把DrawingContext转换成几何？

Question

有谁知道是否有可能保存或将DrawingContext转换为Geometry？

例如，之后

using (DrawingContext dc = RenderOpen())
{
    dc.DrawLine(penSelected, Data.MidTop, Data.MidTop + vertical);
    dc.DrawLine(pen, Data.MidTop - horizontal, Data.MidTop + thickness);
    dc.DrawLine(pen, Data.MidTop + vertical - thickness, Data.MidTop + horizontal + vertical);
    dc.DrawText(new FormattedText(Data.Time2.ToString("0.0"), cultureinfo, FlowDirection.LeftToRight, typeface, 8, Brushes.Black),
        Data.MidTop + 3 * thickness);
    dc.DrawText(new FormattedText(Data.Time2.ToString("0.0"), cultureinfo, FlowDirection.LeftToRight, typeface, 8, Brushes.Black),
        Data.MidTop + vertical - horizontal - 3 * thickness);
}

以某种方式将绘制的对象保存在几何图形中？

Answer 1

当您用可视化内容填充DrawingVisual时，实际上是创建了一个绘图对象的层次化集合，这些对象可以通过DrawingVisual的Drawing属性(类型为DrawingGroup)访问。这些绘图对象中的每一个实际上属于下列类型之一：

• GeometryDrawing
• GlyphRunDrawing
• ImageDrawing
• VideoDrawing
• DrawingGroup

其中两个提供了获得几何的性质或方法。显然，GeometryDrawing有一个Geometry属性，而GlyphRunDrawing有一个返回GlyphRun对象的GlyphRun属性，而后者又有一个BuildGeometry方法。这个方法返回了GlyphRun文本的轮廓的几何。

从DrawingGroup创建几何的静态帮助方法可能如下所示：

public static Geometry CreateGeometry(DrawingGroup drawingGroup)
{
    var geometry = new GeometryGroup();

    foreach (var drawing in drawingGroup.Children)
    {
        if (drawing is GeometryDrawing)
        {
            geometry.Children.Add(((GeometryDrawing)drawing).Geometry);
        }
        else if (drawing is GlyphRunDrawing)
        {
            geometry.Children.Add(((GlyphRunDrawing)drawing).GlyphRun.BuildGeometry());
        }
        else if (drawing is DrawingGroup)
        {
            geometry.Children.Add(CreateGeometry((DrawingGroup)drawing));
        }
    }

    geometry.Transform = drawingGroup.Transform;
    return geometry;
}

您只需将DrawingVisual的Drawing属性的值传递给此方法：

var geometry = CreateGeometry(visual.Drawing);