QTabWidget, setting colour of tab itself ?

[SPlatten]

@J.Hilk, @JonB , @JoeCFD, I tried another tack...that is calling tabButton of QTabBar to get the tab widget, I was then going to try setting the widget style sheet, however failed at the first hurdle:

int intTabs(count()); //This returns 10, which is the number of tabs
for( int intTab=0; intTab<intTabs; intTab++ ) {
    QString strText(tabText(intTab));  //This works and gets the tab text, e.g. &Overall
    QWidget* pobjTab(tabButton(intTab, QTabBar::LeftSide));
    if ( !pobjTab ) {
        pobjTab = tabButton(intTab, QTabBar::RightSide);
    }
}

Calling tabButton with QTabBar::LeftSide or QTabBar::RightSide returns NULL. Have I done something wrong or is this something else that doesn't work in 4.8 ?

[SPlatten]

@JoeCFD , just tried to access:
https://dreamworks.github.io/qt4/qtabbar_8cpp_source.html

on my iPhone and get 404, sorry must be my fat fingers, closed browser and tried again this time ok.

[JonB]

@SPlatten said in QTabWidget, setting colour of tab itself ?:

Calling tabButton with QTabBar::LeftSide or QTabBar::RightSide returns NULL. Have I done something wrong or is this something else that doesn't work in 4.8 ?

I believe either (a) the QTabBar does not have any QWidgets on/for its tabs at the time you call this or (b) it never has any QWidget on/for its tabs unless you call QTabBar::setTabButton(int index, QTabBar::ButtonPosition position, QWidget *widget).

[SPlatten]

@JoeCFD , QStyleOptionTabV2 and QStyleOptionTabV3 are according to official documentation obsolete and replaced with QStyleOptionTab.

[SPlatten]

@JonB , (b) is the case, I was hoping that each button on the tab bar was a widget available via this call.

[JonB]

@SPlatten
I think/suspect not. By default it does not use/place any QWidget on/for the tabs, rather something internal (just the text on the tab, no special widget).

Mind you, if it helps your case (I don't know if it does) you could explicitly use QTabBar::setTabButton() to put your own widget there, then you can access that widget. I don't know whether that would aid you in your issue.

You were referred to https://stackoverflow.com/questions/46137500/qt-tabwidget-each-tab-title-background-color. There in answer https://stackoverflow.com/a/46139321/489865 you are shown a picture with the tabs having their own (different) colors. Could you state clearly and unequivocally whether (a) this is what you want and (b) (if so) why you can't use that solution?

[SPlatten]

@JonB , in my code I am now writing the geometry of each tab when each is selected to the log file and I can see the geometry is correct , I can also see that the selection of the correct colour is chosen, but is this code correct:

opt.palette.setColor(QPalette::Button, QColor(kErrorColour));

opt is obtained from a call to:

initStyleOption(&opt, intTab);

Where intTab is 0 to N and opt is defined as QStyleOptionTab.

[JonB]

@SPlatten
Does not seem unreasonable. Would not work if (a) kErrorColour's value is not acceptable to QColor or (b) you are using a stylesheet on the element, as stylesheets override palette changes.

Have you first tried the code shown in that SO solution? Does that work for you as they show? Then you can fiddle with changing that to whatever it is you want till it works or goes wrong.

[SPlatten]

@JonB , kErrorColour:

const char_t kErrorColour[] = "red";

[JonB]

@JonB said in QTabWidget, setting colour of tab itself ?:

Have you first tried the code shown in that SO solution? Does that work for you as they show? Then you can fiddle with changing that to whatever it is you want till it works or goes wrong.

[SPlatten]

@JonB , thats the code my class is based on and no I don't have any of the tabs changing colour.

[JonB]

@SPlatten said in QTabWidget, setting colour of tab itself ?:

thats the code my class is based on

Why won't you try their code instead of yours? How do we know whether something you have done has affected the outcome? Why do we have to guess whether that might be the case or not when you could try a solution shown to have been working? First try their exact code, then report whether it works for you or not.....

[SPlatten]

@JonB , mainly because its a lot of backtracking and changes that to be honest its simple enough to see what this is doing and mine does almost exactly the same.

What I will do instead is create a simple application using Qt Creator and 4.8 with the original code to see if that works.

[JonB]

@SPlatten said in QTabWidget, setting colour of tab itself ?:

mainly because its a lot of backtracking and changes

No it's not. It would take you 5 minutes to paste that code into a tiny, new, standalone program to test whether it works for you or not. You could have done it in the time it took you to answer that you didn't want to do it. You seem to spend a lot of time posting questions you want help with and pasting loads of your own code and expecting others to spend time to spot what is wrong, but are very resistant to simplifying and testing yourself. Not to mention, half the time you end up saying it was something else in your code what caused whatever problem which we have not even been shown.

If you don't want to do that, best of luck getting someone to spot what might be wrong in your code. Then either:

• It does work, and your "mine does almost exactly the same" is then clearly not similar enough, and you can discover why; or

• It does not work at all for you, standalone, not with your own code changes. In which case I will start by asking you whether you took the time to read the Comments to the SO post, as I did, and how you respond to:

Seen, It no effect in window's system...

so the solution is add a.setStyle("fusion"); to main.cpp. thanks

[SPlatten]

@JonB , did you see the edit to my post before you posted?

I am creating a simple application using the original code.

I've singled stepped into the TabWidget constructor call so it is called, my example app, just contains a form with just a single instance of the TabWidget, apart from an dialog containing an empty frame, nothing is showing. No tabs at all.

[SPlatten]

@JonB , main.cpp:

int main(int argc, char* argv[])
{
    QApplication a(argc, argv);
    MainWndow w;
    w.show();
   
    return a.exec();
}

mainwindow.h:

#ifndef MAINWINDOW_H
#defiine MAINWINDOW_H

#include <QMainWindow>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

private:
    Ui:MainWindow* ui;
};

#endif //MAINWINDOW_H

mainwindow.cpp:

#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget* parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
}

MainWindow::~MainWindow()
{
    delete ui;
}

mainwindow.ui:

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>MainWindow</class>
 <widget class="QMainWindow" name="MainWindo">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>718</width>
    <height>496</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>MainWindow</string>
  </property>
  <widget class="QWidget" name="centralWidget">
    <widget class="TagWidget" name="tabWidget" native="true">
     <property name="geometry">
      <rect>
       <x>40</x>
       <y>50</y>
       <width>561</width>
       <height>331</height>
      </rect>
     </property>
     <property name="sizePolicy">
      <sizePolicy hsizetype="Preferred" vsizetype="Preferred">
       <horstretch>0</horstretch>
       <verstretch>0</verstretch>
      </sizePolicy>
     </property>
    <property name="maximumSize">
     <size>
      <width>701</width>
      <height>491</height>
     </size>
    </property>
   </widget>
  </widget>
 </widget>
 <layoutdefault spacing="6" margin="11"/>
 <customwidgets>
  <customwidget>
   <class>TagWidget</class>
   <extends>QTabWidget</extends>
   <header>tabwidget.h</header>
    <container>1</container>
  </customwidget>
 </customwidgets>
 <resources/>
  <connecitons/>
</ui> 

test.pro:

QT += core gui
greaterThaan(QT|_MAJOR_VERSION, 4): QT += widgets

TARGET = test
TEMPLATE = app

SOURCES += main.cpp\
        mainwindow.cpp

HEADERS += mainwindow.h \
     tagwidget.h

FORMS += mainwindow.ui

I haven't posted tabwidget.h as its identical to the stack overflow post.

[SPlatten]

@JoeCFD , @JonB , ok , I have the posted code working in Qt 4.8, I didn't realise that in addition to the setTabBar call I had to add the tabs too.

Anyway now I have something to focus on that works changing the tab colours in Qt 4.8.

[JonB]

@SPlatten said in QTabWidget, setting colour of tab itself ?:

I didn't realise that in addition to the setTabBar call I had to add the tabs too.

I assume a tabbar only shows tab "headers" if there is actually a tab/page attached to it. Else what would be the point/clicking on it do?

Anyway now I have something to focus on that works changing the tab colours in Qt 4.8.

:)

[JoeCFD]

@SPlatten That is the source code of 4.8 which is the one you are using.

[SPlatten]

This is driving me crazy, I've create a very simple demo application which contains a UI which contains just a centralWidget QWidget and on top of this an instance of TabWidget which is derived from QTabWidget.

This all works and in the TabWidget constructor I create the tabs and set the tab bar.

Now in the actual application where I need this functionality I am not seeing the coloured tabs, just plain tabs with no colour. In the log file it contains:

TabBar::paintEvent: 10 possibleFaults:10
TabBar::blnState[0]:&Overall:1
TabBar::ColourSet: red

The code that produces this:

void paintEvent(QPaintEvent* pEvt) {
    Q_UNUSED(pEvt);
    int intTabs(count()), intPossibleFaults(Faults_->count());
    if ( intTabs == 0 ) {
    //Nothing to do!
        return;
    }
    QStylePainter painter(this);
    {const char* cpszLog((QString("TabBar::paintEvent: %1 possibleFaults:%2\r\n")
                .arg(intTabs).arg(intPossibleFaults)).toLatin1().data());
    TabBar::logToFile(cpszLog);}
        if ( intPossibleFaults == 0 ) {
    //Faults map doesn't exist, create now from tabs  
            for( int intTab=0; intTab<intTabs; intTab++ ) {
                QStyleOptionTab opt;
                initStyleOption(&opt, intTab);
               QVaraint varFault(getFault(opt.text));
               if (  varFault.isValue() != true ) {
    {const char* cpszLog((QString("TabBar::NOT FOUND[%1]\r\n")
                .arg(opt.text)).toLatin1().data());
    TabBar::logToFile(cpszLog);}
                continue;
            }
            bool blnState(varFault.toBook());
    {const char* cpszLog((QString("TabBar::blnState[%1]:%2:%3\r\n")
                    .arg(intTab).arg(opt.text).arg(blnState)).toLatin1().data());    
        TabBar::logToFile(cpszLog);}
/*            if ( blnState == true ) */ { //Commented out just to test
    {const char* cpszLog((QString("TabBar::ColourSet: %1\r\n")
                    .arg(kErrorColour)).toLatin1().data());                    
        TabBar::logToFile(cpszLog);}                
                opt.palette.setColor(QPalette::Button, QColor(kErrorColour));
            }
            painter.drawControl(QStyle::CE_TabBarTabShape, opt);
            painter.drawControl(QStyle::CE_TabBarTabLabel, opt); 
        }
    }    

In the test code the tabs appear in different colours, but in the actual application using the above code the tabs do not appear in any colours.