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Qt 5.6.1 with Opencv

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  • N navya.dubey

    @joeQ
    I tried with / as well as with \ and the problem is same anyhow.
    I deleted the repetition, problem still remains.

    joeQJ Offline
    joeQJ Offline
    joeQ
    wrote on last edited by
    #10

    @navya.dubey

    did you include opencv head files?

    Just do it!

    1 Reply Last reply
    0
    • SGaistS Offline
      SGaistS Offline
      SGaist
      Lifetime Qt Champion
      wrote on last edited by
      #11

      Hi,

      In addition to all the good clues @joeQ provided, the main problem here is: trying to build an application with MinGW and link to a C++ library built with Visual Studio. It's not possible. You have to use a MinGW build of OpenCV to link to your application. Or use a VS build of Qt to link to your OpenCV lib built with Visual Studio. Note that prior to Visual Studio 2017, you also have to exactly match the versions of Visual Studio used to build everything C++ you might use in your project.

      VS2017 has backward compatibility but only with VS2015.

      Interested in AI ? www.idiap.ch
      Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

      N 1 Reply Last reply
      2
      • SGaistS SGaist

        Hi,

        In addition to all the good clues @joeQ provided, the main problem here is: trying to build an application with MinGW and link to a C++ library built with Visual Studio. It's not possible. You have to use a MinGW build of OpenCV to link to your application. Or use a VS build of Qt to link to your OpenCV lib built with Visual Studio. Note that prior to Visual Studio 2017, you also have to exactly match the versions of Visual Studio used to build everything C++ you might use in your project.

        VS2017 has backward compatibility but only with VS2015.

        N Offline
        N Offline
        navya.dubey
        wrote on last edited by
        #12

        @SGaist hey I tried to build opencv using cmake following this tutorial
        https://www.youtube.com/watch?v=ZOSu-2Oju-A
        there are several errors while building the code 0_1502347280180_Screenshot (8).png
        I followed all the steps in the video but the output is not same as of the video tutorial, I hope you understood the basic problem please help.

        1 Reply Last reply
        0
        • SGaistS Offline
          SGaistS Offline
          SGaist
          Lifetime Qt Champion
          wrote on last edited by
          #13

          You have to tell CMake where to find Qt in order for it to build its libhighgui with the Qt backend.

          Interested in AI ? www.idiap.ch
          Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

          N 1 Reply Last reply
          0
          • SGaistS SGaist

            You have to tell CMake where to find Qt in order for it to build its libhighgui with the Qt backend.

            N Offline
            N Offline
            navya.dubey
            wrote on last edited by
            #14

            @SGaist how to tell cmake where to find qt because I have set the environment variables of the system to know the location of mingw compiler in qt.
            what to do next?

            mrjjM 1 Reply Last reply
            0
            • N navya.dubey

              @SGaist how to tell cmake where to find qt because I have set the environment variables of the system to know the location of mingw compiler in qt.
              what to do next?

              mrjjM Offline
              mrjjM Offline
              mrjj
              Lifetime Qt Champion
              wrote on last edited by
              #15

              @navya.dubey
              Hi

              like
              cmake .. -DCMAKE_PREFIX_PATH="C:\Qt\5.7\msvc2015\lib\cmake\Qt5"

              N 1 Reply Last reply
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              • mrjjM mrjj

                @navya.dubey
                Hi

                like
                cmake .. -DCMAKE_PREFIX_PATH="C:\Qt\5.7\msvc2015\lib\cmake\Qt5"

                N Offline
                N Offline
                navya.dubey
                wrote on last edited by mrjj
                #16

                Where to add it

                mrjjM 1 Reply Last reply
                0
                • N navya.dubey

                  Where to add it

                  mrjjM Offline
                  mrjjM Offline
                  mrjj
                  Lifetime Qt Champion
                  wrote on last edited by
                  #17

                  @navya.dubey
                  Sorry, i miss scrolled and edited your post.

                  You use it as commandline option when you call cmake as shown

                  N 1 Reply Last reply
                  0
                  • mrjjM mrjj

                    @navya.dubey
                    Sorry, i miss scrolled and edited your post.

                    You use it as commandline option when you call cmake as shown

                    N Offline
                    N Offline
                    navya.dubey
                    wrote on last edited by
                    #18

                    @mrjj You mean I have to go to the location where CMake is present and then I have to execute this command, right?

                    mrjjM 1 Reply Last reply
                    0
                    • N navya.dubey

                      @mrjj You mean I have to go to the location where CMake is present and then I have to execute this command, right?

                      mrjjM Offline
                      mrjjM Offline
                      mrjj
                      Lifetime Qt Champion
                      wrote on last edited by mrjj
                      #19

                      @navya.dubey

                      No, you make sure there is path to cmake
                      then you go to the project folder where the Cmake.tx file is and then
                      call cmake

                      if no paths, you can fully tell

                      c:\programfile\whatever\cmake .. OPTION

                      Same way as done here
                      https://forum.qt.io/topic/82074/creating-a-multi-purpose-node-editor-if-there-is-none-available/20
                      its also a Cmake project

                      1 Reply Last reply
                      0
                      • SGaistS Offline
                        SGaistS Offline
                        SGaist
                        Lifetime Qt Champion
                        wrote on last edited by
                        #20

                        You can also add that using the GUI you showed in your post.

                        Interested in AI ? www.idiap.ch
                        Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                        1 Reply Last reply
                        0

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