void imageBox_EventScrollGesture(Widget source, EventArgs e)
{
context.addReference(); //Keep context alive even if this widget is disposed during this event
try
{
Element element = context.GetFocusElement();
//Find the parent element that scrolls
while (element != null && element.ScrollHeight <= element.ClientHeight && element.ScrollWidth <= element.ClientWidth)
{
element = element.ParentNode;
}
if (element != null)
{
ScrollGestureEventArgs sgea = (ScrollGestureEventArgs)e;
element.ScrollLeft -= sgea.DeltaX;
element.ScrollTop -= sgea.DeltaY;
}
}
finally
{
context.removeReference();
}
}
private void OnScrollGesture(object sender, ScrollGestureEventArgs e)
{
if (Extent.Height > Viewport.Height || Extent.Width > Viewport.Width)
{
var scrollable = Child as ILogicalScrollable;
bool isLogical = scrollable?.IsLogicalScrollEnabled == true;
double x = Offset.X;
double y = Offset.Y;
Vector delta = default;
if (isLogical)
{
_activeLogicalGestureScrolls?.TryGetValue(e.Id, out delta);
}
delta += e.Delta;
if (Extent.Height > Viewport.Height)
{
double dy;
if (isLogical)
{
var logicalUnits = delta.Y / LogicalScrollItemSize;
delta = delta.WithY(delta.Y - logicalUnits * LogicalScrollItemSize);
dy = logicalUnits * scrollable.ScrollSize.Height;
}
else
{
dy = delta.Y;
}
y += dy;
y = Math.Max(y, 0);
y = Math.Min(y, Extent.Height - Viewport.Height);
}
if (Extent.Width > Viewport.Width)
{
double dx;
if (isLogical)
{
var logicalUnits = delta.X / LogicalScrollItemSize;
delta = delta.WithX(delta.X - logicalUnits * LogicalScrollItemSize);
dx = logicalUnits * scrollable.ScrollSize.Width;
}
else
{
dx = delta.X;
}
x += dx;
x = Math.Max(x, 0);
x = Math.Min(x, Extent.Width - Viewport.Width);
}
if (isLogical)
{
if (_activeLogicalGestureScrolls == null)
{
_activeLogicalGestureScrolls = new Dictionary <int, Vector>();
}
_activeLogicalGestureScrolls[e.Id] = delta;
}
Offset = new Vector(x, y);
e.Handled = true;
}
}
private void OnScrollGesture(object sender, ScrollGestureEventArgs e)
{
e.Handled = e.Handled || OwningGrid.UpdateScroll(-e.Delta);
}
