/// <summary>
/// Returns all the child visual objects within this parent that satisfies a condition.
/// </summary>
/// <param name="parent">The parent visual whose children to look through.</param>
/// <param name="predicate">A function to test each visual for a condition.</param>
/// <param name="treeTraverseStrategy">The strategy to use.</param>
public static IEnumerable <Visual> GetVisualChildCollection(this Visual parent, Func <Visual, bool> predicate, TreeTraverseStrategy treeTraverseStrategy = TreeTraverseStrategy.BreadthFirst)
{
ICollection visuals;
switch (treeTraverseStrategy)
{
case TreeTraverseStrategy.BreadthFirst:
visuals = new Queue <Visual>();
((Queue <Visual>)visuals).Enqueue(parent);
break;
case TreeTraverseStrategy.DepthFirst:
visuals = new Stack <Visual>();
((Stack <Visual>)visuals).Push(parent);
break;
default:
throw new NotImplementedException($"Uknown TreeTraverseStrategy: '{treeTraverseStrategy}'.");
}
bool firstTime = true;
while (visuals.Count > 0)
{
Visual visual;
switch (treeTraverseStrategy)
{
case TreeTraverseStrategy.BreadthFirst:
visual = ((Queue <Visual>)visuals).Dequeue();
break;
case TreeTraverseStrategy.DepthFirst:
visual = ((Stack <Visual>)visuals).Pop();
break;
default:
throw new NotImplementedException($"Uknown TreeTraverseStrategy: '{treeTraverseStrategy}'.");
}
if (firstTime)
{
// parent should not be tested because it is not a child
firstTime = false;
}
else if (predicate(visual))
{
yield return(visual);
}
int childrenCount = VisualTreeHelper.GetChildrenCount(visual);
for (int i = childrenCount - 1; i >= 0; --i)
{
DependencyObject child = VisualTreeHelper.GetChild(visual, i);
if (!(child is Visual childVisual))
{
continue;
}
switch (treeTraverseStrategy)
{
case TreeTraverseStrategy.BreadthFirst:
((Queue <Visual>)visuals).Enqueue(childVisual);
break;
case TreeTraverseStrategy.DepthFirst:
((Stack <Visual>)visuals).Push(childVisual);
break;
default:
throw new NotImplementedException($"Uknown TreeTraverseStrategy: '{treeTraverseStrategy}'.");
}
}
}
}
/// <summary>
/// Returns all the child visual objects of the specified generic types within the specified parent.
/// </summary>
/// <typeparam name="T1">The first type of visuals to search for.</typeparam>
/// <typeparam name="T2">The second type of visuals to search for.</typeparam>
/// <param name="parent">The parent visual whose children to look through.</param>
/// <param name="treeTraverseStrategy">The strategy to use.</param>
public static IEnumerable <Visual> GetVisualChildCollection <T1, T2>(this Visual parent, TreeTraverseStrategy treeTraverseStrategy = TreeTraverseStrategy.BreadthFirst) where T1 : Visual where T2 : Visual
{
return(GetVisualChildCollection(parent, new List <Type>()
{
typeof(T1), typeof(T2)
}, treeTraverseStrategy));
}
/// <summary>
/// Returns all the child visual objects of the specified types within the specified parent.
/// </summary>
/// <param name="parent">The parent visual whose children to look through.</param>
/// <param name="typesOfChildren">The types of visuals to search for. All the types should be child types of <see cref="Visual"/>.</param>
/// <param name="treeTraverseStrategy">The strategy to use.</param>
public static IEnumerable <Visual> GetVisualChildCollection(this Visual parent, IEnumerable <Type> typesOfChildren, TreeTraverseStrategy treeTraverseStrategy = TreeTraverseStrategy.BreadthFirst)
{
return(GetVisualChildCollection(parent, (Visual v) =>
{
Type childType = v.GetType();
return typesOfChildren.Any(type => type.IsAssignableFrom(childType));
}, treeTraverseStrategy));
}
/// <summary>
/// Returns all the child visual objects of the specified visual type within the specified parent.
/// </summary>
/// <typeparam name="T">The type of visuals to search for.</typeparam>
/// <param name="parent">The parent visual whose children to look through.</param>
/// <param name="treeTraverseStrategy">The strategy to use.</param>
public static IEnumerable <T> GetVisualChildCollection <T>(this Visual parent, TreeTraverseStrategy treeTraverseStrategy = TreeTraverseStrategy.BreadthFirst) where T : Visual
{
return(GetVisualChildCollection(parent, new List <Type>()
{
typeof(T)
}, treeTraverseStrategy).Cast <T>());
}
