BreezeStyleSheets/example/placeholder_text.py

#!/usr/bin/env python
#
# The MIT License (MIT)
#
# Copyright (c) <2022-Present> <Alex Huszagh>
#
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'''
    placeholder_text
    ================

    Example showing how to style the placeholder text for QLineEdit,
    QTextEdit, and QPlainTextEdit, since in Qt6 is can be styled as
    the default text color. This seems to be an issue with palettes for
    Qt6 in `QPalette::PlaceholderText`, since both the stylesheets
    and palette edits correctly affect styles in Qt5, but not Qt6.
'''

import shared
import sys

parser = shared.create_parser()
parser.add_argument(
    '--set-app-palette',
    help='''set the placeholder text palette globally.''',
    action='store_true'
)
parser.add_argument(
    '--set-widget-palette',
    help='''set the placeholder text palette for the affected widgets.''',
    action='store_true'
)
args, unknown = shared.parse_args(parser)
QtCore, QtGui, QtWidgets = shared.import_qt(args)
compat = shared.get_compat_definitions(args)
colors = shared.get_colors(args, compat)


def set_palette(widget, role, color):
    '''Set the palette for the placeholder text. This only works in Qt5.'''

    palette = widget.palette()
    palette.setColor(role, color)
    widget.setPalette(palette)

def set_placeholder_palette(widget):
    set_palette(widget, compat.PlaceholderText, colors.PlaceholderColor)


class Ui:
    '''Main class for the user interface.'''

    def setup(self, MainWindow):
        MainWindow.setObjectName('MainWindow')
        MainWindow.resize(1068, 824)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName('centralwidget')
        self.layout = QtWidgets.QVBoxLayout(self.centralwidget)
        self.layout.setObjectName('layout')
        self.layout.setAlignment(compat.AlignHCenter)
        MainWindow.setCentralWidget(self.centralwidget)

        self.textEdit = QtWidgets.QTextEdit(self.centralwidget)
        self.textEdit.setObjectName('textEdit')
        self.textEdit.setPlaceholderText('Placeholder Text')
        self.layout.addWidget(self.textEdit)

        self.plainTextEdit = QtWidgets.QPlainTextEdit(self.centralwidget)
        self.plainTextEdit.setObjectName('plainTextEdit')
        self.plainTextEdit.setPlaceholderText('Placeholder Text')
        self.layout.addWidget(self.plainTextEdit)

        self.lineEdit = QtWidgets.QLineEdit(self.centralwidget)
        self.lineEdit.setObjectName('lineEdit')
        self.lineEdit.setPlaceholderText('Placeholder Text')
        self.layout.addWidget(self.lineEdit)
        # Set the palettes.
        if args.set_widget_palette:
            set_placeholder_palette(self.textEdit)
            set_placeholder_palette(self.plainTextEdit)
            set_placeholder_palette(self.lineEdit)

def main():
    'Application entry point'

    app, window = shared.setup_app(args, unknown, compat)
    if args.set_app_palette:
        set_placeholder_palette(app)

    # setup ui
    ui = Ui()
    ui.setup(window)
    window.setWindowTitle('Stylized Placeholder Text.')

    shared.set_stylesheet(args, app, compat)
    return shared.exec_app(args, app, window, compat)

if __name__ == '__main__':
    sys.exit(main())