view test/testjoystick.c @ 2318:0c653886cce7

HandleEvent() returns done each time it is called. If done was set to 0 the program should quit, but because done is not checked until *all* events are handled a following event can reset done to 1 and prevent the program from terminating when told to. I fixed the while loop that handles events to check for the state of done after handling each event. That could leave some events unhandled when the program exits, but it ensures that the program will exit.
author Bob Pendleton <bob@pendleton.com>
date Wed, 20 Feb 2008 23:27:33 +0000
parents 6280c111ee80
children 450a9bf50c37 f55c87ae336b
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[6][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);
        }

        for (i = 0;
             i < SDL_JoystickNumAxes(joystick) / 2
             && i < SDL_arraysize(axis_area); ++i) {
            /* Erase previous axes */
            SDL_FillRect(screen, &axis_area[i][draw], 0x0000);

            /* Draw the X/Y axis */
            draw = !draw;
            x = (((int) SDL_JoystickGetAxis(joystick, i * 2 + 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, i * 2 + 1)) + 32768);
            y *= SCREEN_HEIGHT;
            y /= 65535;
            if (y < 0) {
                y = 0;
            } else if (y > (SCREEN_HEIGHT - 16)) {
                y = SCREEN_HEIGHT - 16;
            }
            axis_area[i][draw].x = (Sint16) x;
            axis_area[i][draw].y = (Sint16) y;
            axis_area[i][draw].w = 16;
            axis_area[i][draw].h = 16;
            SDL_FillRect(screen, &axis_area[i][draw], 0xFFFF);

            SDL_UpdateRects(screen, 2, axis_area[i]);
        }
    }
}

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);
}