From f9a63ec272a6051bd2f1a92a580640018124a34c Mon Sep 17 00:00:00 2001
From: Romain Vimont <rvimont@genymobile.com>
Date: Mon, 12 Mar 2018 09:37:46 +0100
Subject: [PATCH] Reverse horizontal scrolling behavior

The SDL mouse wheel event seems inconsistent between horizontal and
vertical scrolling.

> Movements to the left generate negative x values and to the right
> generate positive x values. Movements down (scroll backward) generate
> negative y values and up (scroll forward) generate positive y values.

<https://wiki.libsdl.org/SDL_MouseWheelEvent#Remarks>

Reverse the horizontal.

Fixes <https://github.com/Genymobile/scrcpy/issues/49>.
---
 app/src/convert.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/app/src/convert.c b/app/src/convert.c
index ec6f1de0..2c17f948 100644
--- a/app/src/convert.c
+++ b/app/src/convert.c
@@ -172,7 +172,10 @@ SDL_bool mouse_wheel_from_sdl_to_android(const SDL_MouseWheelEvent *from,
     to->scroll_event.position = position;
 
     int mul = from->direction == SDL_MOUSEWHEEL_NORMAL ? 1 : -1;
-    to->scroll_event.hscroll = mul * from->x;
+    // SDL behavior seems inconsistent between horizontal and vertical scrolling
+    // so reverse the horizontal
+    // <https://wiki.libsdl.org/SDL_MouseWheelEvent#Remarks>
+    to->scroll_event.hscroll = -mul * from->x;
     to->scroll_event.vscroll = mul * from->y;
 
     return SDL_TRUE;