view test/testjoystick.c @ 4216:5b99971a27b4 SDL-1.2

Fixed bug #698 Hans de Goede 2009-02-13 01:10:52 PST Since the new "glitch free" version of pulseaudio (used in Fedora 10 amongst others), the sound of SDL using apps (like a simple playmus call) has been crackling. While looking in to fixing this I noticed that the current pulseaudio code in SDL uses pa_simple. However pa_simple uses a thread to pump pulseaudio events and ipc, given that SDL already has its own thread for audio handling this is clearly suboptimal, leading to unnecessary context switching IPC, etc. Also pa_simple does not allow one to implement the WaitAudio() callback for SDL audiodrivers properly. Given that my work is mostly a rewrite (although some original pieces remain) I'm attaching the new .c and .h file, as that is easier to review then the huge diff. Let me know if you also want the diff. This new version has the following features: -no longer use an additional thread next to the SDL sound thread -do not crackle with glitch free audio -when used with a newer pulse, which does glitch free audio, the total latency is the same as with the alsa driver -proper WaitAudio() implementation, saving another mixlen worth of latency -adds a WaitDone() implementation This patch has been written in consultancy with Lennart Poetering (the pulseaudio author) and has been reviewed by him for correct use of the pa API.
author Sam Lantinga <slouken@libsdl.org>
date Mon, 21 Sep 2009 09:27:08 +0000
parents 0dd0ca51d941
children
line wrap: on
line source


/* Simple program to test the SDL joystick routines */

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

#include "SDL.h"

#define SCREEN_WIDTH	640
#define SCREEN_HEIGHT	480

void WatchJoystick(SDL_Joystick *joystick)
{
	SDL_Surface *screen;
	const char *name;
	int i, done;
	SDL_Event event;
	int x, y, draw;
	SDL_Rect axis_area[2];

	/* Set a video mode to display joystick axis position */
	screen = SDL_SetVideoMode(SCREEN_WIDTH, SCREEN_HEIGHT, 16, 0);
	if ( screen == NULL ) {
		fprintf(stderr, "Couldn't set video mode: %s\n",SDL_GetError());
		return;
	}

	/* Print info about the joystick we are watching */
	name = SDL_JoystickName(SDL_JoystickIndex(joystick));
	printf("Watching joystick %d: (%s)\n", SDL_JoystickIndex(joystick),
	       name ? name : "Unknown Joystick");
	printf("Joystick has %d axes, %d hats, %d balls, and %d buttons\n",
	       SDL_JoystickNumAxes(joystick), SDL_JoystickNumHats(joystick),
	       SDL_JoystickNumBalls(joystick),SDL_JoystickNumButtons(joystick));

	/* Initialize drawing rectangles */
	memset(axis_area, 0, (sizeof axis_area));
	draw = 0;

	/* Loop, getting joystick events! */
	done = 0;
	while ( ! done ) {
		while ( SDL_PollEvent(&event) ) {
			switch (event.type) {
			    case SDL_JOYAXISMOTION:
				printf("Joystick %d axis %d value: %d\n",
				       event.jaxis.which,
				       event.jaxis.axis,
				       event.jaxis.value);
				break;
			    case SDL_JOYHATMOTION:
				printf("Joystick %d hat %d value:",
				       event.jhat.which,
				       event.jhat.hat);
				if ( event.jhat.value == SDL_HAT_CENTERED )
					printf(" centered");
				if ( event.jhat.value & SDL_HAT_UP )
					printf(" up");
				if ( event.jhat.value & SDL_HAT_RIGHT )
					printf(" right");
				if ( event.jhat.value & SDL_HAT_DOWN )
					printf(" down");
				if ( event.jhat.value & SDL_HAT_LEFT )
					printf(" left");
				printf("\n");
				break;
			    case SDL_JOYBALLMOTION:
				printf("Joystick %d ball %d delta: (%d,%d)\n",
				       event.jball.which,
				       event.jball.ball,
				       event.jball.xrel,
				       event.jball.yrel);
				break;
			    case SDL_JOYBUTTONDOWN:
				printf("Joystick %d button %d down\n",
				       event.jbutton.which,
				       event.jbutton.button);
				break;
			    case SDL_JOYBUTTONUP:
				printf("Joystick %d button %d up\n",
				       event.jbutton.which,
				       event.jbutton.button);
				break;
			    case SDL_KEYDOWN:
				if ( event.key.keysym.sym != SDLK_ESCAPE ) {
					break;
				}
				/* Fall through to signal quit */
			    case SDL_QUIT:
				done = 1;
				break;
			    default:
				break;
			}
		}
		/* Update visual joystick state */
		for ( i=0; i<SDL_JoystickNumButtons(joystick); ++i ) {
			SDL_Rect area;

			area.x = i*34;
			area.y = SCREEN_HEIGHT-34;
			area.w = 32;
			area.h = 32;
			if (SDL_JoystickGetButton(joystick, i) == SDL_PRESSED) {
				SDL_FillRect(screen, &area, 0xFFFF);
			} else {
				SDL_FillRect(screen, &area, 0x0000);
			}
			SDL_UpdateRects(screen, 1, &area);
		}

		/* Erase previous axes */
		SDL_FillRect(screen, &axis_area[draw], 0x0000);

		/* Draw the X/Y axis */
		draw = !draw;
		x = (((int)SDL_JoystickGetAxis(joystick, 0))+32768);
		x *= SCREEN_WIDTH;
		x /= 65535;
		if ( x < 0 ) {
			x = 0;
		} else
		if ( x > (SCREEN_WIDTH-16) ) {
			x = SCREEN_WIDTH-16;
		}
		y = (((int)SDL_JoystickGetAxis(joystick, 1))+32768);
		y *= SCREEN_HEIGHT;
		y /= 65535;
		if ( y < 0 ) {
			y = 0;
		} else
		if ( y > (SCREEN_HEIGHT-16) ) {
			y = SCREEN_HEIGHT-16;
		}
		axis_area[draw].x = (Sint16)x;
		axis_area[draw].y = (Sint16)y;
		axis_area[draw].w = 16;
		axis_area[draw].h = 16;
		SDL_FillRect(screen, &axis_area[draw], 0xFFFF);

		SDL_UpdateRects(screen, 2, axis_area);
	}
}

int main(int argc, char *argv[])
{
	const char *name;
	int i;
	SDL_Joystick *joystick;

	/* Initialize SDL (Note: video is required to start event loop) */
	if ( SDL_Init(SDL_INIT_VIDEO|SDL_INIT_JOYSTICK) < 0 ) {
		fprintf(stderr, "Couldn't initialize SDL: %s\n",SDL_GetError());
		exit(1);
	}

	/* Print information about the joysticks */
	printf("There are %d joysticks attached\n", SDL_NumJoysticks());
	for ( i=0; i<SDL_NumJoysticks(); ++i ) {
		name = SDL_JoystickName(i);
		printf("Joystick %d: %s\n",i,name ? name : "Unknown Joystick");
		joystick = SDL_JoystickOpen(i);
		if (joystick == NULL) {
			fprintf(stderr, "SDL_JoystickOpen(%d) failed: %s\n", i, SDL_GetError());
		} else {
			printf("       axes: %d\n", SDL_JoystickNumAxes(joystick));
			printf("      balls: %d\n", SDL_JoystickNumBalls(joystick));
			printf("       hats: %d\n", SDL_JoystickNumHats(joystick));
			printf("    buttons: %d\n", SDL_JoystickNumButtons(joystick));
			SDL_JoystickClose(joystick);
		}
	}

	if ( argv[1] ) {
		joystick = SDL_JoystickOpen(atoi(argv[1]));
		if ( joystick == NULL ) {
			printf("Couldn't open joystick %d: %s\n", atoi(argv[1]),
			       SDL_GetError());
		} else {
			WatchJoystick(joystick);
			SDL_JoystickClose(joystick);
		}
	}
	SDL_QuitSubSystem(SDL_INIT_VIDEO|SDL_INIT_JOYSTICK);

	return(0);
}