ccircle.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.Drawing;

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

	public class CCircle:CGElement
	{
		protected PointF m_Center;
		protected PointF m_pCircle;
		Module m=new Module();

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

		public PointF PCircle
		{
			get{return m_pCircle;}
			set{m_pCircle=value;}
		}

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

		public CCircle()
		{
            Init();
		}
		
		public CCircle(PointF pCenter,PointF pCircle) 
		{
			Init();
			m_Center=pCenter;
			m_pCircle=pCircle;
		}

		public CCircle(CCircle aCircle) 
		{
			m_Center=aCircle.Center;
			m_pCircle=aCircle.PCircle;
		}

		private new void Init()
		{
			base.Init();
			m_Center=new PointF(0,0);
			m_pCircle=new PointF(0,0);
		}

		//绘圆
		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);

			//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);
			//把空刷子选入绘图环境
			Win32API.SelectObject(hdc, Win32API.GetStockObject(5));
			//绘圆
	        Win32API.Ellipse(hdc, (int)(ec.X - Radius), 
				  (int)(ec.Y + Radius),
		          (int)(ec.X + Radius), 
				  (int)(ec.Y - Radius));
			//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);
		}

	}
}