Displaying multiple images

edit

Hi All,

i tried to update an outdated sample code on opencv/wiki

The changes I have made up to now are as follows.

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

using namespace cv;
using namespace std;

int showManyImages( const String winName, const vector<Mat> images );

int main( int argc, char** argv )
{
    vector<Mat> images;

    for ( int i = 0; i < 15; i++ )
    {
        Mat image( 240,320,CV_8UC3, Scalar( (rand()&255), (rand()&255), (rand()&255) ));
        circle( image, Point( image.cols / 2, image.rows / 2 ), image.cols / 3, Scalar( (rand()&255), (rand()&255), (rand()&255) ) );
        images.push_back( image );
        showManyImages("showManyImages test", images);
        waitKey();
    }
    return 0;
}

int showManyImages( const String winName, const vector<Mat> images )
{
    int nImg = images.size() > 12 ? 12 : (int)images.size();

    int size;
    int x, y;

    // w - Maximum number of images in a row
    // h - Maximum number of images in a column
    int w, h;
    // scale - How much we have to resize the image
    float scale;
    int max;

    // TODO: code-block #1 - should be replaced with more robust code 
    // start of code-block #1
    if (nImg <= 0) 
    {
        return -1;
    }
    else if (nImg == 1)
    {
        w = h = 1;
        size = 300;
    }
    else if (nImg == 2)
    {
        w = 2;
        h = 1;
        size = 300;
    }
    else if (nImg == 3 || nImg == 4)
    {
        w = 2;
        h = 2;
        size = 300;
    }
    else if (nImg == 5 || nImg == 6)
    {
        w = 3;
        h = 2;
        size = 200;
    }
    else if (nImg == 7 || nImg == 8)
    {
        w = 4;
        h = 2;
        size = 200;
    }
    else
    {
        w = 4;
        h = 3;
        size = 150;
    }
    // end of code-block #1
    Mat dispayImage = Mat::zeros(Size(100 + size*w, 60 + size*h), CV_8UC3);

    for (int i= 0, m=20, n=20; i <nImg; i++, m+=(20+size))
    {
        x = images[i].cols;
        y = images[i].rows;

        max = ( x > y ) ? x : y;
        scale = (float) ( (float) max / size );

        if ( i%w == 0 && m != 20 )
        {
            m = 20;
            n += 20 + size;
        }

        Mat imageROI = dispayImage( Rect( m, n, (int)( x / scale ), (int)( y / scale )));
        resize( images[i], imageROI, Size((int)( x / scale ), (int)( y / scale )));
    }

    imshow( winName, dispayImage );
    return 0;
}

i think the part marked as code-block #1 should be replaced with more robust code.

any suggestion and contribution is welcome

EDIT

I found a simple way to replace the block #1

int w = images.size() == 2 ? 2 : cvCeil( sqrt( images.size() ));
int h = cvRound( sqrt( images.size() ));
int size = images.size() <= 2 ? 300 : 300 / w * 2;

github link