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How to increment Image name ?

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  • hamzaelaziziH hamzaelazizi

    @Cobra91151 it returns the image number, let's say we took 8 pictures, "id" will b equal to 8. it increments with the number of images taken, but its problem is whenever i want to reset it to 0 it doesn't do that it keeps its last value.

    jsulmJ Offline
    jsulmJ Offline
    jsulm
    Lifetime Qt Champion
    wrote on last edited by
    #6

    @hamzaelazizi I would suggest to not to use the id passed from the signal. Use your own id variable (as class member).

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

    1 Reply Last reply
    0
    • Cobra91151C Cobra91151

      @hamzaelazizi

      @KroMignon

      Your solution works well but counts from the second picture 2.png, since 1 + (id % 11), otherwise the second count would start from 0. So, I have improved it a bit by removing the 1 + from modulo operation and adding the check for < 1 .

      @jsulm

      Your solution using class member variable as identifier would also work nice.

      My code:

      QCamera *camera = new QCamera(this);
      QCameraImageCapture *imageCapture = new QCameraImageCapture(camera);
      connect(imageCapture, &QCameraImageCapture::imageCaptured, [=](int id, QImage img) {
             qDebug() << "ID: " << id;
             int imgID = id % 11;
      
             if (imgID < 1) {
                 imgID = 1;
             }
      
             QString path = QString("%1/%2.png").arg(QStandardPaths::writableLocation(QStandardPaths::PicturesLocation), QString::number(imgID));
             qDebug() << path;
             img.save(path, "PNG");
        });
      
      camera->setCaptureMode(QCamera::CaptureStillImage);
      camera->start();
      ui->pushButton_4->setText("Capture");
      connect(ui->pushButton_4, &QPushButton::clicked, [camera, imageCapture, this]() {
           camera->searchAndLock();
           imageCapture->capture();
           camera->unlock();
      });
      

      Result:

      ID:  1
      "C:/Users/cobra/Pictures/1.png"
      ID:  2
      "C:/Users/cobra/Pictures/2.png"
      ID:  3
      "C:/Users/cobra/Pictures/3.png"
      ID:  4
      "C:/Users/cobra/Pictures/4.png"
      ID:  5
      "C:/Users/cobra/Pictures/5.png"
      ID:  6
      "C:/Users/cobra/Pictures/6.png"
      ID:  7
      "C:/Users/cobra/Pictures/7.png"
      ID:  8
      "C:/Users/cobra/Pictures/8.png"
      ID:  9
      "C:/Users/cobra/Pictures/9.png"
      ID:  10
      "C:/Users/cobra/Pictures/10.png"
      ID:  11
      "C:/Users/cobra/Pictures/1.png"
      ID:  12
      "C:/Users/cobra/Pictures/1.png"
      ID:  13
      "C:/Users/cobra/Pictures/2.png"
      ID:  14
      "C:/Users/cobra/Pictures/3.png"
      ID:  15
      "C:/Users/cobra/Pictures/4.png"
      ID:  16
      "C:/Users/cobra/Pictures/5.png"
      ID:  17
      "C:/Users/cobra/Pictures/6.png"
      ID:  18
      "C:/Users/cobra/Pictures/7.png"
      ID:  19
      "C:/Users/cobra/Pictures/8.png"
      ID:  20
      "C:/Users/cobra/Pictures/9.png"
      ID:  21
      "C:/Users/cobra/Pictures/10.png"
      ID:  22
      "C:/Users/cobra/Pictures/1.png"
      ID:  23
      "C:/Users/cobra/Pictures/1.png"
      ID:  24
      "C:/Users/cobra/Pictures/2.png"
      ID:  25
      "C:/Users/cobra/Pictures/3.png"
      ID:  27
      "C:/Users/cobra/Pictures/5.png"
      ID:  29
      "C:/Users/cobra/Pictures/7.png"
      ID:  31
      "C:/Users/cobra/Pictures/9.png"
      ID:  32
      "C:/Users/cobra/Pictures/10.png"
      ID:  33
      "C:/Users/cobra/Pictures/1.png"
      

      Solution by class member variable:

      .h file

      class Dialog : public QDialog
      {
          Q_OBJECT
      
      public:
          Dialog(QWidget *parent = nullptr);
          ~Dialog();
      private:
          Ui::Dialog *ui;
          int imgID;
      };
      

      .cpp file

      Dialog::Dialog(QWidget *parent)
          : QDialog(parent), ui(new Ui::Dialog), imgID(0)
      {
          QCamera *camera = new QCamera;
          QCameraImageCapture *imageCapture = new QCameraImageCapture(camera);
          connect(imageCapture, &QCameraImageCapture::imageCaptured, [=](int id, QImage img) {
             qDebug() << "ID: " << id;
             imgID++;
      
             if (imgID >= 11) {
                 imgID = 1;
             }
      
             QString path = QString("%1/%2.png").arg(QStandardPaths::writableLocation(QStandardPaths::PicturesLocation), QString::number(imgID));
             qDebug() << path;
             img.save(path, "PNG");
          });
      
          camera->setCaptureMode(QCamera::CaptureStillImage);
          camera->start();
          ui->pushButton_4->setText("Capture");
          connect(ui->pushButton_4, &QPushButton::clicked, [camera, imageCapture, this]() {
              //on half pressed shutter button
              camera->searchAndLock();
              //on shutter button pressed
              imageCapture->capture();
              //on shutter button released
              camera->unlock();
          });
      }
      

      Output:

      ID:  1
      "C:/Users/cobra/Pictures/1.png"
      ID:  2
      "C:/Users/cobra/Pictures/2.png"
      ID:  3
      "C:/Users/cobra/Pictures/3.png"
      ID:  4
      "C:/Users/cobra/Pictures/4.png"
      ID:  5
      "C:/Users/cobra/Pictures/5.png"
      ID:  6
      "C:/Users/cobra/Pictures/6.png"
      ID:  7
      "C:/Users/cobra/Pictures/7.png"
      ID:  8
      "C:/Users/cobra/Pictures/8.png"
      ID:  9
      "C:/Users/cobra/Pictures/9.png"
      ID:  10
      "C:/Users/cobra/Pictures/10.png"
      ID:  11
      "C:/Users/cobra/Pictures/1.png"
      ID:  12
      "C:/Users/cobra/Pictures/2.png"
      ID:  13
      "C:/Users/cobra/Pictures/3.png"
      ID:  14
      "C:/Users/cobra/Pictures/4.png"
      ID:  15
      "C:/Users/cobra/Pictures/5.png"
      ID:  16
      "C:/Users/cobra/Pictures/6.png"
      ID:  18
      "C:/Users/cobra/Pictures/7.png"
      ID:  20
      "C:/Users/cobra/Pictures/8.png"
      ID:  21
      "C:/Users/cobra/Pictures/9.png"
      ID:  23
      "C:/Users/cobra/Pictures/10.png"
      ID:  25
      "C:/Users/cobra/Pictures/1.png"
      ID:  26
      "C:/Users/cobra/Pictures/2.png"
      ID:  28
      "C:/Users/cobra/Pictures/3.png"
      ID:  30
      "C:/Users/cobra/Pictures/4.png"
      ID:  31
      "C:/Users/cobra/Pictures/5.png"
      ID:  33
      "C:/Users/cobra/Pictures/6.png"
      ID:  35
      "C:/Users/cobra/Pictures/7.png"
      ID:  36
      "C:/Users/cobra/Pictures/8.png"
      ID:  37
      "C:/Users/cobra/Pictures/9.png"
      ID:  39
      "C:/Users/cobra/Pictures/10.png"
      ID:  41
      "C:/Users/cobra/Pictures/1.png"
      ID:  42
      "C:/Users/cobra/Pictures/2.png"
      ID:  43
      "C:/Users/cobra/Pictures/3.png"
      ID:  44
      "C:/Users/cobra/Pictures/4.png"
      ID:  45
      "C:/Users/cobra/Pictures/5.png"
      
      hamzaelaziziH Offline
      hamzaelaziziH Offline
      hamzaelazizi
      wrote on last edited by
      #7

      @Cobra91151 it didn't work, it gave me this error at first "error: assignment of read-only variable ‘imgID’
      imgID = id;"
      but when i took "imgID" inside the method, it kept only overwriting on image N°1.

      jsulmJ 1 Reply Last reply
      0
      • hamzaelaziziH hamzaelazizi

        @Cobra91151 it didn't work, it gave me this error at first "error: assignment of read-only variable ‘imgID’
        imgID = id;"
        but when i took "imgID" inside the method, it kept only overwriting on image N°1.

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

        @hamzaelazizi The method suggested by @Cobra91151 will not work as changing a parameter passed by value has NO effect on the original variable! Use your own id as I suggested above.

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

        1 Reply Last reply
        1
        • hamzaelaziziH hamzaelazizi

          Hello Everyone, as i was continuing to work on an application, i came across this issue an i still couldn't solve it for more than 4 days now. The issue is that i cannot increment the naming of the saved images to a certain number and then comeback to the number 0 and start overwriting those images until i reach than number again and so on repeatedly!
          let me give u an example : i want to save 10 Images and i want them to be names "1.png", "2.png"......"10.png", but i want the 11th one to overwrite the "1.png", 12th to overwrite the "2.png" and so on.

          i've tried multiple approaches but none of them worked! :(

          here's my code, thank you

          QObject::connect(_image_capture.data(), &QCameraImageCapture::imageCaptured, [=] (int id, QImage img) {
             QString fileName = QString::number(id)+ ".png";
             QString path = QStandardPaths::writableLocation(QStandardPaths::PicturesLocation) + "/" + fileName;
             img.save(path, "PNG");
           });
          
          KroMignonK Offline
          KroMignonK Offline
          KroMignon
          wrote on last edited by KroMignon
          #9

          @hamzaelazizi said in How to increment Image name ?:

          i've tried multiple approaches but none of them worked! :(

          I don't know how you are generating the ID, if it is a free running counter why not use the modulo function?

          QString fileName = QString("%1.png").arg(1 + (id % 11));
          

          It is an old maxim of mine that when you have excluded the impossible, whatever remains, however improbable, must be the truth. (Sherlock Holmes)

          jsulmJ hamzaelaziziH 2 Replies Last reply
          2
          • KroMignonK KroMignon

            @hamzaelazizi said in How to increment Image name ?:

            i've tried multiple approaches but none of them worked! :(

            I don't know how you are generating the ID, if it is a free running counter why not use the modulo function?

            QString fileName = QString("%1.png").arg(1 + (id % 11));
            
            jsulmJ Offline
            jsulmJ Offline
            jsulm
            Lifetime Qt Champion
            wrote on last edited by
            #10

            @KroMignon The id is comming from https://doc.qt.io/qt-5/qcameraimagecapture.html#imageCaptured

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

            KroMignonK 1 Reply Last reply
            0
            • jsulmJ jsulm

              @KroMignon The id is comming from https://doc.qt.io/qt-5/qcameraimagecapture.html#imageCaptured

              KroMignonK Offline
              KroMignonK Offline
              KroMignon
              wrote on last edited by
              #11

              @jsulm said in How to increment Image name ?:

              The id is comming from https://doc.qt.io/qt-5/qcameraimagecapture.html#imageCaptured

              I see! :D

              So this would also not work!
              Then I don't see another solution as what @jsulm already suggested: use class member to store the counter value

              It is an old maxim of mine that when you have excluded the impossible, whatever remains, however improbable, must be the truth. (Sherlock Holmes)

              jsulmJ 1 Reply Last reply
              0
              • KroMignonK KroMignon

                @hamzaelazizi said in How to increment Image name ?:

                i've tried multiple approaches but none of them worked! :(

                I don't know how you are generating the ID, if it is a free running counter why not use the modulo function?

                QString fileName = QString("%1.png").arg(1 + (id % 11));
                
                hamzaelaziziH Offline
                hamzaelaziziH Offline
                hamzaelazizi
                wrote on last edited by
                #12

                @KroMignon I wanted to use it, in fact i was trying it over and over but since i'm new to Qt i didn't know how to get it to work :( (i feel ashamed now), when i tried your solution, it seems like it's working! i don't know if i will be running into some issues in the futur, but i guess that would be a problem for another day, Thank you

                1 Reply Last reply
                0
                • KroMignonK KroMignon

                  @jsulm said in How to increment Image name ?:

                  The id is comming from https://doc.qt.io/qt-5/qcameraimagecapture.html#imageCaptured

                  I see! :D

                  So this would also not work!
                  Then I don't see another solution as what @jsulm already suggested: use class member to store the counter value

                  jsulmJ Offline
                  jsulmJ Offline
                  jsulm
                  Lifetime Qt Champion
                  wrote on last edited by
                  #13

                  @KroMignon said in How to increment Image name ?:

                  So this would also not work!

                  Actually it should :-)

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

                  KroMignonK 1 Reply Last reply
                  0
                  • jsulmJ jsulm

                    @KroMignon said in How to increment Image name ?:

                    So this would also not work!

                    Actually it should :-)

                    KroMignonK Offline
                    KroMignonK Offline
                    KroMignon
                    wrote on last edited by
                    #14

                    @jsulm said in How to increment Image name ?:

                    Actually it should :-)

                    Okay, I never used QCameraImageCapture, so I supposed the ID would be the ID of the used camera and not if the image...
                    Maybe I should avoid the reply to posts for topics I not experimented in!

                    It is an old maxim of mine that when you have excluded the impossible, whatever remains, however improbable, must be the truth. (Sherlock Holmes)

                    hamzaelaziziH 1 Reply Last reply
                    0
                    • KroMignonK KroMignon

                      @jsulm said in How to increment Image name ?:

                      Actually it should :-)

                      Okay, I never used QCameraImageCapture, so I supposed the ID would be the ID of the used camera and not if the image...
                      Maybe I should avoid the reply to posts for topics I not experimented in!

                      hamzaelaziziH Offline
                      hamzaelaziziH Offline
                      hamzaelazizi
                      wrote on last edited by
                      #15

                      @KroMignon Sir, your solution helped me, so i think you should keep relying to this kind of posts :D, i have one last question, @jsulm how can i use my own id variable ? should i create a variable inside this class ? i don't understand !

                      jsulmJ 1 Reply Last reply
                      0
                      • hamzaelaziziH hamzaelazizi

                        @KroMignon Sir, your solution helped me, so i think you should keep relying to this kind of posts :D, i have one last question, @jsulm how can i use my own id variable ? should i create a variable inside this class ? i don't understand !

                        jsulmJ Offline
                        jsulmJ Offline
                        jsulm
                        Lifetime Qt Champion
                        wrote on last edited by
                        #16

                        @hamzaelazizi said in How to increment Image name ?:

                        should i create a variable inside this class ?

                        Yes and you initialize it with 0. Each time your slot is called you increment it and check whether it is bigger than the max id value you want to use, if it is you set it back to 0.

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

                        hamzaelaziziH 1 Reply Last reply
                        0
                        • jsulmJ jsulm

                          @hamzaelazizi said in How to increment Image name ?:

                          should i create a variable inside this class ?

                          Yes and you initialize it with 0. Each time your slot is called you increment it and check whether it is bigger than the max id value you want to use, if it is you set it back to 0.

                          hamzaelaziziH Offline
                          hamzaelaziziH Offline
                          hamzaelazizi
                          wrote on last edited by
                          #17

                          @jsulm something like this ?

                          
                          QObject::connect(_image_capture.data(), &QCameraImageCapture::imageCaptured, [=] (int id=0, QImage img) {
                           int idx = 0;
                           if(idx>=11)
                           {
                                   idx=0;
                           }
                           else
                           {
                                   idx++;
                           }
                            QString fileName = QString::number(idx) + ".png";
                            QString path = QStandardPaths::writableLocation(QStandardPaths::PicturesLocation) + "/" + fileName;
                            img.save(path, "PNG");
                                      });
                          

                          Because i've tried this and it didn't work :/

                          jsulmJ Cobra91151C 2 Replies Last reply
                          0
                          • hamzaelaziziH hamzaelazizi

                            @jsulm something like this ?

                            
                            QObject::connect(_image_capture.data(), &QCameraImageCapture::imageCaptured, [=] (int id=0, QImage img) {
                             int idx = 0;
                             if(idx>=11)
                             {
                                     idx=0;
                             }
                             else
                             {
                                     idx++;
                             }
                              QString fileName = QString::number(idx) + ".png";
                              QString path = QStandardPaths::writableLocation(QStandardPaths::PicturesLocation) + "/" + fileName;
                              img.save(path, "PNG");
                                        });
                            

                            Because i've tried this and it didn't work :/

                            jsulmJ Offline
                            jsulmJ Offline
                            jsulm
                            Lifetime Qt Champion
                            wrote on last edited by
                            #18

                            @hamzaelazizi said in How to increment Image name ?:

                            something like this ?

                            No.
                            In your code idx is a local variable and not a class member...

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

                            hamzaelaziziH 1 Reply Last reply
                            0
                            • hamzaelaziziH hamzaelazizi

                              @jsulm something like this ?

                              
                              QObject::connect(_image_capture.data(), &QCameraImageCapture::imageCaptured, [=] (int id=0, QImage img) {
                               int idx = 0;
                               if(idx>=11)
                               {
                                       idx=0;
                               }
                               else
                               {
                                       idx++;
                               }
                                QString fileName = QString::number(idx) + ".png";
                                QString path = QStandardPaths::writableLocation(QStandardPaths::PicturesLocation) + "/" + fileName;
                                img.save(path, "PNG");
                                          });
                              

                              Because i've tried this and it didn't work :/

                              Cobra91151C Offline
                              Cobra91151C Offline
                              Cobra91151
                              wrote on last edited by
                              #19

                              @hamzaelazizi

                              I have updated my previous post. Please, try it again.

                              1 Reply Last reply
                              0
                              • jsulmJ jsulm

                                @hamzaelazizi said in How to increment Image name ?:

                                something like this ?

                                No.
                                In your code idx is a local variable and not a class member...

                                hamzaelaziziH Offline
                                hamzaelaziziH Offline
                                hamzaelazizi
                                wrote on last edited by
                                #20

                                @jsulm i see, but whenever i declare a variable outside the method i get this error saying that the variable i created is a Read-only

                                JonBJ jsulmJ 2 Replies Last reply
                                0
                                • hamzaelaziziH hamzaelazizi

                                  @jsulm i see, but whenever i declare a variable outside the method i get this error saying that the variable i created is a Read-only

                                  JonBJ Offline
                                  JonBJ Offline
                                  JonB
                                  wrote on last edited by
                                  #21

                                  @hamzaelazizi Depends what you write and where.

                                  1 Reply Last reply
                                  0
                                  • hamzaelaziziH hamzaelazizi

                                    @jsulm i see, but whenever i declare a variable outside the method i get this error saying that the variable i created is a Read-only

                                    jsulmJ Offline
                                    jsulmJ Offline
                                    jsulm
                                    Lifetime Qt Champion
                                    wrote on last edited by
                                    #22

                                    @hamzaelazizi said in How to increment Image name ?:

                                    outside the method

                                    I never suggested to declare it outside of the method. I suggested to declare it as a class member:

                                    class YOUR_CLASS:
                                    {
                                    private:
                                        int idx{0};
                                    

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

                                    hamzaelaziziH 1 Reply Last reply
                                    2
                                    • jsulmJ jsulm

                                      @hamzaelazizi said in How to increment Image name ?:

                                      outside the method

                                      I never suggested to declare it outside of the method. I suggested to declare it as a class member:

                                      class YOUR_CLASS:
                                      {
                                      private:
                                          int idx{0};
                                      
                                      hamzaelaziziH Offline
                                      hamzaelaziziH Offline
                                      hamzaelazizi
                                      wrote on last edited by
                                      #23

                                      @jsulm i understand now, thank you for your explanation

                                      1 Reply Last reply
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