public void ScrollLast()
{
VirtualStackPanel vsp = getPanel();
if (vsp != null)
{
updateHorizOffset(vsp.ExtentWidth);
}
}
public void ScrollFirst()
{
VirtualStackPanel vsp = getPanel();
if (vsp != null)
{
updateHorizOffset(0);
}
}
public void ScrollRight()
{
VirtualStackPanel vsp = getPanel();
if (vsp != null)
{
updateHorizOffset(ScrollOffset + vsp.ViewportWidth);
}
}
private VirtualStackPanel getPanel()
{
if (_scroll != null)
{
ItemsPresenter ip = UITools.FindVisualChild <ItemsPresenter>(this);
VirtualStackPanel vsp = UITools.FindVisualChild <VirtualStackPanel>(ip);
return(vsp);
}
return(null);
}
public bool CanScrollLeft()
{
VirtualStackPanel vsp = getPanel();
if (vsp != null)
{
if (vsp.ExtentWidth < vsp.ViewportWidth)
{
return(false);
}
}
return(finalOFfset > 0);
}
private void updateScrollViewer()
{
if (_scroll != null)
{
ItemsPresenter ip = UITools.FindVisualChild <ItemsPresenter>(this);
VirtualStackPanel vsp = UITools.FindVisualChild <VirtualStackPanel>(ip);
if (vsp != null)
{
double itemFitInViewPort = vsp.ViewportWidth / ActualHeight;
double offsetMiddle = ((vsp.ViewportWidth + ActualHeight) / 2);
//double newOffset = (ChildWidth * (SelectedIndex - (itemFitInViewPort / 2)));
double newOffset = (ActualHeight * (SelectedIndex + 1)) - offsetMiddle;
updateHorizOffset(newOffset);
}
}
}
private void updateHorizOffset(double offset)
{
VirtualStackPanel vsp = UITools.FindVisualChild <VirtualStackPanel>(this);
//ppanel.Dispatcher.BeginInvoke(DispatcherPriority.Background, new ThreadStart(() =>
CommandManager.InvalidateRequerySuggested(); //));
finalOFfset = offset;
DoubleAnimation moveAnimation = new DoubleAnimation();
moveAnimation.To = offset;
bool largeChange = Math.Abs(ScrollOffset - offset) > ActualHeight;
moveAnimation.Duration = new Duration(TimeSpan.FromSeconds(AutoPlay ? 0 : largeChange ? 1 : 0.5));
this.BeginAnimation(PreviewPanelBase.ScrollOffsetProperty, moveAnimation);
}
