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Can't access image (.jpeg) folder in main() using OpenCV

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  • mrjjM mrjj

    @georgiav
    Hi
    So exact same source and .pro file can be compiled and run when compiling in shell
    but in Creator you get undefined errors?

    G Offline
    G Offline
    georgiav
    wrote on last edited by georgiav
    #7

    @mrjj Just the c++ file with the program which is supposed to be a photo collage , not the qt part. I fixed the .pro file for one library name was spelled wrong sorry about that, and now it works but I only get an empty MainWindow

    and the result should be this ( it's the same code)
    Screenshot from 2021-02-14 12-41-39.png

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    • G georgiav

      @JonB I had the problem with linking the libraries before and it's been solved, I don't have errors like 'Mat object undefined' and the paths should be fine as the same program works fine when run from a shell

      JonBJ Offline
      JonBJ Offline
      JonB
      wrote on last edited by JonB
      #8

      @georgiav said in Can't access image (.jpeg) folder in main() using OpenCV:

      I had the problem with linking the libraries before and it's been solved,

      What "has been solved"?

      I don't have errors like 'Mat object undefined'

      No, instead you have "undefined reference" at link time on some cv functions.

      and the paths should be fine as the same program works fine when run from a shell

      What program? The errors show that you cannot link the executable. So no "program" is being generated in this build. If you have something you linked before, you have some other (successfully-linked, maybe library search path was different, or other difference) executable elsewhere, not the one not-generated from this link.

      G 1 Reply Last reply
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      • JonBJ JonB

        @georgiav said in Can't access image (.jpeg) folder in main() using OpenCV:

        I had the problem with linking the libraries before and it's been solved,

        What "has been solved"?

        I don't have errors like 'Mat object undefined'

        No, instead you have "undefined reference" at link time on some cv functions.

        and the paths should be fine as the same program works fine when run from a shell

        What program? The errors show that you cannot link the executable. So no "program" is being generated in this build. If you have something you linked before, you have some other (successfully-linked, maybe library search path was different, or other difference) executable elsewhere, not the one not-generated from this link.

        G Offline
        G Offline
        georgiav
        wrote on last edited by
        #9

        @JonB check post above ( the link to the libraries is now ok and works, a library name was misspelled.) The program compiles and runs but only shows an empty window.

        80ab96d7-a68c-4057-ac39-8c00241e95b7-image.png

        Can I do something about it?

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        • Christian EhrlicherC Offline
          Christian EhrlicherC Offline
          Christian Ehrlicher
          Lifetime Qt Champion
          wrote on last edited by
          #10

          Isn't there a forum for OpenCV out there? Or what is the relation to Qt here?

          Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
          Visit the Qt Academy at https://academy.qt.io/catalog

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          • Christian EhrlicherC Christian Ehrlicher

            Isn't there a forum for OpenCV out there? Or what is the relation to Qt here?

            G Offline
            G Offline
            georgiav
            wrote on last edited by
            #11

            @Christian-Ehrlicher since the program works fine using just OpenCV and it doesn't work when trying to run it in QT I thought it's more likely to be a Qt problem rather than an Opencv one. Maybe there are specific things to add in the .pro file or other settings I'm not aware of since I'm new to Qt.

            mrjjM Christian EhrlicherC 2 Replies Last reply
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            • G georgiav

              @Christian-Ehrlicher since the program works fine using just OpenCV and it doesn't work when trying to run it in QT I thought it's more likely to be a Qt problem rather than an Opencv one. Maybe there are specific things to add in the .pro file or other settings I'm not aware of since I'm new to Qt.

              mrjjM Offline
              mrjjM Offline
              mrjj
              Lifetime Qt Champion
              wrote on last edited by
              #12

              @georgiav
              Hi
              But the code you have shown in the first post does nothing with MainWindow ( or even has one)
              So what is the thing that doesn't work ?
              What should been on the MainWindow ?
              and how did you add it ?

              G 1 Reply Last reply
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              • mrjjM mrjj

                @georgiav
                Hi
                But the code you have shown in the first post does nothing with MainWindow ( or even has one)
                So what is the thing that doesn't work ?
                What should been on the MainWindow ?
                and how did you add it ?

                G Offline
                G Offline
                georgiav
                wrote on last edited by
                #13

                @mrjj Hi, I think those were the mainwindow.cpp and mainwindow.h files that were already there when I created the project but I didn't add anything in them so I just removed them and tried to run again and now I get this :

                fe630f7c-b690-4597-bd37-bd5298cfedf9-image.png

                but unfortunately I don't understand where those errors come from

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                • G georgiav

                  @Christian-Ehrlicher since the program works fine using just OpenCV and it doesn't work when trying to run it in QT I thought it's more likely to be a Qt problem rather than an Opencv one. Maybe there are specific things to add in the .pro file or other settings I'm not aware of since I'm new to Qt.

                  Christian EhrlicherC Offline
                  Christian EhrlicherC Offline
                  Christian Ehrlicher
                  Lifetime Qt Champion
                  wrote on last edited by Christian Ehrlicher
                  #14

                  @georgiav said in Can't access image (.jpeg) folder in main() using OpenCV:

                  Since the program works fine using just OpenCV and it doesn't work when trying to run it in QT I thought it's more likely to be a Qt problem rather than an Opencv

                  Your code does not use any Qt class at all...

                  Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
                  Visit the Qt Academy at https://academy.qt.io/catalog

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                  • Christian EhrlicherC Christian Ehrlicher

                    @georgiav said in Can't access image (.jpeg) folder in main() using OpenCV:

                    Since the program works fine using just OpenCV and it doesn't work when trying to run it in QT I thought it's more likely to be a Qt problem rather than an Opencv

                    Your code does not use any Qt class at all...

                    G Offline
                    G Offline
                    georgiav
                    wrote on last edited by
                    #15

                    @Christian-Ehrlicher I'm trying to create a GUI for my program but first the c++ program should run fine , right?

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                    • mrjjM Offline
                      mrjjM Offline
                      mrjj
                      Lifetime Qt Champion
                      wrote on last edited by
                      #16

                      Hi
                      I wonder if you need to link additional libs
                      besides opencv_core
                      like opencv_imgcodecs

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                      • G Offline
                        G Offline
                        georgiav
                        wrote on last edited by
                        #17

                        Hi, no, I figure it out what it was , I didn't write QApplication a(argc, argv); at the beginning in the main function. Now it works fine ! Thank you anyway for trying to help.

                        mrjjM 1 Reply Last reply
                        1
                        • G georgiav

                          Hi, no, I figure it out what it was , I didn't write QApplication a(argc, argv); at the beginning in the main function. Now it works fine ! Thank you anyway for trying to help.

                          mrjjM Offline
                          mrjjM Offline
                          mrjj
                          Lifetime Qt Champion
                          wrote on last edited by
                          #18

                          @georgiav

                          Oh so after you added that all the other errors went away ?
                          well good it works :)
                          happy coding

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