Mercurial > sdl-ios-xcode
annotate src/thread/generic/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 |
| rev | line source |
|---|---|
| 0 | 1 /* |
| 2 SDL - Simple DirectMedia Layer | |
|
769
b8d311d90021
Updated copyright information for 2004 (Happy New Year!)
Sam Lantinga <slouken@libsdl.org>
parents:
297
diff
changeset
|
3 Copyright (C) 1997-2004 Sam Lantinga |
| 0 | 4 |
| 5 This library is free software; you can redistribute it and/or | |
| 6 modify it under the terms of the GNU Library General Public | |
| 7 License as published by the Free Software Foundation; either | |
| 8 version 2 of the License, or (at your option) any later version. | |
| 9 | |
| 10 This library is distributed in the hope that it will be useful, | |
| 11 but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| 13 Library General Public License for more details. | |
| 14 | |
| 15 You should have received a copy of the GNU Library General Public | |
| 16 License along with this library; if not, write to the Free | |
| 17 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
| 18 | |
| 19 Sam Lantinga | |
|
252
e8157fcb3114
Updated the source with the correct e-mail address
Sam Lantinga <slouken@libsdl.org>
parents:
0
diff
changeset
|
20 slouken@libsdl.org |
| 0 | 21 */ |
| 22 | |
| 23 #ifdef SAVE_RCSID | |
| 24 static char rcsid = | |
| 25 "@(#) $Id$"; | |
| 26 #endif | |
| 27 | |
| 28 /* An implementation of mutexes using semaphores */ | |
| 29 | |
| 30 #include <stdio.h> | |
| 31 #include <stdlib.h> | |
| 32 | |
| 33 #include "SDL_error.h" | |
| 34 #include "SDL_thread.h" | |
| 35 #include "SDL_systhread_c.h" | |
| 36 | |
| 37 | |
| 38 struct SDL_mutex { | |
| 39 int recursive; | |
| 40 Uint32 owner; | |
| 41 SDL_sem *sem; | |
| 42 }; | |
| 43 | |
| 44 /* Create a mutex */ | |
| 45 SDL_mutex *SDL_CreateMutex(void) | |
| 46 { | |
| 47 SDL_mutex *mutex; | |
| 48 | |
| 49 /* Allocate mutex memory */ | |
| 50 mutex = (SDL_mutex *)malloc(sizeof(*mutex)); | |
| 51 if ( mutex ) { | |
| 52 /* Create the mutex semaphore, with initial value 1 */ | |
| 53 mutex->sem = SDL_CreateSemaphore(1); | |
| 54 mutex->recursive = 0; | |
| 55 mutex->owner = 0; | |
| 56 if ( ! mutex->sem ) { | |
| 57 free(mutex); | |
| 58 mutex = NULL; | |
| 59 } | |
| 60 } else { | |
| 61 SDL_OutOfMemory(); | |
| 62 } | |
| 63 return mutex; | |
| 64 } | |
| 65 | |
| 66 /* Free the mutex */ | |
| 67 void SDL_DestroyMutex(SDL_mutex *mutex) | |
| 68 { | |
| 69 if ( mutex ) { | |
| 70 if ( mutex->sem ) { | |
| 71 SDL_DestroySemaphore(mutex->sem); | |
| 72 } | |
| 73 free(mutex); | |
| 74 } | |
| 75 } | |
| 76 | |
| 77 /* Lock the semaphore */ | |
| 78 int SDL_mutexP(SDL_mutex *mutex) | |
| 79 { | |
| 80 #ifdef DISABLE_THREADS | |
| 81 return 0; | |
| 82 #else | |
| 83 Uint32 this_thread; | |
| 84 | |
| 85 if ( mutex == NULL ) { | |
| 86 SDL_SetError("Passed a NULL mutex"); | |
| 87 return -1; | |
| 88 } | |
| 89 | |
| 90 this_thread = SDL_ThreadID(); | |
| 91 if ( mutex->owner == this_thread ) { | |
| 92 ++mutex->recursive; | |
| 93 } else { | |
| 94 /* The order of operations is important. | |
| 95 We set the locking thread id after we obtain the lock | |
| 96 so unlocks from other threads will fail. | |
| 97 */ | |
| 98 SDL_SemWait(mutex->sem); | |
| 99 mutex->owner = this_thread; | |
| 100 mutex->recursive = 0; | |
| 101 } | |
| 102 | |
| 103 return 0; | |
| 104 #endif /* DISABLE_THREADS */ | |
| 105 } | |
| 106 | |
| 107 /* Unlock the mutex */ | |
| 108 int SDL_mutexV(SDL_mutex *mutex) | |
| 109 { | |
| 110 #ifdef DISABLE_THREADS | |
| 111 return 0; | |
| 112 #else | |
| 113 if ( mutex == NULL ) { | |
| 114 SDL_SetError("Passed a NULL mutex"); | |
| 115 return -1; | |
| 116 } | |
| 117 | |
| 118 /* If we don't own the mutex, we can't unlock it */ | |
| 119 if ( SDL_ThreadID() != mutex->owner ) { | |
| 120 SDL_SetError("mutex not owned by this thread"); | |
| 121 return -1; | |
| 122 } | |
| 123 | |
| 124 if ( mutex->recursive ) { | |
| 125 --mutex->recursive; | |
| 126 } else { | |
| 127 /* The order of operations is important. | |
| 128 First reset the owner so another thread doesn't lock | |
| 129 the mutex and set the ownership before we reset it, | |
| 130 then release the lock semaphore. | |
| 131 */ | |
| 132 mutex->owner = 0; | |
| 133 SDL_SemPost(mutex->sem); | |
| 134 } | |
| 135 return 0; | |
| 136 #endif /* DISABLE_THREADS */ | |
| 137 } |