学习OpenCV（七）——随机数发生器和绘制文字

本次范例是在上一次博客学习OpenCV范例（六）——基本绘图的基础上，加上随机数发生器和文字显示，进行更加有趣的开发，当本次范例学习完之后，基本的绘图函数也就学习完了。

1、介绍

范例通过使用 随机数发生器类 (RNG) 并得到均匀分布的随机数，代入到绘制函数的参数里面，使得产生各种各样的图案，通过使用函数 putText 显示文字，最后通过循环，产生动态效果。

2、代码实现

#include "stdafx.h"

/**
* @file Drawing_2.cpp
* @brief Simple sample code
*/

#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <iostream>
#include <stdio.h>

using namespace cv;

/// Global Variables
const int NUMBER = 100;
const int DELAY = 5;

const int window_width = 900;
const int window_height = 600;
int x_1 = -window_width/2;
int x_2 = window_width*3/2;
int y_1 = -window_height/2;
int y_2 = window_height*3/2;

/// Function headers
static Scalar randomColor( RNG& rng );
int Drawing_Random_Lines( Mat image, char* window_name, RNG rng );//画线
int Drawing_Random_Rectangles( Mat image, char* window_name, RNG rng );//画矩形
int Drawing_Random_Ellipses( Mat image, char* window_name, RNG rng );//画一些弧线
int Drawing_Random_Polylines( Mat image, char* window_name, RNG rng );// 画一些折线
int Drawing_Random_Filled_Polygons( Mat image, char* window_name, RNG rng );// 画被填充的多边形
int Drawing_Random_Circles( Mat image, char* window_name, RNG rng );// 画圆
int Displaying_Random_Text( Mat image, char* window_name, RNG rng );// 在随机的地方绘制文字
int Displaying_Big_End( Mat image, char* window_name, RNG rng );//显示最后结果

/**
* @function main
*/
int main( void )
{
int c;

/// Start creating a window
char window_name[] = "Drawing_2 Tutorial";

/// Also create a random object (RNG)
RNG rng( 0xFFFFFFFF );

/// Initialize a matrix filled with zeros
Mat image = Mat::zeros( window_height, window_width, CV_8UC3 );
/// Show it in a window during DELAY ms
imshow( window_name, image );
waitKey( DELAY );

/// Now, let's draw some lines
c = Drawing_Random_Lines(image, window_name, rng);
if( c != 0 ) return 0;

/// Go on drawing, this time nice rectangles
c = Drawing_Random_Rectangles(image, window_name, rng);
if( c != 0 ) return 0;

/// Draw some ellipses
c = Drawing_Random_Ellipses( image, window_name, rng );
if( c != 0 ) return 0;

/// Now some polylines
c = Drawing_Random_Polylines( image, window_name, rng );
if( c != 0 ) return 0;

/// Draw filled polygons
c = Drawing_Random_Filled_Polygons( image, window_name, rng );
if( c != 0 ) return 0;

/// Draw circles
c = Drawing_Random_Circles( image, window_name, rng );
if( c != 0 ) return 0;

/// Display text in random positions
c = Displaying_Random_Text( image, window_name, rng );
if( c != 0 ) return 0;

/// Displaying the big end!
c = Displaying_Big_End( image, window_name, rng );
if( c != 0 ) return 0;

waitKey(0);
return 0;
}

/// Function definitions

/**
* @function randomColor
* @brief Produces a random color given a random object
*/
static Scalar randomColor( RNG& rng )
{
int icolor = (unsigned) rng;
return Scalar( icolor&255, (icolor>>8)&255, (icolor>>16)&255 );
}

/**
* @function Drawing_Random_Lines
*/
int Drawing_Random_Lines( Mat image, char* window_name, RNG rng )
{
Point pt1, pt2;

for( int i = 0; i < NUMBER; i++ )
{
pt1.x = rng.uniform( x_1, x_2 );
pt1.y = rng.uniform( y_1, y_2 );
pt2.x = rng.uniform( x_1, x_2 );
pt2.y = rng.uniform( y_1, y_2 );

line( image, pt1, pt2, randomColor(rng), rng.uniform(1, 10), 8 );
imshow( window_name, image );
if( waitKey( DELAY ) >= 0 )
{ return -1; }
}

return 0;
}

/**
* @function Drawing_Rectangles
*/
int Drawing_Random_Rectangles( Mat image, char* window_name, RNG rng )
{
Point pt1, pt2;
int lineType = 8;
int thickness = rng.uniform( -3, 10 );

for( int i = 0; i < NUMBER; i++ )
{
pt1.x = rng.uniform( x_1, x_2 );
pt1.y = rng.uniform( y_1, y_2 );
pt2.x = rng.uniform( x_1, x_2 );
pt2.y = rng.uniform( y_1, y_2 );

rectangle( image, pt1, pt2, randomColor(rng), MAX( thickness, -1 ), lineType );

imshow( window_name, image );
if( waitKey( DELAY ) >= 0 )
{ return -1; }
}

return 0;
}

/**
* @function Drawing_Random_Ellipses
*/
int Drawing_Random_Ellipses( Mat image, char* window_name, RNG rng )
{
int lineType = 8;

for ( int i = 0; i < NUMBER; i++ )
{
Point center;
center.x = rng.uniform(x_1, x_2);
center.y = rng.uniform(y_1, y_2);

Size axes;
axes.width = rng.uniform(0, 200);
axes.height = rng.uniform(0, 200);

double angle = rng.uniform(0, 180);

ellipse( image, center, axes, angle, angle - 100, angle + 200,
randomColor(rng), rng.uniform(-1,9), lineType );

imshow( window_name, image );

if( waitKey(DELAY) >= 0 )
{ return -1; }
}

return 0;
}

/**
* @function Drawing_Random_Polylines
*/
int Drawing_Random_Polylines( Mat image, char* window_name, RNG rng )
{
int lineType = 8;

for( int i = 0; i< NUMBER; i++ )
{
Point pt[2][3];
pt[0][0].x = rng.uniform(x_1, x_2);
pt[0][0].y = rng.uniform(y_1, y_2);
pt[0][1].x = rng.uniform(x_1, x_2);
pt[0][1].y = rng.uniform(y_1, y_2);
pt[0][2].x = rng.uniform(x_1, x_2);
pt[0][2].y = rng.uniform(y_1, y_2);
pt[1][0].x = rng.uniform(x_1, x_2);
pt[1][0].y = rng.uniform(y_1, y_2);
pt[1][1].x = rng.uniform(x_1, x_2);
pt[1][1].y = rng.uniform(y_1, y_2);
pt[1][2].x = rng.uniform(x_1, x_2);
pt[1][2].y = rng.uniform(y_1, y_2);

const Point* ppt[2] = {pt[0], pt[1]};
int npt[] = {3, 3};

polylines(image, ppt, npt, 2, true, randomColor(rng), rng.uniform(1,10), lineType);

imshow( window_name, image );
if( waitKey(DELAY) >= 0 )
{ return -1; }
}
return 0;
}

/**
* @function Drawing_Random_Filled_Polygons
*/
int Drawing_Random_Filled_Polygons( Mat image, char* window_name, RNG rng )
{
int lineType = 8;

for ( int i = 0; i < NUMBER; i++ )
{
Point pt[2][3];
pt[0][0].x = rng.uniform(x_1, x_2);
pt[0][0].y = rng.uniform(y_1, y_2);
pt[0][1].x = rng.uniform(x_1, x_2);
pt[0][1].y = rng.uniform(y_1, y_2);
pt[0][2].x = rng.uniform(x_1, x_2);
pt[0][2].y = rng.uniform(y_1, y_2);
pt[1][0].x = rng.uniform(x_1, x_2);
pt[1][0].y = rng.uniform(y_1, y_2);
pt[1][1].x = rng.uniform(x_1, x_2);
pt[1][1].y = rng.uniform(y_1, y_2);
pt[1][2].x = rng.uniform(x_1, x_2);
pt[1][2].y = rng.uniform(y_1, y_2);

const Point* ppt[2] = {pt[0], pt[1]};
int npt[] = {3, 3};

fillPoly( image, ppt, npt, 2, randomColor(rng), lineType );

imshow( window_name, image );
if( waitKey(DELAY) >= 0 )
{ return -1; }
}
return 0;
}

/**
* @function Drawing_Random_Circles
*/
int Drawing_Random_Circles( Mat image, char* window_name, RNG rng )
{
int lineType = 8;

for (int i = 0; i < NUMBER; i++)
{
Point center;
center.x = rng.uniform(x_1, x_2);
center.y = rng.uniform(y_1, y_2);

circle( image, center, rng.uniform(0, 300), randomColor(rng),
rng.uniform(-1, 9), lineType );

imshow( window_name, image );
if( waitKey(DELAY) >= 0 )
{ return -1; }
}

return 0;
}

/**
* @function Displaying_Random_Text
*/
int Displaying_Random_Text( Mat image, char* window_name, RNG rng )
{
int lineType = 8;

for ( int i = 1; i < NUMBER; i++ )
{
Point org;
org.x = rng.uniform(x_1, x_2);
org.y = rng.uniform(y_1, y_2);

putText( image, "Testing text rendering", org, rng.uniform(0,8),
rng.uniform(0,100)*0.05+0.1, randomColor(rng), rng.uniform(1, 10), lineType);

imshow( window_name, image );
if( waitKey(DELAY) >= 0 )
{ return -1; }
}

return 0;
}

/**
* @function Displaying_Big_End
*/
int Displaying_Big_End( Mat image, char* window_name, RNG )
{
Size textsize = getTextSize("OpenCV forever!", FONT_HERSHEY_COMPLEX, 3, 5, 0);
Point org((window_width - textsize.width)/2, (window_height - textsize.height)/2);
int lineType = 8;

Mat image2;

for( int i = 0; i < 255; i += 2 )
{
image2 = image - Scalar::all(i);
putText( image2, "OpenCV forever!", org, FONT_HERSHEY_COMPLEX, 3,
Scalar(i, i, 255), 5, lineType );

imshow( window_name, image2 );
if( waitKey(DELAY) >= 0 )
{ return -1; }
}

return 0;
}

3、运行结果

点击这里还可以看我录制的关于程序运行的视频，用手机拍的，效果不是很好，希望大神们可以给点建议，如何录制视频。

密码为cool

4、用到的类和函数

RNG:

功能：随机数发生器

实例化一个发生器

RNG rng( 0xFFFFFFFF );

用数值 0xFFFFFFFF 来实例化的一个RNG对象

RNG操作

功能：产生服从均匀分布的随机数

int RNG::uniform(int a, int b）
double RNG::gaussian(double sigma)
float RNG::uniform(float a, float b)double RNG::uniform(double a, double b)

a:随机数产生的左边界，左边界为闭区间

b:随机数产生的右边界，右边界为开区间

功能：产生服从高斯分布的随机数

double RNG::gaussian(double sigma)

sigma：高斯分布的标准差

polylines：

功能：画多边形曲线

结构：

void polylines(Mat& img, const Point** pts, const int* npts, int ncontours, bool isClosed, const Scalar& color, int thickness=1, int lineType=8, int shift=0 )

img：输入图片

pts：多边形顶点集

npts：要绘制的多边形顶点数目

ncontours：要绘制的多边形数目

isClosed：绘制的曲线是否闭合

color：颜色值

thickness：线的粗细程度，如果为负数，则说明圆内被填充。

lineType：线的类型，默认为8联通

getTextSize：

功能：计算一个文本字符串的宽度和高度

结构：

getTextSize(const string& text, int fontFace, double fontScale, int thickness, int* baseLine)

text：文本字符串

fontFace：字体的类型

fontScale：字体的缩放比例

thickness：字体的粗细

baseLine:不知

putText:

功能：绘制文字

结构：

void putText(Mat& img, const string& text, Point org, int fontFace, double fontScale, Scalar color, int thickness=1, int lineType=8, bool bottomLeftOrigin=false )

img：输入图片

text：绘制的文本

org：文字的左下角将用点 org 指定

fontFace：字体的类型

fontScale：字体的缩放比例

color：字体的颜色

thickness：字体的粗细