Skip to content
  • Categories
  • Recent
  • Tags
  • Popular
  • Users
  • Groups
  • Search
  • Get Qt Extensions
  • Unsolved
Collapse
Brand Logo
  1. Home
  2. Qt Development
  3. General and Desktop
  4. what is the best way to update UI by data(got from the non-mainThread)?
Qt 6.11 is out! See what's new in the release blog

what is the best way to update UI by data(got from the non-mainThread)?

Scheduled Pinned Locked Moved Unsolved General and Desktop
20 Posts 4 Posters 2.5k Views
  • Oldest to Newest
  • Newest to Oldest
  • Most Votes
Reply
  • Reply as topic
Log in to reply
This topic has been deleted. Only users with topic management privileges can see it.
  • O opengpu

    @jsulm thank you .
    and how is the speed, as i have to emit a not small Struct across threads

    jsulmJ Offline
    jsulmJ Offline
    jsulm
    Lifetime Qt Champion
    wrote on last edited by
    #7

    @opengpu Depends on the size of the struct and how often you emit the signal

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

    1 Reply Last reply
    4
    • O Offline
      O Offline
      opengpu
      wrote on last edited by
      #8

      emit very frequently, but the struct is not very big

      1 Reply Last reply
      0
      • O Offline
        O Offline
        opengpu
        wrote on last edited by
        #9

        is custom Struct used as param of connect effiecnt?

        J.HilkJ 1 Reply Last reply
        0
        • O opengpu

          is custom Struct used as param of connect effiecnt?

          J.HilkJ Offline
          J.HilkJ Offline
          J.Hilk
          Moderators
          wrote on last edited by
          #10

          @opengpu said in what is the best way to update UI by data(got from the non-mainThread)?:

          is custom Struct used as param of connect effiecnt?

          totally depends on the efficiency of your copy constructor of your struct


          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.

          O 1 Reply Last reply
          2
          • J.HilkJ J.Hilk

            @opengpu said in what is the best way to update UI by data(got from the non-mainThread)?:

            is custom Struct used as param of connect effiecnt?

            totally depends on the efficiency of your copy constructor of your struct

            O Offline
            O Offline
            opengpu
            wrote on last edited by
            #11

            @J.Hilk thank you.
            but as signal and slot are not in the same thread. is there any other way except these 2 method?

            1. pass Struct as value;
            2. SetData() {mutex; m_data = data;} @the signal thread
              GetData() {mutex; return m_data;} @the slot thread
            jsulmJ 1 Reply Last reply
            0
            • O opengpu

              @J.Hilk thank you.
              but as signal and slot are not in the same thread. is there any other way except these 2 method?

              1. pass Struct as value;
              2. SetData() {mutex; m_data = data;} @the signal thread
                GetData() {mutex; return m_data;} @the slot thread
              jsulmJ Offline
              jsulmJ Offline
              jsulm
              Lifetime Qt Champion
              wrote on last edited by
              #12

              @opengpu How big is your struct and how often do you emit the signal?

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

              O 1 Reply Last reply
              0
              • jsulmJ jsulm

                @opengpu How big is your struct and how often do you emit the signal?

                O Offline
                O Offline
                opengpu
                wrote on last edited by opengpu
                #13

                @jsulm ```
                class Data
                {
                public:
                VARIANT data1;
                VARIANT data11;
                VARIANT data111;
                VARIANT data1111;
                LONG errorCode;
                public:
                Data();
                ~Data();
                };

                
                maybe emit every second, or even more frequently
                jsulmJ 1 Reply Last reply
                0
                • O Offline
                  O Offline
                  opengpu
                  wrote on last edited by opengpu
                  #14

                  is this a good way to emit signal in the non-thread non-qt Callback function?

                  WINAPI Callback(const Data& data)
                  {//here is not mainThread; so i have to pass the data by value to the slot which is in mainThread; or i use mutex & save data to m_data, and then in slot mainThread getData also with mutex protect thread-safety
                      g_qtObj->emit mySignal();
                  }
                  
                  class QtObj : public QObject
                  {
                  Q_OBJECT
                  signals:
                      void mySignal();
                  }
                  QtObj g_obj;
                  QtObj* g_qtObj = &g_obj;
                  
                  1 Reply Last reply
                  0
                  • O opengpu

                    @jsulm ```
                    class Data
                    {
                    public:
                    VARIANT data1;
                    VARIANT data11;
                    VARIANT data111;
                    VARIANT data1111;
                    LONG errorCode;
                    public:
                    Data();
                    ~Data();
                    };

                    
                    maybe emit every second, or even more frequently
                    jsulmJ Offline
                    jsulmJ Offline
                    jsulm
                    Lifetime Qt Champion
                    wrote on last edited by
                    #15

                    @opengpu And how big is VARIANT?
                    1HZ isn't something I would care. In such a case I would exchange the data via signals/slots between the threads instead of messing up with threads synchronisation.

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

                    O 1 Reply Last reply
                    0
                    • jsulmJ jsulm

                      @opengpu And how big is VARIANT?
                      1HZ isn't something I would care. In such a case I would exchange the data via signals/slots between the threads instead of messing up with threads synchronisation.

                      O Offline
                      O Offline
                      opengpu
                      wrote on last edited by
                      #16

                      @jsulm
                      https://docs.microsoft.com/en-us/windows/desktop/winauto/variant-structure
                      https://docs.microsoft.com/en-us/windows/desktop/api/oaidl/ns-oaidl-tagvariant

                      J.HilkJ 1 Reply Last reply
                      0
                      • O opengpu

                        @jsulm
                        https://docs.microsoft.com/en-us/windows/desktop/winauto/variant-structure
                        https://docs.microsoft.com/en-us/windows/desktop/api/oaidl/ns-oaidl-tagvariant

                        J.HilkJ Offline
                        J.HilkJ Offline
                        J.Hilk
                        Moderators
                        wrote on last edited by J.Hilk
                        #17

                        @opengpu doesn't really answer @jsulm question, as WORD can be 16, 32, or 64 bits (go Microsoft) x)

                        even worst case, the size of your struct isn't big at all and any repeating signal with an interval > 100ms is (usually)more than fine


                        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.

                        O 1 Reply Last reply
                        0
                        • J.HilkJ J.Hilk

                          @opengpu doesn't really answer @jsulm question, as WORD can be 16, 32, or 64 bits (go Microsoft) x)

                          even worst case, the size of your struct isn't big at all and any repeating signal with an interval > 100ms is (usually)more than fine

                          O Offline
                          O Offline
                          opengpu
                          wrote on last edited by
                          #18

                          @J.Hilk windows10 & x64

                          1 Reply Last reply
                          0
                          • O Offline
                            O Offline
                            opengpu
                            wrote on last edited by
                            #19

                            ok, so i will pass it by-value in connect & across theads

                            1 Reply Last reply
                            0
                            • O Offline
                              O Offline
                              opengpu
                              wrote on last edited by
                              #20

                              my exe recieve data from internet then update and show the data realtime, such as stock market realtime price changing very fast.

                              1 Reply Last reply
                              0

                              • Login

                              • Login or register to search.
                              • First post
                                Last post
                              0
                              • Categories
                              • Recent
                              • Tags
                              • Popular
                              • Users
                              • Groups
                              • Search
                              • Get Qt Extensions
                              • Unsolved