From 5b3f6e0424b03cd6703c5cf9c7a7fe8e7d1f39f8 Mon Sep 17 00:00:00 2001
From: "J?rgen P. Tjern?" <jorgen@valvesoftware.com>
Date: Thu, 25 Apr 2013 18:40:29 -0700
Subject: [PATCH] Mac: Fix relative mode message after gaining focus.

This fixes a bug where relative mode would give a large jump if the
cursor was moved when the app doesn't have focus.
---
 src/events/SDL_mouse_c.h         |  3 +++
 src/video/cocoa/SDL_cocoamouse.h |  7 +++++++
 src/video/cocoa/SDL_cocoamouse.m | 25 ++++++++++++++++++++++---
 3 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/src/events/SDL_mouse_c.h b/src/events/SDL_mouse_c.h
index 7cb13cb3d..9994bc640 100644
--- a/src/events/SDL_mouse_c.h
+++ b/src/events/SDL_mouse_c.h
@@ -73,6 +73,9 @@ typedef struct
     SDL_Cursor *def_cursor;
     SDL_Cursor *cur_cursor;
     SDL_bool cursor_shown;
+
+    /* Driver-dependent data. */
+    void *driverdata;
 } SDL_Mouse;
 
 
diff --git a/src/video/cocoa/SDL_cocoamouse.h b/src/video/cocoa/SDL_cocoamouse.h
index 992af549f..0e5822ab3 100644
--- a/src/video/cocoa/SDL_cocoamouse.h
+++ b/src/video/cocoa/SDL_cocoamouse.h
@@ -23,11 +23,18 @@
 #ifndef _SDL_cocoamouse_h
 #define _SDL_cocoamouse_h
 
+#include "SDL_cocoavideo.h"
+
 extern void Cocoa_InitMouse(_THIS);
 extern void Cocoa_HandleMouseEvent(_THIS, NSEvent * event);
 extern void Cocoa_HandleMouseWheel(SDL_Window *window, NSEvent * event);
 extern void Cocoa_QuitMouse(_THIS);
 
+typedef struct {
+    int deltaXOffset;
+    int deltaYOffset;
+} SDL_MouseData;
+
 #endif /* _SDL_cocoamouse_h */
 
 /* vi: set ts=4 sw=4 expandtab: */
diff --git a/src/video/cocoa/SDL_cocoamouse.m b/src/video/cocoa/SDL_cocoamouse.m
index 23e8796e0..2c0f2b7d6 100644
--- a/src/video/cocoa/SDL_cocoamouse.m
+++ b/src/video/cocoa/SDL_cocoamouse.m
@@ -24,7 +24,7 @@
 
 #include "SDL_assert.h"
 #include "SDL_events.h"
-#include "SDL_cocoavideo.h"
+#include "SDL_cocoamouse.h"
 
 #include "../../events/SDL_mouse_c.h"
 
@@ -193,6 +193,16 @@
     point.x = (float)window->x + x;
     point.y = (float)window->y + y;
 
+    {
+        /* This makes Cocoa_HandleMouseEvent ignore this delta in the next
+         * movement event.
+         */
+        SDL_MouseData *driverdata = (SDL_MouseData*)mouse->driverdata;
+        NSPoint location =  [NSEvent mouseLocation];
+        driverdata->deltaXOffset = location.x - point.x;
+        driverdata->deltaYOffset = point.y - location.y;
+    }
+
     /* According to the docs, this was deprecated in 10.6, but it's still
      * around. The substitute requires a CGEventSource, but I'm not entirely
      * sure how we'd procure the right one for this event.
@@ -228,6 +238,8 @@
 {
     SDL_Mouse *mouse = SDL_GetMouse();
 
+    mouse->driverdata = SDL_calloc(1, sizeof(SDL_MouseData));
+
     mouse->CreateCursor = Cocoa_CreateCursor;
     mouse->CreateSystemCursor = Cocoa_CreateSystemCursor;
     mouse->ShowCursor = Cocoa_ShowCursor;
@@ -248,8 +260,11 @@
          [event type] == NSLeftMouseDragged ||
          [event type] == NSRightMouseDragged ||
          [event type] == NSOtherMouseDragged)) {
-        float x = [event deltaX];
-        float y = [event deltaY];
+        SDL_MouseData *driverdata = (SDL_MouseData*)mouse->driverdata;
+        float x = [event deltaX] + driverdata->deltaXOffset;
+        float y = [event deltaY] + driverdata->deltaYOffset;
+        driverdata->deltaXOffset = driverdata->deltaYOffset = 0;
+
         SDL_SendMouseMotion(mouse->focus, mouse->mouseID, 1, (int)x, (int)y);
     }
 }
@@ -278,6 +293,10 @@
 void
 Cocoa_QuitMouse(_THIS)
 {
+    SDL_Mouse *mouse = SDL_GetMouse();
+    if (mouse) {
+        SDL_free(mouse->driverdata);
+    }
 }
 
 #endif /* SDL_VIDEO_DRIVER_COCOA */