在我的这一方面,我保留了最小的拇指长度,因为触摸输入需要最小尺寸的拇指才能进行触摸优化。
您可以定义一个ScrollViewer ControlTemplate,它将使用TouchScrollBar作为其水平和垂直滚动条。
有关数学方面的内容,请查看UpdateViewPort方法。
抱歉,我不认为显式设置滚动条拇指以覆盖轨道长度的百分比是必要的用例。
public class TouchScrollBar : System.Windows.Controls.Primitives.ScrollBar
{
#region Fields
#region Dependency properties
public static readonly DependencyProperty MinThumbLengthProperty =
DependencyProperty.Register
("MinThumbLength", typeof(double), typeof(TouchScrollBar), new UIPropertyMetadata((double)0, OnMinThumbLengthPropertyChanged));
#endregion
private double? m_originalViewportSize;
#endregion
#region Properties
public double MinThumbLength
{
get { return (double)GetValue(MinThumbLengthProperty); }
set { SetValue(MinThumbLengthProperty, value); }
}
#endregion
#region Constructors
public TouchScrollBar()
{
SizeChanged += OnSizeChanged;
}
private bool m_trackSubscribed;
void OnSizeChanged(object sender, SizeChangedEventArgs e)
{
SubscribeTrack();
}
private void SubscribeTrack()
{
if (!m_trackSubscribed && Track != null)
{
Track.SizeChanged += OnTrackSizeChanged;
m_trackSubscribed = true;
}
}
#endregion
#region Protected and private methods
#region Event handlers
#region Dependency properties event handlers
private void OnMinThumbLengthPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
TouchScrollBar instance = d as TouchScrollBar;
if(instance != null)
{
instance.OnMinThumbLengthChanged(e);
}
}
#endregion
protected void OnTrackSizeChanged(object sender, SizeChangedEventArgs e)
{
SubscribeTrack();
UpdateViewPort();
}
protected override void OnMaximumChanged(double oldMaximum, double newMaximum)
{
base.OnMaximumChanged(oldMaximum, newMaximum);
SubscribeTrack();
UpdateViewPort();
}
protected override void OnMinimumChanged(double oldMinimum, double newMinimum)
{
base.OnMinimumChanged(oldMinimum, newMinimum);
SubscribeTrack();
UpdateViewPort();
}
protected void OnMinThumbLengthChanged(DependencyPropertyChangedEventArgs e)
{
SubscribeTrack();
UpdateViewPort();
}
#endregion
private void UpdateViewPort()
{
if(Track != null)
{
if(m_originalViewportSize == null)
{
m_originalViewportSize = ViewportSize;
}
double trackLength = Orientation == Orientation.Vertical ? Track.ActualHeight : Track.ActualWidth;
double thumbHeight = m_originalViewportSize.Value / (Maximum - Minimum + m_originalViewportSize.Value) * trackLength;
if (thumbHeight < MinThumbLength && !double.IsNaN(thumbHeight))
{
ViewportSize = (MinThumbLength * (Maximum - Minimum)) / (trackLength + MinThumbLength);
}
}
}
#endregion
}
}