From 537fcd9021c019963691e4303514c6e58a63ed27 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Sun, 8 Dec 2019 08:50:42 +0530
Subject: [PATCH] Allow using an env var on linux for dark mode

---
 src/calibre/gui2/__init__.py | 33 ++++++++++-----------------------
 src/calibre/gui2/palette.py  | 31 +++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+), 23 deletions(-)
 create mode 100644 src/calibre/gui2/palette.py

diff --git a/src/calibre/gui2/__init__.py b/src/calibre/gui2/__init__.py
index f788833486..3f7f9c11d7 100644
--- a/src/calibre/gui2/__init__.py
+++ b/src/calibre/gui2/__init__.py
@@ -1009,27 +1009,8 @@ class Application(QApplication):
         load_builtin_fonts()
 
     def set_dark_mode_palette(self):
-        p = self.palette()
-        dark_color = QColor(45,45,45)
-        disabled_color = QColor(127,127,127)
-        p.setColor(p.Window, dark_color)
-        p.setColor(p.WindowText, Qt.white)
-        p.setColor(p.Base, QColor(18,18,18))
-        p.setColor(p.AlternateBase, dark_color)
-        p.setColor(p.ToolTipBase, Qt.white)
-        p.setColor(p.ToolTipText, Qt.white)
-        p.setColor(p.Text, Qt.white)
-        p.setColor(p.Disabled, p.Text, disabled_color)
-        p.setColor(p.Button, dark_color)
-        p.setColor(p.ButtonText, Qt.white)
-        p.setColor(p.Disabled, p.ButtonText, disabled_color)
-        p.setColor(p.BrightText, Qt.red)
-        p.setColor(p.Link, QColor(42, 130, 218))
-
-        p.setColor(p.Highlight, QColor(42, 130, 218))
-        p.setColor(p.HighlightedText, Qt.black)
-        p.setColor(p.Disabled, p.HighlightedText, disabled_color)
-        self.set_palette(p)
+        from calibre.gui2.palette import dark_palette
+        self.set_palette(dark_palette())
 
     def setup_styles(self, force_calibre_style):
         if iswindows or isosx:
@@ -1038,8 +1019,14 @@ class Application(QApplication):
             using_calibre_style = os.environ.get('CALIBRE_USE_SYSTEM_THEME', '0') == '0'
         if force_calibre_style:
             using_calibre_style = True
-        if iswindows and windows_is_system_dark_mode_enabled() and using_calibre_style:
-            self.set_dark_mode_palette()
+        if using_calibre_style:
+            use_dark_palette = False
+            if iswindows:
+                use_dark_palette = windows_is_system_dark_mode_enabled()
+            elif not isosx:
+                use_dark_palette = os.environ.get('CALIBRE_USE_DARK_PALETTE') == '1'
+            if use_dark_palette:
+                self.set_dark_mode_palette()
 
         self.using_calibre_style = using_calibre_style
         if DEBUG:
diff --git a/src/calibre/gui2/palette.py b/src/calibre/gui2/palette.py
new file mode 100644
index 0000000000..b708a7e833
--- /dev/null
+++ b/src/calibre/gui2/palette.py
@@ -0,0 +1,31 @@
+#!/usr/bin/env python2
+# vim:fileencoding=utf-8
+# License: GPL v3 Copyright: 2019, Kovid Goyal <kovid at kovidgoyal.net>
+
+from __future__ import absolute_import, division, print_function, unicode_literals
+
+from PyQt5.Qt import QColor, QPalette, Qt
+
+
+def dark_palette():
+    p = QPalette()
+    dark_color = QColor(45,45,45)
+    disabled_color = QColor(127,127,127)
+    p.setColor(p.Window, dark_color)
+    p.setColor(p.WindowText, Qt.white)
+    p.setColor(p.Base, QColor(18,18,18))
+    p.setColor(p.AlternateBase, dark_color)
+    p.setColor(p.ToolTipBase, Qt.white)
+    p.setColor(p.ToolTipText, Qt.white)
+    p.setColor(p.Text, Qt.white)
+    p.setColor(p.Disabled, p.Text, disabled_color)
+    p.setColor(p.Button, dark_color)
+    p.setColor(p.ButtonText, Qt.white)
+    p.setColor(p.Disabled, p.ButtonText, disabled_color)
+    p.setColor(p.BrightText, Qt.red)
+    p.setColor(p.Link, QColor(42, 130, 218))
+
+    p.setColor(p.Highlight, QColor(42, 130, 218))
+    p.setColor(p.HighlightedText, Qt.black)
+    p.setColor(p.Disabled, p.HighlightedText, disabled_color)
+    return p