opencv学习笔记基本图像的绘制——直线椭圆矩形圆和多边形

Posted 2021-06-29 非晚非晚

本文主要涉及的opencv函数包括：

• 用于绘制直线的line函数；
• 用于绘制椭圆的ellipse函数；
• 用于绘制矩形的rectangle函数；
• 用于绘制圆的circle函数；（可以作为粗的点）
• 用于绘制填充的多边形的fillPoly函数。
• 画点：直接对Mat进行元素颜色修改即可。

1. DrawEllipse函数的写法

自定义的绘制函数，实现了绘制了不同角度、相同尺度的椭圆。函数中DrawElipse调用了OpenCV中的ellipse函数，将椭圆画到图像img上。

void DrawEllipse(Mat img, double angle)
{
	int thickness = 2;
	int lineType = 8;
	ellipse(	img,//将椭圆画到img图像上
		Point(WINDOW_WIDTH / 2, WINDOW_WIDTH / 2),//椭圆中心点
		Size(WINDOW_WIDTH/4, WINDOW_WIDTH/16),//长和宽，被矩形包围
		angle,//椭圆旋转角度
		0,//扩展弧度从0度到360度
		360,
		Scalar(255, 129, 0),//图形颜色为蓝色
		thickness,//线宽
		lineType);//线型
}

2. DrawFilledCircle()函数的写法

DrawFilledCircle()调用了OpenCV中的circle函数，将圆画到图像img上。

void DrawFilledCircle( Mat img, Point center )
{
	int thickness = -1;
	int lineType = 8;
 
	circle( img,
		center,//圆心由点center定义
		WINDOW_WIDTH/32,//圆的半径
		Scalar( 0, 0, 255 ),//圆的颜色
		thickness,//线粗
		lineType );
}

3. DrawPolygon()函数的写法

DrawPolygon()调用了OpenCV的fillPoly函数，将多边形画到图像img上。

void DrawPolygon( Mat img )
{
	int lineType = 8;
 
	//创建一些点
	Point rookPoints[1][20];
	rookPoints[0][0]  = Point(    WINDOW_WIDTH/4,   7*WINDOW_WIDTH/8 );
	rookPoints[0][1]  = Point(  3*WINDOW_WIDTH/4,   7*WINDOW_WIDTH/8 );
	rookPoints[0][2]  = Point(  3*WINDOW_WIDTH/4,  13*WINDOW_WIDTH/16 );
	rookPoints[0][3]  = Point( 11*WINDOW_WIDTH/16, 13*WINDOW_WIDTH/16 );
	rookPoints[0][4]  = Point( 19*WINDOW_WIDTH/32,  3*WINDOW_WIDTH/8 );
	rookPoints[0][5]  = Point(  3*WINDOW_WIDTH/4,   3*WINDOW_WIDTH/8 );
	rookPoints[0][6]  = Point(  3*WINDOW_WIDTH/4,     WINDOW_WIDTH/8 );
	rookPoints[0][7]  = Point( 26*WINDOW_WIDTH/40,    WINDOW_WIDTH/8 );
	rookPoints[0][8]  = Point( 26*WINDOW_WIDTH/40,    WINDOW_WIDTH/4 );
	rookPoints[0][9]  = Point( 22*WINDOW_WIDTH/40,    WINDOW_WIDTH/4 );
	rookPoints[0][10] = Point( 22*WINDOW_WIDTH/40,    WINDOW_WIDTH/8 );
	rookPoints[0][11] = Point( 18*WINDOW_WIDTH/40,    WINDOW_WIDTH/8 );
	rookPoints[0][12] = Point( 18*WINDOW_WIDTH/40,    WINDOW_WIDTH/4 );
	rookPoints[0][13] = Point( 14*WINDOW_WIDTH/40,    WINDOW_WIDTH/4 );
	rookPoints[0][14] = Point( 14*WINDOW_WIDTH/40,    WINDOW_WIDTH/8 );
	rookPoints[0][15] = Point(    WINDOW_WIDTH/4,     WINDOW_WIDTH/8 );
	rookPoints[0][16] = Point(    WINDOW_WIDTH/4,   3*WINDOW_WIDTH/8 );
	rookPoints[0][17] = Point( 13*WINDOW_WIDTH/32,  3*WINDOW_WIDTH/8 );
	rookPoints[0][18] = Point(  5*WINDOW_WIDTH/16, 13*WINDOW_WIDTH/16 );
	rookPoints[0][19] = Point(    WINDOW_WIDTH/4,  13*WINDOW_WIDTH/16 );
 
	const Point* ppt[1] = { rookPoints[0] };
	int npt[] = { 20 };
 
	fillPoly( img,
		ppt,      //多边形的顶点集
		npt,      //多边形定点数目
		1,        //多边形数量
		Scalar( 255, 255, 255 ),    //多边形的颜色
		lineType );
}

4. DrawLine()函数的写法

DrawLine()调用了OpenCV中的line函数，用于在图像img上画一条直线段。

void DrawLine( Mat img, Point start, Point end )
{
	int thickness = 2;
	int lineType = 8;
	line( img,
		start,    //线段始点
		end,      //线段终点
		Scalar( 0, 0, 0 ),  //黑色线条
		thickness,          //线粗
		lineType );
}

5. 绘制矩形函数：rectangle

	rectangle( rookImage,
		Point( 0, 7*WINDOW_WIDTH/8 ),//左上角
		Point( WINDOW_WIDTH, WINDOW_WIDTH),//右下角
		Scalar( 0, 255, 255 ),
		-1,
		8 );

6. 整体代码示例

#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
using namespace cv;
#include <opencv2/imgproc/imgproc.hpp>
 
//-----------------------------------【宏定义部分】-------------------------------------------- 
//		描述：定义一些辅助宏 
//------------------------------------------------------------------------------------------------ 
#define WINDOW_NAME1 "【绘制图1】"        //为窗口标题定义的宏 
#define WINDOW_NAME2 "【绘制图2】"        //为窗口标题定义的宏 
#define WINDOW_WIDTH 600//定义窗口大小的宏
 
//--------------------------------【全局函数声明部分】-------------------------------------
//		描述：全局函数声明
//-----------------------------------------------------------------------------------------------
void DrawEllipse( Mat img, double angle );//绘制椭圆
void DrawFilledCircle( Mat img, Point center );//绘制圆
void DrawPolygon( Mat img );//绘制多边形
void DrawLine( Mat img, Point start, Point end );//绘制线段
 
//---------------------------------------【main( )函数】--------------------------------------
//		描述：控制台应用程序的入口函数，我们的程序从这里开始执行
//-----------------------------------------------------------------------------------------------
int main( void )
{
 
	// 创建空白的Mat图像
	Mat atomImage = Mat::zeros( WINDOW_WIDTH, WINDOW_WIDTH, CV_8UC3 );
	Mat rookImage = Mat::zeros( WINDOW_WIDTH, WINDOW_WIDTH, CV_8UC3 );
 
	// ---------------------<1>绘制化学中的原子示例图------------------------
 
	//【1.1】先绘制出椭圆
	DrawEllipse( atomImage, 90 );
	DrawEllipse( atomImage, 0 );
	DrawEllipse( atomImage, 45 );
	DrawEllipse( atomImage, -45 );
 
	//【1.2】再绘制圆心
	DrawFilledCircle( atomImage, Point( WINDOW_WIDTH/2, WINDOW_WIDTH/2) );
 
	// ----------------------------<2>绘制组合图-----------------------------
	//【2.1】先绘制出多边形
	DrawPolygon( rookImage );
 
	// 【2.2】绘制矩形
	rectangle( rookImage,
		Point( 0, 7*WINDOW_WIDTH/8 ),//左上角
		Point( WINDOW_WIDTH, WINDOW_WIDTH),//右下角
		Scalar( 0, 255, 255 ),
		-1,
		8 );
 
	// 【2.3】绘制一些线段
	DrawLine( rookImage, Point( 0, 15*WINDOW_WIDTH/16 ), Point( WINDOW_WIDTH, 15*WINDOW_WIDTH/16 ) );
	DrawLine( rookImage, Point( WINDOW_WIDTH/4, 7*WINDOW_WIDTH/8 ), Point( WINDOW_WIDTH/4, WINDOW_WIDTH ) );
	DrawLine( rookImage, Point( WINDOW_WIDTH/2, 7*WINDOW_WIDTH/8 ), Point( WINDOW_WIDTH/2, WINDOW_WIDTH ) );
	DrawLine( rookImage, Point( 3*WINDOW_WIDTH/4, 7*WINDOW_WIDTH/8 ), Point( 3*WINDOW_WIDTH/4, WINDOW_WIDTH ) );
 
	// ---------------------------<3>显示绘制出的图像------------------------
	imshow( WINDOW_NAME1, atomImage );
	moveWindow( WINDOW_NAME1, 0, 200 );//窗口显示的位置，让两幅图像对齐
	imshow( WINDOW_NAME2, rookImage );
	moveWindow( WINDOW_NAME2, WINDOW_WIDTH, 200 );
 
	waitKey( 0 );
	return(0);
}

输出如下：