我怎么画圆 [英] how can i draw circle

问题描述

我该如何在C#Windows窗体中绘制一个圆(一半是彩色，一半不是)
我知道如何绘制圆圈，但我不能为它上色
我希望你能理解我
这就是我画圆的方式

how can i draw a circle in c# windows form( half colored and half not)
i know how draw circle but i cant color it
i hope you understand me
and this how i draw circle

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace WindowsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Paint(object sender, PaintEventArgs e)
        {
            e.Graphics.DrawEllipse(Pens.Red, 50, 50, 100, 100);
        }
    }
}

是对的还是不对的?

is that right or not

推荐答案

如果您希望它一半被着色"(您的意思是填入正确的符号?)而另一半不被着色，那不是圆圈.这是两个弧度.使用 Graphics.DrawArc [

If you want it half ''coloured'' (you mean filled in right?) and half not, it''s not a circle. It''s two arcs. Use Graphics.DrawArc[^] and FillPie.

( Whose idea was it to call the Fill and Draw items different things ...)

Bob的回答是正确的.请参阅下面的一些更重要的详细信息:

您所需要的只是DrawEllipse的System.Drawing.Graphics.FillPie(Brush, Rectangle) 之前，请参见 http://msdn.microsoft.com/en-us/library/dw5wshbd.aspx [

Bob''s answer is correct. See some more important details below:

All you need is System.Drawing.Graphics.FillPie(Brush, Rectangle) before of DrawEllipse, see http://msdn.microsoft.com/en-us/library/dw5wshbd.aspx[^].

If you want to allocate a brush, don''t dispose it manually as UJimbo advised. That code is wrong because it will leak memory/resources in the case of exceptions. The right approach is using using statement:

Rectangle ellipseBounds = new Rectangle(50, 50, 100, 100); //like in your code sample
using (Brush brush = new SolidBrush(/* some parameters */)) {
    e.Graphics.FillPie(brush, ellipseBounds, 0, 180); //for example, do it before drawing lines.
    e.Graphics.DrawEllipse(Color.Red, ellipseBounds);
} //brush.Dispose will be automatically called here, even if exception is thrown

关于分配笔等的事情也一样.

—SA

Same thing about allocation of pens, etc.

—SA

您可以感谢BobJanova，DrawArc是一个很好的提示.

You can thank BobJanova for that, DrawArc was a good hint.

System.Drawing.SolidBrush brush0 = new System.Drawing.SolidBrush(System.Drawing.Color.Black);
System.Drawing.SolidBrush brush1 = new System.Drawing.SolidBrush(System.Drawing.Color.Red);
System.Drawing.SolidBrush brush2 = new System.Drawing.SolidBrush(System.Drawing.Color.Blue);

System.Drawing.Pen thePen = new System.Drawing.Pen(brush0);
System.Drawing.Graphics formGraphics = this.CreateGraphics();

formGraphics.DrawArc(thePen, new System.Drawing.Rectangle(150, 50, 100, 100), 0, 180);
formGraphics.DrawArc(thePen, new System.Drawing.Rectangle(150, 50, 100, 100), 180, 360);
formGraphics.FillPie(brush1, new System.Drawing.Rectangle(150, 50, 100, 100), 0, 180);
formGraphics.FillPie(brush2, new System.Drawing.Rectangle(150, 50, 100, 100), 180, 180);

brush0.Dispose();
brush1.Dispose();
brush2.Dispose();
thePen.Dispose();
formGraphics.Dispose();

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