cline.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>
	/// CLine 的摘要说明。
	/// </summary>
	/// 

	//直线段类
	[Serializable()]public class CLine:CGElement
	{
		protected PointF m_Begin;
		protected PointF m_End;
		Module m=new Module();

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

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

		public CLine()
		{
            Init();
		}

		public CLine(PointF pBegin,PointF pEnd)
		{
			Init();
			m_Begin=pBegin;
			m_End=pEnd;
		}

		public CLine(CLine aline)
		{
			m_Begin=aline.LBegin;
			m_End=aline.LEnd;
		}

		private new void Init()
		{
			base.Init();
			m_Begin=new PointF(0,0);
			m_End=new PointF(0,0);
		}

		//绘直线段
		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 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);
			Win32API.LPPOINT prePos=new Win32API.LPPOINT();
		    //把画笔移动到直线段的起点处
	        Win32API.MoveToEx(hdc, (int)(eb.X), (int)(eb.Y), prePos);
	        //绘直线段到终点
	        Win32API.LineTo(hdc, (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);
		}

		//计算包围矩形
		override public CBox GetBox()
		{
			CBox aBox=new CBox();
			if (m_Begin.X==m_End.X)
			{
				aBox.minX=m_Begin.X-Const.PickRadius;
				aBox.minY=Math.Min(m_Begin.Y,m_End.Y);
				aBox.maxX=m_Begin.X+Const.PickRadius;
				aBox.maxY=Math.Max(m_Begin.Y,m_End.Y);
			}
			else if (m_Begin.Y==m_End.Y)
			{
			    aBox.minX=Math.Min(m_Begin.X,m_End.X);
				aBox.minY=m_Begin.Y-Const.PickRadius;
				aBox.maxX=Math.Max(m_Begin.X,m_End.X);
				aBox.maxY=m_Begin.Y+Const.PickRadius;
			}
			else
			{
				aBox.minX=Math.Min(m_Begin.X,m_End.X);
				aBox.minY=Math.Min(m_Begin.Y,m_End.Y);
				aBox.maxX=Math.Max(m_Begin.X,m_End.X);          
				aBox.maxY=Math.Max(m_Begin.Y,m_End.Y);
			}

			return aBox;
		}


		//计算点到直线段的距离
		private float distPtoL(PointF aPos,CLine aLine)
		{
			float px,py,dist;
            float distX,distY;
			float[] kc;

			px=aPos.X;
			py=aPos.Y;

			//获取直线段的截距式方程，返回斜率和截距
			kc=aLine.LineKX();
			//如果为水平直线段
			if (kc[0]==0) 
			{
				distX=10000;
				distY=Math.Abs(py-aLine.LBegin.Y);
			}
			//如果为竖直直线段
			else if (kc[0]==10000) 
			{
				distX=Math.Abs(px-aLine.LBegin.X);
				distY=10000;
			}
			//如果为斜线
			else 
			{
				distX=Math.Abs(px-(py-kc[1])/kc[0]);
				distY=Math.Abs(py-(kc[0]*px+kc[1]));
			}
			//返回水平距离和竖直距离之间的小值
			dist=Math.Min(distX,distY);
			return dist;
		}

    
		//计算直线段的截距式方程
		private float[] LineKX() 
		{
			float kc0,kc1;
		    //若直线段不为竖直线段
			if (m_Begin.X!=m_End.X) 
			{
			    kc0=(m_End.Y-m_Begin.Y)/(m_End.X-m_Begin.X);
			}
			//如果是竖直线段
			else 
			{
				kc0=10000f;
			}
			//计算截距
			kc1=m_Begin.Y-kc0*m_Begin.X;

			float[] kc={kc0,kc1};

			return kc;
		}


		//拾取直线段
		override public bool Pick(PointF aPos) 
		{
			CBox geBox=new CBox();

			//判断拾取点是否在测试包围矩形中，若不是，
			//则直线段不被拾取
			if (!(m.InBox(GetBox(),aPos))) 
			{
				return false;
			}
			else 
			{
				if (distPtoL(aPos,this)<Const.PickRadius) 
				{
					return true;
				}
				else 
				{
					return false;
				}
			}
		}

		//判断拾取点是否位于包围矩形中
		private  bool InBox(CBox aBox,PointF aPos) 
		{
		     if (aPos.X>aBox.minX && aPos.Y>aBox.minY
				&& aPos.X<aBox.maxX && aPos.Y<aBox.maxY) 
			{
				return true;
			}
			else 
			{
				return false;
			}
		}

		//平移变换
		override public  void Move(Graphics g,PointF  basePos,PointF desPos)
		{
			float xx,yy;
			//计算在X和Y两个方向上的位移量
			xx = desPos.X - basePos.X;
			yy = desPos.Y - basePos.Y;
			m_Begin.X += xx;
			m_Begin.Y += yy;
			m_End.X += xx;
			m_End.Y += yy;
		}


		//旋转变换
		override public void Rotate(Graphics g,PointF basePos, float aAngle)
		{
			m_Begin = m.pRotate(basePos, m_Begin, aAngle);
			m_End = m.pRotate(basePos, m_End, aAngle);
		}

		//镜像变换
		override public void Mirror(Graphics g,PointF pPos1,PointF pPos2)
		{
			m_Begin = m.pMirror(pPos1, pPos2, m_Begin);
			m_End = m.pMirror(pPos1, pPos2, m_End);
		}

		//比例变换
		override public void Scale(Graphics g, float sx,float sy)
		{
			m_Begin.X *=sx;
			m_Begin.Y *= sy;
			m_End.X *= sx;
			m_End.Y *=sy;
		}
	}
}