QTabWidget, setting colour of tab itself ?

[JonB]

@SPlatten
Nothing in https://stackoverflow.com/questions/46137500/qt-tabwidget-each-tab-title-background-color creates multiple QTabBars or changes the QWidgets which are the content/pages of each tab to themselves be QTabBars!

[SPlatten]

@JonB , no as I said I goofed up, looking at it again now.

[SPlatten]

@J.Hilk, @JonB , @JoeCFD, so I've finally got everything the way it should be and in my debug output I can see that various bits are being called, but it doesn't do what it is supposed to do, I'm not seeing the tabs in a different colour.

The modified classes:

typedef QMap<QString, QVariant> mpFaults;

class TabBar : public QTabBar {
private:
    mpFault* Faults_;

protected:
    void paintEvent(QPaintEvent* evt) {
        int intTabs(count()), intPossibleFaults(Faults_->count());
        QStylePainter painter(this);
        QStyleOptionTab opt;
 const char* cpszLog((QString("TabBar::paintEvent: %1 possibleFaults:%2\r\n")
                          .arg(intTabs).arg(intPossibleFaults)).toLatin1().data());
TabBar::logToFile(cpszLog);
        if ( intTabs > 0 && intPossibleFaults == 0 ) {
            for ( int intTab=0; intTab<intTabs; intTab++ ) {
                QString strText(tabText(intTab));
                Faults_->insert(strText, QVariant(false));
            }
        }
        for( int intTab=0; intTab<intTabs; intTab++ ) {
            initStyleOption(&opt, intTab);
const char* cpszLog((QString("TabBar::tab: %1\r\n")
              .arg(opt.text)).toLatin1().data());
TabBar::logToFile(cpszLog);
            mpFaults::iterator itTab(Faults_->find(opt.text));
            if ( itTab != Faults_->end() ) {
                QVariant varValue(itTab.value());
                bool blnState(varValue.toBool());
const char* cpszLog((QString("TabBar::blnState: %1\r\n")
              .arg(blnState)).toLatin1().data());
TabBar::logToFile(cpszLog);
                if ( blnState == true ) {
const char* cpszLog((QString("TabBar::ColourSet: %1\r\n")
              . arg(kErrorColour)).toLatin1().data());
                    opt.palette.setColor(QPalette::Button, QColor(kErrorColour));
                }
            }
            painter.drawControl(QStyle::CE_TabBarTabShape, opt);
            painter.drawControl(QStyle::CE_TabBarTabLabel, opt);
        }
    }
public:
    static void logToFile(const char* cpszMsg) {
        FILE* fp(fopen("/usr/local/cgu/paint.txt", "at"));
        if ( fp ) {
            fputs(cpszMsg, fp);
            fclose(fp);
        }
    } 
    TabBar(QWidget* pParent = 0) : QTabBar(pParent) {
TabBar::logToFile("TabBar::TabBar!!\r\n");
        Faults_ = new mpFaults();
    }
    bool setFault (QString& strText, bool blnState) {
        mpFaults::iterator itTab(Faults_->find(strText));
const char* cpszLog((QString("TabBar::setFault(%1,%2)\r\n")
                .arg(strText).arg(blnState)).toLatin1().data());
TabBar::logToFile(cpszLog);
        if ( itTab != Faults_->end() ) {
            itTab.value() = QVariant(blnState);
            return true;
        }
        return false;
    }
};

class TabWidget : public QTabWidget {
public:
    TabWidget(QWidget* pParent = 0) : QTabWidget(pParent) {
        setTabBar(new TabBar());
    }
    bool setFault(QString& strText, bool blnState) {
        TabBar* pTabBar(dynamic_cast<TabBar*>(tabBar()));
        if ( pTabBar ) {
            return pTabBar->setFault(strText, blnState);
        }
        return false;
    }
};

I see all the various debug messages in the log file, but tab is not showing as red which is the string literal assigned to kErrorColour:

const char_t kErrorColour[] = "red";

Logged to file:

TabBar::paintEvent: 10 possibileFaults:10
TabBar::tab: &Overall
TabBar::blnState: 1
TabBar::ColourSet: red

[JoeCFD]

You really want to add flashing icons to the tabs or simply change their colors?

[SPlatten]

@JoeCFD , changing the colour of the tab is the intention but it isn't working.

[JoeCFD]

You can not change it with style sheet? My suggestion for you was to flash the icons on the tabs.

[SPlatten]

@JoeCFD , unfortunately not....I've been through this loop, the class I found and have linked to is supposed to work, but I can't get it to work...could it be due to Qt 4.8 ?

[JoeCFD]

@SPlatten Probably. 4.8 is ancient code. Nobody here will try 4.8 for you. It is amazing that the people still have patience to use it. Poor you.

Let me check my code to see if you can use tabbar to change the color. But my code is much more customized.

[SPlatten]

@JoeCFD , unfortunately its completely out of my control and the company using it won't be updating it anytime soon as there are other dependencies / reasons why they can't.

[JoeCFD]

@SPlatten You may push them for an update and get more contracts.

[SPlatten]

@JoeCFD , the company is a world wide provider of defence and weapon tech....they're clients are governments and the equipment is years out of date, again, I have requested an updated, but I can't do anything about it.

[JoeCFD]

1. 4.8 qtabbar_cpp source code is here. copy line 1569 to 1648 to your paint event. Not sure if this will work.
   https://dreamswork.github.io/qt4/qtabbar_8cpp_source.html
   painting of tabs is done at line 1622.
2. Look at lines 1594 and 1595. These lines call initStyleOption() to create QStyleOptionTabV3 tab for each tab which is a subclass of QStyleOption
   https://dreamswork.github.io/qt4/classQTabBar.html#a41b394d892263b6b5a0705fb979f3c8e
   and each QStyleOption has a public palette with background color. You can change it. Try to print out the background color to see what it is.
3. you can find QStyleOptionTabV3 and QStyleOptionTab here
   https://dreamswork.github.io/qt4/qstyleoption_8h_source.html
   This way may be simpler. Good luck.

[JonB]

@SPlatten
Without wanting to digress this thread. I am surprised given the age of an old 4.8 implementation they now insist they want a change in a tab colour! Can't you say "Sorry, I have looked into it, this old version won't let me do that" ?

[SPlatten]

@JoeCFD , unfortunately the company firewall will not allow access to the dreamswork domain.

[SPlatten]

@JonB , I was brought into this company 5 months ago and the project is very old, there is a lot of issues to resolve and this is just one of many.

[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.