carc.cs

苏金明编写的《用VB.NET和VC#.NET开发交互式CAD系统》一书的源代码

using System;
using System.Collections;
using System.Drawing;

namespace VCSharp
{
	/// <summary>
	/// CArc 的摘要说明。
	/// </summary>
	/// 

	public class CArc:CGElement
	{
		protected PointF m_Center;
		protected PointF m_Begin;
		protected PointF m_End;
		Module m=new Module();

		public PointF Center
		{
			get{return m_Center;}
			set{m_Center=value;}
		}

		public PointF ABegin
		{
			get{return m_Begin;}
			set{m_Begin=value;}
		}

		public PointF AEnd
		{
			get{return m_End;}
			set{m_End=value;}
		}

		public float Radius
		{
			get
			{
				float r=m.DistPtoP(m_Center,m_Begin);
				return r;
			}
		}

		public float AngleBegin
		{
			get
			{
				float aAngle=m.GetAngle(m_Center,m_Begin);
				return aAngle;
			}
		}

		public float AngleEnd
		{
			get
			{
				float aAngle=m.GetAngle(m_Center,m_End);
				return aAngle;
			}
		}

		public CArc()
		{
            Init();
		}

		//构造函数，用已知的圆心、起点和另一点进行构造
		public  CArc(PointF pCenter,PointF p1,PointF p2)
		{
			Init();
			m_Center=pCenter;
			m_Begin=p1;
			float r=m.DistPtoP(m_Center,m_Begin);
			float angle2=m.GetAngle(m_Center,p2);
			m_End.X=(float)(r*Math.Cos(angle2))+m_Center.X;;
			m_End.Y=(float)(r*Math.Sin(angle2))+m_Center.Y;
		}

		//构造函数，用已知的一个圆弧进行构造
		public  CArc(CArc aArc)
		{
			m_Center=aArc.Center;
			m_Begin=aArc.ABegin;
			m_End=aArc.AEnd;
		}

        //初始化圆弧
		private new void Init()
		{
			base.Init();
			m_Center=new PointF(0,0);
			m_Begin=new PointF(0,0);
			m_End=new PointF(0,0);
		}

		//绘图
		override public void Draw(Graphics g,DrawMode aDrawMode){
			long aPen,oldP;

			//将控制点的坐标由世界坐标转换为页面坐标
			PointF ec=m.WorldtoPage(m_Center);
			PointF eb=m.WorldtoPage(m_Begin);
			PointF ee=m.WorldtoPage(m_End);

			//获得当前绘图环境的句柄
			IntPtr hdc=g.GetHdc();

			//设置画笔参数
			int[] penPara=DrawSettings(hdc,aDrawMode);
			//创建画笔
            aPen=Win32API.CreatePen(penPara[0],penPara[1],penPara[2]);
			//把画笔选入绘图环境，并返回原来的画笔
			oldP=Win32API.SelectObject(hdc,aPen);
			//用刚刚创建的画笔绘圆弧
			Win32API.Arc(hdc, (int)(ec.X - Radius), (int)(ec.Y + Radius),
			    (int)(ec.X + Radius), (int)(ec.Y - Radius), (int)(eb.X), 
			    (int)(eb.Y), (int)(ee.X), (int)(ee.Y));
	        //把原来的画笔选入绘图环境
	        Win32API.SelectObject(hdc, oldP);
	        //删除新创建的画笔
	        Win32API.DeleteObject(aPen);
	        //释放绘图环境句柄
	        g.ReleaseHdc(hdc);
		}

	}
}