Scrolling

Introduction

Gum includes controls which have built-in scrolling support. These are:

• ListBox

• ItemsControl

• ScrollViewer

Both ListBox and ItemsControl inherit from ScrollViewer, so many of the properties for scrolling are the same across all controls.

Built-In Scrolling Behavior

All controls support the following built-in actions for scrolling:

• Mouse/touch screen interactions with scroll bars

• Mouse wheel scrolling

• Touch screen swipe scrolling

Scrolling Speed

Scrolling speed is controlled by the following two variables:

• SmallChange - The amount to scroll when a scroll bar button is clicked, or when a tick is scrolled on the mouse wheel

• LargeChange - The amount to scroll when the user clicks on the scroll bar track

The following code creates two ListBoxes to compare the scrolling speed of each.

var defaultListBox = new ListBox();
defaultListBox.AddToRoot();
defaultListBox.Anchor(Anchor.Center);
defaultListBox.X = -100;
for (int i = 0; i < 20; i++)
{
    defaultListBox.Items.Add(i);
}

var fastListBox = new ListBox();
fastListBox.AddToRoot();
fastListBox.Anchor(Anchor.Center);
fastListBox.X = 100;
// default is 10:
fastListBox.SmallChange = 50;
for (int i = 0; i < 20; i++)
{
    fastListBox.Items.Add(i);
}

Two ListBoxes with different SmallChange values