PR: Add a dialog to manage app preferences

qtapputils/widgets/configdialog.py

@@ -0,0 +1,275 @@
+# -*- coding: utf-8 -*-
+# -----------------------------------------------------------------------------
+# Copyright © QtAppUtils Project Contributors
+# https://github.com/jnsebgosselin/qtapputils
+#
+# This file is part of QtAppUtils.
+# Licensed under the terms of the MIT License.
+# -----------------------------------------------------------------------------
+
+# ---- Standard library imports
+import sys
+
+# ---- Third party imports
+from qtpy.QtCore import (
+    Qt, Signal, Slot, QRect, QPoint)
+from qtpy.QtGui import QIcon, QPixmap
+from qtpy.QtWidgets import (
+    QAbstractButton, QApplication, QStyle, QStylePainter,
+    QDialog, QPushButton, QDialogButtonBox, QWidget, QTabWidget,
+    QGridLayout, QTabBar, QStyleOptionTab)
+
+
+class HorizontalTabBar(QTabBar):
+    """
+    A custom tabbar to show tabs on the side, while keeping the text
+    orientation horitontal.
+    """
+    # https://www.manongdao.com/q-367474.html
+
+    def tabSizeHint(self, index):
+        s = QTabBar.tabSizeHint(self, index)
+        s.transpose()
+        return s
+
+    def paintEvent(self, event):
+        painter = QStylePainter(self)
+        opt = QStyleOptionTab()
+
+        for i in range(self.count()):
+            self.initStyleOption(opt, i)
+            painter.drawControl(QStyle.CE_TabBarTabShape, opt)
+
+            s = opt.rect.size()
+            s.transpose()
+            r = QRect(QPoint(), s)
+            r.moveCenter(opt.rect.center())
+            opt.rect = r
+
+            # We are painting the text ourselves so to align it
+            # horizontally to the left.
+            text = opt.text
+            opt.text = ''
+
+            # Set state to 'Enable' to avoid vertical flickering of the
+            # icon when tab is selected.
+            opt.state = QStyle.State_Enabled
+
+            c = self.tabRect(i).center()
+            painter.save()
+            painter.translate(c)
+            painter.rotate(90)
+            painter.translate(-c)
+            painter.drawControl(QStyle.CE_TabBarTabLabel, opt)
+            painter.restore()
+
+            # Draw text.
+            rect = self.tabRect(i)
+            hspacing = QApplication.instance().style().pixelMetric(
+                QStyle.PM_ButtonMargin)
+            if not opt.icon.isNull():
+                hspacing += self.iconSize().width() + 8
+            rect.translate(hspacing, 0)
+            painter.drawItemText(
+                rect, int(Qt.AlignLeft | Qt.AlignVCenter),
+                self.palette(), True, text)
+
+
+class ConfDialog(QDialog):
+    """
+    A dialog window to manage app preferences.
+    """
+
+    def __init__(self, main, icon: QIcon = None, resizable: bool = True):
+        super().__init__(main)
+        self.main = main
+
+        self.setWindowTitle('Preferences')
+        if icon is not None:
+            self.setWindowIcon(icon)
+        self.setWindowFlags(
+            self.windowFlags() & ~Qt.WindowContextHelpButtonHint)
+        self.setModal(True)
+        self.setMinimumHeight(500)
+
+        self.confpages_tabwidget = QTabWidget()
+        self.confpages_tabwidget.setTabBar(HorizontalTabBar())
+        self.confpages_tabwidget.setTabPosition(QTabWidget.West)
+        self._confpages = {}
+
+        # Setup the dialog button box.
+        self.ok_button = QPushButton('OK')
+        self.ok_button.setDefault(False)
+        self.ok_button.setAutoDefault(False)
+        self.apply_button = QPushButton('Apply')
+        self.apply_button.setDefault(True)
+        self.apply_button.setEnabled(False)
+        self.cancel_button = QPushButton('Cancel')
+        self.cancel_button.setDefault(False)
+        self.cancel_button.setAutoDefault(False)
+
+        button_box = QDialogButtonBox()
+        button_box.addButton(self.ok_button, button_box.ApplyRole)
+        button_box.addButton(self.cancel_button, button_box.RejectRole)
+        button_box.addButton(self.apply_button, button_box.ApplyRole)
+        button_box.layout().insertSpacing(1, 100)
+        button_box.clicked.connect(self._handle_button_click_event)
+
+        # Setup the main layout.
+        main_layout = QGridLayout(self)
+        main_layout.addWidget(self.confpages_tabwidget)
+        main_layout.addWidget(button_box)
+        main_layout.setRowStretch(0, 1)
+        if resizable is False:
+            main_layout.setSizeConstraint(main_layout.SetFixedSize)
+
+    def count(self):
+        "Return the number of configuration pages added to this dialog."
+        return len(self._confpages)
+
+    def get_confpage(self, confpage_name):
+        """Return the confpage corresponding to the given name."""
+        return self._confpages.get(confpage_name, None)
+
+    def add_confpage(self, confpage):
+        """Add confpage to this config dialog."""
+        self._confpages[confpage.name()] = confpage
+        self.confpages_tabwidget.addTab(
+            confpage, confpage.icon(), confpage.label())
+        confpage.sig_configs_changed.connect(
+            self._handle_confpage_configs_changed)
+
+    @Slot(QAbstractButton)
+    def _handle_button_click_event(self, button):
+        """
+        Handle when a button is clicked on the dialog button box.
+        """
+        if button == self.cancel_button:
+            self.close()
+        elif button == self.apply_button:
+            for confpage in self._confpages.values():
+                confpage.apply_changes()
+        elif button == self.ok_button:
+            for confpage in self._confpages.values():
+                confpage.apply_changes()
+            self.close()
+        self.apply_button.setEnabled(False)
+
+    def closeEvent(self, event):
+        """
+        Override this QT to revert confpage configs to the value saved in
+        the user configuration files.
+        """
+        for confpage in self._confpages.values():
+            if confpage.is_modified():
+                confpage.load_configs_from_conf()
+        self.apply_button.setEnabled(False)
+        super().closeEvent(event)
+
+    def _handle_confpage_configs_changed(self):
+        """
+        Handle when the configs in one of the registered pages changed.
+        """
+        for confpage in self._confpages.values():
+            if confpage.is_modified():
+                self.apply_button.setEnabled(True)
+                break
+        else:
+            self.apply_button.setEnabled(False)
+
+
+class ConfPageBase(QWidget):
+    """
+    Basic functionality for app configuration pages.
+
+    WARNING: Don't override any methods or attributes present here unless you
+    know what you are doing.
+    """
+    sig_configs_changed = Signal()
+
+    def __init__(self, name: str, label: str, icon: QIcon = None):
+        super().__init__()
+        self._name = name
+        self._label = label
+        if icon is None:
+            empty_pixmap = QPixmap(20, 20)
+            empty_pixmap.fill(Qt.transparent)
+            icon = QIcon(empty_pixmap)
+        self._icon = QIcon() if icon is None else icon
+
+        self.setup_page()
+        self.load_configs_from_conf()
+
+    def name(self):
+        """
+        Return the name that will be used to reference this confpage
+        in the code.
+        """
+        return self._name
+
+    def label(self):
+        """
+        Return the label that will be used to reference this confpage in the
+        graphical interface.
+        """
+        return self._label
+
+    def icon(self):
+        """Return configuration page icon"""
+        return self._icon
+
+    def is_modified(self):
+        return self.get_configs() != self.get_configs_from_conf()
+
+    def apply_changes(self):
+        """Apply changes."""
+        self.save_configs_to_conf()
+
+
+class ConfPage(ConfPageBase):
+    """
+    App configuration page class.
+
+    All configuration page *must* inherit this class and
+    reimplement its interface.
+    """
+
+    def __init__(self, name: str, label: str, icon: QIcon = None):
+        """
+        Parameters
+        ----------
+        name: str
+            The name that is used to reference this confpage in the code.
+        label: str
+            The label that is used to reference this confpage in the
+            graphical interface.
+        icon: QIcon
+            The icon that appears in the tab for that confpage
+            in the tab bar of the configuration dialog
+        """
+        super().__init__(name, label, icon)
+
+    def setup_page(self):
+        """Setup configuration page widget"""
+        raise NotImplementedError
+
+    def get_configs(self):
+        """Return the configs that are set in this configuration page."""
+        raise NotImplementedError
+
+    def get_configs_from_conf(self):
+        """Get configs from the user configuration files."""
+        raise NotImplementedError
+
+    def load_configs_from_conf(self):
+        """Load configs from the user configuration files."""
+        raise NotImplementedError
+
+    def save_configs_to_conf(self):
+        """Save configs to the user configuration files."""
+        raise NotImplementedError
+
+
+if __name__ == '__main__':
+    app = QApplication(sys.argv)
+    sys.exit(app.exec_())