To: sdl@libsdl.org From: Christian Walther <cwalther@gmx.ch> Date: Thu, 15 Dec 2005 21:19:53 +0100 Subject: [SDL] More mouse enhancements for Mac OS X The attached patch brings two more enhancements to mouse handling on Mac OS X (Quartz): 1. Currently, after launching an SDL application, SDL's notion of the mouse position is stuck in the top left corner (0,0) until the first time the mouse is moved. That's because the UpdateMouse() function isn't implemented in the Quartz driver. This patch adds it. 2. When grabbing input while the mouse cursor is hidden, the function CGAssociateMouseAndMouseCursorPosition(0) is called, which prevents the system's notion of the mouse location from moving (and therefore leaving the SDL window) even when the mouse is moved. However, apparently the Wacom tablet driver (and maybe other special pointing device drivers) doesn't care about that setting and still allows the mouse location to go outside of the window. Interestingly, the system cursor, which is made visible by the existing code in SDL in that case, does not follow the mouse location, but appears in the middle of the SDL window. The mouse location being outside of the window however means that mouse button events go to background applications (or the dock or whatever is there), which is very confusing to the user who sees no cursor outside of the SDL window. I have not found any way of intercepting these events (and that's probably by design, as "normal" applications shouldn't prevent the user from bringing other applications' windows to the front by clicking on them). An idea would be placing a fully transparent, screen-filling window in front of everything, but I fear that this might affect rendering performance (by doing unnecessary compositing, using up memory, or whatever). The deluxe solution to the problem would be talking to the tablet driver using AppleEvents to tell it to constrain its mapped area to the window (see Wacom's "TabletEventDemo" sample app, http://www.wacomeng.com/devsupport/mac/downloads.html), but I think that the bloat that solution would add to SDL would outweigh its usefulness. What I did instead in my patch is reassociating mouse and cursor when the mouse leaves the window while an invisible grab is in effect, and restoring the grab when the window is entered. That way, the grab can still be effectively broken by a tablet, but at least it's obvious to the user that it is broken. That change is minimal - it doesn't affect operation with a mouse (or a trackpad), and the code that it adds is not executed on every PumpEvents() call, only when entering and leaving the window. Unless there are any concerns about the patch, please apply. Feel free to shorten the lengthy comment in SDL_QuartzEvents.m if you think it's too verbose. Thanks -Christian

/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2004 Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public
    License along with this library; if not, write to the Free
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    Sam Lantinga
    slouken@libsdl.org
*/

#ifdef SAVE_RCSID
static char rcsid =
 "@(#) $Id$";
#endif

/* This is the system specific header for the SDL CD-ROM API */

/* Structure of CD audio control functions */
extern struct CDcaps {
	/* Get the name of the specified drive */
	const char *(*Name)(int drive);

	/* Open the specified drive, returning a drive id, or -1 on error */
	int (*Open)(int drive);

	/* Get table-of-contents (number of tracks + track info) for disk.
	   The TOC information should be stored in the cdrom structure.
	   This function should return 0 on success, or -1 on error.
	 */
	int (*GetTOC)(SDL_CD *cdrom);

	/* Return the current status and play position, in frames, of the
	   drive.  'position' may be NULL, and if so, should be ignored.
	 */
	CDstatus (*Status)(SDL_CD *cdrom, int *position);

	/* Play from frame 'start' to 'start+len' */
	int (*Play)(SDL_CD *cdrom, int start, int len); 

	/* Pause play */
	int (*Pause)(SDL_CD *cdrom);

	/* Resume play */
	int (*Resume)(SDL_CD *cdrom);

	/* Stop play */
	int (*Stop)(SDL_CD *cdrom);

	/* Eject the current disk */
	int (*Eject)(SDL_CD *cdrom);

	/* Close the specified drive */
	void (*Close)(SDL_CD *cdrom);
} SDL_CDcaps;

/* The number of available CD-ROM drives on the system */
extern int SDL_numcds;

/* Function to scan the system for CD-ROM drives and fill SDL_CDcaps.
 * This function should set SDL_numcds to the number of available CD
 * drives.  Drive 0 should be the system default CD-ROM.
 * It should return 0, or -1 on an unrecoverable fatal error.
*/
extern int  SDL_SYS_CDInit(void);

/* Function to perform any system-specific CD-ROM related cleanup */
extern void SDL_SYS_CDQuit(void);