Declaration of function and use it


  • Lifetime Qt Champion

    well you should make a pair of .h and .cpp files for the opencv stuff
    lets call it myopenvc.h and myopenvc.cpp

    in h. you can declare the function u want rest of program to use

    void setupOPENVC();

    and in .cpp

    void setupOPENVC() {
    // the code from the old c- main. !
    src = imread( argv[1] );
    xxxx
    }

    then in Mainwindow.cpp
    #include "myopencv.h"

    and now u can call your function
    void mainwidow::Process_image_clicke()
    {
    setupOPENVC();
    }

    ps:
    In event driven programs. ( like Qt)
    stuff like
    waitKey(0);
    or FOREVER loops are not to be used as it
    will freeze the program and it stops working.



  • @mrjj Hello i did it sir.
    but error occurs.



  • @jsulm Yes sir see i have a c code of opencv which process the image.
    Now my problem is i want to use this code with qt as when button is pressed my push button calls the function of that C code in which main part of Process is defined.
    Here is the C code.
    #include "opencv2/imgproc/imgproc.hpp"
    #include "opencv2/highgui/highgui.hpp"
    #include <stdlib.h>
    #include <stdio.h>

    using namespace cv;

    /// Global variables

    Mat src, src_gray;
    Mat dst, detected_edges;

    int edgeThresh = 1;
    int lowThreshold;
    int const max_lowThreshold = 100;
    int ratio = 3;
    int kernel_size = 3;
    char* window_name = "Edge Map";

    /**

    @function CannyThreshold
    @brief Trackbar callback - Canny thresholds input with a ratio 1:3
    /
    void CannyThreshold(int, void)
    {
    /// Reduce noise with a kernel 3x3
    blur( src_gray, detected_edges, Size(3,3) );
    /// Canny detector
    Canny( detected_edges, detected_edges, lowThreshold, lowThreshold*ratio, kernel_size );

    /// Using Canny's output as a mask, we display our result
    dst = Scalar::all(0);

    src.copyTo( dst, detected_edges);
    imshow( window_name, dst );
    }

    /** @function main /
    int main( int argc, char* argv )
    {
    /// Load an image
    src = imread( argv[1] );

    if( !src.data )
    { return -1; }

    /// Create a matrix of the same type and size as src (for dst)
    dst.create( src.size(), src.type() );

    /// Convert the image to grayscale
    cvtColor( src, src_gray, CV_BGR2GRAY );

    /// Create a window
    namedWindow( window_name, CV_WINDOW_AUTOSIZE );

    /// Create a Trackbar for user to enter threshold
    createTrackbar( "Min Threshold:", window_name, &lowThreshold, max_lowThreshold, CannyThreshold );

    /// Show the image
    CannyThreshold(0, 0);

    /// Wait until user exit program by pressing a key
    waitKey(0);

    return 0;
    }
    Now i make a Push button Name Process_image in MainWindow.ui and connect to slot as clicked() by right clicking of mouse.
    here comes the slot to mainwindow.cpp
    void mainwidow::Process_image_clicke()
    {
    }
    Now i don't understand how to make function of my C code and use it in Pusebutton.


  • Qt Champions 2018

    @gauravsharma0190 Well, you can put that C code in

    void mainwidow::Process_image_clicke()
    {
        // Put C code here
    }
    

    But I'm not sure whether you should remove waitKey(0); as it could be problematic in a Qt program.



  • @jsulm
    i put it into Process_image_click()
    {
    //code
    }
    but error occurs.
    as ontrackball function not declare


  • Qt Champions 2018

    @gauravsharma0190 What is ontrackball? Where is it declared? Do you have to include a header file where it is declared?



  • Yes it is function which is declare in the Opencv C code.
    Here is the function.
    @brief Trackbar callback - Canny thresholds input with a ratio 1:3
    /
    void onTrackball(int, void)
    {
    /// Reduce noise with a kernel 3x3
    blur( src_gray, detected_edges, Size(3,3) );
    /// Canny detector
    Canny( detected_edges, detected_edges, lowThreshold, lowThreshold*ratio, kernel_size );

    /// Using Canny's output as a mask, we display our result
    dst = Scalar::all(0);

    src.copyTo( dst, detected_edges);
    imshow( window_name, dst );
    }



  • @jsulm Yes it is function which is declare in the Opencv C code.
    Here is the function.
    @brief Trackbar callback - Canny thresholds input with a ratio 1:3
    /
    void onTrackball(int, void)
    {
    /// Reduce noise with a kernel 3x3
    blur( src_gray, detected_edges, Size(3,3) );
    /// Canny detector
    Canny( detected_edges, detected_edges, lowThreshold, lowThreshold*ratio, kernel_size );

    /// Using Canny's output as a mask, we display our result
    dst = Scalar::all(0);

    src.copyTo( dst, detected_edges);
    imshow( window_name, dst );
    }

    less than a minute ago


  • Qt Champions 2018

    @gauravsharma0190 Where is this function declared? In which header file? "function not declared" means the function is not known. You have to make it visible including the header file. It is the same story as in C.



  • @jsulm i Declare it in mainwindow.h
    file as void onTrackball.
    and i will send you all my code which i did .



  • @jsulm
    Here i am sending you my all code.
    **

    • /////main.cpp///**
      #include "mainwindow.h"
      #include <QApplication>
      #include<QSplashScreen>
      #include<QTimer>
      #include<opencv2/highgui/highgui.hpp>
      #include<opencv2/core/core.hpp>
      #include<opencv2/opencv.hpp>
      using namespace cv;
      using namespace std;
      int main(int argc, char *argv[])
      {

      QApplication a(argc, argv);
      QSplashScreen *splash =new QSplashScreen;
      splash->setPixmap(QPixmap("/home/pi/Desktop/ceeri1.jpg"));
      splash->show();

      MainWindow w;
      QTimer::singleShot(3500,splash,SLOT(close()));

      QTimer::singleShot(3500,&w,SLOT(show()));

      //w.show();

      return a.exec();
      }
      ////mainwindow.h
      #ifndef MAINWINDOW_H
      #define MAINWINDOW_H

    #include <QMainWindow>
    //using namespace cv;
    namespace Ui {
    class MainWindow;
    }

    class MainWindow : public QMainWindow
    {
    Q_OBJECT

    public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

    private slots:
    void showTime();

    void on_pushButton_5_clicked();
    

    void onTrackball_clicked(int,void*);

    private:
    Ui::MainWindow *ui;
    };

    #endif // MAINWINDOW_H
    ///mainwindow.c

    #include "mainwindow.h"
    #include "ui_mainwindow.h"
    #include<opencv2/opencv.hpp>
    #include <opencv2/highgui/highgui.hpp>
    #include <opencv2/core/core.hpp>
    #include<QFileDialog>
    #include<QMessageBox>
    #include <iostream>
    #include <string>
    #include <fstream>
    #include<time.h>
    #include<QTimer>
    #include<QDateTime>
    using namespace cv;
    using namespace std;
    MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
    {
    ui->setupUi(this);
    QTimer *timer=new QTimer(this);
    connect(timer,SIGNAL(timeout()),this,SLOT(showTime()));
    timer->start();
    QDateTime dateTime=QDateTime::currentDateTime();
    QString datetimetext=dateTime.toString();
    ui->DateTime->setText(datetimetext);

    }
    ////////Time///////////////
    void MainWindow:: showTime()
    {
    QTime time=QTime::currentTime();
    QString time_text=time.toString("hh : mm : ss");
    if((time.second() % 2)==0)
    {
    time_text[3] =' ';
    time_text[8] =' ';
    }
    ui->Digital->setText(time_text);

    }

    MainWindow::~MainWindow()
    {
    delete ui;
    }

    void MainWindow::on_pushButton_4_clicked()
    {

    }

    void MainWindow::on_pushButton_5_clicked()
    {
    QString filename=QFileDialog::getOpenFileName(
    this,
    tr("Open file") ,
    "/home/pi/Desktop",
    tr("All files(*.png *.jpg)"));

    QMessageBox::information(this,tr("Filename"),filename);
    if(QString::compare(filename,QString())!=0)
    {
        QImage image;
        bool valid=image.load(filename);
        if(valid)
        {
            image=image.scaledToWidth(ui->Picture->width(),Qt::SmoothTransformation);
            ui->Picture->setPixmap(QPixmap::fromImage(image));
    
        }
    

    void MainWindow::onTrackball_clicked(int,void*)
    {
    //Here wite the all function//
    ///Now how to put this code in this.

    ////////This is the code i have to input in this push button////
    Mat src, src_gray;
    Mat dst, detected_edges;

    int edgeThresh = 1;
    int lowThreshold;
    int const max_lowThreshold = 100;
    int ratio = 3;
    int kernel_size = 3;
    char* window_name = "Edge Map";

    /**

    @function CannyThreshold
    @brief Trackbar callback - Canny thresholds input with a ratio 1:3
    /
    void CannyThreshold(int, void)
    {
    /// Reduce noise with a kernel 3x3
    blur( src_gray, detected_edges, Size(3,3) );
    /// Canny detector
    Canny( detected_edges, detected_edges, lowThreshold, lowThreshold*ratio, kernel_size );

    /// Using Canny's output as a mask, we display our result
    dst = Scalar::all(0);

    src.copyTo( dst, detected_edges);
    imshow( window_name, dst );
    }

    /** @function main /
    int main( int argc, char* argv )
    {
    /// Load an image
    src = imread( argv[1] );

    if( !src.data )
    { return -1; }

    /// Create a matrix of the same type and size as src (for dst)
    dst.create( src.size(), src.type() );

    /// Convert the image to grayscale
    cvtColor( src, src_gray, CV_BGR2GRAY );

    /// Create a window
    namedWindow( window_name, CV_WINDOW_AUTOSIZE );

    /// Create a Trackbar for user to enter threshold
    createTrackbar( "Min Threshold:", window_name, &lowThreshold, max_lowThreshold, CannyThreshold );

    /// Show the image
    CannyThreshold(0, 0);

    /// Wait until user exit program by pressing a key
    waitKey(0);

    return 0;
    }

    }
    }

  • Qt Champions 2018

    Sorry, but the code you posted is invalid C/C++! First of all: why do you have 2 main functions?
    Why did you put other functions inside void MainWindow::onTrackball_clicked(int,void*)? This is not going to compile and I'm not going to fix it for you. How familiar are you actually with C/C++?
    What you have to do is: do not put the C function definitions inside void MainWindow::onTrackball_clicked(int,void*), instead put them inside another source code file and header, include the header file in MainWindow and then call the functions in void MainWindow::onTrackball_clicked(int,void*). As an alternative you can have those C functions in MainWindow.cpp but not inside void MainWindow::onTrackball_clicked(int,void*) !



  • @jsulm
    i don't put these function definition inside voidmainwindow::ontrackball
    but i am asking you how can i call that function inside my void mainwindow::ontrackball

    void CannyThreshold(int, void)
    {
    /// Reduce noise with a kernel 3x3
    blur( src_gray, detected_edges, Size(3,3) );
    /// Canny detector
    Canny( detected_edges, detected_edges, lowThreshold, lowThreshold*ratio, kernel_size );
    
    /// Using Canny's output as a mask, we display our result
    dst = Scalar::all(0);
    
    src.copyTo( dst, detected_edges);
    imshow( window_name, dst );
    }
    

    Mean i hyave done .cpp and .h file of this and include in my code both.


  • Qt Champions 2018

    @gauravsharma0190 Like this?

    CannyThreshold(1, nullptr);
    

    So, what exactly is the problem?
    In the code you posted you DID put these function definitions inside void MainWindow::onTrackball_clicked(int,void*) (just check what you posted).


  • Qt Champions 2018

    @gauravsharma0190 Shouldn't

    void CannyThreshold(int, void)
    

    be

    void CannyThreshold(int, void*)
    

    ?



  • ok now i will send you refresh code just wait.
    Thank you.
    i will send you refresh code and errors.



  • @jsulm
    hey here is the code i have done with that.
    /////main.cpp////

    #include<opencv2/highgui/highgui.hpp>
    #include<opencv2/core/core.hpp>
    #include<opencv2/opencv.hpp>
    using namespace cv;
    using namespace std;
    int main(int argc, char *argv[])
    {
    
        QApplication a(argc, argv);
        QSplashScreen *splash =new QSplashScreen;
        splash->setPixmap(QPixmap("/home/pi/Desktop/ceeri1.jpg"));
        splash->show();
    
        MainWindow w;
        QTimer::singleShot(3500,splash,SLOT(close()));
    
        QTimer::singleShot(3500,&w,SLOT(show()));
    
      //w.show();
    
        return a.exec();
    }
    

    ///mainwindow.h///

    #ifndef MAINWINDOW_H
    #define MAINWINDOW_H
    
    #include <QMainWindow>
    //using namespace cv;
    namespace Ui {
    class MainWindow;
    }
    
    class MainWindow : public QMainWindow
    {
    Q_OBJECT
    
    public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
    
    private slots:
    void showTime();
    
    void on_pushButton_5_clicked();
    void onTrackball_clicked(int,void*);
    
    private:
    Ui::MainWindow *ui;
    };
    
    #endif // MAINWINDOW_H
    

    ///ontrack.h///

    #ifndef __ONTRACK_h
    #define __ONTRACK_h
    void cannyThresold(int,void*);
    #endif
    

    ///ontrack.cpp

    #include "ontrack.h"
    #include<opencv2/opencv.hpp>
    #include <opencv2/highgui/highgui.hpp>
    #include <opencv2/core/core.hpp>
    void CannyThreshold(int, void)
    {
    /// Reduce noise with a kernel 3x3
    blur( src_gray, detected_edges, Size(3,3) );
    /// Canny detector
    Canny( detected_edges, detected_edges, lowThreshold, lowThreshold*ratio, kernel_size );
    
    /// Using Canny's output as a mask, we display our result
    dst = Scalar::all(0);
    
    src.copyTo( dst, detected_edges);
    imshow( window_name, dst );
    }
    

    //Here Comes Mainwindow.cpp///

    #include "ui_mainwindow.h"
    #include<opencv2/opencv.hpp>
    #include <opencv2/highgui/highgui.hpp>
    #include <opencv2/core/core.hpp>
    #include "ontrack.h"
    #include<QFileDialog>
    #include<QMessageBox>
    #include <iostream>
    #include <string>
    #include <fstream>
    #include<time.h>
    #include<QTimer>
    #include<QDateTime>
    using namespace cv;
    using namespace std;
    MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
    {
    ui->setupUi(this);
    QTimer *timer=new QTimer(this);
    connect(timer,SIGNAL(timeout()),this,SLOT(showTime()));
    timer->start();
    QDateTime dateTime=QDateTime::currentDateTime();
    QString datetimetext=dateTime.toString();
    ui->DateTime->setText(datetimetext);
    
    }
    ////////Time///////////////
    void MainWindow:: showTime()
    {
    QTime time=QTime::currentTime();
    QString time_text=time.toString("hh : mm : ss");
    if((time.second() % 2)==0)
    {
    time_text[3] =' ';
    time_text[8] =' ';
    }
    ui->Digital->setText(time_text);
    
    }
    
    MainWindow::~MainWindow()
    {
    delete ui;
    }
    
    void MainWindow::on_pushButton_4_clicked()
    {
    
    }
    
    void MainWindow::on_pushButton_5_clicked()
    {
    QString filename=QFileDialog::getOpenFileName(
    this,
    tr("Open file") ,
    "/home/pi/Desktop",
    tr("All files(*.png *.jpg)"));
    
    QMessageBox::information(this,tr("Filename"),filename);
    if(QString::compare(filename,QString())!=0)
    {
        QImage image;
        bool valid=image.load(filename);
        if(valid)
        {
            image=image.scaledToWidth(ui->Picture->width(),Qt::SmoothTransformation);
            ui->Picture->setPixmap(QPixmap::fromImage(image));
    
        }
    void MainWindow::onTrackball_clicked(int,void*)
    {
    
    
    Mat src, src_gray;
    Mat dst, detected_edges;
    
    int edgeThresh = 1;
    int lowThreshold;
    int const max_lowThreshold = 100;
    int ratio = 3;
    int kernel_size = 3;
    char* window_name = "Edge Map";
    
    
    
    @function CannyThreshold
    @brief Trackbar callback - Canny thresholds input with a ratio 1:3
    /
    
    
    /// Load an image
    src = imread( argv[1] );
    
    if( !src.data )
    { return -1; }
    
    /// Create a matrix of the same type and size as src (for dst)
    dst.create( src.size(), src.type() );
    
    /// Convert the image to grayscale
    cvtColor( src, src_gray, CV_BGR2GRAY );
    
    /// Create a window
    namedWindow( window_name, CV_WINDOW_AUTOSIZE );
    
    /// Create a Trackbar for user to enter threshold
    createTrackbar( "Min Threshold:", window_name, &lowThreshold, max_lowThreshold, CannyThreshold );
    
    /// Show the image
    CannyThreshold(0, 0);
    
    }
    }
    ...
    But error occurs defination of function outside the class.


  • @gauravsharma0190 said:

    Sorry in ontrack.cpp i again add
    Mat src, src_gray;
    Mat dst, detected_edges;


  • Qt Champions 2018

    @gauravsharma0190 Can you post the whole error message?
    Why do you have int and void* parameter in onTrackball_clicked which you do not use?


  • Qt Champions 2018

    @gauravsharma0190 Take a look at this:

    
    void MainWindow::on_pushButton_5_clicked()
    {
    QString filename=QFileDialog::getOpenFileName(
    this,
    tr("Open file") ,
    "/home/pi/Desktop",
    tr("All files(*.png *.jpg)"));
    
    QMessageBox::information(this,tr("Filename"),filename);
    if(QString::compare(filename,QString())!=0)
    {
        QImage image;
        bool valid=image.load(filename);
        if(valid)
        {
            image=image.scaledToWidth(ui->Picture->width(),Qt::SmoothTransformation);
            ui->Picture->setPixmap(QPixmap::fromImage(image));
    
        }
    void MainWindow::onTrackball_clicked(int,void*)
    {
    

    void MainWindow::onTrackball_clicked(int,void*) is inside void MainWindow::on_pushButton_5_clicked() - this is invalid!



  • @jsulm
    but i am not defining ontrack_clicked in push button its different.


  • Lifetime Qt Champion

    @gauravsharma0190

    Are you sure ?
    it really, really looks like you do :)



  • @mrjj
    sir i again improving it.
    as

    void MainWindow::on_pushButton_6_clicked()
    {
       /* Mat src , dst;
    
    
     //   char* source_window = "Source image";
       // char* equalized_window = "Equalized Image";
    
        /// Load image
        src = imread( "/home/pi/Desktop/b4.jpg" );
    
    
    
        /// Convert to grayscale
        cvtColor( src, src, CV_BGR2GRAY );
    
        /// Apply Histogram Equalization
        equalizeHist( src, dst );
    
        /// Display results
        namedWindow( "source", CV_WINDOW_NORMAL );
        namedWindow( "equalized", CV_WINDOW_NORMAL );
    
        imshow( "source", src );
        imshow( "equalized", dst );
    
        /// Wait until user exits the program
      //  waitKey(0);*/
    
    
    
        Mat src_base, hsv_base;
        Mat src_test1, hsv_test1;
        Mat src_test2, hsv_test2;
        Mat hsv_half_down;
    
        /// Load three images with different environment settings
    
        src_base = imread( "/home/pi/Desktop/b4.jpg" );
        src_test1 = imread( "/home/pi/Desktop/b4.jpg" );
        src_test2 = imread( "/home/pi/Desktop/b3.jpg" );
    
        /// Convert to HSV
        cvtColor( src_base, hsv_base, COLOR_BGR2HSV );
        cvtColor( src_test1, hsv_test1, COLOR_BGR2HSV );
        cvtColor( src_test2, hsv_test2, COLOR_BGR2HSV );
    
        hsv_half_down = hsv_base( Range( hsv_base.rows/2, hsv_base.rows - 1 ), Range( 0, hsv_base.cols - 1 ) );
    
        /// Using 50 bins for hue and 60 for saturation
        int h_bins = 50; int s_bins = 60;
        int histSize[] = { h_bins, s_bins };
    
        // hue varies from 0 to 179, saturation from 0 to 255
        float h_ranges[] = { 0, 180 };
        float s_ranges[] = { 0, 256 };
    
        const float* ranges[] = { h_ranges, s_ranges };
    
        // Use the o-th and 1-st channels
        int channels[] = { 0, 1 };
    
    
        /// Histograms
        MatND hist_base;
        MatND hist_half_down;
        MatND hist_test1;
        MatND hist_test2;
    
        /// Calculate the histograms for the HSV images
        calcHist( &hsv_base, 1, channels, Mat(), hist_base, 2, histSize, ranges, true, false );
        normalize( hist_base, hist_base, 0, 1, NORM_MINMAX, -1, Mat() );
    
        calcHist( &hsv_half_down, 1, channels, Mat(), hist_half_down, 2, histSize, ranges, true, false );
        normalize( hist_half_down, hist_half_down, 0, 1, NORM_MINMAX, -1, Mat() );
    
        calcHist( &hsv_test1, 1, channels, Mat(), hist_test1, 2, histSize, ranges, true, false );
        normalize( hist_test1, hist_test1, 0, 1, NORM_MINMAX, -1, Mat() );
    
        calcHist( &hsv_test2, 1, channels, Mat(), hist_test2, 2, histSize, ranges, true, false );
        normalize( hist_test2, hist_test2, 0, 1, NORM_MINMAX, -1, Mat() );
    
        /// Apply the histogram comparison methods
        for( int i = 0; i < 4; i++ )
        {
            int compare_method = i;
            double base_base = compareHist( hist_base, hist_base, compare_method );
            double base_half = compareHist( hist_base, hist_half_down, compare_method );
            double base_test1 = compareHist( hist_base, hist_test1, compare_method );
            double base_test2 = compareHist( hist_base, hist_test2, compare_method );
    
            printf( " Method [%d] Perfect, Base-Half, Base-Test(1), Base-Test(2) : %f, %f, %f, %f \n", i, base_base, base_half , base_test1, base_test2 );
        }
    
    
    
    
        }
    
    
    
    void MainWindow::on_onTrackball_clicked()
    {
    
        Mat src, src_gray;
        Mat dst, detected_edges;
    
        int edgeThresh = 1;
        int lowThreshold;
        int const max_lowThreshold = 100;
        int ratio = 3;
        int kernel_size = 3;
        char* window_name = "Edge Map";
    
    
    
        /// Load image
        src = imread( "/home/pi/Desktop/b4.jpg");
         /// Create a matrix of the same type and size as src (for dst)
    
    
    
        dst.create( src.size(), src.type() );
    
        /// Convert the image to grayscale
        cvtColor( src, src_gray, CV_BGR2GRAY );
    
        /// Create a window
        namedWindow( window_name, CV_WINDOW_NORMAL );
    
        /// Create a Trackbar for user to enter threshold
      //  createTrackbar( "Min Threshold:", window_name, &lowThreshold, max_lowThreshold, CannyThreshold );
    
        /// Show the image
        CannyThreshold(0, 0);
    
    
        /// Separate the image in 3 places ( B, G and R )
        vector<Mat> bgr_planes;
        split( src, bgr_planes );
    
        /// Establish the number of bins
        int histSize = 256;
    
        /// Set the ranges ( for B,G,R) )
        float range[] = { 0, 256 } ;
        const float* histRange = { range };
    
        bool uniform = true;
        bool accumulate = false;
    
        Mat b_hist, g_hist, r_hist;
    
        /// Compute the histograms:
        calcHist( &bgr_planes[0], 1, 0, Mat(), b_hist, 1, &histSize, &histRange, uniform, accumulate );
        calcHist( &bgr_planes[1], 1, 0, Mat(), g_hist, 1, &histSize, &histRange, uniform, accumulate );
        calcHist( &bgr_planes[2], 1, 0, Mat(), r_hist, 1, &histSize, &histRange, uniform, accumulate );
    
        // Draw the histograms for B, G and R
        int hist_w = 512; int hist_h = 400;
       int bin_w = cvRound( (double) hist_w/histSize );
    
        Mat histImage( hist_h, hist_w, CV_8UC3, Scalar( 0,0,0) );
    
        /// Normalize the result to [ 0, histImage.rows ]
        normalize(b_hist, b_hist, 0, histImage.rows, NORM_MINMAX, -1, Mat() );
        normalize(g_hist, g_hist, 0, histImage.rows, NORM_MINMAX, -1, Mat() );
        normalize(r_hist, r_hist, 0, histImage.rows, NORM_MINMAX, -1, Mat() );
    
        /// Draw for each channel
        for( int i = 1; i < histSize; i++ )
        {
            line( histImage, Point( bin_w*(i-1), hist_h - cvRound(b_hist.at<float>(i-1)) ) ,
                             Point( bin_w*(i), hist_h - cvRound(b_hist.at<float>(i)) ),
                             Scalar( 255, 0, 0), 2, 8, 0  );
            line( histImage, Point( bin_w*(i-1), hist_h - cvRound(g_hist.at<float>(i-1)) ) ,
                             Point( bin_w*(i), hist_h - cvRound(g_hist.at<float>(i)) ),
                             Scalar( 0, 255, 0), 2, 8, 0  );
            line( histImage, Point( bin_w*(i-1), hist_h - cvRound(r_hist.at<float>(i-1)) ) ,
                             Point( bin_w*(i), hist_h - cvRound(r_hist.at<float>(i)) ),
                             Scalar( 0, 0, 255), 2, 8, 0  );
        }
    
        /// Display
        namedWindow("calcHist Demo", CV_WINDOW_AUTOSIZE );
        imshow("calcHist Demo", histImage );
      imwrite("calcHist Demo2.jpg", histImage);
        waitKey(-1);
    
    
      }
    
    
    ...
    This is new improved code .but there are error or build issue
    1.In member function'void mainwindow::on_on_trackball_clicked()
    ****canny Thresol was not declered in this scope .(function which i declare and define in .h and .c file.
    unsed variable 'edgeThresh'.

  • Lifetime Qt Champion

    @gauravsharma0190 said:

    CannyThreshold

    this function ?
    CannyThreshold
    that you call with
    CannyThreshold(0, 0);

    and you do include the .h file where its defined?



  • @mrjj
    it is defined as

    ///ontrack.h///
    
    #ifndef __ONTRACK_h
    #define __ONTRACK_h
    void cannyThresold(int,void*);
    #endif
    ......
    
    ///ontrack.cpp
    #include "ontrack.h"
    #include<opencv2/opencv.hpp>
    #include <opencv2/highgui/highgui.hpp>
    #include <opencv2/core/core.hpp>
    void CannyThreshold(int, void*)
    {
    /// Reduce noise with a kernel 3x3
    blur( src_gray, detected_edges, Size(3,3) );
    /// Canny detector
    Canny( detected_edges, detected_edges, lowThreshold, lowThreshold*ratio, kernel_size );
    
    /// Using Canny's output as a mask, we display our result
    dst = Scalar::all(0);
    
    src.copyTo( dst, detected_edges);
    imshow( window_name, dst );
    }
    

    .....
    thus i include ontrack.h in mainwindow.cpp code.
    but error occurs.
    Why??
    i can't understand.


  • Lifetime Qt Champion

    I dont understand either.
    Seems fine.
    try to define a test function
    as in
    ontrack.h
    void mytest();
    and call that from main.

    If that is still not known, it means that mainwinow do not really include ontrack.h for some reason.


  • Qt Champions 2018

    @gauravsharma0190 You call it like this CannyThreshold(0, 0); and in ontrack.cpp it is defined like void CannyThreshold(int, void*). But in ontrack.h it is void cannyThresold(int,void*); please fix the name of the function.


  • Lifetime Qt Champion

    @jsulm
    heh Good spotted. completely missed "old" :)



  • @mrjj
    I fix canny as Canny in .h file
    but again error occurs.



  • @jsulm
    Hey i fixed it .But again error.


  • Qt Champions 2018

    @gauravsharma0190 "But again error" - why don't you say what error you get now?



  • @jsulm
    yes it tells undefined reference to 'CannyThresold(int,void*)'.
    collect2:error ld returned 1 exit status.


  • Qt Champions 2018

    @gauravsharma0190 Is ontrack.cpp part of your project and is it built?
    "undefined reference to 'CannyThresold(int,void*)" - means linker cannot find CannyThresold(int,void*)



  • @jsulm
    Actually i put .h and .cpp file in my qt project folder.


  • Qt Champions 2018

    @gauravsharma0190 But did you add them to your project?
    They should be in the PRO file, like:

    SOURCES += main.cpp\
            mainwindow.cpp\
            ontrack.cpp
    
    HEADERS  += mainwindow.h\
            ontrack.h
    


  • @jsulm
    i added it but gives error as
    parse error onTrack.cpp
    Makefile error 3


  • Qt Champions 2018

    @gauravsharma0190 After changing PRO file you need to rerun qmake (right-click on the project in QtCreator and then "Run qmake". Then do a rebuild.



  • @jsulm
    I done it
    Now gives many error regarding onTrack.cpp file.


  • Qt Champions 2018

    @gauravsharma0190 Well, I guess you have many issues there...



  • @jsulm
    Yeap.
    are they function's issuses or anything.
    I can't undersatnd everything is all right so Why all these issuses are there.
    I will send you these issue.


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