Added OS X implementation of sf::Window::setCursorGrabbed

This implementation uses the following workaround:
 - resize flag is removed from the window when the cursor is grabbed
 - when grabbed, the cursor is projected inside the view if needed
 - to avoid letting the user clic outside the view, the cursor is
   disconnected and manually moved using relative motion
 - the initial potential projection of the cursor results in a big
   delta for the next move and needed to be somehow ignored (see
   note about m_deltaXBuffer and m_deltaYBuffer in SFOpenGLView.h)

src/SFML/Window/OSX/SFOpenGLView+mouse.mm

@@ -27,6 +27,7 @@
 // Headers
 ////////////////////////////////////////////////////////////
 #include <SFML/Window/OSX/WindowImplCocoa.hpp>
+#include <cmath>
 
 #import <SFML/Window/OSX/SFOpenGLView.h>
 #import <SFML/Window/OSX/SFOpenGLView+mouse_priv.h>
@@ -52,20 +53,29 @@
 ////////////////////////////////////////////////////////
 -(void)updateMouseState
 {
+    // Update in/out state
     BOOL mouseWasIn = m_mouseIsIn;
     m_mouseIsIn = [self isMouseInside];
 
-    if (m_requester == 0)
-        return;
-
     // Send event if needed.
+    if (m_requester != 0)
+    {
         if (mouseWasIn && !m_mouseIsIn)
             m_requester->mouseMovedOut();
         else if (!mouseWasIn && m_mouseIsIn)
             m_requester->mouseMovedIn();
+    }
 }
 
 
+////////////////////////////////////////////////////////
+-(void)setCursorGrabbed:(BOOL)grabbed
+{
+    m_cursorGrabbed = grabbed;
+
+    [self updateCursorGrabbed];
+}
+
 
 ////////////////////////////////////////////////////////
 -(void)mouseDown:(NSEvent*)theEvent
@@ -200,17 +210,68 @@
 ////////////////////////////////////////////////////////
 -(void)handleMouseMove:(NSEvent*)theEvent
 {
-    if (m_requester != 0)
-    {
     NSPoint loc = [self cursorPositionFromEvent:theEvent];
 
+    // If the cursor is grabbed, cursorPositionFromEvent: will
+    // return its correct position but not move actually it
+    // so we do it now.
+    if ([self isCursorCurrentlyGrabbed])
+        [self moveCursorTo:loc];
+
     // Make sure the point is inside the view.
     // (mouseEntered: and mouseExited: are not immediately called
     //  when the mouse is dragged. That would be too easy!)
     [self updateMouseState];
-        if (m_mouseIsIn)
+    if ((m_requester != 0) && m_mouseIsIn)
         m_requester->mouseMovedAt(loc.x, loc.y);
+}
+
+
+////////////////////////////////////////////////////////
+-(BOOL)isCursorCurrentlyGrabbed
+{
+    return [[self window] isKeyWindow] && (m_cursorGrabbed || m_fullscreen);
+}
+
+
+////////////////////////////////////////////////////////
+-(void)updateCursorGrabbed
+{
+    // Disable/enable normal movements of the cursor
+    // and project the cursor if needed.
+    if ([self isCursorCurrentlyGrabbed])
+    {
+        CGAssociateMouseAndMouseCursorPosition(NO);
+
+        // Similarly to handleMouseMove: but without event.
+        NSPoint loc = [self cursorPositionFromEvent:nil];
+        [self moveCursorTo:loc];
     }
+    else
+    {
+        CGAssociateMouseAndMouseCursorPosition(YES);
+    }
+}
+
+
+////////////////////////////////////////////////////////
+-(void)moveCursorTo:(NSPoint)loc
+{
+    // Convert the point from SFML coord system to screen coord system.
+    NSPoint screenLocation = [self computeGlobalPositionOfRelativePoint:loc];
+
+    // This won't produce a move event, which is perfect if the cursor was grabbed
+    // as we move it manually based on delta values of the cursor.
+    CGDisplayMoveCursorToPoint([self displayId], NSPointToCGPoint(screenLocation));
+}
+
+
+////////////////////////////////////////////////////////
+-(CGDirectDisplayID)displayId
+{
+    NSScreen* screen = [[self window] screen];
+    NSNumber* displayId = [[screen deviceDescription] objectForKey:@"NSScreenNumber"];
+    return [displayId intValue];
 }
 
 
@@ -247,17 +308,73 @@
 ////////////////////////////////////////////////////////
 -(NSPoint)cursorPositionFromEvent:(NSEvent*)eventOrNil
 {
-    NSPoint loc;
+    NSPoint rawPos;
+
     // If no event given then get current mouse pos.
     if (eventOrNil == nil)
-    {
-        NSPoint rawPos = [[self window] mouseLocationOutsideOfEventStream];
-        loc = [self convertPoint:rawPos fromView:nil];
-    }
+        rawPos = [[self window] mouseLocationOutsideOfEventStream];
     else
+        rawPos = [eventOrNil locationInWindow];
+
+    if ([self isCursorCurrentlyGrabbed])
     {
-        loc = [self convertPoint:[eventOrNil locationInWindow] fromView:nil];
+        if (eventOrNil != nil)
+        {
+            // Special case when the mouse is grabbed:
+            // we need to take into account the delta since the cursor
+            // is dissociated from its position.
+
+            // Ignore any non-move related event
+            if (([eventOrNil type] == NSMouseMoved)        ||
+                ([eventOrNil type] == NSLeftMouseDragged)  ||
+                ([eventOrNil type] == NSRightMouseDragged) ||
+                ([eventOrNil type] == NSOtherMouseDragged))
+            {
+                // Without this factor, the cursor flies around waaay too fast!
+                // But I don't know if it because of retina display or because
+                // some event are sent twice (and that in itself is another mystery).
+                CGFloat factor = 2;
+
+                // Also, this factor is not the same when keeping track of how much
+                // we move the cursor (buffers) when projecting the cursor into the
+                // view when grabbing the cursor for the first time.
+                CGFloat factorBuffer = m_fullscreen ? 1 : 2;
+
+                CGFloat deltaX = [eventOrNil deltaX];
+                CGFloat deltaY = [eventOrNil deltaY];
+
+                // If the buffer for X is empty, move the cursor;
+                // otherwise decrement this buffer a bit.
+                if (m_deltaXBuffer <= 0)
+                    rawPos.x += deltaX / factor;
+                else
+                    m_deltaXBuffer -= std::abs(deltaX / factorBuffer);
+
+                // Rinse and repeat for Y.
+                if (m_deltaYBuffer <= 0)
+                    rawPos.y -= deltaY / factor;
+                else
+                    m_deltaYBuffer -= std::abs(deltaY / factorBuffer);
             }
+        }
+
+        // We also make sure the new point is inside the view
+        NSSize  size   = [self frame].size;
+        NSPoint origin = [self frame].origin;
+        NSPoint oldPos = rawPos;
+        rawPos.x = std::min(std::max(origin.x, rawPos.x), origin.x + size.width - 1);
+        rawPos.y = std::min(std::max(origin.y + 1, rawPos.y), origin.y + size.height);
+        // Note: the `-1` and `+1` on the two lines above prevent the user to click
+        // on the left or below the window, repectively, and therefore prevent the
+        // application to lose focus by accident. The sign of this offset is determinded
+        // by the direction of the x and y axis.
+
+        // Increase X and Y buffer with the distance of the projection
+        m_deltaXBuffer += std::abs(rawPos.x - oldPos.x);
+        m_deltaYBuffer += std::abs(rawPos.y - oldPos.y);
+    }
+
+    NSPoint loc = [self convertPoint:rawPos fromView:nil];
 
     // Don't forget to change to SFML coord system.
     float h = [self frame].size.height;

src/SFML/Window/OSX/SFOpenGLView+mouse_priv.h

@@ -66,6 +66,37 @@
 ////////////////////////////////////////////////////////////
 -(void)handleMouseMove:(NSEvent*)theEvent;
 
+////////////////////////////////////////////////////////////
+/// \brief Check whether the cursor is grabbed or not
+///
+/// The cursor is grabbed if the window is active (key) and
+/// either it is in fullscreen mode or the user wants to
+/// grab it.
+///
+////////////////////////////////////////////////////////////
+-(BOOL)isCursorCurrentlyGrabbed;
+
+////////////////////////////////////////////////////////////
+/// \brief (Dis)connect the cursor's movements from/to the system
+///        and project the cursor into the view
+///
+////////////////////////////////////////////////////////////
+-(void)updateCursorGrabbed;
+
+////////////////////////////////////////////////////////////
+/// \brief Move the cursor to the given location
+///
+/// \param loc location expressed in SFML coordinate system
+///
+////////////////////////////////////////////////////////////
+-(void)moveCursorTo:(NSPoint)loc;
+
+////////////////////////////////////////////////////////////
+/// \brief Get the display identifier on which the view is
+///
+////////////////////////////////////////////////////////////
+-(CGDirectDisplayID)displayId;
+
 ////////////////////////////////////////////////////////////
 /// \brief Convert the NSEvent mouse button type to SFML type
 ///

src/SFML/Window/OSX/SFOpenGLView.h

@@ -52,6 +52,19 @@ namespace sf {
 /// implementation. However, all attributes are defined in the main
 /// interface declaration right below.
 ///
+/// Note about deltaXBuffer and deltaYBuffer: when grabbing the cursor
+/// for the first time, either by entering fullscreen or through
+/// setCursorGrabbed:, the cursor might be projected into the view.
+/// Doing this will result in a big delta (relative movement) in the
+/// next move event (cursorPositionFromEvent:), because no move event
+/// is generated, which in turn will give the impression that the user
+/// want to move the cursor by the same distance it was projected. To
+/// prevent the cursor to fly twice the distance we keep track of how
+/// much the cursor was projected in deltaXBuffer and deltaYBuffer. In
+/// cursorPositionFromEvent: we can then reduce/augment those buffers
+/// to determine when a move event should result in an actual move of
+/// the cursor (that was disconnected from the system).
+///
 ////////////////////////////////////////////////////////////
 @interface SFOpenGLView : NSOpenGLView
 {
@@ -61,6 +74,9 @@ namespace sf {
     NSTrackingArea*               m_trackingArea;   ///< Mouse tracking area
     BOOL                          m_fullscreen;     ///< Indicate whether the window is fullscreen or not
     CGFloat                       m_scaleFactor;    ///< Display scale factor (e.g. 1x for classic display, 2x for retina)
+    BOOL                          m_cursorGrabbed;  ///< Is the mouse cursor trapped?
+    CGFloat                       m_deltaXBuffer;   ///< See note about cursor grabbing above
+    CGFloat                       m_deltaYBuffer;   ///< See note about cursor grabbing above
 
     // Hidden text view used to convert key event to actual chars.
     // We use a silent responder to prevent sound alerts.
@@ -143,6 +159,8 @@ namespace sf {
 ///
 /// \param eventOrNil if nil the cursor position is the current one
 ///
+/// \return the mouse position in SFML coord system
+///
 ////////////////////////////////////////////////////////////
 -(NSPoint)cursorPositionFromEvent:(NSEvent*)eventOrNil;
 
@@ -154,4 +172,22 @@ namespace sf {
 ////////////////////////////////////////////////////////////
 -(BOOL)isMouseInside;
 
+////////////////////////////////////////////////////////////
+/// Clips or releases the mouse cursor
+///
+/// Generate a MouseEntered event when it makes sense.
+///
+/// \param grabbed YES to grab, NO to release
+///
+////////////////////////////////////////////////////////////
+-(void)setCursorGrabbed:(BOOL)grabbed;
+
+////////////////////////////////////////////////////////////
+/// Update the cursor position according to the grabbing behaviour
+///
+/// This function has to be called when the window's state change
+///
+////////////////////////////////////////////////////////////
+-(void)updateCursorGrabbed;
+
 @end

src/SFML/Window/OSX/SFOpenGLView.mm

@@ -108,6 +108,9 @@
 
         m_fullscreen = isFullscreen;
         m_scaleFactor = 1.0; // Default value; it will be updated in finishInit
+        m_cursorGrabbed = NO;
+        m_deltaXBuffer = 0;
+        m_deltaYBuffer = 0;
 
         // Create a hidden text view for parsing key down event properly
         m_silentResponder = [[SFSilentResponder alloc] init];
@@ -163,8 +166,9 @@
                                                  name:NSWindowDidChangeScreenProfileNotification
                                                object:[self window]];
 
-    // Now that we have a window, set up correctly the scale factor
+    // Now that we have a window, set up correctly the scale factor and cursor grabbing
     [self updateScaleFactor];
+    [self updateCursorGrabbed]; // update for fullscreen
 }
 
 
@@ -245,6 +249,7 @@
 
     // Update mouse internal state.
     [self updateMouseState];
+    [self updateCursorGrabbed];
 
     // Update the OGL view to fit the new size.
     [self update];
@@ -263,6 +268,8 @@
 {
     (void)notification;
 
+    [self updateCursorGrabbed];
+
     if (m_requester)
         m_requester->windowGainedFocus();
 
@@ -276,6 +283,8 @@
 {
     (void)notification;
 
+    [self updateCursorGrabbed];
+
     if (m_requester)
         m_requester->windowLostFocus();
 

src/SFML/Window/OSX/SFViewController.mm

@@ -121,6 +121,13 @@
 }
 
 
+////////////////////////////////////////////////////////
+-(void)setCursorGrabbed:(BOOL)grabbed
+{
+    [m_oglView setCursorGrabbed:grabbed];
+}
+
+
 ////////////////////////////////////////////////////////////
 -(NSPoint)position
 {

src/SFML/Window/OSX/SFWindowController.h

@@ -49,6 +49,11 @@ namespace sf {
 /// Used when SFML handle everything and when a NSWindow* is given
 /// as handle to WindowImpl.
 ///
+/// When grabbing the cursor, if the window is resizeable, m_restoreResize is
+/// set to YES and the window is marked as not resizeable. This is to prevent
+/// accidental resize by the user. When the cursor is released, the window
+/// style is restored.
+///
 ////////////////////////////////////////////////////////////
 @interface SFWindowController : NSResponder <WindowImplDelegateProtocol, NSWindowDelegate>
 {
@@ -56,6 +61,7 @@ namespace sf {
     SFOpenGLView*               m_oglView;          ///< OpenGL view for rendering
     sf::priv::WindowImplCocoa*  m_requester;        ///< Requester
     BOOL                        m_fullscreen;       ///< Indicate whether the window is fullscreen or not
+    BOOL                        m_restoreResize;    ///< See note above
 }
 
 ////////////////////////////////////////////////////////////

src/SFML/Window/OSX/SFWindowController.mm

@@ -97,6 +97,8 @@
         m_window = nil;
         m_oglView = nil;
         m_requester = 0;
+        m_fullscreen = NO; // assuming this is the case... too hard to handle anyway.
+        m_restoreResize = NO;
 
         // Retain the window for our own use.
         m_window = [window retain];
@@ -148,6 +150,7 @@
         m_oglView = nil;
         m_requester = 0;
         m_fullscreen = (style & sf::Style::Fullscreen);
+        m_restoreResize = NO;
 
         if (m_fullscreen)
             [self setupFullscreenViewWithMode:mode];
@@ -345,6 +348,29 @@
 }
 
 
+////////////////////////////////////////////////////////
+-(void)setCursorGrabbed:(BOOL)grabbed
+{
+    // Remove or restore resizeable style if needed
+    BOOL resizeable = [m_window styleMask] & NSResizableWindowMask;
+    if (grabbed && resizeable)
+    {
+        m_restoreResize = YES;
+        NSUInteger newStyle = [m_window styleMask] & ~NSResizableWindowMask;
+        [m_window setStyleMask:newStyle];
+    }
+    else if (!grabbed && m_restoreResize)
+    {
+        m_restoreResize = NO;
+        NSUInteger newStyle = [m_window styleMask] | NSResizableWindowMask;
+        [m_window setStyleMask:newStyle];
+    }
+
+    // Forward to our view
+    [m_oglView setCursorGrabbed:grabbed];
+}
+
+
 ////////////////////////////////////////////////////////////
 -(NSPoint)position
 {
@@ -379,6 +405,9 @@
 
     // Place the window.
     [m_window setFrameTopLeftPoint:point];
+
+    // In case the cursor was grabbed we need to update its position
+    [m_oglView updateCursorGrabbed];
 }
 
 

src/SFML/Window/OSX/WindowImplCocoa.hpp

@@ -316,7 +316,7 @@ public:
     ////////////////////////////////////////////////////////////
     /// \brief Grab or release the mouse cursor
     ///
-    /// \param grabbed True to enable, false to disable
+    /// \param grabbed True to grab, false to release
     ///
     ////////////////////////////////////////////////////////////
     virtual void setMouseCursorGrabbed(bool grabbed);

src/SFML/Window/OSX/WindowImplCocoa.mm

@@ -489,7 +489,7 @@ void WindowImplCocoa::setMouseCursorVisible(bool visible)
 ////////////////////////////////////////////////////////////
 void WindowImplCocoa::setMouseCursorGrabbed(bool grabbed)
 {
-
+    [m_delegate setCursorGrabbed:grabbed];
 }
 
 

src/SFML/Window/OSX/WindowImplDelegateProtocol.h

@@ -99,8 +99,10 @@ namespace sf {
 ////////////////////////////////////////////////////////////
 /// \brief Grab or release the mouse cursor
 ///
+/// \param grabbed YES to grab, NO to release
+///
 ////////////////////////////////////////////////////////////
--(void)setCursorGrabbed:(bool)grabbed;
+-(void)setCursorGrabbed:(BOOL)grabbed;
 
 ////////////////////////////////////////////////////////////
 /// \brief Get window position