view test/threadwin.c @ 4139:568c9b3c0167 SDL-1.2

* Added configure option --enable-screensaver, to allow enabling the screensaver by default. * Use XResetScreenSaver() instead of disabling screensaver entirely. Full discussion summary from Erik on the SDL mailing list: Current behaviour ================= SDL changes the user's display power management settings without permission from the user and without telling the user. The interface that it uses to do so is DPMSDisable/DPMSEnable, which should only ever be used by configuration utilities like KControl, never by normal application programs, let alone by the libraries that they use. Using an interface that is not at all intended for what SDL tries to achieve means that it will not work as it should. Firstly, the power management is completely disabled during the whole lifetime of the SDL program, not only when it should be. Secondly, it makes SDL non-reentrant, meaning that things will break when multiple SDL programs are clients of the same X server simultaneously. Thirdly, no cleanup mechanism ensures that the setting is restored if the client does not do that (for example if it crashes). In addition to that, this interface is broken on xorg, [http://bugs.freedesktop.org/show_bug.cgi?id=13962], so what SDL tries to do does not work at all on that implementation of the X Window System. (The reason that the DPMSEnable works in KControl is that it calls DPMSSetTimeout immediately after, [http://websvn.kde.org/tags/KDE/3.5.9/kdebase/kcontrol/energy/energy.cpp?annotate=774532#l343]). The problems that the current behaviour causes ============================================== 1. Information leak. When the user is away, someone might see what the user has on the display when the user counts on the screensaver preventing this. This does not even require physical access to the workstation, it is enough to see it from a distance. 2. Draining battery. An SDL program that runs on a laptop will quickly drain the battery while the user is away. The system will soon shut down and require recharging before being usable again, while it should in fact have consumed very little energy if the user's settings would have been obeyed. 3. Wasting energy. Even if battery issues are not considered, energy as such is wasted. 4. Display wear. The display may be worn out. The problems that the current behaviour tries to solve ====================================================== 1. Preventing screensaver while playing movies. Many SDL applications are media players. They have reasons to prevent screensavers from being activated while a movie is being played. When a user clicks on the play button it can be interpreted as saying "play this movie, but do not turn off the display while playing it, because I will watch it even though I do not interact with the system". 2. Preventing screensaver when some input bypasses X. Sometimes SDL uses input from another source than the X server, so that the X server is bypassed. This obviously breaks the screensaver handling. SDL tries to work around that. 3. Preventing screensaver when all input bypasses X. There is something called Direct Graphics Access mode, where a program takes control of both the display and the input devices from the X server. This obviously means that the X server can not handle the screensaver alone, since screensaver handling depends on input handling. SDL does not do what it should to help the X server to handle the screensaver. Nor does SDL take care of screeensaver handling itself. SDL simply disables the screensaver completely. How the problems should be solved ================================= The correct way for an application program to prevent the screensaver under X is to call XResetScreenSaver. This was recently discovered and implemented by the mplayer developers, [http://svn.mplayerhq.hu/mplayer?view=rev&revision=25637]. SDL needs to wrap this in an API call (SDL_ResetScreenSaver) and implement it for the other video targets (if they do not have a corresponding call, SDL should do what it takes on that particular target, for example sending fake key events). 1. When a movie is played, the player should reset the screensaver when the animation is advanced to a new frame. The same applies to anything similar, like slideshows. 2. When the X server is handling input, it must handle all input (keyboards, mice, gamepads, ...). This is necessary, not only to be able to handle the screensaver, but also so that it can send the events to the correct (the currently active) client. If there is an input device that the X server can not handle for some reason (such as lack of Plug and Play capability), the program that handles the device as a workaround must simulate what would happen if the X server would have handled the device, by calling XResetScreenSaver when input is received from the device. 3. When the X server is not handling the input, it depends on the program that does to call XResetScreenSaver whenever an input event occurs. Alternatively the program must handle the screensaver countdown internally and call XActivateScreenSaver.
author Sam Lantinga <slouken@libsdl.org>
date Fri, 29 Feb 2008 13:55:44 +0000
parents 3868bebb9f5b
children
line wrap: on
line source


/* Test out the multi-threaded event handling functions */

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

#include "SDL.h"
#include "SDL_thread.h"

/* Are we done yet? */
static int done = 0;

/* Is the cursor visible? */
static int visible = 1;

/* Call this instead of exit(), so we can clean up SDL: atexit() is evil. */
static void quit(int rc)
{
	SDL_Quit();
	exit(rc);
}

SDL_Surface *LoadIconSurface(char *file, Uint8 **maskp)
{
	SDL_Surface *icon;
	Uint8       *pixels;
	Uint8       *mask;
	int          mlen, i;

	*maskp = NULL;

	/* Load the icon surface */
	icon = SDL_LoadBMP(file);
	if ( icon == NULL ) {
		fprintf(stderr, "Couldn't load %s: %s\n", file, SDL_GetError());
		return(NULL);
	}

	/* Check width and height */
	if ( (icon->w%8) != 0 ) {
		fprintf(stderr, "Icon width must be a multiple of 8!\n");
		SDL_FreeSurface(icon);
		return(NULL);
	}
	if ( icon->format->palette == NULL ) {
		fprintf(stderr, "Icon must have a palette!\n");
		SDL_FreeSurface(icon);
		return(NULL);
	}

	/* Set the colorkey */
	SDL_SetColorKey(icon, SDL_SRCCOLORKEY, *((Uint8 *)icon->pixels));

	/* Create the mask */
	pixels = (Uint8 *)icon->pixels;
	printf("Transparent pixel: (%d,%d,%d)\n",
				icon->format->palette->colors[*pixels].r,
				icon->format->palette->colors[*pixels].g,
				icon->format->palette->colors[*pixels].b);
	mlen = icon->w*icon->h;
	mask = (Uint8 *)malloc(mlen/8);
	if ( mask == NULL ) {
		fprintf(stderr, "Out of memory!\n");
		SDL_FreeSurface(icon);
		return(NULL);
	}
	memset(mask, 0, mlen/8);
	for ( i=0; i<mlen; ) {
		if ( pixels[i] != *pixels )
			mask[i/8] |= 0x01;
		++i;
		if ( (i%8) != 0 )
			mask[i/8] <<= 1;
	}
	*maskp = mask;
	return(icon);
}

int SDLCALL FilterEvents(const SDL_Event *event)
{
	static int reallyquit = 0;

	switch (event->type) {

		case SDL_ACTIVEEVENT:
			/* See what happened */
			printf("App %s ",
				event->active.gain ? "gained" : "lost");
			if ( event->active.state & SDL_APPACTIVE )
				printf("active ");
			if ( event->active.state & SDL_APPMOUSEFOCUS )
				printf("mouse ");
			if ( event->active.state & SDL_APPINPUTFOCUS )
				printf("input ");
			printf("focus\n");

			/* See if we are iconified or restored */
			if ( event->active.state & SDL_APPACTIVE ) {
				printf("App has been %s\n",
					event->active.gain ?
						 "restored" : "iconified");
			}
			return(0);

		/* This is important!  Queue it if we want to quit. */
		case SDL_QUIT:
			if ( ! reallyquit ) {
				reallyquit = 1;
				printf("Quit requested\n");
				return(0);
			}
			printf("Quit demanded\n");
			return(1);

		/* Mouse and keyboard events go to threads */
		case SDL_MOUSEMOTION:
		case SDL_MOUSEBUTTONDOWN:
		case SDL_MOUSEBUTTONUP:
		case SDL_KEYDOWN:
		case SDL_KEYUP:
			return(1);

		/* Drop all other events */
		default:
			return(0);
	}
}

int SDLCALL HandleMouse(void *unused)
{
	SDL_Event events[10];
	int i, found;
	Uint32 mask;

	/* Handle mouse events here */
	mask = (SDL_MOUSEMOTIONMASK|SDL_MOUSEBUTTONDOWNMASK|SDL_MOUSEBUTTONUPMASK);
	while ( ! done ) {
		found = SDL_PeepEvents(events, 10, SDL_GETEVENT, mask);
		for ( i=0; i<found; ++i ) {
			switch(events[i].type) {
				/* We want to toggle visibility on buttonpress */
				case SDL_MOUSEBUTTONDOWN:
				case SDL_MOUSEBUTTONUP:
					if ( events[i].button.state == SDL_PRESSED ) {
						visible = !visible;
						SDL_ShowCursor(visible);
					}
					printf("Mouse button %d has been %s\n",
						events[i].button.button,
						(events[i].button.state == SDL_PRESSED) ?
						"pressed" : "released");
					break;
				/* Show relative mouse motion */
				case SDL_MOUSEMOTION:
					printf("Mouse relative motion: {%d,%d}\n",
							events[i].motion.xrel, events[i].motion.yrel);
					break;
			}
		}
		/* Give up some CPU to allow events to arrive */
		SDL_Delay(20);
	}
	return(0);
}

int SDLCALL HandleKeyboard(void *unused)
{
	SDL_Event events[10];
	int i, found;
	Uint32 mask;

	/* Handle mouse events here */
	mask = (SDL_KEYDOWNMASK|SDL_KEYUPMASK);
	while ( ! done ) {
		found = SDL_PeepEvents(events, 10, SDL_GETEVENT, mask);
		for ( i=0; i<found; ++i ) {
			switch(events[i].type) {
			    /* We want to toggle visibility on buttonpress */
			    case SDL_KEYDOWN:
			    case SDL_KEYUP:
			    	printf("Key '%c' (keysym==%d) has been %s\n",
						events[i].key.keysym.unicode,
						(int) events[i].key.keysym.sym,
					(events[i].key.state == SDL_PRESSED) ?
						"pressed" : "released");

			    	/* Allow hitting <ESC> to quit the app */
			    	if ( events[i].key.keysym.sym == SDLK_ESCAPE ) {
			    		done = 1;
			    	}

					/* skip events now that aren't KEYUPs... */
					if (events[i].key.state == SDL_PRESSED)
						break;

			    	if ( events[i].key.keysym.sym == SDLK_f ) {
						int rc = 0;
						printf("attempting to toggle fullscreen...\n");
						rc = SDL_WM_ToggleFullScreen(SDL_GetVideoSurface());
                        printf("SDL_WM_ToggleFullScreen returned %d.\n", rc);
			    	}

			    	if ( events[i].key.keysym.sym == SDLK_g ) {
						SDL_GrabMode m;
						m = SDL_WM_GrabInput(SDL_GRAB_QUERY) == SDL_GRAB_ON ?
								SDL_GRAB_OFF : SDL_GRAB_ON;
						printf("attempting to toggle input grab to %s...\n",
                                m == SDL_GRAB_ON ? "ON" : "OFF");
                        SDL_WM_GrabInput(m);
						printf("attempt finished.\n");
			    	}

			    	break;
			}
		}
		/* Give up some CPU to allow events to arrive */
		SDL_Delay(20);
	}
	return(0);
}

int main(int argc, char *argv[])
{
	SDL_Surface *screen;
	SDL_Surface *icon;
	Uint8 *icon_mask;
	int i, parsed;
	Uint8 *buffer;
	SDL_Color palette[256];
	Uint32 init_flags;
	Uint8  video_bpp;
	Uint32 video_flags;
	SDL_Thread *mouse_thread;
	SDL_Thread *keybd_thread;

	/* Set the options, based on command line arguments */
	init_flags = SDL_INIT_VIDEO;
	video_bpp = 8;
	video_flags = SDL_SWSURFACE;
	parsed = 1;
	while ( parsed ) {
		/* If the threaded option is enabled, and the SDL library hasn't
		   been compiled with threaded events enabled, then the mouse and
		   keyboard won't respond.
		 */
		if ( (argc >= 2) && (strcmp(argv[1], "-threaded") == 0) ) {
			init_flags |= SDL_INIT_EVENTTHREAD;
			argc -= 1;
			argv += 1;
			printf("Running with threaded events\n");
		} else
		if ( (argc >= 2) && (strcmp(argv[1], "-fullscreen") == 0) ) {
			video_flags |= SDL_FULLSCREEN;
			argc -= 1;
			argv += 1;
		} else
		if ( (argc >= 3) && (strcmp(argv[1], "-bpp") == 0) ) {
			video_bpp = atoi(argv[2]);
			argc -= 2;
			argv += 2;
		} else {
			parsed = 0;
		}
	}

	/* Initialize SDL with the requested flags */
	if ( SDL_Init(init_flags) < 0 ) {
		fprintf(stderr,
			"Couldn't initialize SDL: %s\n", SDL_GetError());
		return(1);
	}

	/* Set the icon -- this must be done before the first mode set */
	icon = LoadIconSurface("icon.bmp", &icon_mask);
	if ( icon != NULL ) {
		SDL_WM_SetIcon(icon, icon_mask);
	}
	if ( icon_mask != NULL )
		free(icon_mask);

	/* Initialize the display */
	screen = SDL_SetVideoMode(640, 480, video_bpp, video_flags);
	if (  screen == NULL ) {
		fprintf(stderr, "Couldn't set 640x480x%d video mode: %s\n",
						video_bpp, SDL_GetError());
		quit(1);
	}
	printf("Running in %s mode\n", screen->flags & SDL_FULLSCREEN ?
						"fullscreen" : "windowed");

	/* Enable printable characters */
	SDL_EnableUNICODE(1);

	/* Set an event filter that discards everything but QUIT */
	SDL_SetEventFilter(FilterEvents);

	/* Create the event handling threads */
	mouse_thread = SDL_CreateThread(HandleMouse, NULL);
	keybd_thread = SDL_CreateThread(HandleKeyboard, NULL);

	/* Set the surface pixels and refresh! */
	for ( i=0; i<256; ++i ) {
		palette[i].r = 255-i;
		palette[i].g = 255-i;
		palette[i].b = 255-i;
	}
	SDL_SetColors(screen, palette, 0, 256);
	if ( SDL_LockSurface(screen) < 0 ) {
		fprintf(stderr, "Couldn't lock display surface: %s\n",
							SDL_GetError());
		quit(2);
	}
	buffer = (Uint8 *)screen->pixels;
	for ( i=0; i<screen->h; ++i ) {
		memset(buffer,(i*255)/screen->h,
				screen->w*screen->format->BytesPerPixel);
		buffer += screen->pitch;
	}
	SDL_UnlockSurface(screen);
	SDL_UpdateRect(screen, 0, 0, 0, 0);

	/* Loop, waiting for QUIT */
	while ( ! done ) {
		if ( ! (init_flags & SDL_INIT_EVENTTHREAD) ) {
			SDL_PumpEvents(); /* Needed when event thread is off */
		}
		if ( SDL_PeepEvents(NULL, 0, SDL_PEEKEVENT, SDL_QUITMASK) ) {
			done = 1;
		}
		/* Give up some CPU so the events can accumulate */
		SDL_Delay(20);
	}
	SDL_WaitThread(mouse_thread, NULL);
	SDL_WaitThread(keybd_thread, NULL);
	SDL_Quit();
	return(0);
}