view src/video/x11/SDL_x11dyn.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 fe7d081a4955
children 19418e4422cb
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
*/

#if 0
#define DEBUG_DYNAMIC_X11 1
#endif

#define __SDL_NO_REDEFINE_X11_HEADER_SYMS 1
#include "SDL_x11dyn.h"

#ifdef DEBUG_DYNAMIC_X11
#include <stdio.h>
#endif

#ifdef X11_DYNAMIC
#include <dlfcn.h>
#include "SDL_name.h"
#include "SDL_loadso.h"
static const char *x11_library = X11_DYNAMIC;
static void *x11_handle = NULL;
static const char *x11ext_library = X11EXT_DYNAMIC;
static void *x11ext_handle = NULL;

static void *X11_GetSym(int required, const char *fnname, int *rc)
{
	void *fn = NULL;
	if (*rc) {  /* haven't already failed on a previous lookup? */
		fn = SDL_LoadFunction(x11_handle, fnname);
		#if DEBUG_DYNAMIC_X11
		if (fn != NULL)
			printf("X11: Found '%s' in libX11 (%p)\n", fnname, fn);
		#endif

		if (fn == NULL) {  /* not found? Check libX11ext ... */
			fn = SDL_LoadFunction(x11ext_handle, fnname);
			#if DEBUG_DYNAMIC_X11
			if (fn != NULL)
				printf("X11: Found '%s' in libXext (%p)\n", fnname, fn);
			else
				printf("X11: Symbol '%s' NOT FOUND!%s\n", fnname,
				       required ? "" : " (...but not required!)");
			#endif
		}
		*rc = ((fn != NULL) || (!required));
	}

	return fn;
}
#endif  /* defined X11_DYNAMIC */

/* Define all the function pointers... */
#define SDL_X11_SYM(req,ret,fn,params) ret (*p##fn) params = NULL;
#include "SDL_x11sym.h"
#undef SDL_X11_SYM

static int x11_load_refcount = 0;

void SDL_X11_UnloadSymbols(void)
{
	/* Don't actually unload if more than one module is using the libs... */
	if (x11_load_refcount > 0) {
		if (--x11_load_refcount == 0) {
			/* set all the function pointers to NULL. */
			#define SDL_X11_SYM(req,ret,fn,params) p##fn = NULL;
			#include "SDL_x11sym.h"
			#undef SDL_X11_SYM

			#ifdef X11_DYNAMIC
			if (x11_handle != NULL) {
				SDL_UnloadObject(x11_handle);
				x11_handle = NULL;
			}
			if (x11ext_handle != NULL) {
				SDL_UnloadObject(x11ext_handle);
				x11ext_handle = NULL;
			}
			#endif
		}
	}
}

/* returns non-zero if all needed symbols were loaded. */
int SDL_X11_LoadSymbols(void)
{
	int rc = 1;

    /* deal with multiple modules (dga, x11, etc) needing these symbols... */
	if (x11_load_refcount++ == 0) {
		#ifdef X11_DYNAMIC
			x11_handle = SDL_LoadObject(x11_library);
			x11ext_handle = SDL_LoadObject(x11ext_library);
			rc = ((x11_handle != NULL) && (x11ext_handle != NULL));
			#define SDL_X11_SYM(req,r,fn,arg) p##fn = X11_GetSym(req,#fn, &rc);
			#include "SDL_x11sym.h"
			#undef SDL_X11_SYM

			if (!rc)
				SDL_X11_UnloadSymbols();  /* in case one of these loaded... */

		#else
			#define SDL_X11_SYM(req,r,fn,arg) p##fn = fn;
			#include "SDL_x11sym.h"
			#undef SDL_X11_SYM
		#endif
	}

	return rc;
}

/* end of SDL_x11dyn.c ... */