Declaration of function and use it

[jsulm]

@gauravsharma0190 Nothing is all right with this code.
"was not declared in this scope" - you have to check where are those declared or why they are not declared (blur, edge, Mat,...). For example:

cedge = Scalar::all(0);

where is cedge declared? You're trying to access a variable which was not declared.

This one says that you first declared the function extern and later static. Why? Since it is just a function it neither has to be static nor extern!

error: 'void CannyThreshold(int, void*)' was declared 'extern' and later 'static' [-fpermissive]
   static void CannyThreshold(int, void*)

You really have to fix your code! And I really don't understand why you think your code is OK although there are really basic issues (not related to Qt at all)!

[gauravsharma0190]

@jsulm
i declare all these variable inside onTrach.cpp file.
blur is function name which is in imgproc.hpp header.
Canny is also function name which is declared in highgui.h header.

[jsulm]

@gauravsharma0190
Can you post onTrach.cpp and onTrach.h?

[gauravsharma0190]

@jsulm

#include"onTrack.h"
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/core/core.hpp>
#include<opencv2/imgproc/imgproc.hpp>
int edgeThresh = 1;
//Mat image,gray,edge,cedge; 

  void CannyThreshold(int, void*)
{
Mat image, gray, edge, cedge;
    blur(gray, edge, Size(3,3));

    // Run the edge detector on grayscale
    Canny(edge, edge, edgeThresh, edgeThresh*3, 3);
    cedge = Scalar::all(0);

    src.copyTo(cedge, edge);
    imshow("Edge map", cedge);
}

.H file

#define ONTRACKBALL_H_
  int CannyThreshold(int,void* );
#endif
//your code here

Mat is opencv function which is declare in highgui.h
header.
all these functions are present in header which i added in code.

[jsulm]

@gauravsharma0190 What is Mat and where is it declared?

[jsulm]

@gauravsharma0190 Didn't you forget

using namespace cv;

in the cpp file?

[gauravsharma0190]

@jsulm
Mat is basically a class with two data parts: the matrix header (containing information such as the size of the matrix, the method used for storing, at which address is the matrix stored, and so on) and a pointer to the matrix containing the pixel values (taking any dimensionality depending on the method chosen for storing) . The matrix header size is constant, however the size of the matrix itself may vary from image to image and usually is larger by orders of magnitude

[gauravsharma0190]

@gauravsharma0190
Hey jslum
thanks very mush i did it without error
Now new problem arises when i clicked the push button it tells
The program has unexpectedly finished.
/home/pi/Desktop/qt /build-Desktop1-GCC Local/Desktop crashed.

[jsulm]

@gauravsharma0190 Most probably it crashes because of an invalid pointer. Debug your application step by step to see where exactly it crashes.

[gauravsharma0190]

@jsulm
Hello sir
i debug the programme but when i press button it tells
the inferior stooped because it receives signal from OS
Signal name SIGABRT
Signal mean Aborted.
Now how to solve it

[jsulm]

@gauravsharma0190 Put a breakpoint in the slot which is called when you press the button and check where exactly it crashes.

[gauravsharma0190]

IT CRASHES WHERE FUNCTION ontrack()
defination
Canny(edge, edge, edgeThresh, edgeThresh*3, 3);
kernel_size issue i think.
int kernel_size =3;
here

[gauravsharma0190]

@jsulm
It crashes when i press the push button .
I debugged it and found it creshes when my function call.
Error found->it takes signal from OS.
Now How to fix it.

[jsulm]

@gauravsharma0190 How to fix what?
What do you mean by "Error found->it takes signal from OS" - what OS signal do you mean? Do you mean SIGABRT?
I don't know how to fix it because I have no idea what the problem is. But usually such problems are caused by bugs in applications. You have to check your code and see what is wrong at the line where your application crashes.

[jsulm]

@gauravsharma0190 Can you post the code and mark the line where it crashes?

[gauravsharma0190]

@jsulm
Mainwindow.cpp

void MainWindow::on_onTrackball_clicked()
{
    int threshold_value = 0;
    int threshold_type = 3;
    int const max_value = 255;
    int const max_type = 4;
   // int const max_BINARY_value = 255;

    Mat src, src_gray, dst;
  //  char* window_name = "Threshold Demo";

    //char* trackbar_type = "Type: \n 0: Binary \n 1: Binary Inverted \n 2: Truncate \n 3: To Zero \n 4: To Zero Inverted";
    //char* trackbar_value = "Value";




    /// Load image
    src = imread( "/home/pi/Desktop/b4.jpg");


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

      /// Create a window to display results
      namedWindow( "Threshold", CV_WINDOW_AUTOSIZE );

      /// Create Trackbar to choose type of Threshold
      createTrackbar( "Type: \n 0: Binary \n 1: Binary Inverted \n 2: Truncate \n 3: To Zero \n 4: To Zero Inverted","Threshold", &threshold_type, max_type, Threshold_Demo );

      createTrackbar( "value","Threshold", &threshold_value, max_value, Threshold_Demo );

      /// Call the function to initialize
@@@   ***Threshold_Demo( 0, 0)***


}

onTrack.h

#ifndef ONTRACKBALL_H_
#define ONTRACKBALL_H_
  void Threshold_Demo( int, void* );
#endif

ontrack.cpp

void Threshold_Demo( int, void* )
{
  /* 0: Binary
     1: Binary Inverted
     2: Threshold Truncated
     3: Threshold to Zero
     4: Threshold to Zero Inverted
   */

@@threshold( src_gray, dst, threshold_value, max_BINARY_value,threshold_type );

  imshow("Threshold", dst );

Here @---> Error

[jsulm]

@gauravsharma0190 What are src_gray, dst, threshold_value, max_BINARY_value,threshold_type? Where are they defined and initialized? Please note: these are NOT same as in MainWindow::on_onTrackball_clicked()!

void Threshold_Demo( int, void* )
{
  /* 0: Binary
     1: Binary Inverted
     2: Threshold Truncated
     3: Threshold to Zero
     4: Threshold to Zero Inverted
   */

@@threshold( src_gray, dst, threshold_value, max_BINARY_value,threshold_type );

  imshow("Threshold", dst );

[gauravsharma0190]

@jsulm
Hey Good morning
These are defined in the same function .cpp files.
Yes These are not in mainwindow

[jsulm]

@gauravsharma0190 Did you initialize these variables? Do they have correct values when you call threshold()?

[gauravsharma0190]

@jsulm
Yes i initialize these with correct values.