view docs/html/sdlblitsurface.html @ 3261:72b542f34739

The new, cleaner, version of the atomic operations. The dummy code is what you should start working with to port atomic ops. The linux code appears to be complete and *should* be the base of all Unix and GCC based versions. The macosx and win32 versions are currently just copies of the dummy code. I will begin working on the windows version as soon as this check in is done. I need someone to work on the Mac OS X version. I'm afraid that this check in will break QNX (Sorry!)
author Bob Pendleton <bob@pendleton.com>
date Thu, 17 Sep 2009 20:35:12 +0000
parents 355632dca928
children
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>SDL_BlitSurface</TITLE
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><H1
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>SDL_BlitSurface</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN2299"
></A
><H2
>Name</H2
>SDL_BlitSurface&nbsp;--&nbsp;This performs a fast blit from the source surface to the destination surface.</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
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></A
><H2
>Synopsis</H2
><DIV
CLASS="FUNCSYNOPSIS"
><A
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><P
></P
><PRE
CLASS="FUNCSYNOPSISINFO"
>#include "SDL.h"</PRE
><P
><CODE
><CODE
CLASS="FUNCDEF"
>int <B
CLASS="FSFUNC"
>SDL_BlitSurface</B
></CODE
>(SDL_Surface *src, SDL_Rect *srcrect, SDL_Surface *dst, SDL_Rect *dstrect);</CODE
></P
><P
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><DIV
CLASS="REFSECT1"
><A
NAME="AEN2309"
></A
><H2
>Description</H2
><P
>This performs a fast blit from the source surface to the destination surface.</P
><P
>The width and height in <TT
CLASS="PARAMETER"
><I
>srcrect</I
></TT
> determine the
size of the copied rectangle. Only the position is used in the
<TT
CLASS="PARAMETER"
><I
>dstrect</I
></TT
> (the width and height are ignored).</P
><P
>If <TT
CLASS="PARAMETER"
><I
>srcrect</I
></TT
> is <TT
CLASS="LITERAL"
>NULL</TT
>, the
entire surface is copied. If <TT
CLASS="PARAMETER"
><I
>dstrect</I
></TT
> is
<TT
CLASS="LITERAL"
>NULL</TT
>, then the destination position (upper left
corner) is (0, 0).</P
><P
>The final blit rectangle is saved in
<TT
CLASS="PARAMETER"
><I
>dstrect</I
></TT
> after all clipping is performed
(<TT
CLASS="PARAMETER"
><I
>srcrect</I
></TT
> is not modified).</P
><P
>The blit function should not be called on a locked surface.</P
><P
>The results of blitting operations vary greatly depending on whether <TT
CLASS="LITERAL"
>SDL_SRCAPLHA</TT
> is set or not. See <A
HREF="sdlsetalpha.html"
>SDL_SetAlpha</A
> for an explaination of how this affects your results. Colorkeying and alpha attributes also interact with surface blitting, as the following pseudo-code should hopefully explain.
<PRE
CLASS="PROGRAMLISTING"
>if (source surface has SDL_SRCALPHA set) {
    if (source surface has alpha channel (that is, format-&#62;Amask != 0))
        blit using per-pixel alpha, ignoring any colour key
    else {
        if (source surface has SDL_SRCCOLORKEY set)
            blit using the colour key AND the per-surface alpha value
        else
            blit using the per-surface alpha value
    }
} else {
    if (source surface has SDL_SRCCOLORKEY set)
        blit using the colour key
    else
        ordinary opaque rectangular blit
}</PRE
></P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN2328"
></A
><H2
>Return Value</H2
><P
>If the blit is successful, it returns <SPAN
CLASS="RETURNVALUE"
>0</SPAN
>,
otherwise it returns <SPAN
CLASS="RETURNVALUE"
>-1</SPAN
>.</P
><P
>If either of the surfaces were in video memory, and the blit returns
<SPAN
CLASS="RETURNVALUE"
>-2</SPAN
>, the video memory was lost, so it should be
reloaded with artwork and re-blitted:
<PRE
CLASS="PROGRAMLISTING"
>        while ( SDL_BlitSurface(image, imgrect, screen, dstrect) == -2 ) {
                while ( SDL_LockSurface(image)) &#60; 0 )
                        SDL_Delay(10);
                -- Write image pixels to image-&#62;pixels --
                SDL_UnlockSurface(image);
        }</PRE
>
This happens under DirectX 5.0 when the system switches away from your
fullscreen application.  Locking the surface will also fail until you
have access to the video memory again.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN2336"
></A
><H2
>See Also</H2
><P
><A
HREF="sdllocksurface.html"
><TT
CLASS="FUNCTION"
>SDL_LockSurface</TT
></A
>,
<A
HREF="sdlfillrect.html"
><TT
CLASS="FUNCTION"
>SDL_FillRect</TT
></A
>,
<A
HREF="sdlsurface.html"
><SPAN
CLASS="STRUCTNAME"
>SDL_Surface</SPAN
></A
>,
<A
HREF="sdlrect.html"
><SPAN
CLASS="STRUCTNAME"
>SDL_Rect</SPAN
></A
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