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How to save images in a different format

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  • K kosai

    i am programming in C++ language , Qt 4.11.1 , on Windows 7, i am using Qt 5.14.2 MinGW 64 bit, input format (png, jpg, jpeg, gif), just(jpeg) as output, i did not have error or either warning , images are being saved succecfully but its not changing the format !

    jsulmJ Offline
    jsulmJ Offline
    jsulm
    Lifetime Qt Champion
    wrote on last edited by
    #4

    @kosai Please show your code

    https://forum.qt.io/topic/113070/qt-code-of-conduct

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    • K Offline
      K Offline
      kosai
      wrote on last edited by
      #5
      void Mwindow::NvlElem(void)
      {
          QDir::setCurrent(m_ImgDir);//setting the Directory file
          if(!Line->text().isEmpty())
          {
              //if user write name of object
              //List->addItem(Line->text());
              List->addItem(Line->text());
              //**
              if(List->count() == 1)
                  List->setCurrentRow(0);
              return;
          }
      
          //get Image
          QString ImgDir = QFileDialog::getOpenFileName(this,
                                                       "Ouvrir un fichier",
                                                       QString(),
                                                       "Images (*.png *.gif *.jpg *.jpeg)");
          //--Display Img on Tab
          ImgPixmap->load(ImgDir);
          ImgWin->setPixmap(*ImgPixmap);
          //--save Img in Items
          Image->load(ImgDir);
          QString ImgExt(ImgDir.right(4)), RImgName, ImgName;
          if(ImgExt[0] != ".")
              ImgExt = ImgDir.right(5);
          //get extention
          //--i did not find a better way to get extention !
          for (int i(ImgDir.length()); i >= 0; i--) {
              if(ImgDir[i] == "/")
                  break;
              RImgName += ImgDir[i];
          }
          for(int i(RImgName.length()-1); i >= 0; i--) {
              if(RImgName[i] == ".")
                  break;
              ImgName += RImgName[i];
          }
          //--here is the prblm !!!!
          if(Image->save(ImgName+ImgExt, "png"))
          {
              List->addItem(ImgName);
          }
          //*
          if(List->count() == 1)
              List->setCurrentRow(0);
      //*****tring another way  using QImageWriter but it doesnt work either!
          ImgWriter->setFileName(ImgName);
          Line->setText(ImgWriter->fileName());
      }
      
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      • Christian EhrlicherC Offline
        Christian EhrlicherC Offline
        Christian Ehrlicher
        Lifetime Qt Champion
        wrote on last edited by
        #6

        The format is 'PNG', not 'png'.
        The extension can be retrieved via QFileInfo and there is no need to create a QImage with new.

        Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
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        • K Offline
          K Offline
          kosai
          wrote on last edited by
          #7

          ok!
          i tried "PNG" its the same problem !

          jsulmJ 1 Reply Last reply
          0
          • K kosai

            ok!
            i tried "PNG" its the same problem !

            jsulmJ Offline
            jsulmJ Offline
            jsulm
            Lifetime Qt Champion
            wrote on last edited by jsulm
            #8

            @kosai In your first post you wrote: "but the extention still the same". This is a different problem than "but its not changing the format". So, did you make sure the format was indeed not changed?

            https://forum.qt.io/topic/113070/qt-code-of-conduct

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            • K Offline
              K Offline
              kosai
              wrote on last edited by
              #9

              the problem is a little bit bizzard !
              it's like changing bytes into the desired format --> if you put saved image with the original you will distinguish the diffrence !
              but unlike if you go to the file on the desktop the extention doesn't change at all !!
              i hope this helps to understand my problem?

              jsulmJ J.HilkJ 2 Replies Last reply
              0
              • K kosai

                the problem is a little bit bizzard !
                it's like changing bytes into the desired format --> if you put saved image with the original you will distinguish the diffrence !
                but unlike if you go to the file on the desktop the extention doesn't change at all !!
                i hope this helps to understand my problem?

                jsulmJ Offline
                jsulmJ Offline
                jsulm
                Lifetime Qt Champion
                wrote on last edited by jsulm
                #10

                @kosai said in How to save images in a different format:

                i hope this helps to understand my problem?

                Not really.
                What exactly is the problem:

                • Wrong file extension?
                • File is not stored as png?

                Please be more clear.
                If the file extension is not what you want then check your code and use @Christian-Ehrlicher suggested to get file extension.

                https://forum.qt.io/topic/113070/qt-code-of-conduct

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                • K kosai

                  the problem is a little bit bizzard !
                  it's like changing bytes into the desired format --> if you put saved image with the original you will distinguish the diffrence !
                  but unlike if you go to the file on the desktop the extention doesn't change at all !!
                  i hope this helps to understand my problem?

                  J.HilkJ Offline
                  J.HilkJ Offline
                  J.Hilk
                  Moderators
                  wrote on last edited by
                  #11

                  @kosai said in How to save images in a different format:

                  ile on the desktop the extention doesn't change at all !!

                  why should the extension change ? you extract it from the select file

                  QString ImgExt(ImgDir.right(4)), RImgName, ImgName;
                      if(ImgExt[0] != ".")
                          ImgExt = ImgDir.right(5);
                  

                  and than append it again to the filename when you save it

                  Image->save(ImgName+ImgExt, "png")
                  

                  without changing it in-between, of course it will have the same extension.


                  Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


                  Q: What's that?
                  A: It's blue light.
                  Q: What does it do?
                  A: It turns blue.

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                  • K Offline
                    K Offline
                    kosai
                    wrote on last edited by
                    #12

                    yeah! you are right i shouldn't put the original extention with the name !
                    thank you everyone !

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                    • SGaistS Offline
                      SGaistS Offline
                      SGaist
                      Lifetime Qt Champion
                      wrote on last edited by
                      #13

                      Another issue in your code, why are you forcing the output to be PNG and yet allow other extensions ? That does not really make sense. Personally I would be very surprised to find PNG while opening for example a .bmp file.

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                      Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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