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

/*
   Header definitions for the MMX routines for the HERMES library
   Copyright (c) 1998 Christian Nentwich (c.nentwich@cs.ucl.ac.uk)
   This source code is licensed under the GNU LGPL
  
   Please refer to the file COPYING.LIB contained in the distribution for
   licensing conditions
*/

#ifndef __HERMES_HEAD_MMX__
#define __HERMES_HEAD_MMX__


/* If you cannot stand ifdefs, then please do not look into this file, it's
   going to end your life :) */

#ifdef X86_ASSEMBLER


#ifdef __cplusplus
extern "C" {
#endif

void STACKCALL ConvertMMX(HermesConverterInterface *);

void STACKCALL ClearMMX_32(HermesClearInterface *);
void STACKCALL ClearMMX_24(HermesClearInterface *);
void STACKCALL ClearMMX_16(HermesClearInterface *);
void STACKCALL ClearMMX_8(HermesClearInterface *);

void ConvertMMXpII32_24RGB888();
void ConvertMMXpII32_16RGB565();
void ConvertMMXpII32_16BGR565();
void ConvertMMXpII32_16RGB555();
void ConvertMMXpII32_16BGR565();
void ConvertMMXpII32_16BGR555();

void ConvertMMXp32_16RGB555();

#ifdef __cplusplus
}
#endif



/* Fix the underscore business with ELF compilers */

#if defined(__ELF__) && defined(__GNUC__)
  #ifdef __cplusplus 
  extern "C" {   
  #endif

  extern void _ConvertMMX(HermesConverterInterface *);
  extern void _ConvertMMXpII32_24RGB888();
  extern void _ConvertMMXpII32_16RGB565();
  extern void _ConvertMMXpII32_16BGR565();
  extern void _ConvertMMXpII32_16RGB555();
  extern void _ConvertMMXpII32_16BGR555();

  #define ConvertMMX _ConvertMMX
  #define ConvertMMXpII32_24RGB888 _ConvertMMXpII32_24RGB888
  #define ConvertMMXpII32_16RGB565 _ConvertMMXpII32_16RGB565
  #define ConvertMMXpII32_16BGR565 _ConvertMMXpII32_16BGR565
  #define ConvertMMXpII32_16RGB555 _ConvertMMXpII32_16RGB555
  #define ConvertMMXpII32_16BGR555 _ConvertMMXpII32_16BGR555

  #ifdef __cplusplus
  }
  #endif

#endif /* ELF and GNUC */




/* Make it work with Watcom */
#ifdef __WATCOMC__
#pragma warning 601 9

#pragma aux ConvertMMX "_*" modify [EAX EBX ECX EDX ESI EDI]

#pragma aux ClearMMX_32 "_*" modify [EAX EBX ECX EDX ESI EDI]
#pragma aux ClearMMX_24 "_*" modify [EAX EBX ECX EDX ESI EDI]
#pragma aux ClearMMX_16 "_*" modify [EAX EBX ECX EDX ESI EDI]
#pragma aux ClearMMX_8 "_*" modify [EAX EBX ECX EDX ESI EDI]

#pragma aux ConvertMMXpII32_24RGB888 "_*"
#pragma aux ConvertMMXpII32_16RGB565 "_*"
#pragma aux ConvertMMXpII32_16BGR565 "_*"
#pragma aux ConvertMMXpII32_16RGB555 "_*"
#pragma aux ConvertMMXpII32_16BGR555 "_*"
#pragma aux ConvertMMXp32_16RGB555 "_*"

#endif /* WATCOM */

#endif /* X86_ASSEMBLER */


#endif