From 5277bad30224fba92368d747e715946e3be5454e Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Tue, 8 Mar 2022 15:02:38 +0530
Subject: [PATCH] Use Qt to detect touchscreen support

---
 src/calibre/gui2/gestures.py | 26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

diff --git a/src/calibre/gui2/gestures.py b/src/calibre/gui2/gestures.py
index 4db96730f2..73a25e773e 100644
--- a/src/calibre/gui2/gestures.py
+++ b/src/calibre/gui2/gestures.py
@@ -2,22 +2,26 @@
 # License: GPLv3 Copyright: 2017, Kovid Goyal <kovid at kovidgoyal.net>
 
 
-import sys, os
-
+import os
+from functools import lru_cache
 from qt.core import (
     QApplication, QEvent, QMouseEvent, QObject, QPointF, QScroller, Qt, QTouchDevice,
     pyqtSignal
 )
 
-from calibre.constants import iswindows
 from calibre.utils.monotonic import monotonic
 from polyglot.builtins import itervalues
 
-touch_supported = False
-if iswindows and sys.getwindowsversion()[:2] >= (6, 2):  # At least windows 7
-    touch_supported = True
-if 'CALIBRE_NO_TOUCH' in os.environ:
-    touch_supported = False
+
+@lru_cache(maxsize=2)
+def touch_supported():
+    if 'CALIBRE_NO_TOUCH' in os.environ:
+        return False
+    for dev in QTouchDevice.devices():
+        if dev.type() == QTouchDevice.DeviceType.TouchScreen:
+            return True
+    return False
+
 
 HOLD_THRESHOLD = 1.0  # seconds
 TAP_THRESHOLD  = 50   # manhattan pixels
@@ -150,7 +154,7 @@ class GestureManager(QObject):
 
     def __init__(self, view):
         QObject.__init__(self, view)
-        if touch_supported:
+        if touch_supported():
             view.viewport().setAttribute(Qt.WidgetAttribute.WA_AcceptTouchEvents)
         self.state = State()
         self.state.tapped.connect(
@@ -162,11 +166,11 @@ class GestureManager(QObject):
         connect_lambda(self.state.tap_hold_finished, self, lambda self, tp: self.handle_tap_hold('end', tp))
         self.evmap = {QEvent.Type.TouchBegin: 'start', QEvent.Type.TouchUpdate: 'update', QEvent.Type.TouchEnd: 'end'}
         self.last_tap_at = 0
-        if touch_supported:
+        if touch_supported():
             self.scroller = QScroller.scroller(view.viewport())
 
     def handle_event(self, ev):
-        if not touch_supported:
+        if not touch_supported():
             return
         etype = ev.type()
         if etype in (QEvent.Type.MouseButtonPress, QEvent.Type.MouseMove, QEvent.Type.MouseButtonRelease, QEvent.Type.MouseButtonDblClick):