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Editors Note: The original patch was modified to use SDL_Delay() instead of nanosleep because nanosleep may not be portable to all systems using SDL with the ALSA backend. This may be a moot point with the switch to blocking writes anyway... Date: Sat, 27 Dec 2003 21:47:36 +0100 From: Michel Daenzer To: Debian Bug Tracking System Subject: [SDL] Bug#225252: [PATCH] ALSA fixes Package: libsdl1.2debian-all Version: 1.2.6-2 Severity: normal Tags: patch For SDL 1.2.6, the ALSA backend was changed to call snd_pcm_open() with SND_PCM_NONBLOCK. That's a good idea per se, however, it causes high CPU usage, interrupted sound and stuttering in some games here. Taking a nanosleep whenever snd_pcm_writei() returns -EAGAIN fixes this, but I think it's more efficient to use blocking mode for the actual sound playback. Feedback from the SDL and ALSA lists appreciated. The patch also fixes the default ALSA device to be used.
author Sam Lantinga <slouken@libsdl.org>
date Sun, 04 Jan 2004 15:40:50 +0000
parents e5bc29de3f0a
children 355632dca928
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>SDL_SetColorKey</TITLE
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><H1
><A
NAME="SDLSETCOLORKEY"
>SDL_SetColorKey</A
></H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN1661"
></A
><H2
>Name</H2
>SDL_SetColorKey&nbsp;--&nbsp;Sets the color key (transparent pixel) in a blittable surface and
RLE acceleration.</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN1664"
></A
><H2
>Synopsis</H2
><DIV
CLASS="FUNCSYNOPSIS"
><A
NAME="AEN1665"
></A
><P
></P
><PRE
CLASS="FUNCSYNOPSISINFO"
>#include "SDL.h"</PRE
><P
><CODE
><CODE
CLASS="FUNCDEF"
>int <B
CLASS="FSFUNC"
>SDL_SetColorKey</B
></CODE
>(SDL_Surface *surface, Uint32 flag, Uint32 key);</CODE
></P
><P
></P
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN1671"
></A
><H2
>Description</H2
><P
> Sets the color key (transparent pixel) in a blittable surface and enables or
 disables RLE blit acceleration.</P
><P
>RLE acceleration can substantially speed up blitting of images with large
horizontal runs of transparent pixels (i.e., pixels that match the
<TT
CLASS="PARAMETER"
><I
>key</I
></TT
> value). The <TT
CLASS="PARAMETER"
><I
>key</I
></TT
> must be of the same pixel format as the <TT
CLASS="PARAMETER"
><I
>surface</I
></TT
>, <A
HREF="sdlmaprgb.html"
><TT
CLASS="FUNCTION"
>SDL_MapRGB</TT
></A
> is often useful for obtaining an acceptable value.</P
><P
>If <TT
CLASS="PARAMETER"
><I
>flag</I
></TT
> is <TT
CLASS="LITERAL"
>SDL_SRCCOLORKEY</TT
> then
<TT
CLASS="PARAMETER"
><I
>key</I
></TT
> is the transparent pixel value in the source image of a
blit.</P
><P
>If <TT
CLASS="PARAMETER"
><I
>flag</I
></TT
> is OR'd with
<TT
CLASS="LITERAL"
>SDL_RLEACCEL</TT
> then the surface will be draw using RLE
acceleration when drawn with
<A
HREF="sdlblitsurface.html"
>SDL_BlitSurface</A
>.  The surface will
actually be encoded for RLE acceleration the first time
<A
HREF="sdlblitsurface.html"
>SDL_BlitSurface</A
> or
<A
HREF="sdldisplayformat.html"
>SDL_DisplayFormat</A
> is called on the
surface.</P
><P
>If <TT
CLASS="PARAMETER"
><I
>flag</I
></TT
> is 0, this function clears
any current color key.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN1692"
></A
><H2
>Return Value</H2
><P
>This function returns <SPAN
CLASS="RETURNVALUE"
>0</SPAN
>, or
<SPAN
CLASS="RETURNVALUE"
>-1</SPAN
> if there was an error.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN1697"
></A
><H2
>See Also</H2
><P
><A
HREF="sdlblitsurface.html"
><TT
CLASS="FUNCTION"
>SDL_BlitSurface</TT
></A
>,
<A
HREF="sdldisplayformat.html"
><TT
CLASS="FUNCTION"
>SDL_DisplayFormat</TT
></A
>,
<A
HREF="sdlmaprgb.html"
><TT
CLASS="FUNCTION"
>SDL_MapRGB</TT
></A
>,
<A
HREF="sdlsetalpha.html"
><TT
CLASS="FUNCTION"
>SDL_SetAlpha</TT
></A
></P
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