Mercurial > sdl-ios-xcode
view docs/html/sdlkeysym.html @ 773:da0a2ad35bf4
Date: Sun, 4 Jan 2004 23:48:19 +0100
From: Max Horn
Subject: Re: Again Audio CD patch
Am 04.01.2004 um 22:38 schrieb Sam Lantinga:
>
> Okay, I fixed the buffering problems by simply using a 4 second buffer
> instead of a 1 second buffer. However, using your code I can't play an
> entire CD - the playback stops after the first song.
>
Found the problem: FSReadFork returns eofErr when the file is finished.
However, we check its return value for errors, and if anything but
noErr occurs, the reader thread aborts its current iteration. That is
bad, because it aborts before it can ever set the flag which tells that
the file is over (also, any remaining data which FSRead did return is
lost - so you'd not hear about to 4 seconds from the end of the file.
Furthermore, the computed data size was 8 bytes to high (I forgot to
account for the fact that the size of an (A)IFF chunk always contains
the chunk header & size fields, too). This is enough to make it work.
However, the end condition is rather fragile, so I tuned some other
things to be pessimistic (check for <= 0 instead of == 0, when eofErr
is encountered enforce mReadFilePosition == mFileLength). You never
know...
The attached patch fixes the issue for me.
author | Sam Lantinga <slouken@libsdl.org> |
---|---|
date | Mon, 05 Jan 2004 00:57:51 +0000 |
parents | e5bc29de3f0a |
children | 355632dca928 |
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<HTML ><HEAD ><TITLE >SDL_keysym</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.64 "><LINK REL="HOME" TITLE="SDL Library Documentation" HREF="index.html"><LINK REL="UP" TITLE="SDL Event Structures." HREF="eventstructures.html"><LINK REL="PREVIOUS" TITLE="SDL_QuitEvent" HREF="sdlquitevent.html"><LINK REL="NEXT" TITLE="SDLKey" HREF="sdlkey.html"></HEAD ><BODY CLASS="REFENTRY" BGCOLOR="#FFF8DC" TEXT="#000000" LINK="#0000ee" VLINK="#551a8b" ALINK="#ff0000" ><DIV CLASS="NAVHEADER" ><TABLE WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >SDL Library Documentation</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="sdlquitevent.html" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="sdlkey.html" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="SDLKEYSYM" >SDL_keysym</A ></H1 ><DIV CLASS="REFNAMEDIV" ><A NAME="AEN4275" ></A ><H2 >Name</H2 >SDL_keysym -- Keysym structure</DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN4278" ></A ><H2 >Structure Definition</H2 ><PRE CLASS="PROGRAMLISTING" >typedef struct{ Uint8 scancode; SDLKey sym; SDLMod mod; Uint16 unicode; } SDL_keysym;</PRE ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN4281" ></A ><H2 >Structure Data</H2 ><DIV CLASS="INFORMALTABLE" ><A NAME="AEN4283" ></A ><P ></P ><TABLE BORDER="0" CLASS="CALSTABLE" ><TBODY ><TR ><TD ALIGN="LEFT" VALIGN="TOP" ><TT CLASS="STRUCTFIELD" ><I >scancode</I ></TT ></TD ><TD ALIGN="LEFT" VALIGN="TOP" >Hardware specific scancode</TD ></TR ><TR ><TD ALIGN="LEFT" VALIGN="TOP" ><TT CLASS="STRUCTFIELD" ><I >sym</I ></TT ></TD ><TD ALIGN="LEFT" VALIGN="TOP" >SDL virtual keysym</TD ></TR ><TR ><TD ALIGN="LEFT" VALIGN="TOP" ><TT CLASS="STRUCTFIELD" ><I >mod</I ></TT ></TD ><TD ALIGN="LEFT" VALIGN="TOP" >Current key modifiers</TD ></TR ><TR ><TD ALIGN="LEFT" VALIGN="TOP" ><TT CLASS="STRUCTFIELD" ><I >unicode</I ></TT ></TD ><TD ALIGN="LEFT" VALIGN="TOP" >Translated character</TD ></TR ></TBODY ></TABLE ><P ></P ></DIV ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN4302" ></A ><H2 >Description</H2 ><P >The <SPAN CLASS="STRUCTNAME" >SDL_keysym</SPAN > structure is used by reporting key presses and releases since it is a part of the <A HREF="sdlkeyboardevent.html" ><SPAN CLASS="STRUCTNAME" >SDL_KeyboardEvent</SPAN ></A >.</P ><P >The <TT CLASS="STRUCTFIELD" ><I >scancode</I ></TT > field should generally be left alone, it is the hardware dependent scancode returned by the keyboard. The <TT CLASS="STRUCTFIELD" ><I >sym</I ></TT > field is extremely useful. It is the SDL-defined value of the key (see <A HREF="sdlkey.html" >SDL Key Syms</A >. This field is very useful when you are checking for certain key presses, like so: <PRE CLASS="PROGRAMLISTING" >. . while(SDL_PollEvent(&event)){ switch(event.type){ case SDL_KEYDOWN: if(event.key.keysym.sym==SDLK_LEFT) move_left(); break; . . . } } . .</PRE > <TT CLASS="STRUCTFIELD" ><I >mod</I ></TT > stores the current state of the keyboard modifiers as explained in <A HREF="sdlgetmodstate.html" ><TT CLASS="FUNCTION" >SDL_GetModState</TT ></A >. The <TT CLASS="STRUCTFIELD" ><I >unicode</I ></TT > is only used when UNICODE translation is enabled with <A HREF="sdlenableunicode.html" ><TT CLASS="FUNCTION" >SDL_EnableUNICODE</TT ></A >. If <TT CLASS="STRUCTFIELD" ><I >unicode</I ></TT > 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: <PRE CLASS="PROGRAMLISTING" >char ch; if ( (keysym.unicode & 0xFF80) == 0 ) { ch = keysym.unicode & 0x7F; } else { printf("An International Character.\n"); }</PRE > UNICODE translation does have a slight overhead so don't enable it unless its needed.</P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN4321" ></A ><H2 >See Also</H2 ><P ><A HREF="sdlkey.html" ><SPAN CLASS="STRUCTNAME" >SDLKey</SPAN ></A ></P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="sdlquitevent.html" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="sdlkey.html" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >SDL_QuitEvent</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="eventstructures.html" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >SDLKey</TD ></TR ></TABLE ></DIV ></BODY ></HTML >