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Date: Mon, 11 Oct 2004 15:17:27 +0300 (EEST) From: Hannu Savolainen Subject: Re: SDL uses obsolete OSS features I did some work on getting OSS to work better with SDL. There have been some problems with select which should be fixed now. I'm having some problems in understanding what is the purpose of the DSP_WaitAudio() routine. I added a return to the very beginning of this routine and commendted out the define for USE_BLOCKING_WRITES. At least lbreakout2 seems to work as well as earlier. The latencies are the same. An ordinary blocking write does exactly the same thing than DSP_WaitAudio does. So I would recommend using the USE_BLOCKING_WRITES approach and removing everything from the DSP_WaitAudio routine. Also enabling USE_BLOCKING_WRITES makes it possible to simplify DSP_PlayAudio() because you don't need to handle the partial writes (the do-while loop). Attached is a patch against SDL-1.2.7. After these changes SDL will use OSS as it's designed to be used (make it as simple as possible). This code should work with all OSS implementations because it uses only the very fundamental features that have been there since the jurassic times.
author Sam Lantinga <slouken@libsdl.org>
date Fri, 12 Nov 2004 21:39:04 +0000
parents 355632dca928
children
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<HTML
><HEAD
><TITLE
>Event Examples</TITLE
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></A
>Event Examples</H1
><P
></P
><DIV
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><H2
CLASS="SECT2"
><A
NAME="AEN375"
></A
>Filtering and Handling Events</H2
><P
><PRE
CLASS="PROGRAMLISTING"
>#include &#60;stdio.h&#62;
#include &#60;stdlib.h&#62;

#include "SDL.h"

/* This function may run in a separate event thread */
int FilterEvents(const SDL_Event *event) {
    static int boycott = 1;

    /* This quit event signals the closing of the window */
    if ( (event-&#62;type == SDL_QUIT) &#38;&#38; boycott ) {
        printf("Quit event filtered out -- try again.\n");
        boycott = 0;
        return(0);
    }
    if ( event-&#62;type == SDL_MOUSEMOTION ) {
        printf("Mouse moved to (%d,%d)\n",
                event-&#62;motion.x, event-&#62;motion.y);
        return(0);    /* Drop it, we've handled it */
    }
    return(1);
}

int main(int argc, char *argv[])
{
    SDL_Event event;

    /* Initialize the SDL library (starts the event loop) */
    if ( SDL_Init(SDL_INIT_VIDEO) &#60; 0 ) {
        fprintf(stderr,
                "Couldn't initialize SDL: %s\n", SDL_GetError());
        exit(1);
    }

    /* Clean up on exit, exit on window close and interrupt */
    atexit(SDL_Quit);

    /* Ignore key events */
    SDL_EventState(SDL_KEYDOWN, SDL_IGNORE);
    SDL_EventState(SDL_KEYUP, SDL_IGNORE);

    /* Filter quit and mouse motion events */
    SDL_SetEventFilter(FilterEvents);

    /* The mouse isn't much use unless we have a display for reference */
    if ( SDL_SetVideoMode(640, 480, 8, 0) == NULL ) {
        fprintf(stderr, "Couldn't set 640x480x8 video mode: %s\n",
                        SDL_GetError());
        exit(1);
    }

    /* Loop waiting for ESC+Mouse_Button */
    while ( SDL_WaitEvent(&#38;event) &#62;= 0 ) {
        switch (event.type) {
            case SDL_ACTIVEEVENT: {
                if ( event.active.state &#38; SDL_APPACTIVE ) {
                    if ( event.active.gain ) {
                        printf("App activated\n");
                    } else {
                        printf("App iconified\n");
                    }
                }
            }
            break;
                    
            case SDL_MOUSEBUTTONDOWN: {
                Uint8 *keys;

                keys = SDL_GetKeyState(NULL);
                if ( keys[SDLK_ESCAPE] == SDL_PRESSED ) {
                    printf("Bye bye...\n");
                    exit(0);
                }
                printf("Mouse button pressed\n");
            }
            break;

            case SDL_QUIT: {
                printf("Quit requested, quitting.\n");
                exit(0);
            }
            break;
        }
    }
    /* This should never happen */
    printf("SDL_WaitEvent error: %s\n", SDL_GetError());
    exit(1);
}</PRE
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