在使用美图秀秀之类工具的时候，发现了一个魔幻笔效果，然后这里用opencv实现了类似效果。
表现效果是，当鼠标左键在图片窗口上按下时候，会从鼠标当前坐标位置，不断的出现小方框向四面八方散去。 使用的基本原理，就是前面讲过的图像比例混合。两种图片，一张是背景图片，另外一种是各色小方框图片。当鼠标按下时候，小方框图片源源不断的生成， 然后和背景图片比例混合后，以随机的速度，发散出去。
#include <math.h> #include <string.h> #include <stdio.h> #include <stdlib.h> #include <opencv2/core/core.hpp> #include <opencv2/highgui/highgui.hpp> #include <opencv/cv.h> #include "lib/normal.h" #include <math.h> using namespace cv; #define RECT_NUMBER 16 Mat src, src2, imageROI; int width=0, height=0; int src2_width, src2_height; int mouse_width, mouse_height; double alpha = 0.3, beta; char pic_name[20]; bool mouse_left = false; int curRectAddr[RECT_NUMBER][5]; Scalar scalar[RECT_NUMBER]; int rect_num = 2; RNG rng(0xFFFFFFFF); void on_mouse( int event, int x, int y, int flags, void* ustc){ int i; if(event == CV_EVENT_LBUTTONDOWN){ mouse_left = true; }else if(event == CV_EVENT_LBUTTONUP){ mouse_left = false; } if(mouse_left){ rect_num ++; if(rect_num >= 2){ for(i=0; i<RECT_NUMBER; i++){ if(curRectAddr[i][4] == 0){ curRectAddr[i][0] = x; /*rect(i)的初始width*/ curRectAddr[i][1] = y; /*rect(i)的初始height*/ curRectAddr[i][2] = rng.uniform(-20, 20); /*rect(i)的width偏移速度*/ curRectAddr[i][3] = rng.uniform(-20, 20); /*rect(i)的height偏移速度*/ if((curRectAddr[i][2] == 0) && (curRectAddr[i][3] == 0)){ curRectAddr[i][2] = 10; curRectAddr[i][3] = 10; } curRectAddr[i][4] = 1; /*rect(i)的存在状态*/ rect_num = 0; scalar[i][0] = rng.uniform(0, 255); scalar[i][1] = rng.uniform(0, 255); scalar[i][2] = rng.uniform(0, 255); break; } } } } } void add_rect(Mat mat, int num){ curRectAddr[num][0] = curRectAddr[num][0] - curRectAddr[num][2]; curRectAddr[num][1] = curRectAddr[num][1] - curRectAddr[num][3]; if((curRectAddr[num][0] < 0) || (curRectAddr[num][1] < 0)){ curRectAddr[num][4] = 0; return; } if(curRectAddr[num][0] > (width - src2_height)){ curRectAddr[num][4] = 0; return; } if(curRectAddr[num][1] > (height - src2_width)){ curRectAddr[num][4] = 0; return; } imageROI = src(cv::Rect(curRectAddr[num][0], curRectAddr[num][1], src2_height, src2_width)); beta = 1 - alpha; addWeighted(imageROI, alpha, src2, beta, 0.0, imageROI); } int main(int agrc, char* argv[]){ char c; int i; memcpy(pic_name,argv[1],sizeof(argv[1])); src=imread(pic_name,1); width = src.cols; height = src.rows; src2_width = width / 10; src2_height = height / 10; src2 = Mat(src2_width, src2_height, CV_8UC3, 1); IplImage img = src2; cvZero(&img); mouse_width = width/2; mouse_height = height/2; namedWindow("src", 1); cvSetMouseCallback("src", on_mouse, NULL); while(1){ c = waitKey(20); if(c == ‘q‘){ break; } if(mouse_left){ src=imread(pic_name,1); for(i=0; i<RECT_NUMBER; i++){ if(curRectAddr[i][4] != 0){ rectangle(src2,cvPoint(0, 0), cvPoint(src2_height, src2_width), scalar[i], -1); add_rect(src, i); } } } imshow("src",src); } cvDestroyAllWindows(); return 0; }
1、首先是打开传入的背景图片src，获得它的相关信息。接着初始化小方块图片，设置它的大小，和将用cvZero进行初始化。
memcpy(pic_name,argv[1],sizeof(argv[1])); src=imread(pic_name,1); width = src.cols; height = src.rows; src2_width = width / 10; src2_height = height / 10; src2 = Mat(src2_width, src2_height, CV_8UC3, 1); IplImage img = src2; cvZero(&img);
2、接着进入一个死循环中，当鼠标没有按下的时候，除了键值等待之外，不做任何操作。注意如果按下键值‘q‘,则会退出程序。
while(1){ c = waitKey(20); if(c == ‘q‘){ break; } .......... imshow("src",src); }
3、鼠标左键按下，mouse_left为true，则对方框进行初始化，rect_num作为方块产生的延时，同时一共设置了最多可以生成RECT_NUMBER 16
个方块。方块参数保存在：curRectAddr和scalar中，假设以第一个方框为例：它的参数就保存在curRectAddr[0]和scalar[0]中。
具体参数解释如下:
curRectAddr[i][0] = x; /*rect(i)的初始width*/
curRectAddr[i][1] = y; /*rect(i)的初始height*/
curRectAddr[i][2] = rng.uniform(-20, 20); /*rect(i)的width偏移速度*/
curRectAddr[i][3] = rng.uniform(-20, 20); /*rect(i)的height偏移速度*/
curRectAddr[i][4] = 1; /*rect(i)的生存状态*/
scalar[0] /*方块的颜色*/
注意，如果随机生成出来的方块width和height的便宜速度都为0的话，则强行设置它们的偏移速度都为10。
当鼠标左键抬起之后，mouse_left为false。停止生成小方块。
void on_mouse( int event, int x, int y, int flags, void* ustc){ int i; if(event == CV_EVENT_LBUTTONDOWN){ mouse_left = true; }else if(event == CV_EVENT_LBUTTONUP){ mouse_left = false; } if(mouse_left){ rect_num ++; if(rect_num >= 2){ for(i=0; i<RECT_NUMBER; i++){ if(curRectAddr[i][4] == 0){ curRectAddr[i][0] = x; /*rect(i)的初始width*/ curRectAddr[i][1] = y; /*rect(i)的初始height*/ curRectAddr[i][2] = rng.uniform(-20, 20); /*rect(i)的width偏移速度*/ curRectAddr[i][3] = rng.uniform(-20, 20); /*rect(i)的height偏移速度*/ if((curRectAddr[i][2] == 0) && (curRectAddr[i][3] == 0)){ curRectAddr[i][2] = 10; curRectAddr[i][3] = 10; } curRectAddr[i][4] = 1; /*rect(i)的存在状态*/ rect_num = 0; scalar[i][0] = rng.uniform(0, 255); scalar[i][1] = rng.uniform(0, 255); scalar[i][2] = rng.uniform(0, 255); break; } } } } }
4、在main的循环中，由于鼠标左键按下，mouse_left为true。就会实时更新存在状态为1的小方块在背景图的位置。当小方块偏移出背景图之后。 就会将该方块生存状态置为0.停止对它的刷新。
void add_rect(Mat mat, int num){ curRectAddr[num][0] = curRectAddr[num][0] - curRectAddr[num][2]; curRectAddr[num][1] = curRectAddr[num][1] - curRectAddr[num][3]; if((curRectAddr[num][0] < 0) || (curRectAddr[num][1] < 0)){ curRectAddr[num][4] = 0; return; } if(curRectAddr[num][0] > (width - src2_height)){ curRectAddr[num][4] = 0; return; } if(curRectAddr[num][1] > (height - src2_width)){ curRectAddr[num][4] = 0; return; } imageROI = src(cv::Rect(curRectAddr[num][0], curRectAddr[num][1], src2_height, src2_width)); beta = 1 - alpha; addWeighted(imageROI, alpha, src2, beta, 0.0, imageROI); } if(mouse_left){ src=imread(pic_name,1); for(i=0; i<RECT_NUMBER; i++){ if(curRectAddr[i][4] != 0){ rectangle(src2,cvPoint(0, 0), cvPoint(src2_height, src2_width), scalar[i], -1); add_rect(src, i); } } }
对应的效果演示如下:
原文地址：http://blog.csdn.net/u011630458/article/details/46012515
