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Date: Thu, 17 Apr 2003 23:27:34 -0400 From: Darrell Walisser Subject: Yet another OS X cursor bug The synopsis: 1. Call SDL_ShowCursor(0); 2. Call SDL_SetVideoMode(); 3. Call SDL_GetEvent(); 3. Call SDL_ShowCursor(1); The result: Sometimes the cursor doesn't come back! Ack! Oddly enough, it does come back when mousing over the dock or clicking in the menu bar. But that's besides the point. The reason why this is happening is a flaw in the handling of activation/deactivation events. The short explanation is that the HideCursor() and ShowCursor() calls must be balanced, but if the cursor was initially hidden, HideCursor() was called again on the activate event - so now the next ShowCursor() fails (as does the next, and the next, for some reason). So, here's the patch. All it does is keep track of the HideCursor()/ShowCursor() calls so that they will always be balanced.
author Sam Lantinga <slouken@libsdl.org>
date Sun, 20 Apr 2003 05:41:16 +0000
parents e5bc29de3f0a
children 355632dca928
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<HTML
><HEAD
><TITLE
>SDL_keysym</TITLE
><META
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><HR
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><H1
><A
NAME="SDLKEYSYM"
>SDL_keysym</A
></H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN4275"
></A
><H2
>Name</H2
>SDL_keysym&nbsp;--&nbsp;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(&#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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