How to draw scrollbars on WPF Canvas

Question

Hi, I am trying to create a canvas with scroll bars. Can anyone help me give some ideas on how to do this? I have already tried using grid of 1 row and 1 column but due to certain constraints I want to use canvas.

Thanks in advance!

Answer 1

You could put the canvas inside of a scrollviewer. I tried this quick test and it allowed me to scroll through the contents of the canvas.

<ScrollViewer Height="100" Width="200">
    <Canvas Height="400" Width="400">
            //Content here
    </Canvas>
</ScrollViewer>

edit: Here is an example where the scroll-bars show up only when needed, and it changes dynamically as the canvas size changes.

<Button Content="Change Canvas Size" Click="ChangeCanvasSize_Click"/>
<ScrollViewer Height="100" Width="200" VerticalScrollBarVisibility="Auto" HorizontalScrollBarVisibility="Auto">
    <Canvas x:Name="TestCanvas">
            <TextBlock Text="Test Test"/>
    </Canvas>

Changing canvas size with button click:

    private void ChangeCanvasSize_Click(object sender, RoutedEventArgs e)
    {
        TestCanvas.Width = 600;
        TestCanvas.Height = 600;
    }

In this example, I start out with no scroll-bars and when I click the button to expand the canvas, scroll-bars appear.

Answer 2

Ok after working with it for sometime I figured out a way. Create a XAML like this

<ScrollViewer>
 <Grid x:Name="drawingGrid" SizeChanged="drawingGrid_SizeChanged">
<Canvas Name="drawingCanvas"> /<Canvas>
</Grid>
</ScrollViewer>

On windowLoad function set the canvas height/width equal to grid height/width. Update the canvas ht/wd: 1. when grid size changes, due to mininmize/maximize. 2. dragging an element beyond the boundaries of canvas or creating a new element too close the edge of canvas

double dHeight = 220; if (drawingCanvas.Height < CurrentPosition.Y + dHeight) { // increase canvas height drawingCanvas.Height += (2 * dHeight); }

Hope this is of some help. Please share if anyone has any better idea or suggestions to improve this.