Change QPushButton Icon on hover and pressed

Question

I'm trying to change the Icon of a QpushButton on hover and pressed, I'm using QtDesigner with stylesheets. I tried this

QpushButton{
       qproperty-icon:url(:/images/start.png);
}

QPushButton:hover
{
       qproperty-icon:url(:/images/start_hov.png);
}

But it doesn't work.

I tried setting it from QtDesigner Menu but it didn't work as well.

Answer 1

Unfortunately, it is a bug of Qt which is still not fixed. There's a workaround suggestion within the comments to that bug, basically you could use empty qproperty-icon and reserve the space necessary for it while actually changing background-image property instead:

QPushButton {
    qproperty-icon: url(" "); /* empty image */
    qproperty-iconSize: 16px 16px; /* space for the background image */
    background-image: url(":/images/start.png");
    background-repeat: no-repeat;
}

QPushButton:hover {
    background-image: url(":/images/start_hov.png");
    background-repeat: no-repeat;
}

But the end result looks... not very satisfactory really. You can get much better results if you use C++ to change the button's icon at runtime, here's a simple example using event filter:

#include <QObject>
#include <QPushButton>
#include <QEvent>

class ButtonHoverWatcher : public QObject
{
    Q_OBJECT
public:
    explicit ButtonHoverWatcher(QObject * parent = Q_NULLPTR);
    virtual bool eventFilter(QObject * watched, QEvent * event) Q_DECL_OVERRIDE;
};

ButtonHoverWatcher::ButtonHoverWatcher(QObject * parent) :
    QObject(parent)
{}

bool ButtonHoverWatcher::eventFilter(QObject * watched, QEvent * event)
{
    QPushButton * button = qobject_cast<QPushButton*>(watched);
    if (!button) {
        return false;
    }

    if (event->type() == QEvent::Enter) {
        // The push button is hovered by mouse
        button->setIcon(QIcon(":/images/start_hov.png"));
        return true;
    }

    if (event->type() == QEvent::Leave){
        // The push button is not hovered by mouse
        button->setIcon(QIcon(":/images/start.png"));
        return true;
    }

    return false;
}

Then somewhere in your code setting up the UI you do something like this:

ButtonHoverWatcher * watcher = new ButtonHoverWatcher(this);
ui->pushButton->installEventFilter(watcher);

And bingo - you get the button's icon changing on hover and unhover!

Answer 2

After reading this article and encountering similar issues. This is my work around in c++ not using style sheet from designer.

1>I create Icons one for being pressed and one for normal. In your case we would address it as the hover condition.

2>Add the icons to the resource file.

3>Use the following code for reference...

Where Add_PB is a QPushButton.

Add_PB->setStyleSheet( "*{border-image: url(:/icons/maximize.bmp);}"  
":pressed{ border-image: url(:/icons/maximize_pressed.bmp);}"); 

The key take away here is you can use setStyleSheet to set diffrent icons for different conditons. I couldnt get the above code to work until I used the * operator or "Universal Selector" in the CSS string.

Reference: http://doc.qt.io/qt-5/stylesheet-syntax.html