From 04fa47ddaf000f702649044b0502765a834241e2 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Fri, 19 May 2023 07:17:05 +0530
Subject: [PATCH] E-book viewer: Handle horizontal wheel events as section
 jumps in paged mode

Also handle horizontal wheel events in cover flow. Fixes #2019426 [vertical mousewheel function not implemented](https://bugs.launchpad.net/calibre/+bug/2019426)
---
 src/calibre/gui2/cover_flow.py   |  5 ++++-
 src/pyj/read_book/paged_mode.pyj | 20 ++++++++++++++------
 2 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/src/calibre/gui2/cover_flow.py b/src/calibre/gui2/cover_flow.py
index f60e12d825..b662f2e55f 100644
--- a/src/calibre/gui2/cover_flow.py
+++ b/src/calibre/gui2/cover_flow.py
@@ -231,7 +231,10 @@ class CoverFlow(pictureflow.PictureFlow):
         return self.minimumSize()
 
     def wheelEvent(self, ev):
-        d = ev.angleDelta().y()
+        if ev.angleDelta().x():
+            d = ev.angleDelta().x()
+        if ev.angleDelta().y():
+            d = ev.angleDelta().y()
         if abs(d) > 0:
             ev.accept()
             (self.showNext if d < 0 else self.showPrevious)()
diff --git a/src/pyj/read_book/paged_mode.pyj b/src/pyj/read_book/paged_mode.pyj
index c868191f5a..23ecb1ee65 100644
--- a/src/pyj/read_book/paged_mode.pyj
+++ b/src/pyj/read_book/paged_mode.pyj
@@ -691,13 +691,18 @@ class HandleWheel:
         self.accumulated_scroll = 0
 
     def onwheel(self, evt):
-        if not evt.deltaY:
+        if not (evt.deltaY or evt.deltaX):
             return
-        backward = evt.deltaY < 0
-        if evt.deltaMode is window.WheelEvent.DOM_DELTA_PIXEL:
-            self.add_pixel_scroll(backward, Math.abs(evt.deltaY))
-        else:
-            self.do_scroll(backward)
+        if evt.deltaY:
+            backward = evt.deltaY < 0
+            if evt.deltaMode is window.WheelEvent.DOM_DELTA_PIXEL:
+                self.add_pixel_scroll(backward, Math.abs(evt.deltaY))
+            else:
+                self.do_scroll(backward)
+        if evt.deltaX:
+            backward = evt.deltaX < 0
+            self.do_section_jump(backward)
+
 
     def add_pixel_scroll(self, backward, deltaY):
         now = window.performance.now()
@@ -721,6 +726,9 @@ class HandleWheel:
         else:
             scroll_to_pos(pos)
 
+    def do_section_jump(self, backward):
+        self.reset()
+        next_spine_item(backward)
 
 wheel_handler = HandleWheel()
 onwheel = wheel_handler.onwheel