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

学习OpenCV（七）——随机数发生器和绘制文字1、介绍2、代码实现3、运行结果4、用到的类和函数

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

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

学习OpenCV（七）——随机数发生器和绘制文字1、介绍2、代码实现3、运行结果4、用到的类和函数

1、介绍

2、代码实现

3、运行结果

4、用到的类和函数

RNG:

polylines：

getTextSize：

putText:

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