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| author | Jesse Hall <jessehall@google.com> | 2012-07-23 10:12:30 -0700 |
|---|---|---|
| committer | android code review <noreply-gerritcodereview@google.com> | 2012-07-23 10:12:30 -0700 |
| commit | 2b3a42e7d0b441f71fc2e2b07269dd1f8151c977 (patch) | |
| tree | ded6ee18c4e1f33df235e53615a6d65e2d64f4ef /distrib/sdl-1.2.15/docs/html/sdlpixelformat.html | |
| parent | 3dcbebfd43e409c3bbff7fc79288e40666a947fd (diff) | |
| parent | 9682c8870b8ff5e4ac2e4c70b759f791c6f38c1f (diff) | |
| download | external_qemu-2b3a42e7d0b441f71fc2e2b07269dd1f8151c977.zip external_qemu-2b3a42e7d0b441f71fc2e2b07269dd1f8151c977.tar.gz external_qemu-2b3a42e7d0b441f71fc2e2b07269dd1f8151c977.tar.bz2 | |
Merge changes I505c4aea,I2ae0529c
* changes:
Import SDL release-1.2.15
Handle SDL windows with BGRA color
Diffstat (limited to 'distrib/sdl-1.2.15/docs/html/sdlpixelformat.html')
| -rw-r--r-- | distrib/sdl-1.2.15/docs/html/sdlpixelformat.html | 528 |
1 files changed, 528 insertions, 0 deletions
diff --git a/distrib/sdl-1.2.15/docs/html/sdlpixelformat.html b/distrib/sdl-1.2.15/docs/html/sdlpixelformat.html new file mode 100644 index 0000000..000ddc0 --- /dev/null +++ b/distrib/sdl-1.2.15/docs/html/sdlpixelformat.html @@ -0,0 +1,528 @@ +<HTML +><HEAD +><TITLE +>SDL_PixelFormat</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_Palette" +HREF="sdlpalette.html"><LINK +REL="NEXT" +TITLE="SDL_Surface" +HREF="sdlsurface.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="sdlpalette.html" +ACCESSKEY="P" +>Prev</A +></TD +><TD +WIDTH="80%" +ALIGN="center" +VALIGN="bottom" +></TD +><TD +WIDTH="10%" +ALIGN="right" +VALIGN="bottom" +><A +HREF="sdlsurface.html" +ACCESSKEY="N" +>Next</A +></TD +></TR +></TABLE +><HR +ALIGN="LEFT" +WIDTH="100%"></DIV +><H1 +><A +NAME="SDLPIXELFORMAT" +></A +>SDL_PixelFormat</H1 +><DIV +CLASS="REFNAMEDIV" +><A +NAME="AEN3178" +></A +><H2 +>Name</H2 +>SDL_PixelFormat -- Stores surface format information</DIV +><DIV +CLASS="REFSECT1" +><A +NAME="AEN3181" +></A +><H2 +>Structure Definition</H2 +><PRE +CLASS="PROGRAMLISTING" +>typedef struct SDL_PixelFormat { + SDL_Palette *palette; + Uint8 BitsPerPixel; + Uint8 BytesPerPixel; + Uint8 Rloss, Gloss, Bloss, Aloss; + Uint8 Rshift, Gshift, Bshift, Ashift; + Uint32 Rmask, Gmask, Bmask, Amask; + Uint32 colorkey; + Uint8 alpha; +} SDL_PixelFormat;</PRE +></DIV +><DIV +CLASS="REFSECT1" +><A +NAME="AEN3184" +></A +><H2 +>Structure Data</H2 +><DIV +CLASS="INFORMALTABLE" +><A +NAME="AEN3186" +></A +><P +></P +><TABLE +BORDER="0" +CLASS="CALSTABLE" +><TBODY +><TR +><TD +ALIGN="LEFT" +VALIGN="TOP" +><TT +CLASS="STRUCTFIELD" +><I +>palette</I +></TT +></TD +><TD +ALIGN="LEFT" +VALIGN="TOP" +>Pointer to the <A +HREF="sdlpalette.html" +>palette</A +>, or <TT +CLASS="LITERAL" +>NULL</TT +> if the <TT +CLASS="STRUCTFIELD" +><I +>BitsPerPixel</I +></TT +>>8</TD +></TR +><TR +><TD +ALIGN="LEFT" +VALIGN="TOP" +><TT +CLASS="STRUCTFIELD" +><I +>BitsPerPixel</I +></TT +></TD +><TD +ALIGN="LEFT" +VALIGN="TOP" +>The number of bits used to represent each pixel in a surface. Usually 8, 16, 24 or 32.</TD +></TR +><TR +><TD +ALIGN="LEFT" +VALIGN="TOP" +><TT +CLASS="STRUCTFIELD" +><I +>BytesPerPixel</I +></TT +></TD +><TD +ALIGN="LEFT" +VALIGN="TOP" +>The number of bytes used to represent each pixel in a surface. Usually one to four.</TD +></TR +><TR +><TD +ALIGN="LEFT" +VALIGN="TOP" +><TT +CLASS="STRUCTFIELD" +><I +>[RGBA]mask</I +></TT +></TD +><TD +ALIGN="LEFT" +VALIGN="TOP" +>Binary mask used to retrieve individual color values</TD +></TR +><TR +><TD +ALIGN="LEFT" +VALIGN="TOP" +><TT +CLASS="STRUCTFIELD" +><I +>[RGBA]loss</I +></TT +></TD +><TD +ALIGN="LEFT" +VALIGN="TOP" +>Precision loss of each color component (2<SUP +>[RGBA]loss</SUP +>)</TD +></TR +><TR +><TD +ALIGN="LEFT" +VALIGN="TOP" +><TT +CLASS="STRUCTFIELD" +><I +>[RGBA]shift</I +></TT +></TD +><TD +ALIGN="LEFT" +VALIGN="TOP" +>Binary left shift of each color component in the pixel value</TD +></TR +><TR +><TD +ALIGN="LEFT" +VALIGN="TOP" +><TT +CLASS="STRUCTFIELD" +><I +>colorkey</I +></TT +></TD +><TD +ALIGN="LEFT" +VALIGN="TOP" +>Pixel value of transparent pixels</TD +></TR +><TR +><TD +ALIGN="LEFT" +VALIGN="TOP" +><TT +CLASS="STRUCTFIELD" +><I +>alpha</I +></TT +></TD +><TD +ALIGN="LEFT" +VALIGN="TOP" +>Overall surface alpha value</TD +></TR +></TBODY +></TABLE +><P +></P +></DIV +></DIV +><DIV +CLASS="REFSECT1" +><A +NAME="AEN3225" +></A +><H2 +>Description</H2 +><P +>A <SPAN +CLASS="STRUCTNAME" +>SDL_PixelFormat</SPAN +> describes the format of the pixel data stored at the <TT +CLASS="STRUCTFIELD" +><I +>pixels</I +></TT +> field of a <A +HREF="sdlsurface.html" +><SPAN +CLASS="STRUCTNAME" +>SDL_Surface</SPAN +></A +>. Every surface stores a <SPAN +CLASS="STRUCTNAME" +>SDL_PixelFormat</SPAN +> in the <TT +CLASS="STRUCTFIELD" +><I +>format</I +></TT +> field.</P +><P +>If you wish to do pixel level modifications on a surface, then understanding how SDL stores its color information is essential.</P +><P +>8-bit pixel formats are the easiest to understand. Since its an 8-bit format, we have 8 <TT +CLASS="STRUCTFIELD" +><I +>BitsPerPixel</I +></TT +> and 1 <TT +CLASS="STRUCTFIELD" +><I +>BytesPerPixel</I +></TT +>. Since <TT +CLASS="STRUCTFIELD" +><I +>BytesPerPixel</I +></TT +> is 1, all pixels are represented by a Uint8 which contains an index into <TT +CLASS="STRUCTFIELD" +><I +>palette</I +></TT +>-><TT +CLASS="STRUCTFIELD" +><I +>colors</I +></TT +>. So, to determine the color of a pixel in a 8-bit surface: we read the color index from <SPAN +CLASS="STRUCTNAME" +>surface</SPAN +>-><TT +CLASS="STRUCTFIELD" +><I +>pixels</I +></TT +> and we use that index to read the <A +HREF="sdlcolor.html" +><SPAN +CLASS="STRUCTNAME" +>SDL_Color</SPAN +></A +> structure from <SPAN +CLASS="STRUCTNAME" +>surface</SPAN +>-><TT +CLASS="STRUCTFIELD" +><I +>format</I +></TT +>-><TT +CLASS="STRUCTFIELD" +><I +>palette</I +></TT +>-><TT +CLASS="STRUCTFIELD" +><I +>colors</I +></TT +>. Like so: +<PRE +CLASS="PROGRAMLISTING" +>SDL_Surface *surface; +SDL_PixelFormat *fmt; +SDL_Color *color; +Uint8 index; + +. +. + +/* Create surface */ +. +. +fmt=surface->format; + +/* Check the bitdepth of the surface */ +if(fmt->BitsPerPixel!=8){ + fprintf(stderr, "Not an 8-bit surface.\n"); + return(-1); +} + +/* Lock the surface */ +SDL_LockSurface(surface); + +/* Get the topleft pixel */ +index=*(Uint8 *)surface->pixels; +color=fmt->palette->colors[index]; + +/* Unlock the surface */ +SDL_UnlockSurface(surface); +printf("Pixel Color-> Red: %d, Green: %d, Blue: %d. Index: %d\n", + color->r, color->g, color->b, index); +. +.</PRE +></P +><P +>Pixel formats above 8-bit are an entirely different experience. They are +considered to be "TrueColor" formats and the color information is stored in the +pixels themselves, not in a palette. The mask, shift and loss fields tell us +how the color information is encoded. The mask fields allow us to isolate each +color component, the shift fields tell us the number of bits to the right of +each component in the pixel value and the loss fields tell us the number of +bits lost from each component when packing 8-bit color component in a pixel. +<PRE +CLASS="PROGRAMLISTING" +>/* Extracting color components from a 32-bit color value */ +SDL_PixelFormat *fmt; +SDL_Surface *surface; +Uint32 temp, pixel; +Uint8 red, green, blue, alpha; +. +. +. +fmt=surface->format; +SDL_LockSurface(surface); +pixel=*((Uint32*)surface->pixels); +SDL_UnlockSurface(surface); + +/* Get Red component */ +temp=pixel&fmt->Rmask; /* Isolate red component */ +temp=temp>>fmt->Rshift;/* Shift it down to 8-bit */ +temp=temp<<fmt->Rloss; /* Expand to a full 8-bit number */ +red=(Uint8)temp; + +/* Get Green component */ +temp=pixel&fmt->Gmask; /* Isolate green component */ +temp=temp>>fmt->Gshift;/* Shift it down to 8-bit */ +temp=temp<<fmt->Gloss; /* Expand to a full 8-bit number */ +green=(Uint8)temp; + +/* Get Blue component */ +temp=pixel&fmt->Bmask; /* Isolate blue component */ +temp=temp>>fmt->Bshift;/* Shift it down to 8-bit */ +temp=temp<<fmt->Bloss; /* Expand to a full 8-bit number */ +blue=(Uint8)temp; + +/* Get Alpha component */ +temp=pixel&fmt->Amask; /* Isolate alpha component */ +temp=temp>>fmt->Ashift;/* Shift it down to 8-bit */ +temp=temp<<fmt->Aloss; /* Expand to a full 8-bit number */ +alpha=(Uint8)temp; + +printf("Pixel Color -> R: %d, G: %d, B: %d, A: %d\n", red, green, blue, alpha); +. +. +.</PRE +></P +></DIV +><DIV +CLASS="REFSECT1" +><A +NAME="AEN3252" +></A +><H2 +>See Also</H2 +><P +><A +HREF="sdlsurface.html" +><SPAN +CLASS="STRUCTNAME" +>SDL_Surface</SPAN +></A +>, +<A +HREF="sdlmaprgb.html" +><TT +CLASS="FUNCTION" +>SDL_MapRGB</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="sdlpalette.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="sdlsurface.html" +ACCESSKEY="N" +>Next</A +></TD +></TR +><TR +><TD +WIDTH="33%" +ALIGN="left" +VALIGN="top" +>SDL_Palette</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_Surface</TD +></TR +></TABLE +></DIV +></BODY +></HTML +> |