WPF 自定义形状
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WPF Custom shape
提问by Luis Garcia
I need to create a custom shape to add on a WPF form. The shape is just a triangle. If you are wondering, yes, I can do that with a Polygon in XAML with this:
我需要创建一个自定义形状以添加到 WPF 表单上。形状只是一个三角形。如果您想知道，是的，我可以使用 XAML 中的 Polygon 做到这一点：
<Polygon Fill="LightBlue" Stroke="Black" Name="Triangle">
<Polygon.Points>
<Point X="0" Y="0"></Point>
<Point X="10" Y="0"></Point>
<Point X="5" Y="-10"></Point>
</Polygon.Points>
</Polygon>
The problem is that we need to bind a property from somewhere else that ultimately determines the size of the shape. So, I wrote a simple extension of the shape class like this:
问题是我们需要从其他地方绑定一个最终决定形状大小的属性。所以，我写了一个形状类的简单扩展，如下所示：
public class Triangle:Shape
{
private double size;
public static readonly DependencyProperty SizeProperty = DependencyProperty.Register("Size", typeof(Double), typeof(Triangle));
public Triangle() {
}
public double Size
{
get { return size; }
set { size = value; }
}
protected override Geometry DefiningGeometry
{
get {
Point p1 = new Point(0.0d,0.0d);
Point p2 = new Point(this.Size, 0.0d);
Point p3 = new Point(this.Size / 2, -this.Size);
List<PathSegment> segments = new List<PathSegment>(3);
segments.Add(new LineSegment(p1,true));
segments.Add(new LineSegment(p2, true));
segments.Add(new LineSegment(p3, true));
List<PathFigure> figures = new List<PathFigure>(1);
PathFigure pf = new PathFigure(p1, segments, true);
figures.Add(pf);
Geometry g = new PathGeometry(figures, FillRule.EvenOdd, null);
return g;
}
}
}
I thought that was good but the shape does not show up anywhere on the form. So, I am not sure if the DefiningGeometry method is well written. And if I cannot see anything very likely is not. Thanks!
我认为这很好，但形状没有出现在表格的任何地方。所以，我不确定 DefiningGeometry 方法是否写得很好。如果我看不到任何东西，很可能不是。谢谢！
回答by McGarnagle
The dependency property isn't set up correctly. Write the Sizegetter/setter like this:
依赖属性设置不正确。 像这样编写Sizegetter/setter：
public double Size
{
get { return (double)this.GetValue(SizeProperty); }
set { this.SetValue(SizeProperty, value); }
}
