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From Bug #36:
There are a couple of issues with the selection of Altivec alpha-blitting
routines in CalculateAlphaBlit() in src/video/SDL_Blit_A.c.
1) There's no check for the presence of Altivec when checking if the
Blit32to565PixelAlphaAltivec() routine can be selected.
2) Altivec cannot be used in video memory, and there's no check if the
destination surface is a hardware surface. (Alpha-blitting to a hardware
surface with GPU support is a bad idea, but somebody's bound to do it anyway.)
Patch to fix these attached.
author | Ryan C. Gordon <icculus@icculus.org> |
---|---|
date | Sun, 08 Jan 2006 21:18:15 +0000 |
parents | 355632dca928 |
children |
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<HTML ><HEAD ><TITLE >SDL_VideoModeOK</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ "><LINK REL="HOME" TITLE="SDL Library Documentation" HREF="index.html"><LINK REL="UP" TITLE="Video" HREF="video.html"><LINK REL="PREVIOUS" TITLE="SDL_ListModes" HREF="sdllistmodes.html"><LINK REL="NEXT" TITLE="SDL_SetVideoMode" HREF="sdlsetvideomode.html"></HEAD ><BODY CLASS="REFENTRY" BGCOLOR="#FFF8DC" TEXT="#000000" LINK="#0000ee" VLINK="#551a8b" ALINK="#ff0000" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation 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="sdllistmodes.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="sdlsetvideomode.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="SDLVIDEOMODEOK" ></A >SDL_VideoModeOK</H1 ><DIV CLASS="REFNAMEDIV" ><A NAME="AEN1202" ></A ><H2 >Name</H2 >SDL_VideoModeOK -- Check to see if a particular video mode is supported.</DIV ><DIV CLASS="REFSYNOPSISDIV" ><A NAME="AEN1205" ></A ><H2 >Synopsis</H2 ><DIV CLASS="FUNCSYNOPSIS" ><A NAME="AEN1206" ></A ><P ></P ><PRE CLASS="FUNCSYNOPSISINFO" >#include "SDL.h"</PRE ><P ><CODE ><CODE CLASS="FUNCDEF" >int <B CLASS="FSFUNC" >SDL_VideoModeOK</B ></CODE >(int width, int height, int bpp, Uint32 flags);</CODE ></P ><P ></P ></DIV ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN1212" ></A ><H2 >Description</H2 ><P ><TT CLASS="FUNCTION" >SDL_VideoModeOK</TT > returns <SPAN CLASS="RETURNVALUE" >0</SPAN > if the requested mode is not supported under any bit depth, or returns the bits-per-pixel of the closest available mode with the given width, height and requested <A HREF="sdlsurface.html" >surface</A > flags (see <A HREF="sdlsetvideomode.html" ><TT CLASS="FUNCTION" >SDL_SetVideoMode</TT ></A >).</P ><P >The bits-per-pixel value returned is only a suggested mode. You can usually request and bpp you want when <A HREF="sdlsetvideomode.html" >setting</A > the video mode and SDL will emulate that color depth with a shadow video surface.</P ><P >The arguments to <TT CLASS="FUNCTION" >SDL_VideoModeOK</TT > are the same ones you would pass to <A HREF="sdlsetvideomode.html" >SDL_SetVideoMode</A ></P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN1225" ></A ><H2 >Example</H2 ><PRE CLASS="PROGRAMLISTING" >SDL_Surface *screen; Uint32 bpp; . . . printf("Checking mode 640x480@16bpp.\n"); bpp=SDL_VideoModeOK(640, 480, 16, SDL_HWSURFACE); if(!bpp){ printf("Mode not available.\n"); exit(-1); } printf("SDL Recommends 640x480@%dbpp.\n", bpp); screen=SDL_SetVideoMode(640, 480, bpp, SDL_HWSURFACE); . .</PRE ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN1228" ></A ><H2 >See Also</H2 ><P ><A HREF="sdlsetvideomode.html" ><TT CLASS="FUNCTION" >SDL_SetVideoMode</TT ></A >, <A HREF="sdlgetvideoinfo.html" ><TT CLASS="FUNCTION" >SDL_GetVideoInfo</TT ></A ></P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="sdllistmodes.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="sdlsetvideomode.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >SDL_ListModes</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="video.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >SDL_SetVideoMode</TD ></TR ></TABLE ></DIV ></BODY ></HTML >