From 059d9e46278989dcea498465c871f750fd0b5b58 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <slouken@libsdl.org>
Date: Sat, 12 Aug 2017 17:41:59 -0700
Subject: [PATCH] Fixed bug 2950 - wrong axes values are set on joystick
 initialization

Edward Rudd

Device: Logitech Rumble Gamepad F510 in Xinput mode.

Upon opening the joystick the values of the axes are queried via PollAllValues are not actually set on the device all the time.

This can easily be seen in the testjoystick or testgamecontroller test programs,as the testjoystick shows all axes in the center until one 'tickles' the triggers., and the testgamecontroller will show the triggers as 'on' until on 'tickles' the triggers.

Upon further research the culprit is the SDL_HINT_JOYSTICK_ALLOW_BACKGROUND_EVENTS hint. In the default value events are ignored until there is an active window, Thus in cases where the joystick system is initialized and controllers opened before the initial window is created & focuses, the initial values will be incorrect.

Here is my current workaround in the game I'm working on porting..

SDL_SetHint(SDL_HINT_JOYSTICK_ALLOW_BACKGROUND_EVENTS, "1");
SDL_GameController* gamepad = SDL_GameControllerOpen(index);
SDL_SetHint(SDL_HINT_JOYSTICK_ALLOW_BACKGROUND_EVENTS, "0");
---
 src/joystick/SDL_joystick.c | 13 ++++---------
 src/video/SDL_sysvideo.h    |  1 +
 src/video/SDL_video.c       |  6 ++++++
 3 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/src/joystick/SDL_joystick.c b/src/joystick/SDL_joystick.c
index d7dbd96ece8a7..dc330c925859b 100644
--- a/src/joystick/SDL_joystick.c
+++ b/src/joystick/SDL_joystick.c
@@ -31,6 +31,7 @@
 #if !SDL_EVENTS_DISABLED
 #include "../events/SDL_events_c.h"
 #endif
+#include "../video/SDL_sysvideo.h"
 
 
 static SDL_bool SDL_joystick_allows_background_events = SDL_FALSE;
@@ -582,16 +583,10 @@ SDL_PrivateJoystickShouldIgnoreEvent()
         return SDL_FALSE;
     }
 
-    if (SDL_WasInit(SDL_INIT_VIDEO)) {
-        if (SDL_GetKeyboardFocus() == NULL) {
-            /* Video is initialized and we don't have focus, ignore the event. */
-            return SDL_TRUE;
-        } else {
-            return SDL_FALSE;
-        }
+    if (SDL_HasWindows() && SDL_GetKeyboardFocus() == NULL) {
+        /* We have windows but we don't have focus, ignore the event. */
+        return SDL_TRUE;
     }
-
-    /* Video subsystem wasn't initialized, always allow the event */
     return SDL_FALSE;
 }
 
diff --git a/src/video/SDL_sysvideo.h b/src/video/SDL_sysvideo.h
index d2b8bf9ff8e96..936837897cde1 100644
--- a/src/video/SDL_sysvideo.h
+++ b/src/video/SDL_sysvideo.h
@@ -403,6 +403,7 @@ extern void *SDL_GetDisplayDriverData( int displayIndex );
 extern void SDL_GL_DeduceMaxSupportedESProfile(int* major, int* minor);
 
 extern int SDL_RecreateWindow(SDL_Window * window, Uint32 flags);
+extern SDL_bool SDL_HasWindows();
 
 extern void SDL_OnWindowShown(SDL_Window * window);
 extern void SDL_OnWindowHidden(SDL_Window * window);
diff --git a/src/video/SDL_video.c b/src/video/SDL_video.c
index 564d108c7bf53..2f15ec528198d 100644
--- a/src/video/SDL_video.c
+++ b/src/video/SDL_video.c
@@ -1606,6 +1606,12 @@ SDL_RecreateWindow(SDL_Window * window, Uint32 flags)
     return 0;
 }
 
+SDL_bool
+SDL_HasWindows()
+{
+    return (_this && _this->windows != NULL);
+}
+
 Uint32
 SDL_GetWindowID(SDL_Window * window)
 {