Panning through mouse in windows 8 app?

Question

I am developing a windows 8 app and have to enable panning on the image through mouse.It is working on the Tablet but somehow I need to enable it from the mouse also.

And I am writing pointer wheel changed event for zooming the image but it is calling just once.
This is my code for Zooming

private void MyScrollView_PointerWheelChanged(object sender, PointerRoutedEventArgs e)
{
    MyScrollView.ChangeView(MyScrollView.HorizontalOffset + 40, MyScrollView.VerticalOffset + 20, MyScrollView.ZoomFactor + 0.1f);
}

Any help would be grateful to me.

Can you show the code where you add the event listener? Either the XAML or C# code. — Jon G Stødle, Jul 29 '15 at 06:46

score 0 · Answer 1 · answered Jul 29 '15 at 07:10

I encountered the same problem while trying to do the same thing. Your code will work as long as the Scrollviewer is not handling scroll event internally.

To explain more closely:
When all of the content of the Scrollviewer is visible (ie no need to scroll), the Scrollviewer will not handle any scroll event internally and the event will fire and you handle it in your code.

If, however, there is content that is larger than the visible area of the Scrollviewer, the scrollbars will show up. At this point the Scrollviewer will handle scroll event (so that when you scroll, you move the scrollbar). This is the expected behaviour, as it is in web browsers and other applications with content that's larger than the viewport or visible area. The event will no longer fire and your handler will not run because the internal logic stops the event from ever reaching your code.

You can capture the event by setting e.Handled to true like so:

private void MyScrollView_PointerWheelChanged(object sender, PointerRoutedEventArgs e)
{
    e.Handled = true; // Tell the event system that the event has been handled and it should not execute any more handlers.
    MyScrollView.ChangeView(MyScrollView.HorizontalOffset + 40, MyScrollView.VerticalOffset + 20, MyScrollView.ZoomFactor + 0.1f);
}

But I found it to be a bad experience. The zooming is not cenetered on the pointer and moves the content in a way that's confusing and jarring. I found no good way to override this.

As a last point, I want to mention that there's built in zoom functionality in the Scrollviewer by using Ctrl+Scroll. Works nicely and it's the same shortcut used in browsers.

Stadle:So,There is no way around that zooming can be done with Wheel?? And Panning on desktop with Mouse?? — Tushar Goyal, Jul 30 '15 at 10:58
As I mentioned you can set `e.Handled = true` and zoom, but the result felt to jarring to me. For panning, you'll have to implement it yourself with something like `ManipulationStart`, `ManipulationDelta` and `ManipulationEnd` — Jon G Stødle, Jul 31 '15 at 12:08
There should be something for panning with mouse also because it happens on the tablet by default. — Tushar Goyal, Oct 30 '15 at 07:28

Panning through mouse in windows 8 app?

1 Answers1