Muokkaa

Jaa

How to: Enumerate Drawing Content of a Visual

  • Artikkeli

The Drawing object provide an object model for enumerating the contents of a Visual.

Example

The following example uses the GetDrawing method to retrieve the DrawingGroup value of a Visual and enumerate it.

Note

When you are enumerating the contents of the visual, you are retrieving Drawing objects, and not the underlying representation of the render data as a vector graphics instruction list. For more information, see WPF Graphics Rendering Overview.

public void RetrieveDrawing(Visual v)
{
    DrawingGroup drawingGroup = VisualTreeHelper.GetDrawing(v);
    EnumDrawingGroup(drawingGroup);
}

// Enumerate the drawings in the DrawingGroup.
public void EnumDrawingGroup(DrawingGroup drawingGroup)
{
    DrawingCollection dc = drawingGroup.Children;

    // Enumerate the drawings in the DrawingCollection.
    foreach (Drawing drawing in dc)
    {
        // If the drawing is a DrawingGroup, call the function recursively.
        if (drawing is DrawingGroup group)
        {
            EnumDrawingGroup(group);
        }
        else if (drawing is GeometryDrawing)
        {
            // Perform action based on drawing type.
        }
        else if (drawing is ImageDrawing)
        {
            // Perform action based on drawing type.
        }
        else if (drawing is GlyphRunDrawing)
        {
            // Perform action based on drawing type.
        }
        else if (drawing is VideoDrawing)
        {
            // Perform action based on drawing type.
        }
    }
}

See also