代码之家 › 专栏 › 技术社区 › serhio

来自.NET的CustomLineCap构造函数的NotImplementedException

notimplementedexception system.drawing gdi+ .net

serhio · 技术社区 · 14 年前

我想画一个自定义的线帽-一个半径为r的等边三角形。显然我不能:

  Dim triangleSide As Single = CSng(3 * r / Math.Sqrt(3))
  Dim triangleHeight As Single = CSng(3 * r / 2)
  path = New GraphicsPath()
  Dim points() As PointF = New PointF() { _ 
      New PointF(-triangleSide / 2, 0), _ 
      New PointF(triangleSide / 2, 0), _
      New PointF(0, triangleHeight) }
  path.AddLines(points)

  ' Not Implemented Exception, Was is Das? '
  _HlpCap = New CustomLineCap(path, Nothing)

编辑:

马克说了这句话后,我试着用 (Nothing, path)

2 回复 | 直到 14 年前

Mark Cidade 14 年前

GDI+库返回 NotImplemented GdipCreateCustomLineCap() 功能。尝试通过笔划路径,而不是 Nothing :

  Dim path2 As GraphicsPath = New GraphicsPath()
  path2.AddLines(points);
  _HlpCap = New CustomLineCap(path, path2)

Ruud 13 年前

显然,路径不能穿过x轴。我使用以下代码创建箭头帽:

  GraphicsPath capPath = new GraphicsPath();
  float arrowSize = 2.0f;
  capPath.AddLines(new PointF[] {
    new PointF(arrowSize, -(float)Math.Sqrt(3.0) * arrowSize),
    new PointF(0.0f, -0.01f),
    new PointF(-arrowSize, -(float)Math.Sqrt(3.0) * arrowSize)
  });

  CustomLineCap arrowCap = new CustomLineCap(capPath, null, LineCap.NoAnchor, (float)Math.Sqrt(3.0) * arrowSize);

Wyck 4 年前

坏的

GraphicsPath 试图在线的末端画一个箭头并导致 System.NotImplementedException

GraphicsPath capPath = new GraphicsPath();
capPath.AddLine(0, 8, -5, 0);
capPath.AddLine(-5, 0, 5, 0);
arrowPen.CustomEndCap = new CustomLineCap(capPath, null); // System.NotImplementedException

这个 remarks in the docs

这个 fillPath 和 strokePath 将被忽略。如果是 null , 填充路径

这是措辞拙劣的情况之一。医生说应该 “拦截”否则你会被逮捕 System.NotImplementedException异常 . 此拦截问题仅适用于 填充路径 ,而不是 . (文档可能也会用到一些图片。)

很好

下面是一个

GraphicsPath capPath = new GraphicsPath();
capPath.AddLine(0, 0, -5, -8);
capPath.AddLine(-5, -8, 5, -8);
arrowPen.CustomEndCap = new CustomLineCap(capPath, null); // OK

修正你的例子

triangleHeight 从y。这会将箭头的尖端放置在0,0处(这是直线末端的坐标),这很可能是您想要的结果,并将三角形的底部放置在0,0处 -triangleHeight .

float radius = 5.0f;
float triangleSide = 3.0f * radius / (float)Math.Sqrt(3.0f);
float triangleHeight = 3.0f * radius / 2.0f;
GraphicsPath capPath = new GraphicsPath();
capPath.AddLines(new PointF[] {
    new PointF(-triangleSide / 2.0f, -triangleHeight),
    new PointF(triangleSide / 2.0f, -triangleHeight),
    new PointF(0, 0) }
);
arrowPen.CustomEndCap = new CustomLineCap(capPath, null);

  Dim points() As PointF = New PointF() { _ 
      New PointF(-triangleSide / 2, -triangleHeight), _ 
      New PointF(triangleSide / 2, -triangleHeight), _
      New PointF(0, 0) }
  path.AddLines(points)

Fabian 4 年前

在我的情况下,我已经使长度的上限部分取决于容器的宽度。每当我缩小窗体超过某个限制时,我的程序总是异常停止。然后我发现异常是在任何段的长度达到1时抛出的。