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[PLEASE HELP] how to make a barcode receiver?

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  • ? A Former User
    12 Aug 2018, 00:03

    I'm trying to make a shop manger application and i want to make a barcode receiver .
    when I connect my barcode reader and point to a barcode it inserts the barcode numbers and press enter automatically, so i want to make a Qtextbox always waiting for input even if it wasn't the active widget.

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    Pablo J. Rogina
    wrote on 13 Aug 2018, 19:02 last edited by
    #10

    @davidlabib said in [PLEASE HELP] how to make a barcode receiver?:

    i want to make a Qtextbox always waiting for input even if it wasn't the active widget

    This is not the original/intended behavior of this widget or any other related widget. The keyboard input is directed to the widget having the focus.

    Given that said:

    1. have you seen any other application working the way you want?
    2. I'd say you may want to override the keyPressEvent() method in MainWindow class and when you "detect a barcode" given the focus is not on it, you paste the value received to it. See this SO question for a related matter.

    Upvote the answer(s) that helped you solve the issue
    Use "Topic Tools" button to mark your post as Solved
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      A Former User
      wrote on 13 Aug 2018, 21:11 last edited by A Former User
      #11

      @Pablo-J-Rogina

      1. you almost understand me yes in this quote
      1. I'd say you may want to override the keyPressEvent() method in MainWindow class and when you "detect a barcode" given the focus is not on it, you paste the value received to it. See this SO question for a related matter.
      1. i know that making a Qtextbox always waiting for input is impossible but it was a phrase describe what i want (something like that) i mean

      2. SO question is not what i mean

      what i mean exactly is
      at any time and under any condition when the barcode scanner hardware detetect any barcaode it will do_something()

      P 1 Reply Last reply 14 Aug 2018, 12:34
      0
      • ? A Former User
        13 Aug 2018, 21:11

        @Pablo-J-Rogina

        1. you almost understand me yes in this quote
        1. I'd say you may want to override the keyPressEvent() method in MainWindow class and when you "detect a barcode" given the focus is not on it, you paste the value received to it. See this SO question for a related matter.
        1. i know that making a Qtextbox always waiting for input is impossible but it was a phrase describe what i want (something like that) i mean

        2. SO question is not what i mean

        what i mean exactly is
        at any time and under any condition when the barcode scanner hardware detetect any barcaode it will do_something()

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        Pablo J. Rogina
        wrote on 14 Aug 2018, 12:34 last edited by
        #12

        @davidlabib said in [PLEASE HELP] how to make a barcode receiver?:

        at any time and under any condition when the barcode scanner hardware detetect any barcaode it will do_something()

        You've changed the requirements :-)
        In this case I'd say you need to change the barcode driver, and work at a lower level than Qt... so the driver code instead of pasting the decoded text/numbers into the keyboard buffer does some kind of notification that your application can trap. But it looks like that work it's out of scope for Qt framework

        Upvote the answer(s) that helped you solve the issue
        Use "Topic Tools" button to mark your post as Solved
        Add screenshots via postimage.org
        Don't ask support requests via chat/PM. Please use the forum so others can benefit from the solution in the future

        J 1 Reply Last reply 15 Aug 2018, 05:15
        1
        • ? Offline
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          A Former User
          wrote on 14 Aug 2018, 13:21 last edited by A Former User
          #13

          @Pablo-J-Rogina
          can you send me your number on whatsapp or telegram or any other messenger so we can have a long conversation in private and after we got the solution i will post it in this topic so other can benefits from it

          P 1 Reply Last reply 14 Aug 2018, 13:25
          0
          • ? A Former User
            14 Aug 2018, 13:21

            @Pablo-J-Rogina
            can you send me your number on whatsapp or telegram or any other messenger so we can have a long conversation in private and after we got the solution i will post it in this topic so other can benefits from it

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            Pablo J. Rogina
            wrote on 14 Aug 2018, 13:25 last edited by
            #14

            @davidlabib please continue this way. I'm not sure I have enough spare time to go on privately. Thanks

            Upvote the answer(s) that helped you solve the issue
            Use "Topic Tools" button to mark your post as Solved
            Add screenshots via postimage.org
            Don't ask support requests via chat/PM. Please use the forum so others can benefit from the solution in the future

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              A Former User
              wrote on 14 Aug 2018, 13:41 last edited by
              #15

              @Pablo-J-Rogina
              OK ,I'm developing a shop manager application.
              I'm beginner on programing i had learned c++ just for a year or less
              and now I'm learning qt lib.
              i don't have problems with sqlite but have problems with the barcode
              of course i can make a line edit and button when the button got clicked it will search on the database for the barcode and so on
              but the problem is what if I selected another line edit and pointed the barcode scanner hardware to a barcode
              it will type on the anther line edit not the barcode line edit
              so what is your ideas to solve this problem .

              1 Reply Last reply
              0
              • P Pablo J. Rogina
                14 Aug 2018, 12:34

                @davidlabib said in [PLEASE HELP] how to make a barcode receiver?:

                at any time and under any condition when the barcode scanner hardware detetect any barcaode it will do_something()

                You've changed the requirements :-)
                In this case I'd say you need to change the barcode driver, and work at a lower level than Qt... so the driver code instead of pasting the decoded text/numbers into the keyboard buffer does some kind of notification that your application can trap. But it looks like that work it's out of scope for Qt framework

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                jsulm
                Lifetime Qt Champion
                wrote on 15 Aug 2018, 05:15 last edited by
                #16

                @Pablo-J.-Rogina said in [PLEASE HELP] how to make a barcode receiver?:

                at any time and under any condition when the barcode scanner hardware detetect any barcaode it will do_something()

                Can't your barcode scanner just write to a string and you then put it in the correct line edit?

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

                ? 1 Reply Last reply 15 Aug 2018, 20:40
                0
                • J jsulm
                  15 Aug 2018, 05:15

                  @Pablo-J.-Rogina said in [PLEASE HELP] how to make a barcode receiver?:

                  at any time and under any condition when the barcode scanner hardware detetect any barcaode it will do_something()

                  Can't your barcode scanner just write to a string and you then put it in the correct line edit?

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                  A Former User
                  wrote on 15 Aug 2018, 20:40 last edited by A Former User
                  #17

                  @jsulm
                  yes it write to a string
                  but it cannot put this string in the correct line edit
                  and what if a button is selected
                  0_1534367535920_542f4758-8857-46ef-8892-598bb52a2f78-image.png
                  not line edit

                  J 1 Reply Last reply 16 Aug 2018, 12:15
                  0
                  • ? A Former User
                    15 Aug 2018, 20:40

                    @jsulm
                    yes it write to a string
                    but it cannot put this string in the correct line edit
                    and what if a button is selected
                    0_1534367535920_542f4758-8857-46ef-8892-598bb52a2f78-image.png
                    not line edit

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                    jsulm
                    Lifetime Qt Champion
                    wrote on 16 Aug 2018, 12:15 last edited by
                    #18

                    @davidlabib To put a string into a line edit this line edit does not need to have focus!
                    Simply:

                    ui->lineEdit_1->setText(someText);
                    

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

                    P 1 Reply Last reply 16 Aug 2018, 12:22
                    0
                    • J jsulm
                      16 Aug 2018, 12:15

                      @davidlabib To put a string into a line edit this line edit does not need to have focus!
                      Simply:

                      ui->lineEdit_1->setText(someText);
                      
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                      Pablo J. Rogina
                      wrote on 16 Aug 2018, 12:22 last edited by Pablo J. Rogina
                      #19

                      @jsulm I think his problem is at a lower level, not just set the "text" for the proper line edit.

                      Most barcode reader drivers mimic the keyboard, so when they scan something they place the data read like the keyboard, and SO is facing the issue that if focus is with another widget, not the line edit, if a scan is done that data will go there, or as his last example with the button, lost.

                      Upvote the answer(s) that helped you solve the issue
                      Use "Topic Tools" button to mark your post as Solved
                      Add screenshots via postimage.org
                      Don't ask support requests via chat/PM. Please use the forum so others can benefit from the solution in the future

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                      • ? Offline
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                        A Former User
                        wrote on 16 Aug 2018, 13:16 last edited by
                        #20

                        @Pablo-J-Rogina

                        @Pablo-J.-Rogina said in [PLEASE HELP] how to make a barcode receiver?:

                        Most barcode reader drivers mimic the keyboard, so when they scan something they place the data read like the keyboard, and SO is facing the issue that if focus is with another widget, not the line edit, if a scan is done that data will go there, or as his last example with the button, lost.

                        that's exactly what I'm talking about
                        You completely understand me

                        but i don't think that it's a lower level problem
                        i think that making thread always waiting for input 13 digit --any right barcode in the world contain 13 digit-- less than 1 second
                        if the input was 13 digit and inputted less than a second then it's a barcode and deal with it as a barcode
                        else what for input again

                        P 1 Reply Last reply 16 Aug 2018, 13:21
                        0
                        • ? A Former User
                          16 Aug 2018, 13:16

                          @Pablo-J-Rogina

                          @Pablo-J.-Rogina said in [PLEASE HELP] how to make a barcode receiver?:

                          Most barcode reader drivers mimic the keyboard, so when they scan something they place the data read like the keyboard, and SO is facing the issue that if focus is with another widget, not the line edit, if a scan is done that data will go there, or as his last example with the button, lost.

                          that's exactly what I'm talking about
                          You completely understand me

                          but i don't think that it's a lower level problem
                          i think that making thread always waiting for input 13 digit --any right barcode in the world contain 13 digit-- less than 1 second
                          if the input was 13 digit and inputted less than a second then it's a barcode and deal with it as a barcode
                          else what for input again

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                          Pablo J. Rogina
                          wrote on 16 Aug 2018, 13:21 last edited by
                          #21

                          @davidlabib said in [PLEASE HELP] how to make a barcode receiver?:

                          always waiting for input 13 digit --any right barcode in the world contain 13 digit

                          Be careful with this assumption, think of EAN 8 for instance...

                          Like the UPC code, there is the EAN-13 symbology with 13 digits, and an abbreviated EAN barcode called the EAN-8 with only 8 digits for smaller goods where space is limited.

                          Upvote the answer(s) that helped you solve the issue
                          Use "Topic Tools" button to mark your post as Solved
                          Add screenshots via postimage.org
                          Don't ask support requests via chat/PM. Please use the forum so others can benefit from the solution in the future

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                          • ? Offline
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                            A Former User
                            wrote on 16 Aug 2018, 23:50 last edited by
                            #22

                            @Pablo-J-Rogina thanks for the warning
                            @mrjj take a look here i think you faced this type of problems
                            https://forum.qt.io/topic/71310/reading-barcode-from-barcode-scanner

                            M P 2 Replies Last reply 17 Aug 2018, 06:27
                            0
                            • ? A Former User
                              16 Aug 2018, 23:50

                              @Pablo-J-Rogina thanks for the warning
                              @mrjj take a look here i think you faced this type of problems
                              https://forum.qt.io/topic/71310/reading-barcode-from-barcode-scanner

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                              mrjj
                              Lifetime Qt Champion
                              wrote on 17 Aug 2018, 06:27 last edited by mrjj
                              #23

                              @davidlabib

                              Yes, that very normal issues when using a
                              scanner in HID mode so it acts like a keyboard.

                              I usually put a button next to input that says scan and it popup dialog
                              to do the scanning in.

                              There is no easy solution to what you try. as unless NOTHING else can have focus. ( you can disable focus for buttons) then user might switch to other edit fields.

                              Often scanner input is terminated with \n\r or similar- check the documentation
                              for the scanner.

                              1 Reply Last reply
                              3
                              • ? A Former User
                                16 Aug 2018, 23:50

                                @Pablo-J-Rogina thanks for the warning
                                @mrjj take a look here i think you faced this type of problems
                                https://forum.qt.io/topic/71310/reading-barcode-from-barcode-scanner

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                                Pablo J. Rogina
                                wrote on 17 Aug 2018, 13:59 last edited by
                                #24

                                @davidlabib I did some grocery shopping yesterday, and looking at the point of sale software the clerk used when I checked out, and also thinking about the shopping cart and checkout process in websites, I wonder why do you need this "always on" scanning phase?

                                I mean, maybe you're overcomplicating your requirements. Do you really have such use case from an actual user/customer of your application?

                                While checking out most of the software overthere that I remember have some steps/phases:

                                1. Initial data (optional)
                                2. 1-N items scanning (using barcode reader!!) so focus is there for just one widget (a list where scanned items are added, or a line edit where you click a "Add" button, whatever)
                                3. When you are ready (by self-checkout or a clerk helping you) a "Proceeed to checkout" button move to next phase, i.e. Delivery information or just Payment (at this point if credit card is read, again focus is only for reading the credit card data)
                                4. "Finish" button to print receipt and move into next customer...

                                Is your use case completely different from this scenario? if so, why!?

                                Upvote the answer(s) that helped you solve the issue
                                Use "Topic Tools" button to mark your post as Solved
                                Add screenshots via postimage.org
                                Don't ask support requests via chat/PM. Please use the forum so others can benefit from the solution in the future

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                                • ? Offline
                                  ? Offline
                                  A Former User
                                  wrote on 18 Aug 2018, 00:22 last edited by
                                  #25

                                  the only payment method is cash only (for now), so we can skip 3

                                  It's not very require to make focus when the barcode input something but i thought that it will be a good extra feature in the application

                                  M R 2 Replies Last reply 18 Aug 2018, 09:40
                                  0
                                  • ? A Former User
                                    18 Aug 2018, 00:22

                                    the only payment method is cash only (for now), so we can skip 3

                                    It's not very require to make focus when the barcode input something but i thought that it will be a good extra feature in the application

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                                    mrjj
                                    Lifetime Qt Champion
                                    wrote on 18 Aug 2018, 09:40 last edited by
                                    #26

                                    @davidlabib
                                    Hi
                                    The complication of trying to guess if its user typing or scanner input
                                    can be complicated. While often a scan is terminated with same
                                    symbols, you first know later if scan or keypress and hence
                                    makes it complicated to handle.

                                    So its actually complicated to make work flawless and hence a
                                    straight way of saying for user. "I want to scan" is often preferred.
                                    As it avoid confusing and guessing.

                                    1 Reply Last reply
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                                    • ? A Former User
                                      18 Aug 2018, 00:22

                                      the only payment method is cash only (for now), so we can skip 3

                                      It's not very require to make focus when the barcode input something but i thought that it will be a good extra feature in the application

                                      R Offline
                                      R Offline
                                      raven-worx
                                      Moderators
                                      wrote on 18 Aug 2018, 19:38 last edited by raven-worx
                                      #27

                                      @davidlabib
                                      just a note:
                                      Some barcode scanners have different modes. One mode is "keyboard" mode (like you are using it now) and another can be via the serial interface. The later would let you use QtSerialPort module to receive the scanned code in plain text.
                                      Those modes can be switched by scanning a special barcode. Take a look at the scanners manual.

                                      --- SUPPORT REQUESTS VIA CHAT WILL BE IGNORED ---
                                      If you have a question please use the forum so others can benefit from the solution in the future

                                      ? 1 Reply Last reply 19 Aug 2018, 12:53
                                      4
                                      • R raven-worx
                                        18 Aug 2018, 19:38

                                        @davidlabib
                                        just a note:
                                        Some barcode scanners have different modes. One mode is "keyboard" mode (like you are using it now) and another can be via the serial interface. The later would let you use QtSerialPort module to receive the scanned code in plain text.
                                        Those modes can be switched by scanning a special barcode. Take a look at the scanners manual.

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                                        A Former User
                                        wrote on 19 Aug 2018, 12:53 last edited by
                                        #28

                                        @raven-worx
                                        0_1534682994843_f52d64be-c499-4ed8-8c2d-61bd38a1de84-image.png
                                        0_1534683017626_314576f9-6b75-42fd-b9a7-8124961e7757-image.png
                                        0_1534683048600_4b9a11df-1307-42af-9058-f90b71a6a88b-image.png
                                        0_1534683072140_89cd40a7-8a36-49d8-92ab-78edd63f4b99-image.png
                                        0_1534683090490_c9b50133-170b-49a0-8fea-138ae9c73956-image.png
                                        0_1534683117128_9f977db8-5b6e-40e8-8f77-80814053f964-image.png
                                        can you help me on setting the right mod and use QtSerialPort

                                        JKSHJ R 2 Replies Last reply 21 Aug 2018, 02:40
                                        0
                                        • ? A Former User
                                          19 Aug 2018, 12:53

                                          @raven-worx
                                          0_1534682994843_f52d64be-c499-4ed8-8c2d-61bd38a1de84-image.png
                                          0_1534683017626_314576f9-6b75-42fd-b9a7-8124961e7757-image.png
                                          0_1534683048600_4b9a11df-1307-42af-9058-f90b71a6a88b-image.png
                                          0_1534683072140_89cd40a7-8a36-49d8-92ab-78edd63f4b99-image.png
                                          0_1534683090490_c9b50133-170b-49a0-8fea-138ae9c73956-image.png
                                          0_1534683117128_9f977db8-5b6e-40e8-8f77-80814053f964-image.png
                                          can you help me on setting the right mod and use QtSerialPort

                                          JKSHJ Offline
                                          JKSHJ Offline
                                          JKSH
                                          Moderators
                                          wrote on 21 Aug 2018, 02:40 last edited by
                                          #29

                                          @davidlabib said in [PLEASE HELP] how to make a barcode receiver?:

                                          can you help me on setting the right mod and use QtSerialPort

                                          If you want to use Qt Serial Port, choose the RS-232 option. You will also need to connect the barcode scanner to a serial port on your computer.

                                          Qt Doc Search for browsers: forum.qt.io/topic/35616/web-browser-extension-for-improved-doc-searches

                                          ? 1 Reply Last reply 21 Aug 2018, 23:38
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