Joystick: Only send joy events when focused.
authorJørgen P. Tjernø <jorgen@valvesoftware.com>
Wed, 05 Jun 2013 15:11:38 -0700
changeset 7279 f7805b13b485
parent 7278 fc8b57a2a541
child 7280 d1681bbd274a
Joystick: Only send joy events when focused. This changes makes it so that you only receive joystick (and implicitly gamecontroller) input events when your application has keyboard focus. If you'd like to still receive events when your application is in the background, set the SDL_JOYSTICK_ALLOW_BACKGROUND_EVENTS hint to "1". This fixes http://bugzilla.libsdl.org/show_bug.cgi?id=1892
include/SDL_hints.h
src/joystick/SDL_joystick.c
--- a/include/SDL_hints.h	Wed Jun 05 23:33:15 2013 +0200
+++ b/include/SDL_hints.h	Wed Jun 05 15:11:38 2013 -0700
@@ -216,6 +216,20 @@
 
 
 /**
+ *  \brief  A variable that lets you enable joystick (and gamecontroller) events even when your app is in the background.
+ *
+ * The default value is "0".
+ *
+ *  The variable can be set to the following values:
+ *    "0"       - Disable joystick & gamecontroller input events when the
+ *                application is in the background.
+ *    "1"       - Enable joystick & gamecontroller input events when the
+ *                application is in the backgroumd.
+ */
+#define SDL_HINT_JOYSTICK_ALLOW_BACKGROUND_EVENTS "SDL_JOYSTICK_ALLOW_BACKGROUND_EVENTS"
+
+
+/**
  *  \brief If set to 0 then never set the top most bit on a SDL Window, even if the video mode expects it.
  *      This is a debugging aid for developers and not expected to be used by end users. The default is "1"
  *
--- a/src/joystick/SDL_joystick.c	Wed Jun 05 23:33:15 2013 +0200
+++ b/src/joystick/SDL_joystick.c	Wed Jun 05 15:11:38 2013 -0700
@@ -25,6 +25,7 @@
 #include "SDL_events.h"
 #include "SDL_sysjoystick.h"
 #include "SDL_assert.h"
+#include "SDL_hints.h"
 
 #if !SDL_EVENTS_DISABLED
 #include "../events/SDL_events_c.h"
@@ -451,6 +452,22 @@
 }
 
 
+static SDL_bool
+SDL_PrivateJoystickShouldIgnoreEvent()
+{
+    const char *hint;
+    if (SDL_GetKeyboardFocus() != NULL) {
+        return SDL_FALSE;
+    }
+
+    hint = SDL_GetHint(SDL_HINT_JOYSTICK_ALLOW_BACKGROUND_EVENTS);
+    if (hint && *hint == '1') {
+        return SDL_FALSE;
+    }
+
+    return SDL_TRUE;
+}
+
 /* These are global for SDL_sysjoystick.c and SDL_events.c */
 
 int
@@ -469,6 +486,15 @@
     }
     joystick->axes[axis] = value;
 
+    /* We ignore events if we don't have keyboard focus, except for centering
+     * events.
+     */
+    if (SDL_PrivateJoystickShouldIgnoreEvent()) {
+        if (!(joystick->closed && joystick->uncentered)) {
+            return 0;
+        }
+    }
+
     /* Post the event, if desired */
     posted = 0;
 #if !SDL_EVENTS_DISABLED
@@ -497,6 +523,16 @@
     /* Update internal joystick state */
     joystick->hats[hat] = value;
 
+    /* We ignore events if we don't have keyboard focus, except for centering
+     * events.
+     */
+    if (SDL_PrivateJoystickShouldIgnoreEvent()) {
+        if (!(joystick->closed && joystick->uncentered)) {
+            return 0;
+        }
+    }
+
+
     /* Post the event, if desired */
     posted = 0;
 #if !SDL_EVENTS_DISABLED
@@ -523,6 +559,11 @@
         return 0;
     }
 
+    /* We ignore events if we don't have keyboard focus. */
+    if (SDL_PrivateJoystickShouldIgnoreEvent()) {
+        return 0;
+    }
+
     /* Update internal mouse state */
     joystick->balls[ball].dx += xrel;
     joystick->balls[ball].dy += yrel;
@@ -568,6 +609,12 @@
         return 0;
     }
 
+    /* We ignore events if we don't have keyboard focus, except for button
+     * release. */
+    if (SDL_PrivateJoystickShouldIgnoreEvent() && event.type == SDL_JOYBUTTONDOWN) {
+        return 0;
+    }
+
     /* Update internal joystick state */
     joystick->buttons[button] = state;
 
@@ -605,7 +652,6 @@
         if ( joystick->closed && joystick->uncentered )
         {
             int i;
-            joystick->uncentered = 0;
 
             /* Tell the app that everything is centered/unpressed...  */
             for (i = 0; i < joystick->naxes; i++)
@@ -617,6 +663,7 @@
             for (i = 0; i < joystick->nhats; i++)
                 SDL_PrivateJoystickHat(joystick, i, SDL_HAT_CENTERED);
 
+            joystick->uncentered = 0;
         }
 
         SDL_updating_joystick = NULL;