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    Solved Issues with loadFromData function in QImage

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    qimage qpixmap taglib image issue
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    • N
      Nick Redwill last edited by Nick Redwill

      Hello, programmers!

      I am using taglib to read music file cover image and that load it into QImage. Here is my code:

      QImage Widget::getCover (QString filename) {
          QImage cover;
      
          MPEG::File * f = new MPEG::File(filename.toStdWString().c_str());
          ID3v2::Tag * id3v2tag = f->ID3v2Tag();
          auto frameList = id3v2tag->frameList("APIC");
      
          if (id3v2tag && !frameList.isEmpty())
          {
              TagLib::ID3v2::AttachedPictureFrame * frame =
                      static_cast<TagLib::ID3v2::AttachedPictureFrame *>(frameList.front());
      
              qDebug() << "Data: " << frame->picture().size();
              if (cover.loadFromData((const uchar *)frame->picture().data(), frame->picture().size())) {
                  qDebug() << "Image loaded!";
              }
      
              qDebug() << cover.size();
          }
          else
          {
              qDebug() << "id3v2 not present";
          }
      
          delete f;
      
          return cover;
      }
      

      Anything works fine (only with MP3 files). But when i put this code into another project, it stops working. I checked that all the code runs perfectly, the data from the file is read without problems and has the same content. Only the loadFromData function does not work as expected and returns false.

      What could be the problem? Thanks in advance! (Sorry for bad english)

      kshegunov 1 Reply Last reply Reply Quote 0
      • SGaist
        SGaist Lifetime Qt Champion last edited by

        Hi and welcome to devnet,

        One thing you could do is check that you get the same data with both your application.

        Another thing I would do is call picture() only once, store the returned value and work with it rather than call it multiple times. Two successive calls are not guaranteed to return the same object.

        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 Reply Quote 1
        • kshegunov
          kshegunov Moderators @Nick Redwill last edited by kshegunov

          @Nick-Redwill said in Issues with loadFromData function in QImage:

          filename.toStdWString().c_str()
          

          This doesn't look quite right.

          PS.

          Nor does this:
          frame->picture().data()

          Read and abide by the Qt Code of Conduct

          N 1 Reply Last reply Reply Quote 2
          • N
            Nick Redwill @SGaist last edited by

            @SGaist I checked, in both applications data and its size absolutely the same. Also, as i already said, in the first app all works fine, meanwhile in second project same code doesn't work. Debugging shows me, that problem in loadFromData function.

            1 Reply Last reply Reply Quote 0
            • N
              Nick Redwill @kshegunov last edited by

              @kshegunov said in Issues with loadFromData function in QImage:

              This doesn't look quite right.

              This code works fine. Its just convert qstring to wstring and then to wchar_t *. This part works identical in both applications.

              The problem occurs on the line with loadFromData function.

              kshegunov 1 Reply Last reply Reply Quote 0
              • kshegunov
                kshegunov Moderators @Nick Redwill last edited by

                @Nick-Redwill said in Issues with loadFromData function in QImage:

                Its just convert qstring to wstring and then to wchar_t *

                No it's not. After the conversion from QString to wstring you're taking a pointer to a temporary.

                Read and abide by the Qt Code of Conduct

                N 1 Reply Last reply Reply Quote 2
                • N
                  Nick Redwill @kshegunov last edited by

                  @kshegunov said in Issues with loadFromData function in QImage:

                  No it's not. After the conversion from QString to wstring you're taking a pointer to a temporary.

                  Okay, I'll fix this later. It doesn't matter now. The problem is in another part of the code.

                  1 Reply Last reply Reply Quote 0
                  • N
                    Nick Redwill last edited by Nick Redwill

                    I also noticed, that in application where code doesn't work occurs warning:

                    libpng warning: ICCP: known incorrect sRGB profile
                    

                    Its occurs right after loadFromData function call.

                    JonB 1 Reply Last reply Reply Quote 0
                    • JonB
                      JonB @Nick Redwill last edited by

                      @Nick-Redwill Google libpng warning: ICCP: known incorrect sRGB profile

                      1 Reply Last reply Reply Quote 1
                      • N
                        Nick Redwill last edited by

                        QByteArray bytes (pic.data(), pic.size());
                        QFile file ("test.png");
                        file.open(QIODevice::WriteOnly);
                        file.write(bytes);
                        file.close();
                        
                        if (coverImg.load("test.png")) {
                             qDebug() << "Image loaded!";
                        } else {
                             qDebug() << "Error image!";
                        }
                        

                        I changed the code to this and it also doesn't work in one project and works in another. Moreover, the file in both projects is created correctly (i can open it using the windows image viewer). The libpng warning is still displayed.

                        Christian Ehrlicher 1 Reply Last reply Reply Quote 0
                        • N
                          Nick Redwill last edited by

                          Why does QImage behave differently in different projects?

                          1 Reply Last reply Reply Quote 0
                          • Christian Ehrlicher
                            Christian Ehrlicher Lifetime Qt Champion @Nick Redwill last edited by

                            @Nick-Redwill said in Issues with loadFromData function in QImage:

                            I changed the code to this and it also doesn't work in one project and works in another.

                            What means 'does not work'.
                            Please proper error description...

                            Qt has to stay free or it will die.

                            1 Reply Last reply Reply Quote 1
                            • N
                              Nick Redwill last edited by

                              I solved the problem! I just needed to add the imageformats folder with dll files to the exe file folder.

                              Christian Ehrlicher 1 Reply Last reply Reply Quote 0
                              • Christian Ehrlicher
                                Christian Ehrlicher Lifetime Qt Champion @Nick Redwill last edited by

                                @Nick-Redwill This is what windeployqt is for...

                                Qt has to stay free or it will die.

                                1 Reply Last reply Reply Quote 2
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