public void TestScrollOf(bool virtualizeItems)
{
var stackSize = new Vector3(100, 200, 300);
var childSize1 = new Vector3(50, 150, 250);
var childSize2 = new Vector3(150, 250, 350);
var childSize3 = new Vector3(250, 250, 350);
var stackPanel = new StackPanel
{
Size = stackSize,
ItemVirtualizationEnabled = virtualizeItems,
Orientation = Orientation.Horizontal,
LayoutingContext = new LayoutingContext()
};
var child1 = new StackPanel { Size = childSize1 };
var child2 = new StackPanel { Size = childSize2 };
var child3 = new StackPanel { Size = childSize3 };
stackPanel.Children.Add(child1);
stackPanel.Children.Add(child2);
stackPanel.Children.Add(child3);
stackPanel.Arrange(Vector3.Zero, false);
// pre-arranged
stackPanel.ScrollOf(childSize1);
Utilities.AssertAreNearlyEqual(1, stackPanel.ScrollPosition);
stackPanel.ScrollOf(childSize1);
Utilities.AssertAreNearlyEqual(1 + 1 / 3f, stackPanel.ScrollPosition);
// post arranged
stackPanel.InvalidateArrange();
stackPanel.ScrollOf(childSize1);
Utilities.AssertAreNearlyEqual(1 + 1 / 3f, stackPanel.ScrollPosition);
stackPanel.Arrange(Vector3.Zero, false);
Utilities.AssertAreNearlyEqual(1 + 2 / 3f, stackPanel.ScrollPosition);
stackPanel.InvalidateArrange();
stackPanel.ScrollOf(- 2 *childSize1);
Utilities.AssertAreNearlyEqual(1 + 2 / 3f, stackPanel.ScrollPosition);
stackPanel.Arrange(Vector3.Zero, false);
Utilities.AssertAreNearlyEqual(1, stackPanel.ScrollPosition);
}