/*M///////////////////////////////////////////////////////////////////////////
// Copyright (c) 2014, sheng
// All rights reserved.
//
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//M*/



#include <iostream>
#include <vector>

#include <assert.h>

#include <opencv2/opencv.hpp>



/**
 * @brief CombineMultiImages  Combine the input images to a single big image.
 * @param Images         The input images.
 * @param NumberOfRows   The number of the rows to put the input images.
 * @param NumberOfCols   The number of the cols to put the input images.
 * @param Distance       The distance between each image.
 * @param ImageWidth     The width of each image in the big image.
 * @param ImageHeight    The height of each image in the big image.
 * @return      The big image if the operation is successed;
 *              otherwise return empty image.
 *
 * @author sheng
 * @date 2015-03-24
 * @version 0.1
 *
 * @history
 *     <author>       <date>         <version>        <description>
 *      sheng       2015-03-24          0.1           build the function
 *
 */
cv::Mat CombineMultiImages(const std::vector<cv::Mat>& Images,
                           const int NumberOfRows,
                           const int NumberOfCols,
                           const int Distance,
                           const int ImageWidth,
                           const int ImageHeight)
{
    // return empty mat if the Number of rows or cols is smaller than 1.
    assert((NumberOfRows > 0) && (NumberOfCols > 0));
    if ((NumberOfRows < 1) || (NumberOfCols < 1))
    {
        std::cout << "The number of the rows or the cols is smaller than 1."
                  << std::endl;
        return cv::Mat();
    }


    // return empty mat if the distance, the width or the height of image
    // is smaller than 1.
    assert((Distance > 0) && (ImageWidth > 0) && (ImageHeight > 0));
    if ((Distance < 1) || (ImageWidth < 1) || (ImageHeight < 1))
    {
        std::cout << "The distance, the width or the height of the image is smaller than 1."
                  << std::endl;
        return cv::Mat();
    }


    // Get the number of the input images
    const int NUMBEROFINPUTIMAGES = Images.size();


    // return empty mat if the number of the input images is too big.
    assert(NUMBEROFINPUTIMAGES <= NumberOfRows * NumberOfCols);
    if (NUMBEROFINPUTIMAGES > NumberOfRows * NumberOfCols)
    {
        std::cout << "The number of images is too big." << std::endl;
        return cv::Mat();
    }


    // return empty mat if the number of the input images is too low.
    assert(NUMBEROFINPUTIMAGES > 0);
    if (NUMBEROFINPUTIMAGES < 1)
    {
        std::cout << "The number of images is too low." << std::endl;
        return cv::Mat();
    }


    // create the big image
    const int WIDTH = Distance * (NumberOfCols + 1) + ImageWidth * NumberOfCols;
    const int HEIGHT = Distance * (NumberOfRows + 1) + ImageHeight * NumberOfRows;
    cv::Scalar Color(255, 255, 255);
    if (Images[0].channels() == 1)
    {
        Color = cv::Scalar(255);
    }
    cv::Mat ResultImage(HEIGHT, WIDTH, Images[0].type(), Color);



    // copy the input images to the big image
    for (int Index = 0; Index < NUMBEROFINPUTIMAGES; Index++)
    {

        assert(Images[Index].type() == ResultImage.type());
        if (Images[Index].type() != ResultImage.type())
        {
            std::cout << "The No." << Index << "image has the different type."
                      << std::endl;
            return cv::Mat();
        }


        // Get the row and the col of No.Index image
        int Rows = Index / NumberOfCols;
        int Cols = Index % NumberOfCols;

        // The start point of No.Index image.
        int StartRows = Distance * (Rows + 1) + ImageHeight * Rows;
        int StartCols = Distance * (Cols + 1) + ImageWidth * Cols;

        // copy  No.Index image to the big image
        cv::Mat ROI = ResultImage(cv::Rect(StartCols, StartRows,
                                           ImageWidth, ImageHeight));
        cv::resize(Images[Index], ROI, cv::Size(ImageWidth, ImageHeight));

    }

    return ResultImage;
}