Various improvements to dark mode support

Now colors can be dynamically changed and more widgets
react appropriately. Also use err/ok indicator colors
that work in both light and dark mode

src/calibre/gui2/__init__.py

@@ -845,8 +845,10 @@ def setup_unix_signals(self):
 class Application(QApplication):
 
     shutdown_signal_received = pyqtSignal()
+    palette_changed = pyqtSignal()
 
     def __init__(self, args, force_calibre_style=False, override_program_name=None, headless=False, color_prefs=gprefs, windows_app_uid=None):
+        self.ignore_palette_changes = False
         QNetworkProxyFactory.setUseSystemConfiguration(True)
         if iswindows:
             self.windows_app_uid = None
@@ -1011,6 +1013,10 @@ class Application(QApplication):
             prints('Using calibre Qt style:', self.using_calibre_style)
         if self.using_calibre_style:
             self.load_calibre_style()
+        self.paletteChanged.connect(self.on_palette_change)
+        self.on_palette_change()
+
+    def fix_dark_theme_colors(self):
         self.is_dark_theme = is_dark_theme()
         if self.is_dark_theme:
             pal = self.palette()
@@ -1022,7 +1028,25 @@ class Application(QApplication):
                 # Workaround for https://bugreports.qt.io/browse/QTBUG-75321
                 # Buttontext is set to black for some reason
                 pal.setColor(pal.ButtonText, pal.color(pal.WindowText))
-            self.setPalette(pal)
+            self.set_palette(pal)
+
+    def set_palette(self, pal):
+        self.ignore_palette_changes = True
+        self.setPalette(pal)
+        # Needed otherwise Qt does not emit the paletteChanged signal when
+        # appearance is changed.
+        self.setAttribute(Qt.AA_SetPalette, False)
+        self.ignore_palette_changes = False
+
+    def on_palette_change(self):
+        if self.ignore_palette_changes:
+            return
+        self.fix_dark_theme_colors()
+        self.palette_changed.emit()
+
+    def stylesheet_for_line_edit(self, is_error=False):
+        return 'QLineEdit { border: 2px solid %s; border-radius: 3px }' % (
+            '#FF2400' if is_error else '#50c878')
 
     def load_calibre_style(self):
         icon_map = self.__icon_map_memory_ = {}

src/calibre/gui2/book_details.py

@@ -555,10 +555,10 @@ class BookInfo(HTMLDisplay):
         ac.data = (None, None, None)
         ac.triggered.connect(self.remove_item_triggered)
         self.setFocusPolicy(Qt.NoFocus)
-        self.document().setDefaultStyleSheet(self.default_css + css())
+        self.setDefaultStyleSheet(css())
 
     def refresh_css(self):
-        self.document().setDefaultStyleSheet(self.default_css + css(True))
+        self.setDefaultStyleSheet(css(True))
 
     def remove_item_triggered(self):
         field, value, book_id = self.remove_item_action.data

src/calibre/gui2/dialogs/book_info.py

@@ -83,7 +83,7 @@ class Details(HTMLDisplay):
     def __init__(self, book_info, parent=None):
         HTMLDisplay.__init__(self, parent)
         self.book_info = book_info
-        self.document().setDefaultStyleSheet(self.default_css + css())
+        self.setDefaultStyleSheet(css())
 
     def sizeHint(self):
         return QSize(350, 350)

src/calibre/gui2/metadata/basic_widgets.py

@@ -42,10 +42,6 @@ from calibre.db import SPOOL_SIZE
 from calibre.ebooks.oeb.polish.main import SUPPORTED as EDIT_SUPPORTED
 from polyglot.builtins import iteritems, unicode_type, range
 
-OK_COLOR = 'rgba(0, 255, 0, 50%)'
-ERR_COLOR = 'rgba(255, 0, 0, 50%)'
-INDICATOR_SHEET = 'QLineEdit { border: 2px solid %s; border-radius: 2px }'
-
 
 def save_dialog(parent, title, msg, det_msg=''):
     d = QMessageBox(parent)
@@ -297,8 +293,7 @@ class TitleSortEdit(TitleEdit, ToMetadataMixin):
     def update_state(self, *args):
         ts = title_sort(self.title_edit.current_val, lang=self.book_lang)
         normal = ts == self.current_val
-        col = OK_COLOR if normal else ERR_COLOR
+        self.setStyleSheet(QApplication.instance().stylesheet_for_line_edit(not normal))
-        self.setStyleSheet(INDICATOR_SHEET % col)
         tt = self.tooltips[0 if normal else 1]
         self.setToolTip(tt)
         self.setWhatsThis(tt)
@@ -508,8 +503,7 @@ class AuthorSortEdit(EnLineEdit, ToMetadataMixin):
         au = self.author_sort_from_authors(string_to_authors(au))
 
         normal = au == self.current_val
-        col = OK_COLOR if normal else ERR_COLOR
+        self.setStyleSheet(QApplication.instance().stylesheet_for_line_edit(not normal))
-        self.setStyleSheet(INDICATOR_SHEET % col)
         tt = self.tooltips[0 if normal else 1]
         self.setToolTip(tt)
         self.setWhatsThis(tt)
@@ -1596,15 +1590,15 @@ class IdentifiersEdit(QLineEdit, ToMetadataMixin):
         tt = self.BASE_TT
         extra = ''
         if not isbn:
-            col = 'none'
+            sheet = ''
         elif check_isbn(isbn) is not None:
-            col = OK_COLOR
+            sheet = QApplication.instance().stylesheet_for_line_edit()
             extra = '\n\n'+_('This ISBN is valid')
         else:
-            col = ERR_COLOR
+            sheet = QApplication.instance().stylesheet_for_line_edit(True)
             extra = '\n\n' + _('This ISBN is invalid')
         self.setToolTip(tt+extra)
-        self.setStyleSheet(INDICATOR_SHEET % col)
+        self.setStyleSheet(sheet)
 
     def paste_identifier(self):
         identifier_found = self.parse_clipboard_for_identifier()
@@ -1725,16 +1719,16 @@ class ISBNDialog(QDialog):  # {{{
     def checkText(self, txt):
         isbn = unicode_type(txt)
         if not isbn:
-            col = 'none'
+            sheet = ''
             extra = ''
         elif check_isbn(isbn) is not None:
-            col = OK_COLOR
+            sheet = QApplication.instance().stylesheet_for_line_edit()
             extra = _('This ISBN is valid')
         else:
-            col = ERR_COLOR
+            sheet = QApplication.instance().stylesheet_for_line_edit(True)
             extra = _('This ISBN is invalid')
         self.line_edit.setToolTip(extra)
-        self.line_edit.setStyleSheet(INDICATOR_SHEET % col)
+        self.line_edit.setStyleSheet(sheet)
 
     def text(self):
         return check_isbn(unicode_type(self.line_edit.text()))

src/calibre/gui2/search_box.py

@@ -108,7 +108,6 @@ class SearchBox2(QComboBox):  # {{{
 
     def __init__(self, parent=None, add_clear_action=True):
         QComboBox.__init__(self, parent)
-        self.normal_background = 'rgba(255, 255, 255, 0%)'
         self.line_edit = SearchLineEdit(self)
         self.setLineEdit(self.line_edit)
         if add_clear_action:
@@ -161,8 +160,7 @@ class SearchBox2(QComboBox):  # {{{
 
     def normalize_state(self):
         self.setToolTip(self.tool_tip_text)
-        self.line_edit.setStyleSheet(
+        self.line_edit.setStyleSheet('')
-            'QLineEdit{color:none;background-color:%s;}' % self.normal_background)
 
     def text(self):
         return self.currentText()
@@ -190,10 +188,10 @@ class SearchBox2(QComboBox):  # {{{
             self.clear(emit_search=False)
             return
         self._in_a_search = ok
-        col = 'rgba(0,255,0,20%)' if ok else 'rgba(255,0,0,20%)'
+        if self.colorize:
-        if not self.colorize:
+            self.line_edit.setStyleSheet(QApplication.instance().stylesheet_for_line_edit(not ok))
-            col = self.normal_background
+        else:
-        self.line_edit.setStyleSheet('QLineEdit{color:black;background-color:%s;}' % col)
+            self.line_edit.setStyleSheet('')
 
     # Comes from the lineEdit control
     def key_pressed(self, event):
@@ -320,7 +318,6 @@ class SavedSearchBox(QComboBox):  # {{{
 
     def __init__(self, parent=None):
         QComboBox.__init__(self, parent)
-        self.normal_background = 'rgba(255, 255, 255, 0%)'
 
         self.line_edit = SearchLineEdit(self)
         self.setLineEdit(self.line_edit)

src/calibre/gui2/tag_browser/view.py

@@ -167,8 +167,9 @@ class TagsView(QTreeView):  # {{{
         # Allowing keyboard focus looks bad in the Qt Fusion style and is useless
         # anyway since the enter/spacebar keys do nothing
         self.setFocusPolicy(Qt.NoFocus)
+        QApplication.instance().palette_changed.connect(self.set_style_sheet, type=Qt.QueuedConnection)
 
-    def set_look_and_feel(self):
+    def set_style_sheet(self):
         stylish_tb = '''
                 QTreeView {
                     background-color: palette(window);
@@ -190,6 +191,9 @@ class TagsView(QTreeView):  # {{{
                 }
         '''.replace('PAD', unicode_type(gprefs['tag_browser_item_padding'])) + (
             '' if gprefs['tag_browser_old_look'] else stylish_tb))
+
+    def set_look_and_feel(self):
+        self.set_style_sheet()
         self.setAlternatingRowColors(gprefs['tag_browser_old_look'])
         self.itemDelegate().old_look = gprefs['tag_browser_old_look']
 

src/calibre/gui2/widgets2.py

@@ -434,13 +434,11 @@ class HTMLDisplay(QTextBrowser):
 
     def __init__(self, parent=None):
         QTextBrowser.__init__(self, parent)
-        self.default_css = ''
+        self.last_set_html = ''
+        self.default_css = self.external_css = ''
         app = QApplication.instance()
-        if app.is_dark_theme:
+        app.palette_changed.connect(self.palette_changed)
-            pal = app.palette()
+        self.palette_changed()
-            col = pal.color(pal.Link)
-            self.default_css = 'a { color: %s }\n\n' % col.name(col.HexRgb)
-            self.document().setDefaultStyleSheet(self.default_css)
         font = self.font()
         f = QFontInfo(font)
         delta = tweaks['change_book_details_font_size_by'] + 1
@@ -456,6 +454,25 @@ class HTMLDisplay(QTextBrowser):
         self.setAcceptDrops(False)
         self.anchorClicked.connect(self.on_anchor_clicked)
 
+    def setHtml(self, html):
+        self.last_set_html = html
+        QTextBrowser.setHtml(self, html)
+
+    def setDefaultStyleSheet(self, css=''):
+        self.external_css = css
+        self.document().setDefaultStyleSheet(self.default_css + self.external_css)
+
+    def palette_changed(self):
+        app = QApplication.instance()
+        if app.is_dark_theme:
+            pal = app.palette()
+            col = pal.color(pal.Link)
+            self.default_css = 'a { color: %s }\n\n' % col.name(col.HexRgb)
+        else:
+            self.default_css = ''
+        self.document().setDefaultStyleSheet(self.default_css + self.external_css)
+        self.setHtml(self.last_set_html)
+
     def on_anchor_clicked(self, qurl):
         if not qurl.scheme() and qurl.hasFragment() and qurl.toString().startswith('#'):
             frag = qurl.fragment(qurl.FullyDecoded)