I added a ScrollViewer to my UWP app for Windows 10.
I want to use it both for zooming and panning.
Here is my XAML:
<Page
x:Class="LiquidTextUWP.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:lt="using:LiquidTextUWP.Controls"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d">
<ScrollViewer VerticalScrollBarVisibility="Hidden" HorizontalScrollBarVisibility="Hidden"
ZoomMode="Enabled" Background="DarkSeaGreen" Name="ScrollArea"
Width="10000" Height="10000">
<Grid Background="LightGray" Name="Workspace">
<!-- here I put all my other controls -->
</Grid>
</ScrollViewer>
</Page>
For Panning, I added a small event handler for the PointerMoved event, like this:
private double previousX = 0;
public void OnPointerMoved(object sender, PointerRoutedEventArgs e)
{
if (!(sender is ScrollViewer scrollViewer))
return;
PointerPoint pp = e.GetCurrentPoint(null);
double deltaX = pp.Position.X - previousX;
previousDeltaX = pp.Position.X
bool res = scrollViewer.ChangeView(scrollViewer.HorizontalOffset - deltaX, null, null);
e.Handled = true;
}
It works nicely (i.e. it actually pans horizontally, and res = true) when scrollViewer.ZoomFactor > 1.
When instead scrollViewer.ZoomFactor < 1, it does nothing (and res = false).
EDIT:
I also noticed that when scrollViewer.ZoomFactor < 1, the properties ScrollableWidth and ScrollableHeight goes to 0, while when scrollViewer.ZoomFactor > 1, the properties ScrollableWidth and ScrollableHeight are positive.
How can I enable the ScrollViewer to return true for ChangeView also when the zoom factor is less than 1?
