如何绘制椭圆类的圆扇区？ [英] How can I draw a circle sector with the ellipse class?

问题描述

我想在WP7上制作一个圆圈。我试图这样做与椭圆类，我发现了很多解决方案，这使一个量表或饼图或某物，但我需要的只是精华。
任何人都可以帮助？

目的是只显示一个圆（或椭圆）的一部分。如同图片中的黄色区域：

解决方案

这里有一个相当简单的解决问题的办法，虽然它不使用 Ellipse ，它需要一个三角学：

 < Path Fill =Black
 Data =M0,0 L0，-100 A100,100 0 0 1 70.7，-70.7 z/> 
  

Data 属性使用路径标记语法。

• 开始时的M告诉钢笔 M 移动到位置0,0。


• L L 从当前位置（0,0）到0，-100。


• A指示笔绘制椭圆 rc从当前位置到70.7，-70.7（100,100部分确定椭圆的水平和垂直半径，0 0 1部分用于 RotationAngle ， IsLargeArc 和 SweepDirection （顺时针为1，逆时针为0） >
  
• z指示笔关闭或完成形状（这将导致一条线从70.7，-70.7回到0,0）。

70.7来自哪里？那么，这个特定的弧从具有半径100的圆扫出45度的角度，因此坐标70.7，-70.7由 100 * sin（45） code> 100 * cos（45）。

I would like to make a sector of a circle on WP7. I tried to do this with the ellipse class and I found a lot of solution, which make a gauge or pie chart or something, but I need just the essence. Could anyone help?

the aim is to show just one part of a circle (or ellipse). Like the yellow area in the picture:

Thanks, Laci

解决方案

Here's a fairly simple solution to the problem, though it does not use an Ellipse and it requires a little trigonometry:

<Path Fill="Black"
      Data="M0,0 L0,-100 A100,100 0 0 1 70.7,-70.7 z" />

The Data property uses Path Markup Syntax.

• The "M" at the beginning tells the pen to Move to the location 0,0.
• The "L" tells the pen to draw a Line from the current location (0, 0) to 0,-100.
• The "A" tells the pen to draw an elliptical Arc from the current location to 70.7,-70.7 (the "100,100" portion determines the horizontal and vertical radius of the ellipse and the "0 0 1" portion is for RotationAngle, IsLargeArc, and SweepDirection (1 for clockwise, 0 for counter-clockwise)).
• The "z" tells the pen to close or complete the shape (which will cause a line to be drawn from 70.7,-70.7 back to 0,0).

Where did the 70.7 come from? Well, this particular arc sweeps out an angle of 45 degrees from a circle with radius 100, so the coordinates 70.7,-70.7 are determined by 100 * sin(45) and 100 * cos(45).

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