private void OnScrollChanged(object sender, ScrollChangedEventArgs e)
{
//Do we need to update the offset?
if (IsEnabled)
{
var horizontal = e.HorizontalChange;
var vertical = e.VerticalChange;
//VerticalOffset means two seperate things based on the CanContentScroll
//property. If this property is true then the offset is the number of
//items to scroll; false then it's in Device Independant Pixels (DIPs).
if (_scrollViewer.CanContentScroll)
{
//We need to either increase the offset or decrease it.
if (e.VerticalChange < 0)
{
var start = (int)e.VerticalOffset;
var end = (int)(e.VerticalOffset - e.VerticalChange);
vertical = -CalculateOffset(start, end);
}
else
{
var start = (int)(e.VerticalOffset - e.VerticalChange);
var end = (int)e.VerticalOffset;
vertical = CalculateOffset(start, end);
}
}
_offset.X += horizontal;
_offset.Y += vertical;
OffsetChanged?.Invoke(this, new OffsetChangedEventArgs(horizontal, vertical));
}
}
private void SliderOnOffsetChanged(object sender, ValueChangedEventArgs e)
{
OffsetChanged?.Invoke(sender, e);
if (sender != SliderEntry)
{
XamarinHelpers.EnsureMainThread(() => { SliderEntry.Text = e.NewValue.ToString(CultureInfo.InvariantCulture); });
}
}
private void UpdateVerticalOffset()
{
var yDiff = _touchEndPosition.y - _touchStartPosition.y;
if (Mathf.Abs(yDiff) > Tolerance)
{
OffsetChanged.Invoke(yDiff);
}
}
protected virtual void OnOffsetChanged()
{
Invalidate();
OffsetChanged.Fire(this);
}
protected void OnOffsetChanged()
{
OffsetChanged?.Invoke(this, EventArgs.Empty);
}
