opencv画彩色矩形.

#include <opencv2/opencv.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>

using namespace cv;

#define WINDOW_NAME "line mix"

const int g_nMaxAlphaValue = 100;
int g_nAlphaValueSlider;
double g_dAlphaValue;
double g_dBetaValue;

void on_MouseHandle(int event, int x, int y, int flags, void* parma);
void DrawRectagle(cv::Mat & img, cv::Rect box);
void ShowHelpText();

Rect g_rectangle;
bool g_bDrawingBox = false;
RNG g_rng(12345);

Mat g_srcImage1;
Mat g_srcImage2;
Mat g_destImage;

void on_Trackbar(int, void*) {
    g_dAlphaValue = (double)g_nAlphaValueSlider / g_nMaxAlphaValue;
    g_dBetaValue = (1.0 - g_dAlphaValue);
    //addWeighted(g_srcImage1, g_dAlphaValue, g_srcImage2, g_dBetaValue, 0.0, g_destImage);
    addWeighted(g_srcImage2, g_dAlphaValue, g_srcImage1, g_dBetaValue, 0.0, g_destImage);

    imshow(WINDOW_NAME, g_destImage);

}

int main(int argc, char**argv) {
    g_rectangle = Rect(-1, -1, 0, 0);
    Mat srcImage(600, 800, CV_8UC3), tempImage;
    srcImage.copyTo(tempImage);
    g_rectangle = Rect(-1, -1, 0, 0);
    srcImage = Scalar::all(0);

    namedWindow(WINDOW_NAME);
    setMouseCallback(WINDOW_NAME, on_MouseHandle, (void*)&srcImage);

    while (1) {
        srcImage.copyTo(tempImage);
        if (g_bDrawingBox)DrawRectagle(tempImage, g_rectangle);
        imshow(WINDOW_NAME, tempImage);
        if (waitKey(10) == 27)break;
    }

    return 0;

}
void on_MouseHandle(int event, int x, int y, int flags, void * param) {
    Mat&image = *(cv::Mat*)param;
    switch (event) {
    case EVENT_MOUSEMOVE:
    {
        if (g_bDrawingBox) {
            g_rectangle.width = x - g_rectangle.x;
            g_rectangle.height = y - g_rectangle.y;

        }
    }
        break;

    case EVENT_LBUTTONDOWN:
    {
        g_bDrawingBox = true;
        g_rectangle = Rect(x, y, 0, 0);
    }
        break;


    case EVENT_LBUTTONUP:
    {
        g_bDrawingBox = false;
        if (g_rectangle.width < 0) {
            g_rectangle.x += g_rectangle.width;
            g_rectangle.width *= -1;
        }
        if (g_rectangle.height < 0) {
            g_rectangle.y += g_rectangle.height;
            g_rectangle.height *= -1;
        }

        DrawRectagle(image, g_rectangle);


    }
        break;
    }

}

void DrawRectagle(cv::Mat & img, cv::Rect box) {
    rectangle(img, box.tl(), box.br(), Scalar(g_rng.uniform(0, 255), g_rng.uniform(0, 255), g_rng.uniform(0, 255)));
}