Creating a WPF Window that allows zooming and panning

Question

I want to create a Window that will hold several controls. However, I would like the user to be able to pan around and zoom in and out to see larger versions of those controls.

I don't even know where to begin looking.

I was going to start at ScaleTransform that responds to the use of the scroll button on the mouse but I am not sure if that is the best idea.

Just need a push in the right direction.

thanks!

Answer 1

This might be a good candidate for a Viewbox.

See here: http://msdn.microsoft.com/en-us/library/system.windows.controls.viewbox(v=vs.110).aspx

Basically, you can Wrap the entire contents of the Window into a Viewbox like so:

<Window>
   <Viewbox>
       <!-- content here -->
   </Viewbox>
</Window>

and then bind to the Viewbox control's width and height to simulate the zooming. For a quick test, you could just listen to scroll wheel events via code-behind, name the Viewbox control, and access the Viewbox directly at change the values there.

Edit: here's a scenario I just found to get you started. They are using an image, but it's the exact same concept that I described above.

http://www.c-sharpcorner.com/uploadfile/yougerthen/working-with-wpf-viewbox-control/

Edit2: Quick working example using mouse-scroll

Xaml:

<Window x:Class="WpfApplication2.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow"
        MouseWheel="MainWindow_OnMouseWheel">
    <Grid>
        <Viewbox x:Name="ZoomViewbox" Stretch="Fill">
            <StackPanel>
                <Label Content="Label" HorizontalAlignment="Left" VerticalAlignment="Top"/>
                <Button Content="Button" HorizontalAlignment="Left" VerticalAlignment="Top" />
            </StackPanel>
        </Viewbox>
    </Grid>
</Window>

C#:

using System.Windows;
using System.Windows.Input;

namespace WpfApplication2
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();

            ZoomViewbox.Width = 100;
            ZoomViewbox.Height = 100;
        }

        private void MainWindow_OnMouseWheel(object sender, MouseWheelEventArgs e)
        {
            UpdateViewBox((e.Delta > 0) ? 5 : -5);
        }

        private void UpdateViewBox(int newValue)
        {
            if ((ZoomViewbox.Width >= 0) && ZoomViewbox.Height >= 0)
            {
                ZoomViewbox.Width += newValue;
                ZoomViewbox.Height += newValue;   
            }
        }
    }
}

Answer 2

You can get functionality out of a ScrollViewer and a ScaleTransform. Here's an example:

<Window x:Class="CSharpWpf.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">

    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="*" />
            <RowDefinition Height="Auto" />
        </Grid.RowDefinitions>

        <!-- This ScrollViewer enables the panning -->
        <ScrollViewer HorizontalScrollBarVisibility="Auto" VerticalScrollBarVisibility="Auto">

            <!-- This StackPanel is the container for the zoomable/pannable content. -->
            <!-- Any container control (StackPanel, DockPanel, Grid, etc) may be used here. -->
            <StackPanel HorizontalAlignment="Left" VerticalAlignment="Top">

                <!-- This ScaleTransform implements the zooming and is bound the Value of the ZoomSlider -->
                <StackPanel.LayoutTransform>
                    <ScaleTransform ScaleX="{Binding ElementName=ZoomSlider, Path=Value}" ScaleY="{Binding ElementName=ZoomSlider, Path=Value}" />
                </StackPanel.LayoutTransform>

                <!-- Here is your custom content -->
                <Button>Foo</Button>
                <Button>Bar</Button>

            </StackPanel>

        </ScrollViewer>

        <!-- This Slider controls the zoom level -->
        <Slider x:Name="ZoomSlider" Orientation="Horizontal" Grid.Row="1" Minimum="0.0" Maximum="8.0" LargeChange="0.25" SmallChange="0.01"  Value="1.0" />

    </Grid>


</Window>