VisualTreeHelper Class

Reference

Definition

Namespace:: System.Windows.Media

Assembly:: PresentationCore.dll

Important

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Provides utility methods that perform common tasks involving nodes in a visual tree.

public ref class VisualTreeHelper abstract sealed

public static class VisualTreeHelper

type VisualTreeHelper = class

Public Class VisualTreeHelper

Inheritance: Object
VisualTreeHelper

Examples

The following example shows how to enumerate all the descendants of a visual object, which is a technique you might want to use if you were interested in serializing all the rendering information of a visual object hierarchy.

// Enumerate all the descendants of the visual object.
public static void EnumVisual(Visual myVisual)
{
    for (int i = 0; i < VisualTreeHelper.GetChildrenCount(myVisual); i++)
    {
        // Retrieve child visual at specified index value.
        Visual childVisual = (Visual)VisualTreeHelper.GetChild(myVisual, i);

        // Do processing of the child visual object.

        // Enumerate children of the child visual object.
        EnumVisual(childVisual);
    }
}

' Enumerate all the descendants of the visual object.
Public Shared Sub EnumVisual(ByVal myVisual As Visual)
    For i As Integer = 0 To VisualTreeHelper.GetChildrenCount(myVisual) - 1
        ' Retrieve child visual at specified index value.
        Dim childVisual As Visual = CType(VisualTreeHelper.GetChild(myVisual, i), Visual)

        ' Do processing of the child visual object.

        ' Enumerate children of the child visual object.
        EnumVisual(childVisual)
    Next i
End Sub

Remarks

Nodes in the visual tree can be either Visual or Visual3D objects. Methods that are specific to a type of visual object are typed as either Visual or Visual3D. However, some methods in the VisualTreeHelper class can accept a DependencyObject value that represents either type of visual object.

WPF supports programmatic access to several different tree structures of objects. Primarily, this is exposed as a visual tree and a logical tree. In some cases, the logical tree is a more useful representation of the elements in a WPF application, but conceptually the logical tree is implemented at a level beyond the Visual class. Unlike the visual tree, the logical tree can represent nonvisual data objects, such as ListItem. For more information on the logical tree, see Trees in WPF. The logical tree also is supported by a similar utility method class, LogicalTreeHelper.

Methods

GetBitmapEffect(Visual)	Returns the BitmapEffect value for the specified Visual.
GetBitmapEffectInput(Visual)	Returns the BitmapEffectInput value for the specified Visual.
GetCacheMode(Visual)	Retrieves the cached representation of the specified Visual.
GetChild(DependencyObject, Int32)	Returns the child visual object from the specified collection index within a specified parent.
GetChildrenCount(DependencyObject)	Returns the number of children that the specified visual object contains.
GetClip(Visual)	Return the clip region of the specified Visual as a Geometry value.
GetContentBounds(Visual)	Returns the cached bounding box rectangle for the specified Visual.
GetContentBounds(Visual3D)	Returns the cached bounding box rectangle for the specified Visual3D.
GetDescendantBounds(Visual)	Returns the union of all the content bounding boxes for all the descendants of the Visual, which includes the content bounding box of the Visual.
GetDescendantBounds(Visual3D)	Returns the union of all the content bounding boxes for all the descendants of the specified Visual3D, which includes the content bounding box of the Visual3D.
GetDpi(Visual)	Gets the DPI information at which this Visual is measured and rendered.
GetDrawing(Visual)	Returns the drawing content of the specified Visual.
GetEdgeMode(Visual)	Returns the edge mode of the specified Visual as an EdgeMode value.
GetEffect(Visual)	Gets the bitmap effect for the specified Visual.
GetOffset(Visual)	Returns the offset of the Visual.
GetOpacity(Visual)	Returns the opacity of the Visual.
GetOpacityMask(Visual)	Returns a Brush value that represents the opacity mask of the Visual.
GetParent(DependencyObject)	Returns a DependencyObject value that represents the parent of the visual object.
GetTransform(Visual)	Returns a Transform value for the Visual.
GetXSnappingGuidelines(Visual)	Returns an X-coordinate (vertical) guideline collection.
GetYSnappingGuidelines(Visual)	Returns a Y-coordinate (horizontal) guideline collection.
HitTest(Visual, HitTestFilterCallback, HitTestResultCallback, HitTestParameters)	Initiates a hit test on the specified Visual, with caller-defined HitTestFilterCallback and HitTestResultCallback methods.
HitTest(Visual, Point)	Returns the topmost Visual object of a hit test by specifying a Point.
HitTest(Visual3D, HitTestFilterCallback, HitTestResultCallback, HitTestParameters3D)	Initiates a hit test on the specified Visual3D, with caller-defined HitTestFilterCallback and HitTestResultCallback methods.
SetRootDpi(Visual, DpiScale)	Updates the DPI information of a Visual. It can only be called on a Visual without a parent.

Applies to

Delen via