C# WPF -Drag an image
14,652
You may add an Image control to the Canvas and modify its Left
and Top
properties on mouse input.
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>
Code behind:
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);
}
}
Author by
Ace
Updated on June 09, 2022Comments
-
Ace almost 2 years
I am trying to get some simple functionality of getting an image from a file, adding it to a Canvas, and then allowing a user to left-click (and hold) on the image and then drag it around the Canvas (i.e. updating the image's location)
Here's what I have so far, what should I be adding?
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"); } }