Use calibre icons for qt standard pixmaps even when using the system theme

src/calibre/gui2/__init__.py

@@ -1088,7 +1088,7 @@ class Application(QApplication):
             args = [override_program_name] + args[1:]
         self.palette_manager = PaletteManager(gprefs['color_palette'], gprefs['ui_style'], force_calibre_style, headless)
         if headless:
-            args.extend(['-platformpluginpath', plugins_loc, '-platform', 'headless'])
+            args.extend(('-platformpluginpath', plugins_loc, '-platform', 'headless'))
         else:
             args.extend(self.palette_manager.args_to_qt)
 

src/calibre/gui2/palette.py

@@ -5,7 +5,7 @@ import os
 import sys
 from contextlib import contextmanager
 from qt.core import (
-    QAbstractNativeEventFilter, QApplication, QColor, QIcon, QPalette, QSettings,
+    QAbstractNativeEventFilter, QApplication, QColor, QIcon, QPalette, QSettings, QProxyStyle,
     QStyle, Qt, QTimer, pyqtSlot, QObject, QDataStream, QByteArray, QIODeviceBase
 )
 
@@ -19,6 +19,15 @@ light_text_color = QColor(0,0,0)
 light_link_color = QColor(0, 0, 255)
 
 
+class UseCalibreIcons(QProxyStyle):
+
+    def standardIcon(self, standard_pixmap, option=None, widget=None):
+        ic = QApplication.instance().get_qt_standard_icon(standard_pixmap)
+        if ic.isNull():
+            return super().standardIcon(standard_pixmap, option, widget)
+        return ic
+
+
 if iswindows:
     import ctypes
 
@@ -288,7 +297,7 @@ class PaletteManager(QObject):
             # own dark mode implementation when using calibre style so
             # prefer that and use darkmode=1
             args.append('-platform')
-            args.append('windows:darkmode=' + '1' if self.using_calibre_style else '2')
+            args.append('windows:darkmode=' + ('1' if self.using_calibre_style else '2'))
         self.args_to_qt = tuple(args)
         if ismacos and not headless and self.has_fixed_palette:
             from calibre_extensions.cocoa import set_appearance
@@ -297,7 +306,7 @@ class PaletteManager(QObject):
     def initialize(self):
         app = QApplication.instance()
         self.setParent(app)
-        if not self.using_calibre_style and self.style().objectName() == 'fusion':
+        if not self.using_calibre_style and app.style().objectName() == 'fusion':
             # Since Qt is using the fusion style anyway, specialize it
             self.using_calibre_style = True
         self.original_palette = QPalette(app.palette())
@@ -332,6 +341,10 @@ class PaletteManager(QObject):
             print('Using calibre Qt style:', self.using_calibre_style, file=sys.stderr)
         if self.using_calibre_style:
             self.load_calibre_style()
+        else:
+            app = QApplication.instance()
+            self.native_proxy_style = UseCalibreIcons(app.style())
+            app.setStyle(self.native_proxy_style)
         self.on_palette_change()
 
     def get_qt_standard_icon(self, standard_pixmap):

src/calibre/utils/rcc/__init__.py

@@ -55,11 +55,6 @@ def compile_icon_dir_as_themes(
     path_to_dir, output_path, theme_name='calibre-default', inherits='',
     for_theme='any', prefix='/icons',
 ):
-    aliases = {
-        # these names are use by Qt commonstyle for line edit clear icons. The
-        # windows system style inherits it from commonstyle
-        'clear_left.png': ('edit-clear-locationbar-ltr.png', 'edit-clear-locationbar-rtl.png')
-    }
     with tempfile.TemporaryDirectory(dir=path_to_dir) as tdir, open(os.path.join(tdir, 'icons.qrc'), 'w') as qrc:
         print('<RCC>', file=qrc)
         print(f'  <qresource prefix="{prefix}">', file=qrc)
@@ -114,10 +109,6 @@ def compile_icon_dir_as_themes(
             dest = theme_dir, 'images', (rp + dest_name)
             safe_link(image_path, os.path.join(tdir, *dest))
             file('/'.join(dest))
-            for alias in aliases.get(image_name, ()):
-                dest = theme_dir, 'images', (rp + alias)
-                safe_link(image_path, os.path.join(tdir, *dest))
-                file('/'.join(dest))
 
         for dirpath, dirnames, filenames in os.walk(path_to_dir):
             if 'textures' in dirnames: