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Compose pointer to property of object

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c++pointerobjectsproperties
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  • M mrjj
    1 Apr 2016, 13:20

    but if you put in list u can do

    for (int dx=0; dx < allPButtons.size(); dx++ )
    allPButtons[dx]->show();

    or
    allPButtons[ID]->show();
    allPButtons[ID]->WhatEverProperty();

    and then u dont need the switch case. ?

    M Offline
    M Offline
    McLion
    wrote on 1 Apr 2016, 13:24 last edited by
    #5

    @mrjj
    Thanks.
    I'll try to implement your idea .. and get back with the result ( or more questions ;-)

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    • M mrjj
      1 Apr 2016, 13:20

      but if you put in list u can do

      for (int dx=0; dx < allPButtons.size(); dx++ )
      allPButtons[dx]->show();

      or
      allPButtons[ID]->show();
      allPButtons[ID]->WhatEverProperty();

      and then u dont need the switch case. ?

      M Offline
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      McLion
      wrote on 4 Apr 2016, 08:39 last edited by
      #6

      @mrjj
      I got stock at some other place.
      What's the best way to create the webGUI's (qWebView) at run-time, only as needed?
      I mean, I always need one at least, but only sometimes more than one and was thinking of not using up the memory by preparing a defined number of copies.
      Any hint's, if possible at all?
      Thanks.

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      • M Offline
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        mrjj
        Lifetime Qt Champion
        wrote on 4 Apr 2016, 08:55 last edited by
        #7

        hi
        its always possible to NEW widgets on demand.
        How you will do it, mostly depends tón the GUI.
        How user will do it.

        At any time you can do
        QWebView *view = new QWebView(parent);
        view->load(QUrl("http://qt-project.org"));
        view->show();

        M 1 Reply Last reply 4 Apr 2016, 09:26
        0
        • M mrjj
          4 Apr 2016, 08:55

          hi
          its always possible to NEW widgets on demand.
          How you will do it, mostly depends tón the GUI.
          How user will do it.

          At any time you can do
          QWebView *view = new QWebView(parent);
          view->load(QUrl("http://qt-project.org"));
          view->show();

          M Offline
          M Offline
          McLion
          wrote on 4 Apr 2016, 09:26 last edited by
          #8

          @mrjj
          Here's what I'm doing:

            QWebView *webGUI = new QWebView(this);
            webGUI->setObjectName(QString::fromUtf8("webGUI"));
            webGUI->setGeometry(QRect(280, 190, 150, 120));
            webGUI->setAcceptDrops(false);
            webGUI->setStyleSheet(QString::fromUtf8("background-color: rgba(127, 127, 127, 0);"));
            webGUI->setUrl(QUrl("about:blank"));
            webGUI->setRenderHints(QPainter::SmoothPixmapTransform|QPainter::TextAntialiasing);
            webGUI->page()->mainFrame()->setScrollBarPolicy( Qt::Vertical, Qt::ScrollBarAlwaysOff );
            webGUI->page()->mainFrame()->setScrollBarPolicy( Qt::Horizontal, Qt::ScrollBarAlwaysOff );
            webGUI->setGeometry(0, 0, SCREEN_SIZE_X, SCREEN_SIZE_Y);
          

          This is in a separate function and does not yet have the code to make it create webGUI[01] .. webGUI[n]. I thought of trying with one first.
          I currently call this from the main constructor.

          Before, the concept used only one webGUI that I created in the Designer - everything worked as supposed.

          I'm accessing these webGUI's from various places in my code.

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          • M Offline
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            mrjj
            Lifetime Qt Champion
            wrote on 4 Apr 2016, 09:31 last edited by
            #9

            hi
            If you make this into a fine function that returns a QWebView *, you
            can easy make more than one.

            I do wonder how the parent QWebView(this); << the "this" can
            show mutiple QWebView ?
            will you use a tab control or a stackedwidetget to allow user to flip between the
            WEbViews or ill the be in same page and just take a smaller share of it ?
            as in share the page/parent ?

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            • M Offline
              M Offline
              McLion
              wrote on 4 Apr 2016, 09:45 last edited by McLion 4 Apr 2016, 09:46
              #10

              'This' might be one of my problems.
              While in Designer I had a centralWidget as parent for all my elements.
              The webGUI's are dynamically loaded with content from a local server and are shown/hidden as needed. They also are placed and sized as needed at run-time and cover all of the screen or or only parts, may overlap with transparency ...
              There is at least one, but should now be extendable on request.

              Am I correct that I will need to create webView01 from the constructor at startup and make it available in *.h. Otherwise all the references to it are not satisfied.

              All references/calls to any webGui need to make use pof the QList, right.

              As you may surely have noted, I never implemented such a logic/functionality before.
              Thanks a lot for your help and guidance!

              M 1 Reply Last reply 4 Apr 2016, 10:21
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              • M McLion
                4 Apr 2016, 09:45

                'This' might be one of my problems.
                While in Designer I had a centralWidget as parent for all my elements.
                The webGUI's are dynamically loaded with content from a local server and are shown/hidden as needed. They also are placed and sized as needed at run-time and cover all of the screen or or only parts, may overlap with transparency ...
                There is at least one, but should now be extendable on request.

                Am I correct that I will need to create webView01 from the constructor at startup and make it available in *.h. Otherwise all the references to it are not satisfied.

                All references/calls to any webGui need to make use pof the QList, right.

                As you may surely have noted, I never implemented such a logic/functionality before.
                Thanks a lot for your help and guidance!

                M Offline
                M Offline
                mrjj
                Lifetime Qt Champion
                wrote on 4 Apr 2016, 10:21 last edited by
                #11

                @McLion said:

                • 'This' might be one of my problems.
                  Well "this" is just the parent. if no parent are giving, it will become a window.
                  So often this will be mainwindow. There nothing wrong having mutiple
                  WebViews in same parent but u might need to arrange them to not overlap.
                  (use move or setGeometry) Since it sounds you will arrange them manually and not use a layout or tabs or something like that.

                • Am I correct that I will need to create webView01 from the constructor at startup and make it available in *.h. Otherwise all the references to it are not satisfied.
                  Well you dont need that.
                  You can have list
                  QList< QWebView *> Webs;
                  QWebView *webGUI = new QWebView(this);
                  ...
                  Webs.append(webGUI); // keep in list

                Then at any time
                QWebView *w = Webs[0]; // take from list
                or Webs[1] , 2,3,4 etc.

                So you dont need a named variable to access it.

                Also, handling signals. You a can use same slot for all webviews.
                the sender() function will tell you which webview
                QWebView * wv= qobject_cast<QWebView *>(sender());
                if (wv) ...
                inside the slot for a signal to know which of the webviews that send the signal.
                Not sure you will need it, so just a note :)

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                • M Offline
                  M Offline
                  McLion
                  wrote on 5 Apr 2016, 09:14 last edited by McLion 4 May 2016, 09:15
                  #12

                  Getting forward :-)
                  The hint with the sender in the signal was great too. As if you would know before, I really stumbled over this - thanks!

                  I came across an issue with the list though.
                  There are no absolute positions in the list. Saying if 3 entries are made (0,1,2) and the second list (1) is cancelled for instance because it's not needed anymore, former entry 2 becomes entry 1.
                  QList seems to always fill from the 0 up and there are no absolute positions.

                  I either did not get all of QList or I may need to switch to some other solution - unfortunately- because it otherwise works a treat.

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                  • M Offline
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                    mrjj
                    Lifetime Qt Champion
                    wrote on 5 Apr 2016, 09:40 last edited by mrjj 4 May 2016, 09:49
                    #13

                    hi
                    Im not sure what wrong with QList since its dynamic and
                    we cant have invalid pointers around ?
                    else use a map
                    http://doc.qt.io/qt-5/qmap.html
                    QMap<int,QWebView * > map;
                    QWebView *webGUI = new QWebView(this);
                    ...
                    map[1] =webGUI ;
                    map[2] =nextwebGUI ;
                    ...
                    QWebView *w=map[2]; // it will stay "2"

                    They wont change position as 1,2 is a key
                    like map["onekey"] =webGUI ;
                    but we use int as no need for string.
                    so even if we remove map[1] then
                    map[2] is still there.

                    So maybe it works better for you ?

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                    • M Offline
                      M Offline
                      McLion
                      wrote on 5 Apr 2016, 09:58 last edited by
                      #14

                      Tried quickly ... and the Map is exactly what I need.
                      Thanks a million! .... I'll be back ;-)

                      M 1 Reply Last reply 5 Apr 2016, 10:02
                      0
                      • M McLion
                        5 Apr 2016, 09:58

                        Tried quickly ... and the Map is exactly what I need.
                        Thanks a million! .... I'll be back ;-)

                        M Offline
                        M Offline
                        mrjj
                        Lifetime Qt Champion
                        wrote on 5 Apr 2016, 10:02 last edited by
                        #15

                        @McLion
                        super
                        notice if you reuse the key
                        map[1] =webGUI ;
                        map[1] =nextwebGUI ;
                        It will replace the web *.

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                        • M Offline
                          M Offline
                          McLion
                          wrote on 5 Apr 2016, 10:03 last edited by
                          #16

                          Thanks for the heads-up.
                          I'll do some testing and experiment.

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                          • M Offline
                            M Offline
                            McLion
                            wrote on 5 Apr 2016, 14:16 last edited by
                            #17

                            So far, everything related to this threads question and the QMap as solution seems to work.

                            I stumbled over something else while relacing the QwebView from the Designer by my 'on-demand' created one:
                            I can not load an url, it crashes with sig11.

                            I get the following connect error on bootup:

                            QMetaObject::connectSlotsByName: No matching signal for on_webGUI_loadFinished(bool)
                            

                            which I dont understand and may be the cause.
                            I have connected:

                            connect(webGUI, SIGNAL(loadFinished(bool)), this, SLOT(on_webGUI_loadFinished(bool)));
                            

                            and in *.h as private slot:

                            void on_webGUI_loadFinished(bool arg1);
                            

                            This worked before, with the QWebView from the Designer.
                            Any idea? Thanks.

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                            • M Offline
                              M Offline
                              mrjj
                              Lifetime Qt Champion
                              wrote on 5 Apr 2016, 14:26 last edited by
                              #18

                              @McLion said:

                              no matching signal for on_webGUI_loadFinished(bool)

                              Hi
                              this warning comes as you name slot on_XXX
                              This will trigger Qt auto connect feature so when you use
                              a concrete connect you should rename it so it dont
                              start with on__
                              (right click it- refactor->rename)

                              also please do
                              qDebug() << "loadfin:" << connect(webGUI, SIGNAL(loadFinixxxx

                              to see if it returns true; ( as in , it can connect)

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                              • M Offline
                                M Offline
                                McLion
                                wrote on 5 Apr 2016, 14:39 last edited by
                                #19

                                I wasn't aware that using on_ in the name will trigger any functionality!
                                Refactoring solved this problem - Thanks !

                                However, the signal 11 crash when trying to load an url seems to have some other cause .... I'm searching ;-)

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                                • J Offline
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                                  jsulm
                                  Lifetime Qt Champion
                                  wrote on 5 Apr 2016, 15:47 last edited by
                                  #20

                                  You're most probably dereferencing a null pointer. Signal 11 means SIGSEGV (segmentation error).

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

                                  M 1 Reply Last reply 6 Apr 2016, 08:21
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                                  • J jsulm
                                    5 Apr 2016, 15:47

                                    You're most probably dereferencing a null pointer. Signal 11 means SIGSEGV (segmentation error).

                                    M Offline
                                    M Offline
                                    McLion
                                    wrote on 6 Apr 2016, 08:21 last edited by
                                    #21

                                    @jsulm
                                    Yes - Thanks . Problem loacted, but not yet solved:

                                    void QTGUI_MainWindow::populateJavaScriptWindowObject()
                                    {
                                      QWebView * webGUI = qobject_cast<QWebView *>(sender());
                                      webGUI->page()->mainFrame()->addToJavaScriptWindowObject("NativeBridge", this);
                                    }
                                    

                                    The sender is the JS and not the QWebView and so I do not get the pointer to the QWebView that I need. Instead, the pointer is 0x0 and then - of course - the addToJ... crashes.

                                    Any idea how I get the pointer to the QWebView from which the JS is sending?
                                    Thanks

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                                    • J Offline
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                                      jsulm
                                      Lifetime Qt Champion
                                      wrote on 6 Apr 2016, 08:42 last edited by
                                      #22

                                      What is JS?

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

                                      M 1 Reply Last reply 6 Apr 2016, 08:45
                                      0
                                      • J jsulm
                                        6 Apr 2016, 08:42

                                        What is JS?

                                        M Offline
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                                        McLion
                                        wrote on 6 Apr 2016, 08:45 last edited by
                                        #23

                                        @jsulm
                                        JavaScript (in/from QWebKit ... more precise page()->mainFrame().

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                                        • M Offline
                                          M Offline
                                          McLion
                                          wrote on 6 Apr 2016, 11:33 last edited by
                                          #24

                                          I posted this as a separate question in the WebKit group.

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