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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 e5bc29de3f0a
children 546f7c1eb755
line wrap: on
line source

.TH "SDL_keysym" "3" "Tue 11 Sep 2001, 23:00" "SDL" "SDL API Reference" 
.SH "NAME"
SDL_keysym\- Keysym structure
.SH "STRUCTURE DEFINITION"
.PP
.nf
\f(CWtypedef struct{
  Uint8 scancode;
  SDLKey sym;
  SDLMod mod;
  Uint16 unicode;
} SDL_keysym;\fR
.fi
.PP
.SH "STRUCTURE DATA"
.TP 20
\fBscancode\fR
Hardware specific scancode
.TP 20
\fBsym\fR
SDL virtual keysym
.TP 20
\fBmod\fR
Current key modifiers
.TP 20
\fBunicode\fR
Translated character
.SH "DESCRIPTION"
.PP
The \fBSDL_keysym\fR structure is used by reporting key presses and releases since it is a part of the \fI\fBSDL_KeyboardEvent\fR\fR\&.
.PP
The \fBscancode\fR field should generally be left alone, it is the hardware dependent scancode returned by the keyboard\&. The \fBsym\fR field is extremely useful\&. It is the SDL-defined value of the key (see \fISDL Key Syms\fR\&. This field is very useful when you are checking for certain key presses, like so: 
.PP
.nf
\f(CW\&.
\&.
while(SDL_PollEvent(&event)){
  switch(event\&.type){
    case SDL_KEYDOWN:
      if(event\&.key\&.keysym\&.sym==SDLK_LEFT)
        move_left();
      break;
    \&.
    \&.
    \&.
  }
}
\&.
\&.\fR
.fi
.PP
 \fBmod\fR stores the current state of the keyboard modifiers as explained in \fI\fBSDL_GetModState\fP\fR\&. The \fBunicode\fR is only used when UNICODE translation is enabled with \fI\fBSDL_EnableUNICODE\fP\fR\&. If \fBunicode\fR is non-zero then this a the UNICODE character corresponding to the keypress\&. If the high 9 bits of the character are 0, then this maps to the equivalent ASCII character: 
.PP
.nf
\f(CWchar ch;
if ( (keysym\&.unicode & 0xFF80) == 0 ) {
  ch = keysym\&.unicode & 0x7F;
}
else {
  printf("An International Character\&.
");
}\fR
.fi
.PP
 UNICODE translation does have a slight overhead so don\&'t enable it unless its needed\&.
.SH "SEE ALSO"
.PP
\fI\fBSDLKey\fR\fR
...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:00