Setting QProxyStyle on TabBar, overrides Palette

[BDC_Patrick]

Hi there..

I wanted to change the Label Orientation in a TabBar to be Horizontal, when the TabBar is set to "West".

This is done with this simple Style Header:

#include <QProxyStyle>
#include <QTabBar>
#include <QStyleOption>

class TGS_CustomTabWest : public QProxyStyle {
public:
    QSize sizeFromContents(ContentsType type, const QStyleOption* option,
                           const QSize& size, const QWidget* widget) const {
        QSize s = QProxyStyle::sizeFromContents(type, option, size, widget);
        if (type == QStyle::CT_TabBarTab) {
            s.transpose();
        }
        return s;
    }

    void drawControl(ControlElement element, const QStyleOption* option, QPainter* painter, const QWidget* widget) const {
        if (element == CE_TabBarTabLabel) {
            if (const QStyleOptionTab* tab = qstyleoption_cast<const QStyleOptionTab*>(option)) {
                QStyleOptionTab opt(*tab);
                opt.shape = QTabBar::RoundedNorth;
                QProxyStyle::drawControl(element, &opt, painter, widget);
                return;
            }
        }
        QProxyStyle::drawControl(element, option, painter, widget);
    }
};

Problem now:
The TabBar is drawn White with white Labels..

Means: Setting the TabBar Style with

ui->tabWidget_DB_Navigation->tabBar()->setStyle(new TGS_CustomTabWest);

Overrides the Application Palette Settings of fusion.

What is the correct way to re-implement the Palette for the TabBar?

I tried doing

ui->tabWidget_DB_Navigation->tabBar()->setPalette(darkPalette);

After setting the Style.. did not work ^^

See:

The Tabs are just White on White.. instead of the Dark palette..

Would be nice if you Guys can help me.

[SGaist]

Hi,

@BDC_Patrick said in Setting QProxyStyle on TabBar, overrides Palette:

drawControl

Does it draw properly if you do not re-implement that method ?

[BDC_Patrick]

@SGaist Yes
The Tabs are drawn Properly, when not doing the QProxyStyle.
But.. vertical Text..

[SGaist]

I did not meant to disable the style, just not override drawControl.

[BDC_Patrick]

@SGaist But.. the rotation of the TabBar Labels is done in drawControl...
Without it, the Labels are vertical again.. But still white Light-Fusion color Palette..

I updated the Startpost with an Image of the problem..

[BDC_Patrick]

I do still stuck on that Task..
:(

[SGaist]

Which version of Qt are you using ?
On which OS ?
Are you using a specific style like fusion ?

[BDC_Patrick]

@SGaist
Current QT is 5.15.2
OS is Windows
Preferred Style is fusion with changing Palettes
Language is Cpp (11+)
IDE: CLion

I´m currently working with the workaround, to spawn multiple buttons in a vertical Box..
Not really beautiful..

So.. if you know help for a TabBar.. it would be nice ^^

[SGaist]

Can you provide a complete minimal example that triggers that behavior ? That way everybody can use the same code to see the issue.

[BDC_Patrick]

This post is deleted!

[BDC_Patrick]

@SGaist said in Setting QProxyStyle on TabBar, overrides Palette:

Can you provide a complete minimal example that triggers that behavior ? That way everybody can use the same code to see the issue.

The ui file:

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>test_verticalTabBar</class>
 <widget class="QWidget" name="test_verticalTabBar">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>819</width>
    <height>605</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>test_verticalTabBar</string>
  </property>
  <layout class="QGridLayout" name="gridLayout">
   <item row="0" column="0">
    <widget class="QTabWidget" name="tabWidget">
     <property name="tabPosition">
      <enum>QTabWidget::West</enum>
     </property>
     <property name="currentIndex">
      <number>0</number>
     </property>
     <widget class="QWidget" name="tab">
      <attribute name="title">
       <string>Tab 1</string>
      </attribute>
     </widget>
     <widget class="QWidget" name="tab_2">
      <attribute name="title">
       <string>Tab 2</string>
      </attribute>
     </widget>
     <widget class="QWidget" name="tab_3">
      <attribute name="title">
       <string>Seite</string>
      </attribute>
     </widget>
     <widget class="QWidget" name="tab_4">
      <attribute name="title">
       <string>Seite</string>
      </attribute>
     </widget>
     <widget class="QWidget" name="tab_5">
      <attribute name="title">
       <string>Seite</string>
      </attribute>
     </widget>
    </widget>
   </item>
  </layout>
 </widget>
 <resources/>
 <connections/>
</ui>

the Header File:

#ifndef TEST_VERTICALTABBAR_H
#define TEST_VERTICALTABBAR_H

#include <QWidget>
#include "tgs_customtabwest.h"


QT_BEGIN_NAMESPACE
namespace Ui { class test_verticalTabBar; }
QT_END_NAMESPACE

class test_verticalTabBar : public QWidget {
Q_OBJECT

public:
    explicit test_verticalTabBar(QWidget *parent = nullptr);

    ~test_verticalTabBar() override;

private:
    Ui::test_verticalTabBar *ui;
};


#endif //TEST_VERTICALTABBAR_H

The Source File:

#include "test_verticaltabbar.h"
#include "ui_test_verticalTabBar.h"


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

    ui->tabWidget->tabBar()->setStyle(new TGS_CustomTabWest);
}

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

Style set via (in main.cpp):

a.setStyle(QStyleFactory::create("Fusion"));

My darkstyle palette (feel free to use it, too):

void SetupDarkPalette(QPalette &palette, int highlighter, int ColorShifter){
    QColor hLColor;
    switch(highlighter){
        case 0:
            hLColor = QColor(42,130,218); //Blue
            break;
        case 1:
            hLColor = QColor(255,150,30); //Orange
            break;
        case 2:
            hLColor = QColor(145,215,0); //Green
            break;
        case 3:
            hLColor = QColor(225,225,0); //Yellow
            break;
        case 4:
            hLColor = QColor(175,90,255); //Purple
            break;
        case 5:
            hLColor = QColor(215,45,0); //Red
            break;
        case 6:
            hLColor = QColor(215,215,215); //White
            break;
        case 7:
            hLColor = QColor(115,115,115); //Grey
            break;
        case 8:
            hLColor = QColor(20,20,20); //Black
            break;
        default:
            break;
    }

    // modify palette to dark
    palette.setColor(QPalette::Window, QColor(53 + ColorShifter, 53 + ColorShifter, 53 + ColorShifter));
    palette.setColor(QPalette::WindowText, Qt::white);
    palette.setColor(QPalette::Disabled, QPalette::WindowText, QColor(127 + ColorShifter, 127 + ColorShifter, 127 + ColorShifter));
    palette.setColor(QPalette::Base, QColor(42 + ColorShifter, 42 + ColorShifter, 42 + ColorShifter));
    palette.setColor(QPalette::AlternateBase, QColor(66 + ColorShifter, 66 + ColorShifter, 66 + ColorShifter));
    palette.setColor(QPalette::ToolTipBase, Qt::white);
    palette.setColor(QPalette::ToolTipText, QColor(53 + ColorShifter, 53 + ColorShifter, 53 + ColorShifter));
    palette.setColor(QPalette::Text, Qt::white);
    palette.setColor(QPalette::Disabled, QPalette::Text, QColor(127 + ColorShifter, 127 + ColorShifter, 127 + ColorShifter));
    palette.setColor(QPalette::Dark, QColor(35 + ColorShifter, 35 + ColorShifter, 35 + ColorShifter));
    palette.setColor(QPalette::Shadow, QColor(20 + ColorShifter, 20 + ColorShifter, 20 + ColorShifter));
    palette.setColor(QPalette::Button, QColor(53 + ColorShifter, 53 + ColorShifter, 53 + ColorShifter));
    palette.setColor(QPalette::ButtonText, Qt::white);
    palette.setColor(QPalette::Disabled, QPalette::ButtonText, QColor(127 + ColorShifter, 127 + ColorShifter, 127 + ColorShifter));
    palette.setColor(QPalette::BrightText, Qt::red);
    palette.setColor(QPalette::Link, QColor(42 + ColorShifter, 130 + ColorShifter, 218 + ColorShifter));
    palette.setColor(QPalette::Highlight, hLColor);
    palette.setColor(QPalette::Disabled, QPalette::Highlight, QColor(80 + ColorShifter, 80 + ColorShifter, 80 + ColorShifter));
    palette.setColor(QPalette::HighlightedText, QColor(255,255,255);
    palette.setColor(QPalette::Disabled, QPalette::HighlightedText, QColor(127 + ColorShifter, 127 + ColorShifter, 127 + ColorShifter));

    backdropColor = QColor(53 + ColorShifter, 53 + ColorShifter, 53 + ColorShifter);
}

And the tgs_customtabwest.h:

#ifndef TGS_CUSTOMTABWEST_H
#define TGS_CUSTOMTABWEST_H

#include <QApplication>
#include <QStyleOptionTab>
#include <QStylePainter>
#include <QProxyStyle>
#include <QTabBar>
#include <QTabWidget>

class TGS_CustomTabWest: public QProxyStyle {
public:
    QSize sizeFromContents(ContentsType type, const QStyleOption* option,
                           const QSize& size, const QWidget* widget) const override {
        QSize s = QProxyStyle::sizeFromContents(type, option, size, widget);
        if (type == QStyle::CT_TabBarTab) {
            s.transpose();
        }
        return s;
    }

    void drawControl(ControlElement element, const QStyleOption* option, QPainter* painter, const QWidget* widget) const override {
        if (element == CE_TabBarTabLabel) {
            if (const auto* tab = qstyleoption_cast<const QStyleOptionTab*>(option)) {
                QStyleOptionTab opt(*tab);
                opt.shape = QTabBar::RoundedNorth;
                QProxyStyle::drawControl(element, &opt, painter, widget);
                return;
            }
        }
        QProxyStyle::drawControl(element, option, painter, widget);
    }
};

#endif //TGS_CUSTOMTABWEST_H

Calling the Widget inside my MainWindow, results in:

[SGaist]

Looks likes there might be a bug that has crept in. I have a related but different issue with the macOS style.