src/events/SDL_mouse.c
author Sam Lantinga
Sat, 21 Aug 2004 12:38:50 +0000
changeset 943 715c32d8f26c
parent 769 b8d311d90021
child 1123 28ac87a38c17
permissions -rw-r--r--
Date: Sun, 18 Jul 2004 00:22:07 -0400
From: "Philippe Anctil"
Subject: [SDL] odd mouse event generated on init

The mouse relative and absolute coordinates appear to be always equal for
the first mouse event.
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/*
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    SDL - Simple DirectMedia Layer
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    Copyright (C) 1997-2004 Sam Lantinga
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    This library is free software; you can redistribute it and/or
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    modify it under the terms of the GNU Library General Public
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    License as published by the Free Software Foundation; either
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    version 2 of the License, or (at your option) any later version.
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    This library is distributed in the hope that it will be useful,
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    but WITHOUT ANY WARRANTY; without even the implied warranty of
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    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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    Library General Public License for more details.
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    You should have received a copy of the GNU Library General Public
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    License along with this library; if not, write to the Free
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    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
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    Sam Lantinga
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    slouken@libsdl.org
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*/
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#ifdef SAVE_RCSID
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static char rcsid =
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 "@(#) $Id$";
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#endif
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/* General mouse handling code for SDL */
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "SDL_events.h"
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#include "SDL_events_c.h"
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#include "SDL_cursor_c.h"
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#include "SDL_sysvideo.h"
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/* These are static for our mouse handling code */
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static Sint16 SDL_MouseX = -1;
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static Sint16 SDL_MouseY = -1;
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static Sint16 SDL_DeltaX = 0;
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static Sint16 SDL_DeltaY = 0;
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static Uint8  SDL_ButtonState = 0;
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/* Public functions */
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int SDL_MouseInit(void)
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{
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	/* The mouse is at (0,0) */
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	SDL_MouseX = -1;
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	SDL_MouseY = -1;
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	SDL_DeltaX = 0;
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	SDL_DeltaY = 0;
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	SDL_ButtonState = 0;
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	/* That's it! */
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	return(0);
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}
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/* We lost the mouse, so post button up messages for all pressed buttons */
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void SDL_ResetMouse(void)
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{
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	Uint8 i;
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	for ( i = 0; i < sizeof(SDL_ButtonState)*8; ++i ) {
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		if ( SDL_ButtonState & SDL_BUTTON(i) ) {
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			SDL_PrivateMouseButton(SDL_RELEASED, i, 0, 0);
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		}
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	}
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}
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Uint8 SDL_GetMouseState (int *x, int *y)
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{
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	if ( x ) {
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		if ( SDL_MouseX < 0 ) {
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			*x = 0;
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		} else {
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			*x = SDL_MouseX;
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		}
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	}
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	if ( y ) {
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		if ( SDL_MouseY < 0 ) {
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			*y = 0;
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		} else {
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			*y = SDL_MouseY;
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		}
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	}
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	return(SDL_ButtonState);
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}
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Uint8 SDL_GetRelativeMouseState (int *x, int *y)
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{
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	if ( x )
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		*x = SDL_DeltaX;
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	if ( y )
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		*y = SDL_DeltaY;
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	SDL_DeltaX = 0;
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	SDL_DeltaY = 0;
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	return(SDL_ButtonState);
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}
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static void ClipOffset(Sint16 *x, Sint16 *y)
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{
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	/* This clips absolute mouse coordinates when the apparent
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	   display surface is smaller than the real display surface.
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	 */
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	if ( SDL_VideoSurface->offset ) {
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		*y -= SDL_VideoSurface->offset/SDL_VideoSurface->pitch;
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		*x -= (SDL_VideoSurface->offset%SDL_VideoSurface->pitch)/
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				SDL_VideoSurface->format->BytesPerPixel;
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	}
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}
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/* These are global for SDL_eventloop.c */
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int SDL_PrivateMouseMotion(Uint8 buttonstate, int relative, Sint16 x, Sint16 y)
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{
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	int posted;
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	Uint16 X, Y;
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	Sint16 Xrel;
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	Sint16 Yrel;
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	/* Don't handle mouse motion if there's no cursor surface */
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	if ( SDL_VideoSurface == NULL ) {
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		return(0);
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	}
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	/* Default buttonstate is the current one */
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	if ( ! buttonstate ) {
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		buttonstate = SDL_ButtonState;
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	}
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	Xrel = x;
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	Yrel = y;
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	if ( relative ) {
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		/* Push the cursor around */
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		x = (SDL_MouseX+x);
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		y = (SDL_MouseY+y);
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	} else {
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		/* Do we need to clip {x,y} ? */
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		ClipOffset(&x, &y);
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	}
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	/* Mouse coordinates range from 0 - width-1 and 0 - height-1 */
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	if ( x < 0 )
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		X = 0;
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	else
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	if ( x >= SDL_VideoSurface->w )
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		X = SDL_VideoSurface->w-1;
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	else
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		X = (Uint16)x;
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	if ( y < 0 )
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		Y = 0;
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	else
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	if ( y >= SDL_VideoSurface->h )
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		Y = SDL_VideoSurface->h-1;
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	else
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		Y = (Uint16)y;
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	/* If not relative mode, generate relative motion from clamped X/Y.
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	   This prevents lots of extraneous large delta relative motion when
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	   the screen is windowed mode and the mouse is outside the window.
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	*/
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	if ( ! relative && SDL_MouseX >= 0 && SDL_MouseY >= 0 ) {
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		Xrel = X-SDL_MouseX;
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		Yrel = Y-SDL_MouseY;
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	}
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	/* Update internal mouse state */
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	SDL_ButtonState = buttonstate;
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	SDL_MouseX = X;
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	SDL_MouseY = Y;
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	SDL_DeltaX += Xrel;
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	SDL_DeltaY += Yrel;
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	SDL_MoveCursor(SDL_MouseX, SDL_MouseY);
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	/* Post the event, if desired */
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	posted = 0;
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	if ( SDL_ProcessEvents[SDL_MOUSEMOTION] == SDL_ENABLE ) {
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		SDL_Event event;
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		memset(&event, 0, sizeof(event));
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		event.type = SDL_MOUSEMOTION;
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		event.motion.state = buttonstate;
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		event.motion.x = X;
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		event.motion.y = Y;
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		event.motion.xrel = Xrel;
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		event.motion.yrel = Yrel;
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		if ( (SDL_EventOK == NULL) || (*SDL_EventOK)(&event) ) {
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			posted = 1;
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			SDL_PushEvent(&event);
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		}
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	}
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	return(posted);
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}
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int SDL_PrivateMouseButton(Uint8 state, Uint8 button, Sint16 x, Sint16 y)
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{
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	SDL_Event event;
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	int posted;
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	int move_mouse;
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	Uint8 buttonstate;
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	memset(&event, 0, sizeof(event));
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	/* Check parameters */
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	if ( x || y ) {
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		ClipOffset(&x, &y);
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		move_mouse = 1;
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		/* Mouse coordinates range from 0 - width-1 and 0 - height-1 */
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		if ( x < 0 )
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			x = 0;
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		else
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		if ( x >= SDL_VideoSurface->w )
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			x = SDL_VideoSurface->w-1;
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		if ( y < 0 )
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			y = 0;
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		else
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		if ( y >= SDL_VideoSurface->h )
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			y = SDL_VideoSurface->h-1;
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	} else {
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		move_mouse = 0;
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	}
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	if ( ! x )
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		x = SDL_MouseX;
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	if ( ! y )
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		y = SDL_MouseY;
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	/* Figure out which event to perform */
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	buttonstate = SDL_ButtonState;
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	switch ( state ) {
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		case SDL_PRESSED:
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			event.type = SDL_MOUSEBUTTONDOWN;
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			buttonstate |= SDL_BUTTON(button);
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			break;
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		case SDL_RELEASED:
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			event.type = SDL_MOUSEBUTTONUP;
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			buttonstate &= ~SDL_BUTTON(button);
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			break;
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		default:
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			/* Invalid state -- bail */
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			return(0);
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	}
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	/* Update internal mouse state */
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	SDL_ButtonState = buttonstate;
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	if ( move_mouse ) {
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		SDL_MouseX = x;
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		SDL_MouseY = y;
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		SDL_MoveCursor(SDL_MouseX, SDL_MouseY);
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	}
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	/* Post the event, if desired */
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	posted = 0;
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	if ( SDL_ProcessEvents[event.type] == SDL_ENABLE ) {
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		event.button.state = state;
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		event.button.button = button;
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		event.button.x = x;
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		event.button.y = y;
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		if ( (SDL_EventOK == NULL) || (*SDL_EventOK)(&event) ) {
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			posted = 1;
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			SDL_PushEvent(&event);
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		}
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	}
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	return(posted);
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}
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