【MFC学习笔记-作业6-sin图像】【OnDraw(CDC* pDC)】

根据这段源代码 一步一步剖析CDC的使用

void CDrawSinXView::OnDraw(CDC* pDC)
{
CDrawSinXDoc* pDoc = GetDocument();
ASSERT_VALID(pDoc);
// TODO: add draw code for native data here
//建立画笔
CPen pen_Zuobixi,pen_sinx;
pen_Zuobixi.CreatePen(PS_SOLID,4,RGB(0,0,0));
pen_sinx.CreatePen(PS_SOLID,2,RGB(0,0,255));
pDC->SelectObject(&pen_Zuobixi);
//指定原点
pDC->SetViewportOrg(100,255);
pDC->SetTextColor(RGB(255,0,0));
//绘制横坐标
CString sPIText[]={"-1/2π","","1/2π","π","3/2π","2π","5/2π","3π","7/2π","4π","9/2π","5π"};
int n=-1;
int nTemp=0;
while (nTemp<=660)
{
   pDC->LineTo(60*n,0);
   pDC->LineTo(60*n,-5);
   pDC->MoveTo(60*n,0);
   pDC->TextOut(60*n-sPIText[n+1].GetLength()*3,16,sPIText[n+1]);
   n++;
   nTemp +=60;
}
pDC->MoveTo(0,0);
CString strTemp;
//绘制纵坐标
for(n=-4,nTemp = 0;nTemp<=180;n++,nTemp+=60)
{
   pDC->LineTo(0,60*n);
   pDC->LineTo(5,60*n);
   pDC->MoveTo(0,60*n);
   strTemp.Format("%d",-n);
   pDC->TextOut(10,60*n,strTemp);
}
   double y,radian; 
pDC->SelectObject(&pen_sinx);
for(int x=-60;x<600;x++)
{
   //弧度=X坐标/曲线宽度*角系数*π
   //Y坐标=振幅*曲线宽度*sin(弧度)
   radian =x/((double)60*2)*PI;
   y=sin(radian)*2*60;
   pDC->MoveTo((int)x,(int)y);
   pDC->LineTo((int)x,(int)y);
}
pen_sinx.DeleteObject();
pen_Zuobixi.DeleteObject();

}

void CDrawSinXView::OnDraw(CDC* pDC)

这个函数在File 中 的view.cpp中.

一个一个剖析..

CDrawSinXDoc* pDoc = GetDocument();
ASSERT_VALID(pDoc);
// TODO: add draw code for native data here

系统自带的，并不清楚有什么卵用....

<span style="font-family: Arial, Helvetica, sans-serif;">//建立画笔</span>

CPen pen_Zuobixi,pen_sinx;
pen_Zuobixi.CreatePen(PS_SOLID,4,RGB(0,0,0));
pen_sinx.CreatePen(PS_SOLID,2,RGB(0,0,255));
pDC->SelectObject(&pen_Zuobixi);

如注释所示

1.用CPen 建立一个画笔，并且规定画笔的虚实线（画笔类型），粗，颜色；

此处详情见

http://blog.sina.com.cn/s/blog_71f17cbd0100qsgn.html

2.通过SelectObject来选择当前的画笔

3.RGB 0 0 0 是黑色

4.RGB 0 0 255是 蓝色 

//指定原点
pDC->SetViewportOrg(100,255);
pDC->SetTextColor(RGB(255,0,0));

1.SetViewportOrg 来设定原点的坐标 ..

2.SetTextColor     设置字体颜色

//绘制横坐标
CString sPIText[]={"-1/2π","","1/2π","π","3/2π","2π","5/2π","3π","7/2π","4π","9/2π","5π"};
int n=-1;
int nTemp=0;
while (nTemp<=660)
{
   pDC->LineTo(60*n,0);
   pDC->LineTo(60*n,-5);
   pDC->MoveTo(60*n,0);
   pDC->TextOut(60*n-sPIText[n+1].GetLength()*3,16,sPIText[n+1]);
   n++;
   nTemp +=60;
}
pDC->MoveTo(0,0);

1.LinkTo,表示画笔从当前位置往（x,y）的位置画去

2.MoveTo 表示画笔回到（x,y)的位置（不留下轨迹）

3.TextOut  (x,y,string);

CString strTemp;
//绘制纵坐标
for(n=-4,nTemp = 0;nTemp<=180;n++,nTemp+=60)
{
   pDC->LineTo(0,60*n);
   pDC->LineTo(5,60*n);
   pDC->MoveTo(0,60*n);
   strTemp.Format("%d",-n);
   pDC->TextOut(10,60*n,strTemp);
}

1.与上面的类似...但是利用FOrmat来得到CSrting;

double y,radian;   //绘制sinx 
pDC->SelectObject(&pen_sinx);
for(int x=-60;x<600;x++)
{
   //弧度=X坐标/曲线宽度*角系数*π
   //Y坐标=振幅*曲线宽度*sin(弧度)
   radian =x/((double)60*2)*PI;
   y=sin(radian)*2*60;
   pDC->MoveTo((int)x,(int)y);
   pDC->LineTo((int)x,(int)y);
}
pen_sinx.DeleteObject();
pen_Zuobixi.DeleteObject();

直接绘制吧..

记得DeleteObject来删除画笔...

照猫画虎 完成了 -2Pi->2Pi 的sin图像。。

代码如下：

void CWj1401_0302140107_6View::OnDraw(CDC* pDC)
{
	CPen pen_Zuobixi,pen_sinx;							//创建画笔
	pen_Zuobixi.CreatePen(PS_SOLID,4,RGB(0,0,0));		//描述画笔
	pen_sinx.CreatePen(PS_SOLID,2,RGB(0,0,255));		//描述画笔
	pDC->SelectObject(&pen_Zuobixi);					//设定谁为现在的画笔
	//指定原点
	pDC->SetViewportOrg(300,255);						//指定原点
	pDC->SetTextColor(RGB(255,0,0));					//指定文本颜色
	//绘制横坐标
   CString sPIText[]={"-2π","-3/2π","-1π","-1/2π","","1/2π","1π","3/2π","2π"};		//创建文本
   int n=-1;
   int nTemp=0;
   while (nTemp<=480)
   {
    pDC->LineTo(60*n,0);
    pDC->LineTo(60*n,-5);
    pDC->MoveTo(60*n,0);
    pDC->TextOut(60*n-sPIText[n+1].GetLength()*3,16,sPIText[n+1]);  // (横坐标,纵坐标,字符串)
    n++;
	nTemp +=60;
	}
	pDC->MoveTo(180,0);
	CString strTemp;
    //绘制纵坐标
for(n=-2,nTemp = 0;nTemp<=240;n++,nTemp+=60)
{
   pDC->LineTo(180,60*n);
   pDC->LineTo(185,60*n);
   pDC->MoveTo(180,60*n);
   strTemp.Format("%d",-n);
   pDC->TextOut(190,60*n,strTemp);
}
   double y,radian; 
    pDC->SelectObject(&pen_sinx);
   for(int x=-60;x<420;x++)
{
   //弧度=X坐标/曲线宽度*角系数*π
   //Y坐标=振幅*曲线宽度*sin(弧度)
   radian =x/((double)60*2)*PI;
   y=-cos(radian)*60;
   pDC->MoveTo((int)x,(int)y);
   pDC->LineTo((int)x,(int)y);
}
pen_sinx.DeleteObject();
pen_Zuobixi.DeleteObject();


}