案例2-直线中点Bresenham算法

课程实验报告步骤为了规范颜色的处事，定义了CRGB类，重载了“+”，“-”、“*”、“\”、“+=”、“-=”、“*=”、“/=”运算符。

成员函数Normalize()将颜色分量red,green,blue规范到[0,1]闭区间内。

RGB.h#pragma onceclass CRGB{public:CRGB();CRGB(double, double, double);~CRGB();friend CRGB operator + (const CRGB&, const CRGB&);friend CRGB operator - (const CRGB&, const CRGB&);friend CRGB operator * (const CRGB&, const CRGB&);friend CRGB operator * (const CRGB&, double);friend CRGB operator * (double, const CRGB&);friend CRGB operator / (const CRGB&, double);friend CRGB operator += (const CRGB&, const CRGB&);friend CRGB operator -= (const CRGB&, const CRGB&);friend CRGB operator *= (const CRGB&, const CRGB&);friend CRGB operator /= (const CRGB&, double);void Normalize();public:double red;double green;double blue;};RGB.cpp#include"stdafx.h"#include"RGB.h"CRGB::CRGB(){red = 1.0;green = 1.0;blue = 1.0;}CRGB::~CRGB(){}CRGB::CRGB(double r, double g, double b){red = r;green = g;blue = b;}CRGB operator +(const CRGB &c1, const CRGB &c2) {CRGB c;c.red = c1.red + c2.red;c.green = c1.green + c2.green;c.blue = c1.blue + c2.blue;return c;}CRGB operator - (const CRGB &c1, const CRGB &c2) {CRGB c;c.red = c1.red - c2.red;c.green = c1.green - c2.green;c.blue = c1.blue - c2.blue;return c;}CRGB operator * (const CRGB&c1, const CRGB&c2) {CRGB c;c.red = c1.red * c2.red;c.green = c1.green * c2.green;c.blue = c1.blue * c2.blue;return c;}CRGB operator * (const CRGB&c1, double k){CRGB c;c.red = c1.red*k;c.green = c1.green*k;c.blue = c1.blue*k;return c;}CRGB operator * (double k, const CRGB&c1){CRGB c;c.red = c1.red*k;c.green = c1.green*k;c.blue = c1.blue*k;return c;}CRGB operator / (double k, const CRGB&c1){CRGB c;c.red = c1.red / k;c.green = c1.green / k;c.blue = c1.blue / k;return c;}CRGB operator +=(const CRGB &c1, const CRGB &c2) {CRGB c;c.red = c1.red + c2.red;c.green = c1.green + c2.green;c.blue = c1.blue + c2.blue;return c;}CRGB operator -= (const CRGB &c1, const CRGB &c2) {CRGB c;c.red = c1.red - c2.red;c.green = c1.green - c2.green;c.blue = c1.blue - c2.blue;return c;}CRGB operator *= (const CRGB&c1, const CRGB&c2) {CRGB c;c.red = c1.red * c2.red;c.green = c1.green * c2.green;c.blue = c1.blue * c2.blue;return c;}CRGB operator /= (const CRGB&c1, double k){CRGB c;c.red = c1.red / k;c.green = c1.green / k;c.blue = c1.blue / k;return c;}void CRGB::Normalize(){red = (red<0.0) ? 0.0 : ((red>1.0) ? 1.0 : red);green = (green<0.0) ? 0.0 : ((green>1.0) ? 1.0 : green);blue = (blue<0.0) ? 0.0 : ((blue>1.0) ? 1.0 : blue);}4、设计Cline直线类定义直线绘制任意斜率的直线，其成员函数为MoveTo()和LineTo()。

Line.h#pragma once#include"P2.h"#include"RGB.h"class CLine{public:CLine();virtual ~CLine();void MoveTo(CDC *, CP2);//移动到指定位置void MoveTo(CDC *, double, double);void LineTo(CDC *, CP2);//绘制直线，不含终点void LineTo(CDC *, double, double);public:CP2P0;//起点CP2P1;//终点};Line.cpp#include"stdafx.h"#include"Line.h"#include"math.h"#define Round(d) int(floor(d+0.5))//四舍五入宏定义#ifdef_DEBUG#undef THIS_FILEstatic char THIS_FILE[] = __FILE__;#define new DEBUG_NEW#endifCLine::CLine(){}CLine::~CLine(){}void CLine::MoveTo(CDC *pDC, CP2p0)//绘制直线起点函数{P0 = p0;}void CLine::MoveTo(CDC *pDC, double x0, double y0)//重载函数{P0 = CP2(x0, y0);}void CLine::LineTo(CDC *pDC, CP2p1){P1 = p1;CP2p, t;CRGB clr = CRGB(0.0, 0.0, 0.0);//黑色像素点if (fabs(P0.x - P1.x)<1e-6)//绘制垂线{if (P0.y>P1.y)//交换顶点,使得起始点低于终点{t = P0; P0 = P1; P1 = t;}for (p = P0; p.y<P1.y; p.y++){pDC->SetPixelV(Round(p.x), Round(p.y), RGB(clr.red* 255, clr.green * 255, clr.blue * 255));}}else{double k, d;k = (P1.y - P0.y) / (P1.x - P0.x);if (k>1.0)//绘制k>1{if (P0.y > P1.y){t = P0; P0 = P1; P1 = t;}d = 1 - 0.5*k;for (p = P0; p.y < P1.y; p.y++){pDC->SetPixelV(Round(p.x), Round(p.y), RGB(clr.red * 255, clr.green * 255, clr.blue * 255));if (d >= 0){p.x++;d += 1 - k;}elsed += 1;}}if (0.0 <= k && k <= 1.0)//绘制0<=k<=1{if (P0.x > P1.x){t = P0; P0 = P1; P1 = t;}d = 0.5 - k;for (p = P0; p.x < P1.x; p.x++){pDC->SetPixelV(Round(p.x), Round(p.y), RGB(clr.red * 255, clr.green * 255, clr.blue * 255));if (d < 0){p.y++;d += 1 - k;}elsed -= k;}}if (k >= -1.0 && k<0.0)//绘制-1<=k<0{if (P0.x>P1.x){t = P0; P0 = P1; P1 = t;}d = -0.5 - k;for (p = P0; p.x<P1.x; p.x++){pDC->SetPixelV(Round(p.x), Round(p.y), RGB(clr.red * 255, clr.green * 255, clr.blue * 255));if (d>0){p.y--;d -= 1 + k;}elsed -= k;}}if (k < -1.0)//绘制k<-1{if (P0.y<P1.y){t = P0; P0 = P1; P1 = t;}d = -1 - 0.5*k;for (p = P0; p.y>P1.y; p.y--){pDC->SetPixelV(Round(p.x), Round(p.y), RGB(clr.red * 255, clr.green * 255, clr.blue * 255));if (d < 0){p.x++;d -= 1 + k;}elsed -= 1;}}}P0 = p1;}void CLine::LineTo(CDC *pDC, double x1, double y1)//重载函数{LineTo(pDC, CP2(x1, y1));}5、添加鼠标消息映射添加WM_LBUTTONDOWN消息映射函数void CTestView::OnLButtonDown(UINT nFlags, CPoint point){// TODO: 在此添加消息处理程序代码和/或调用默认值p0.x = point.x;p0.y = point.y;p0.x = p0.x - rect.Width() / 2; //设备坐标系向自定义坐标系转换p0.y = rect.Height() / 2 - p0.y;CView::OnLButtonDown(nFlags, point);}添加WM_LBUTTONUP消息映射函数void CTestView::OnLButtonUp(UINT nFlags, CPoint point){// TODO: 在此添加消息处理程序代码和/或调用默认值p1.x=point.x;p1.y=point.y;CLine *line=new CLine;CDC *pDC=GetDC();//定义设备上下文指针//与案例比新加的语句GetClientRect(rect);pDC->SetMapMode(MM_ANISOTROPIC); //自定义坐标系pDC->SetWindowExt(rect.Width(),rect.Height()); //设置窗口比例pDC->SetViewportExt(rect.Width(),-rect.Height()); //设置视区比例，且x轴水平向右，y轴垂直向上pDC->SetViewportOrg(rect.Width()/2,rect.Height()/2);//设置客户区中心为坐标系原点rect.OffsetRect(-rect.Width()/2,-rect.Height()/2); //矩形与客户区重合/*pDC->MoveTo(0, 0);pDC->LineTo(100, 200);*/p1.x=p1.x-rect.Width()/2;p1.y=rect.Height()/2-p1.y;line->MoveTo(pDC,p0);line->LineTo(pDC,p1);delete line;ReleaseDC(pDC);CView::OnLButtonUp(nFlags, point);}调试过程及实验结果总结本案例实现的Cline类的成员函数类似于CDC类的MoveTo()函数和LineTo()函数，用于绘制任意斜的直线段。