view src/thread/linux/SDL_sysmutex.c @ 1287:15a89a0c52bf

Date: Tue, 15 Feb 2005 21:28:48 +0900 (JST) From: "Michael Leonhard" Subject: [SDL] resize bug on Win32 and patch This is my first post to this mailing list. In this email I will detail a bug in the behavior of resizable SDL windows on Win32. Then I will explain the solution and provide a patch. Symptoms: Under Windows, an SDL display created with the SDL_RESIZABLE flag exhibits quirky behavior when being maximized. The window is resized to the proper size, but it is shifted upwards about half the height of the title bar. Similarly, a window whose origin is above the top of the screen will spontaneously move its upper-left origin upon being resized. After two such resize-induced moves, the title bar will be entirely off the top edge of the screen. Subsequently, when the mouse is clicked and released on the window border, the window will shrink its height spontaneously. This height shrinkage occurs even if the user did not resize the border. To observe this curious situation, please invoke: SDL-1.2.8/test/testwm.exe -resize Cause: A pair of integers, SDL_windowX and SDL_windowY, are defined in video/wincommon/SDL_sysevents.c. They are used by the DirectX video driver and the DIB video driver: video/windx5/SDL_dx5video.c video/windib/SDL_dibvideo.c As I understand the source code, the primary use of these variables is to create a rectangle that represents the surface area in CLIENT SPACE. Client space refers to a coordinate system that originates at the upper left corner of a Win32 Window's drawable area. This is just inside the window border and title bar. This client space rectangle, called bounds, is subsequently converted to screen space with a call to AdjustWindowRectEx. The problem is found in SDL's handling of the WM_WINDOWPOSCHANGED message. According to MSDN, "The WM_WINDOWPOSCHANGED message is sent to a window whose size, position, or place in the Z order has changed as a result of a call to the SetWindowPos function or another window-management function." I have confirmed that this message is indeed being sent to the SDL window when the mouse is clicked on the window border, even if the window border is not dragged. In video/wincommon/SDL_sysevents.c, on line 464, in response to the WM_WINDOWPOSCHANGED message, the (potentially) new client rectangle is obtained. This rectangle is translated into screen coordinates and THEN assigned to the SDL_windowX and Y variables. Thus screen coordinates are being assigned to client coordinate variables. Once this is understood, the solution is apparent: assign SDL_windowX and Y before translating the rectangle to screen coordinates. This is accomplished by the following patch. -Mike_L
author Sam Lantinga <slouken@libsdl.org>
date Sun, 29 Jan 2006 08:50:06 +0000
parents b8d311d90021
children c9b51268668f
line wrap: on
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/*
    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

#ifdef linux
/* Look to see if glibc is available, and if so, what version */
#include <features.h>

#if (__GLIBC__ == 2) && (__GLIBC_MINOR__ == 0)
#warning Working around a bug in glibc 2.0 pthreads
#undef SDL_USE_PTHREADS
/* The bug is actually a problem where threads are suspended, but don't
   wake up when the thread manager sends them a signal.  This is a problem
   with thread creation too, but it happens less often. :-/
   We avoid this by using System V IPC for mutexes.
 */
#endif /* glibc 2.0 */
#endif /* linux */

#ifdef SDL_USE_PTHREADS

#include <stdlib.h>
#include <stdio.h>
#include <pthread.h>

#include "SDL_error.h"
#include "SDL_thread.h"


struct SDL_mutex {
	pthread_mutex_t id;
#ifdef PTHREAD_NO_RECURSIVE_MUTEX
	int recursive;
	pthread_t owner;
#endif
};

SDL_mutex *SDL_CreateMutex (void)
{
	SDL_mutex *mutex;
	pthread_mutexattr_t attr;

	/* Allocate the structure */
	mutex = (SDL_mutex *)calloc(1, sizeof(*mutex));
	if ( mutex ) {
		pthread_mutexattr_init(&attr);
#ifdef PTHREAD_NO_RECURSIVE_MUTEX
		/* No extra attributes necessary */
#else
#ifdef linux
		pthread_mutexattr_setkind_np(&attr, PTHREAD_MUTEX_RECURSIVE_NP);
#else
		pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
#endif
#endif /* PTHREAD_NO_RECURSIVE_MUTEX */
		if ( pthread_mutex_init(&mutex->id, &attr) != 0 ) {
			SDL_SetError("pthread_mutex_init() failed");
			free(mutex);
			mutex = NULL;
		}
	} else {
		SDL_OutOfMemory();
	}
	return(mutex);
}

void SDL_DestroyMutex(SDL_mutex *mutex)
{
	if ( mutex ) {
		pthread_mutex_destroy(&mutex->id);
		free(mutex);
	}
}

/* Lock the mutex */
int SDL_mutexP(SDL_mutex *mutex)
{
	int retval;
#ifdef PTHREAD_NO_RECURSIVE_MUTEX
	pthread_t this_thread;
#endif

	if ( mutex == NULL ) {
		SDL_SetError("Passed a NULL mutex");
		return -1;
	}

	retval = 0;
#ifdef PTHREAD_NO_RECURSIVE_MUTEX
	this_thread = pthread_self();
	if ( mutex->owner == this_thread ) {
		++mutex->recursive;
	} else {
		/* The order of operations is important.
		   We set the locking thread id after we obtain the lock
		   so unlocks from other threads will fail.
		*/
		if ( pthread_mutex_lock(&mutex->id) == 0 ) {
			mutex->owner = this_thread;
			mutex->recursive = 0;
		} else {
			SDL_SetError("pthread_mutex_lock() failed");
			retval = -1;
		}
	}
#else
	if ( pthread_mutex_lock(&mutex->id) < 0 ) {
		SDL_SetError("pthread_mutex_lock() failed");
		retval = -1;
	}
#endif
	return retval;
}

int SDL_mutexV(SDL_mutex *mutex)
{
	int retval;

	if ( mutex == NULL ) {
		SDL_SetError("Passed a NULL mutex");
		return -1;
	}

	retval = 0;
#ifdef PTHREAD_NO_RECURSIVE_MUTEX
	/* We can only unlock the mutex if we own it */
	if ( pthread_self() == mutex->owner ) {
		if ( mutex->recursive ) {
			--mutex->recursive;
		} else {
			/* The order of operations is important.
			   First reset the owner so another thread doesn't lock
			   the mutex and set the ownership before we reset it,
			   then release the lock semaphore.
			 */
			mutex->owner = 0;
			pthread_mutex_unlock(&mutex->id);
		}
	} else {
		SDL_SetError("mutex not owned by this thread");
		retval = -1;
	}

#else
	if ( pthread_mutex_unlock(&mutex->id) < 0 ) {
		SDL_SetError("pthread_mutex_unlock() failed");
		retval = -1;
	}
#endif /* PTHREAD_NO_RECURSIVE_MUTEX */

	return retval;
}

#else /* Use semaphore implementation */

#include "generic/SDL_sysmutex.c"

#endif /* SDL_USE_PTHREADS */