image;
        Panel.SetZIndex(draggedImage,1); // in case of multiple images
    }
}

private void CanvasMouseLeftButtonUp(object sender,MouseButtonEventArgs e)
{
    if (draggedImage != null)
    {
        canvas.ReleaseMouseCapture();
        Panel.SetZIndex(draggedImage,0);
        draggedImage = null;
    }
}

private void CanvasMouseMove(object sender,MouseEventArgs e)
{
    if (draggedImage != null)
    {
        var position = e.GetPosition(canvas);
        var offset = position - mousePosition;
        mousePosition = position;
        Canvas.SetLeft(draggedImage,Canvas.GetLeft(draggedImage) + offset.X);
        Canvas.SetTop(draggedImage,Canvas.GetTop(draggedImage) + offset.Y);
    }
}

（编辑：李大同）

【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容!