When use ListView, i want to find it's child :scrollViewer.use code as bellow:
svALlItems = (ScrollViewer)(VisualTreeHelper.GetChild(lvAllItems, 0) as Border).Child;
when change theme from areo to non-aero ,for example as classic theme, application crash,the reason at above statement.
Use VisualTreeHelper to see VisualTree,The method as bellow:
string GetVisualTreeInfo(DependencyObject target)
{
int i = 0;
int childCount = 0;
DependencyObject parentObject = target;
DependencyObject childObject = null;
string format = "Rank:{0} childIndex:{1} {2} ";
StringBuilder stringBuilder = new StringBuilder();
stringBuilder.AppendLine("VisualTree:");
while (true)
{
childCount = VisualTreeHelper.GetChildrenCount(parentObject);
if (childCount == 0) break;
for (int j = 0; j < childCount; j++)
{
childObject = VisualTreeHelper.GetChild(parentObject, j);
stringBuilder.AppendLine(string.Format(format, i, j, childObject));
}
if (childObject == null) break;
parentObject = childObject;
i++;
}
Debug.WriteLine(stringBuilder.ToString());
return stringBuilder.ToString();
}
When aero theme,visualTree is :
Rank:0 childIndex:0 System.Windows.Controls.Border Rank:1 childIndex:0 System.Windows.Controls.ScrollViewer Rank:2 childIndex:0 System.Windows.Controls.Grid Rank:3 childIndex:0 System.Windows.Shapes.Rectangle Rank:3 childIndex:1 System.Windows.Controls.ScrollContentPresenter Rank:3 childIndex:2 System.Windows.Controls.Primitives.ScrollBar Minimum:0 Maximum:0 Value:0 Rank:3 childIndex:3 System.Windows.Controls.Primitives.ScrollBar Minimum:0 Maximum:0 Value:0
When non-aero theme,as classic, visualTree is :
Rank:0 childIndex:0 Microsoft.Windows.Themes.ClassicBorderDecorator Rank:1 childIndex:0 System.Windows.Controls.ScrollViewer Rank:2 childIndex:0 System.Windows.Controls.Grid Rank:3 childIndex:0 System.Windows.Shapes.Rectangle Rank:3 childIndex:1 System.Windows.Controls.ScrollContentPresenter Rank:3 childIndex:2 System.Windows.Controls.Primitives.ScrollBar Minimum:0 Maximum:0 Value:0 Rank:3 childIndex:3 System.Windows.Controls.Primitives.ScrollBar Minimum:0 Maximum:0 Value:0
the first child is different ,so when we use VisualTreeHelper like this,plase take care !~
the above statement should change as fllow:
var svALlItems = (ScrollViewer)(VisualTreeHelper.GetChild(listView1, 0) as Decorator).Child;