Mac: Improve moving relative mode windows.

This makes it possible to move windows by their title bar, even if they're in
relative mode, if you click the title bar when the window does not have focus.

Bug: https://bugzilla.libsdl.org/show_bug.cgi?id=2396

src/video/cocoa/SDL_cocoamouse.m

@@ -29,6 +29,14 @@
 
 #include "../../events/SDL_mouse_c.h"
 
+/* #define DEBUG_COCOAMOUSE */
+
+#ifdef DEBUG_COCOAMOUSE
+#define DLog(fmt, ...) printf("%s: " fmt "\n", __func__, ##__VA_ARGS__)
+#else
+#define DLog(...) do { } while (0)
+#endif
+
 @implementation NSCursor (InvisibleCursor)
 + (NSCursor *)invisibleCursor
 {
@@ -203,6 +211,15 @@ Cocoa_ShowCursor(SDL_Cursor * cursor)
 static void
 Cocoa_WarpMouse(SDL_Window * window, int x, int y)
 {
+    SDL_WindowData *data = (SDL_WindowData *) window->driverdata;
+    if ([data->listener isMoving])
+    {
+        DLog("Postponing warp, window being moved.");
+        [data->listener setPendingMoveX:x
+                                      Y:y];
+        return;
+    }
+
     SDL_Mouse *mouse = SDL_GetMouse();
     CGPoint point = CGPointMake(x + (float)window->x, y + (float)window->y);
 
@@ -214,6 +231,7 @@ Cocoa_WarpMouse(SDL_Window * window, int x, int y)
         NSPoint location =  [NSEvent mouseLocation];
         driverdata->deltaXOffset = location.x - point.x;
         driverdata->deltaYOffset = point.y - location.y;
+        DLog("Warp to (%g, %g), offsetting next movement event by (%i, %i)", point.x, point.y, driverdata->deltaXOffset, driverdata->deltaYOffset);
     }
 
     /* According to the docs, this was deprecated in 10.6, but it's still
@@ -238,8 +256,10 @@ Cocoa_SetRelativeMouseMode(SDL_bool enabled)
     CGError result;
 
     if (enabled) {
+        DLog("Turning on.");
         result = CGAssociateMouseAndMouseCursorPosition(NO);
     } else {
+        DLog("Turning off.");
         result = CGAssociateMouseAndMouseCursorPosition(YES);
     }
     if (result != kCGErrorSuccess) {
@@ -272,18 +292,42 @@ Cocoa_HandleMouseEvent(_THIS, NSEvent *event)
 {
     SDL_Mouse *mouse = SDL_GetMouse();
 
-    if (mouse->relative_mode &&
-        ([event type] == NSMouseMoved ||
-         [event type] == NSLeftMouseDragged ||
-         [event type] == NSRightMouseDragged ||
-         [event type] == NSOtherMouseDragged)) {
+    /* Non-relative movement is handled in -[Cocoa_WindowListener mouseMoved:] */
+    if (!mouse->relative_mode) {
+        return;
+    }
+
+    switch ([event type])
+    {
+        case NSMouseMoved:
+        case NSLeftMouseDragged:
+        case NSRightMouseDragged:
+        case NSOtherMouseDragged:
+            break;
+
+        default:
+            /* Ignore any other events. */
+            return;
+    }
+
+    /* Ignore events that aren't inside the client area (i.e. title bar.) */
+    if ([event window]) {
+        NSRect windowRect = [[[event window] contentView] frame];
+        if (!NSPointInRect([event locationInWindow], windowRect)) {
+            return;
+        }
+    }
+
     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);
+    if (driverdata->deltaYOffset > 0 || driverdata->deltaXOffset > 0) {
+        DLog("Relative move was (%g, %g), offset to (%g, %g)", [event deltaX], [event deltaY], x, y);
     }
+
+    SDL_SendMouseMotion(mouse->focus, mouse->mouseID, 1, (int)x, (int)y);
 }
 
 void

src/video/cocoa/SDL_cocoawindow.h

@@ -43,6 +43,8 @@ typedef enum
     BOOL isFullscreenSpace;
     BOOL inFullscreenTransition;
     PendingWindowOperation pendingWindowOperation;
+    BOOL isMoving;
+    int pendingWindowWarpX, pendingWindowWarpY;
 }
 
 -(void) listen:(SDL_WindowData *) data;
@@ -54,6 +56,10 @@ typedef enum
 -(void) addPendingWindowOperation:(PendingWindowOperation) operation;
 -(void) close;
 
+-(BOOL) isMoving;
+-(void) setPendingMoveX:(int)x Y:(int)y;
+-(void) windowDidFinishMoving;
+
 /* Window delegate functionality */
 -(BOOL) windowShouldClose:(id) sender;
 -(void) windowDidExpose:(NSNotification *) aNotification;
@@ -105,6 +111,7 @@ struct SDL_WindowData
     NSWindow *nswindow;
     NSMutableArray *nscontexts;
     SDL_bool created;
+    SDL_bool inWindowMove;
     Cocoa_WindowListener *listener;
     struct SDL_VideoData *videodata;
 };

src/video/cocoa/SDL_cocoawindow.m

@@ -39,6 +39,44 @@
 #include "SDL_cocoamouse.h"
 #include "SDL_cocoaopengl.h"
 
+@interface SDLWindow : NSWindow
+/* These are needed for borderless/fullscreen windows */
+- (BOOL)canBecomeKeyWindow;
+- (BOOL)canBecomeMainWindow;
+- (void)sendEvent:(NSEvent *)event;
+@end
+
+@implementation SDLWindow
+- (BOOL)canBecomeKeyWindow
+{
+    return YES;
+}
+
+- (BOOL)canBecomeMainWindow
+{
+    return YES;
+}
+
+- (void)sendEvent:(NSEvent *)event
+{
+  [super sendEvent:event];
+
+  if ([event type] != NSLeftMouseUp) {
+      return;
+  }
+
+  id delegate = [self delegate];
+  if (![delegate isKindOfClass:[Cocoa_WindowListener class]]) {
+      return;
+  }
+
+  if ([delegate isMoving]) {
+      [delegate windowDidFinishMoving];
+  }
+}
+@end
+
+
 static Uint32 s_moveHack;
 
 static void ConvertNSRect(NSRect *r)
@@ -130,6 +168,7 @@ SetWindowStyle(SDL_Window * window, unsigned int style)
     isFullscreenSpace = NO;
     inFullscreenTransition = NO;
     pendingWindowOperation = PENDING_OPERATION_NONE;
+    isMoving = NO;
 
     center = [NSNotificationCenter defaultCenter];
 
@@ -315,6 +354,34 @@ SetWindowStyle(SDL_Window * window, unsigned int style)
     }
 }
 
+- (BOOL)isMoving
+{
+    return isMoving;
+}
+
+-(void) setPendingMoveX:(int)x Y:(int)y
+{
+    pendingWindowWarpX = x;
+    pendingWindowWarpY = y;
+}
+
+- (void)windowDidFinishMoving
+{
+    if ([self isMoving])
+    {
+        isMoving = NO;
+
+        SDL_Mouse *mouse = SDL_GetMouse();
+        if (pendingWindowWarpX >= 0 && pendingWindowWarpY >= 0) {
+            mouse->WarpMouse(_data->window, pendingWindowWarpX, pendingWindowWarpY);
+            pendingWindowWarpX = pendingWindowWarpY = -1;
+        }
+        if (mouse->relative_mode && SDL_GetMouseFocus() == _data->window) {
+            mouse->SetRelativeMouseMode(SDL_TRUE);
+        }
+    }
+}
+
 - (BOOL)windowShouldClose:(id)sender
 {
     SDL_SendWindowEvent(_data->window, SDL_WINDOWEVENT_CLOSE, 0, 0);
@@ -326,6 +393,14 @@ SetWindowStyle(SDL_Window * window, unsigned int style)
     SDL_SendWindowEvent(_data->window, SDL_WINDOWEVENT_EXPOSED, 0, 0);
 }
 
+- (void)windowWillMove:(NSNotification *)aNotification
+{
+    if ([_data->nswindow isKindOfClass:[SDLWindow class]]) {
+        pendingWindowWarpX = pendingWindowWarpY = -1;
+        isMoving = YES;
+    }
+}
+
 - (void)windowDidMove:(NSNotification *)aNotification
 {
     int x, y;
@@ -407,6 +482,9 @@ SetWindowStyle(SDL_Window * window, unsigned int style)
 {
     SDL_Window *window = _data->window;
     SDL_Mouse *mouse = SDL_GetMouse();
+    if (mouse->relative_mode && ![self isMoving]) {
+        mouse->SetRelativeMouseMode(SDL_TRUE);
+    }
 
     /* We're going to get keyboard events, since we're key. */
     SDL_SetKeyboardFocus(window);
@@ -431,6 +509,11 @@ SetWindowStyle(SDL_Window * window, unsigned int style)
 
 - (void)windowDidResignKey:(NSNotification *)aNotification
 {
+    SDL_Mouse *mouse = SDL_GetMouse();
+    if (mouse->relative_mode) {
+        mouse->SetRelativeMouseMode(SDL_FALSE);
+    }
+
     /* Some other window will get mouse events, since we're not key. */
     if (SDL_GetMouseFocus() == _data->window) {
         SDL_SetMouseFocus(NULL);
@@ -624,8 +707,6 @@ SetWindowStyle(SDL_Window * window, unsigned int style)
 
     if (x < 0 || x >= window->w || y < 0 || y >= window->h) {
         if (window->flags & SDL_WINDOW_INPUT_GRABBED) {
-            CGPoint cgpoint;
-
             if (x < 0) {
                 x = 0;
             } else if (x >= window->w) {
@@ -638,6 +719,8 @@ SetWindowStyle(SDL_Window * window, unsigned int style)
             }
 
 #if !SDL_MAC_NO_SANDBOX
+            CGPoint cgpoint;
+
             /* When SDL_MAC_NO_SANDBOX is set, this is handled by
              * SDL_cocoamousetap.m.
              */
@@ -754,24 +837,6 @@ SetWindowStyle(SDL_Window * window, unsigned int style)
 
 @end
 
-@interface SDLWindow : NSWindow
-/* These are needed for borderless/fullscreen windows */
-- (BOOL)canBecomeKeyWindow;
-- (BOOL)canBecomeMainWindow;
-@end
-
-@implementation SDLWindow
-- (BOOL)canBecomeKeyWindow
-{
-    return YES;
-}
-
-- (BOOL)canBecomeMainWindow
-{
-    return YES;
-}
-@end
-
 @interface SDLView : NSView
 
 /* The default implementation doesn't pass rightMouseDown to responder chain */
@@ -1338,7 +1403,8 @@ void
 Cocoa_SetWindowGrab(_THIS, SDL_Window * window, SDL_bool grabbed)
 {
     /* Move the cursor to the nearest point in the window */
-    if (grabbed) {
+    SDL_WindowData *data = (SDL_WindowData *) window->driverdata;
+    if (grabbed && data && ![data->listener isMoving]) {
         int x, y;
         CGPoint cgpoint;