Difference between revisions of "PushButton Based On Action"

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(fix formatting error, use C++11/Qt5 (esp. new signal/slot syntax))
(Adoped coding style to Qt and use C++11 member init)
Line 25: Line 25:
 
private:
 
private:
 
     // The action associated to this button.
 
     // The action associated to this button.
     QAction* actionOwner;
+
     QAction *actionOwner = nullptr;
  
 
public:
 
public:
 
     // Default constructor. Parent the widget parent of this button
 
     // Default constructor. Parent the widget parent of this button
     explicit ActionButton(QWidget* parent = nullptr);
+
     explicit ActionButton(QWidget *parent = nullptr);
  
 
     /*!
 
     /*!
Line 39: Line 39:
 
     * action the action to associate to this button
 
     * action the action to associate to this button
 
     */
 
     */
     void setAction(QAction* action);
+
     void setAction(QAction *action);
  
 
public slots:
 
public slots:
Line 60: Line 60:
 
#include "actionbutton.h"
 
#include "actionbutton.h"
  
ActionButton::ActionButton(QWidget* parent) :
+
ActionButton::ActionButton(QWidget *parent) :
     QPushButton(parent),
+
     QPushButton(parent)
    actionOwner(nullptr)
 
 
{}
 
{}
  
void ActionButton::setAction(QAction* action)
+
void ActionButton::setAction(QAction *action)
 
{
 
{
 
     // if I've got already an action associated to the button
 
     // if I've got already an action associated to the button
 
     // remove all connections
 
     // remove all connections
     if ( actionOwner && actionOwner != action ) {
+
     if (actionOwner && actionOwner != action) {
 
         disconnect(actionOwner, &QAction::changed,
 
         disconnect(actionOwner, &QAction::changed,
 
                   this, &ActionButton::updateButtonStatusFromAction);
 
                   this, &ActionButton::updateButtonStatusFromAction);
Line 96: Line 95:
 
void ActionButton::updateButtonStatusFromAction()
 
void ActionButton::updateButtonStatusFromAction()
 
{
 
{
     if(!actionOwner)
+
     if (!actionOwner)
 
         return;
 
         return;
     setText( actionOwner->text() );
+
     setText(actionOwner->text());
     setStatusTip( actionOwner->statusTip() );
+
     setStatusTip(actionOwner->statusTip());
     setToolTip( actionOwner->toolTip() );
+
     setToolTip(actionOwner->toolTip());
     setIcon( actionOwner->icon() );
+
     setIcon(actionOwner->icon());
     setEnabled( actionOwner->isEnabled() );
+
     setEnabled(actionOwner->isEnabled());
     setCheckable( actionOwner->isCheckable() );
+
     setCheckable(actionOwner->isCheckable());
     setChecked( actionOwner->isChecked());
+
     setChecked(actionOwner->isChecked());
 
}
 
}
 
</code>
 
</code>

Revision as of 18:49, 26 April 2018

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QPushButton does not allow itself to be configured by a QAction. In the case when you need to share a QAction among different components like menus, buttons, and so on, you can simply extend the QPushButton class with code similar to the following:

  1. ifndef ACTIONBUTTON_H
  2. define ACTIONBUTTON_H
  1. include <QPushButton>
  2. include <QAction>

/*!

* An extension of a QPushButton that supports QAction.
* This class represents a QPushButton extension that can be
* connected to an action and that configures itself depending
* on the status of the action.
* When the action changes its state, the button reflects
* such changes, and when the button is clicked the action
* is triggered.
*/

class ActionButton : public QPushButton {

   Q_OBJECT

private:

   // The action associated to this button.
   QAction *actionOwner = nullptr;

public:

   // Default constructor. Parent the widget parent of this button
   explicit ActionButton(QWidget *parent = nullptr);
   /*!
    * Set the action owner of this button, that is the action
    * associated to the button. The button is configured immediately
    * depending on the action status and the button and the action
    * are connected together so that when the action is changed the button
    * is updated and when the button is clicked the action is triggered.
    * action the action to associate to this button
    */
   void setAction(QAction *action);

public slots:

   /*!
    * Update the button status depending on a change
    * on the action status. This slot is invoked each time the action
    * "changed" signal is emitted.
    */
   void updateButtonStatusFromAction();

};

  1. endif // ACTIONBUTTON_H

The idea is to extend QPushButton and to provide a setAction method that will immediately configure the button itself with the action data. After that, the button will connect to the action, so that when the button is clicked the action is triggered and vice-versa: when the action is changed the button is re-configured.

The following is the implementation:

  1. include "actionbutton.h"

ActionButton::ActionButton(QWidget *parent) :

   QPushButton(parent)

{}

void ActionButton::setAction(QAction *action) {

   // if I've got already an action associated to the button
   // remove all connections
   if (actionOwner && actionOwner != action) {
       disconnect(actionOwner, &QAction::changed,
                  this, &ActionButton::updateButtonStatusFromAction);
       disconnect(this, &ActionButton::clicked,
                  actionOwner, &QAction::trigger);
   }
   // store the action
   actionOwner = action;
   // configure the button
   updateButtonStatusFromAction();
   // connect the action and the button
   // so that when the action is changed the
   // button is changed too!
   connect(action, &QAction::changed,
           this, &ActionButton::updateButtonStatusFromAction);
   // connect the button to the slot that forwards the
   // signal to the action
   connect(this, &ActionButton::clicked,
           actionOwner, &QAction::trigger);

}

void ActionButton::updateButtonStatusFromAction() {

   if (!actionOwner)
       return;
   setText(actionOwner->text());
   setStatusTip(actionOwner->statusTip());
   setToolTip(actionOwner->toolTip());
   setIcon(actionOwner->icon());
   setEnabled(actionOwner->isEnabled());
   setCheckable(actionOwner->isCheckable());
   setChecked(actionOwner->isChecked());

}