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Date: Tue, 16 Mar 2004 12:40:33 +0000 From: Alan Swanson Subject: [SDL] [PATCH] Linux joystick evdev axis count fix The event device configuration under Linux does not check the returned ioctl value when reading the axis information. This means extra undefined axes are returned. Note, in EV_HandleEvents, the default for case EV_ABS is to return any axis information which is fine as we have already checked for all valid absolute axes. No new axes should be returned after opening the device. (Unless, of course, the evdev allows closing and reassigning a new device while in use and I can't believe that happens.)
author Sam Lantinga <slouken@libsdl.org>
date Sun, 16 May 2004 22:48:06 +0000
parents 355632dca928
children
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<HTML
><HEAD
><TITLE
>SDL_keysym</TITLE
><META
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><H1
><A
NAME="SDLKEYSYM"
></A
>SDL_keysym</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN4659"
></A
><H2
>Name</H2
>SDL_keysym&nbsp;--&nbsp;Keysym structure</DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN4662"
></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="AEN4665"
></A
><H2
>Structure Data</H2
><DIV
CLASS="INFORMALTABLE"
><A
NAME="AEN4667"
></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="AEN4686"
></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(&#38;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 &#38; 0xFF80) == 0 ) {
  ch = keysym.unicode &#38; 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
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><A
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></A
><H2
>See Also</H2
><P
><A
HREF="sdlkey.html"
><SPAN
CLASS="STRUCTNAME"
>SDLKey</SPAN
></A
></P
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