QStyleSheet property for QPushButton with empty text

Question

I'm attempting to do something like this:

QPushButton[text=""] {
    background-color: rgb(255, 0, 0);
}

QPushButton {
    background-color: rgb(0, 0, 0);
}

Basically, some of my QPushButtons have text, and some don't, and I want to style the ones that do differently from the ones that do not.

This works if I switch on an actual string value, ie

QPushButton[text="Ok"] {
    background-color: rgb(255, 0, 0);
}

Then any buttons that say "Ok" have a red background. But what do I pass in for a button with no text?

Answer 1

This style sheet works for me (Linux, Qt 5.3):

QPushButton[text] {
    background-color: "green";
}

QPushButton[text="some text"] {
    background-color: "red";
}

QPushButton {
    background-color: "blue";
}

Answer 2

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LAST EDITED : 9 / 8 / 2014 1:05

OK, I'm sorry for my misunderstood the question. I have same problem with you to set empty text. But It work in Qt Designer. (Why ? I don't know.) And I can't find other property.

I have solution, I create my property 'isEmpty' in QPushButton by inheritance them. And, add is property, Like this;

import sys
from PyQt4 import QtCore, QtGui

class customQPushButton (QtGui.QPushButton):
    def setPropertyIsStringEmpty (self, text):
        self.setProperty('isEmpty', QtCore.QVariant(False if len(text) > 0 else True))

    def setText (self, text):
        self.setPropertyIsStringEmpty(text)
        QtGui.QPushButton.setText(self, text)

class exampleQMainWindow (QtGui.QMainWindow):
    def __init__ (self):
        super(exampleQMainWindow, self).__init__()
        self.testQPushButton = customQPushButton(self)
        self.testQPushButton.setText('')
        self.setStyleSheet ('''
            QPushButton {
                color: rgb(255, 255, 255);
            }
            QPushButton[text="Ok"] {
                background-color: rgb(255, 0, 0);
            }
            QPushButton[isEmpty=true] {
                background-color: rgb(0, 0, 255);
            }
        ''')
        self.setCentralWidget(self.testQPushButton)
        self.testQPushButton.keyPressEvent = self.keyPressEvent

app = QtGui.QApplication([])
window = exampleQMainWindow()
window.show()
sys.exit(app.exec_())

It's OK from your create new object. But, If create by Qt Designer, I have to refresh Property by call setPropertyIsStringEmpty (self, text).

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Regards,

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MESSAGE BY 9 / 8 / 2014 1:05 : This is my old post. if useless, please avoid them.

It's possible If you create your style sheet pattern and put this style sheet in your code or statement to you want setting.

I have example, this example show i handle arrow (not down key only) key press event and set new color of button;

import sys
from PyQt4 import QtCore, QtGui

ENUM_COLOR_RED   = 0
ENUM_COLOR_GREEN = 1
ENUM_COLOR_BLUE  = 2

def getStyleSheetQPushButtonRed ():
    return '''
        QPushButton {
            color: rgb(255, 255, 255);
            background-color: rgb(255, 0, 0);
        }
    '''
def getStyleSheetQPushButtonGreen ():
    return '''
        QPushButton {
            color: rgb(255, 255, 255);
            background-color: rgb(0, 255, 0);
        }
    '''

def getStyleSheetQPushButtonBlue ():
    return '''
        QPushButton {
            color: rgb(255, 255, 255);
            background-color: rgb(0, 0, 255);
        }
    '''

class exampleQMainWindow (QtGui.QMainWindow):
    def __init__ (self):
        super(exampleQMainWindow, self).__init__()
        self.testQPushButton = QtGui.QPushButton('KM', self)
        self.setCentralWidget(self.testQPushButton)
        self.testQPushButton.keyPressEvent = self.keyPressEvent

    def setText (self, text, color):
        styleSheet = {
            ENUM_COLOR_RED   : getStyleSheetQPushButtonRed,
            ENUM_COLOR_GREEN : getStyleSheetQPushButtonGreen,
            ENUM_COLOR_BLUE  : getStyleSheetQPushButtonBlue
        } [color]()
        self.testQPushButton.setText(text)
        self.testQPushButton.setStyleSheet(styleSheet)

    def keyPressEvent (self, eventQKeyEvent):
        key = eventQKeyEvent.key()
        if key == QtCore.Qt.Key_Left:
            self.setText('LEFT', ENUM_COLOR_RED)
        elif key == QtCore.Qt.Key_Up:
            self.setText('UP', ENUM_COLOR_GREEN)
        elif key == QtCore.Qt.Key_Right:
            self.setText('RIGHT', ENUM_COLOR_BLUE)

app = QtGui.QApplication([])
window = exampleQMainWindow()
window.show()
sys.exit(app.exec_())

Advantages : you can put color independent text in button.

Cons : You color style sheet have set anytime when have event by statement.

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This is useful for implement Style Sheet, I hope is helps;

Reference : http://qt-project.org/doc/qt-4.8/stylesheet-syntax.html

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Regards,