QPushButton icon aligned left with text centered

Question

In my Qt 5.7.1 application I've some buttons, I want to align button's icons to left and centre text, but there is no option in designer to do this.

I can align icon and text left by adding to button stylesheet this code:

text-align:left;

But it's not what I want to achieve. So, could you please tell me, If there is any option to align icon to left, and keep text aligned center? Thank you for help.

Answer 1

Simply specialize QPushButton and override paintEvent and sizeHint, as proposed by cbuchart here. Then use it as a regular QPushButton.

MyButton declaration and implementation:

mybutton.h:

#pragma once

#include <QPushButton>

class MyButton : public QPushButton
{
public:
    explicit MyButton(QWidget* parent = nullptr);
    virtual ~MyButton();

    void setPixmap(const QPixmap& pixmap);

    virtual QSize sizeHint() const override;

protected:
    virtual void paintEvent(QPaintEvent* e) override;

private:
    QPixmap m_pixmap;
};

mybutton.cpp:

#include "mybutton.h"

#include <QPainter>

MyButton::MyButton(QWidget* parent) : QPushButton(parent)
{
}

MyButton::~MyButton()
{
}

QSize MyButton::sizeHint() const
{
    const auto parentHint = QPushButton::sizeHint();
    // add margins here if needed
    return QSize(parentHint.width() + m_pixmap.width(), std::max(parentHint.height(), m_pixmap.height()));
}

void MyButton::setPixmap(const QPixmap& pixmap)
{
    m_pixmap = pixmap;
}

void MyButton::paintEvent(QPaintEvent* e)
{
    QPushButton::paintEvent(e);

    if (!m_pixmap.isNull())
    {
        const int y = (height() - m_pixmap.height()) / 2; // add margin if needed
        QPainter painter(this);
        painter.drawPixmap(5, y, m_pixmap); // hardcoded horizontal margin
    }
}

Exemple of usage:

Here is an example where "Promote widget" feature in Qt Designer was used to create MyButton from .ui files:

mainframe.ui:

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>MainWindow</class>
 <widget class="QMainWindow" name="MainWindow">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>400</width>
    <height>300</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>MainWindow</string>
  </property>
  <widget class="QWidget" name="centralWidget">
   <layout class="QVBoxLayout" name="verticalLayout">
    <item>
     <widget class="MyButton" name="button1">
      <property name="text">
       <string>Button</string>
      </property>
     </widget>
    </item>
    <item>
     <widget class="MyButton" name="button2">
      <property name="text">
       <string>Other button</string>
      </property>
     </widget>
    </item>
   </layout>
  </widget>
  <widget class="QMenuBar" name="menuBar">
   <property name="geometry">
    <rect>
     <x>0</x>
     <y>0</y>
     <width>400</width>
     <height>20</height>
    </rect>
   </property>
  </widget>
  <widget class="QToolBar" name="mainToolBar">
   <attribute name="toolBarArea">
    <enum>TopToolBarArea</enum>
   </attribute>
   <attribute name="toolBarBreak">
    <bool>false</bool>
   </attribute>
  </widget>
  <widget class="QStatusBar" name="statusBar"/>
 </widget>
 <layoutdefault spacing="6" margin="11"/>
 <customwidgets>
  <customwidget>
   <class>MyButton</class>
   <extends>QPushButton</extends>
   <header>mybutton.h</header>
  </customwidget>
 </customwidgets>
 <resources/>
 <connections/>
</ui>

mainwindow.h:

#pragma once

#include <QMainWindow>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

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

private:
    Ui::MainWindow *ui;
};

mainwindow.cpp:

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QStyle>

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

    QStyle* style = qApp->style();
    // set buttons pixmaps:
    ui->button1->setPixmap( style->standardPixmap(QStyle::SP_ComputerIcon) );
    ui->button2->setPixmap( style->standardPixmap(QStyle::SP_TrashIcon) );
}

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

main.cpp:

#include "mainwindow.h"
#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();

    return a.exec();
}

Results in:

• Compared to docsteer answer, this solution makes it possible to apply the new style to only some buttons of your project. And the code is also smaller.
• Compared to IGHOR answer, you can still use the button as a regular QPushButton (using QPushButton::setText), you don't need to keep a reference to a mockup QLabel to change button's text.