pixmap.h

来自「VLC媒体播放程序」· C头文件 代码 · 共 165 行

/*****************************************************************************
 * Common pixel/chroma manipulation routines.
 *****************************************************************************
 * Copyright (C) 2003, 2004 VideoLAN
 * $Id: pixmap.h,v 1.6 2004/01/31 23:33:02 rocky Exp $
 *
 * Author: Rocky Bernstein
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
 *****************************************************************************/

#ifndef PIXMAP_H
#define PIXMAP_H 

/** Color and transparency of a pixel or a palette (CLUT) entry 
*/
typedef union {
  uint8_t plane[4];
  struct {
    uint8_t y;
    uint8_t v;
    uint8_t u;
    uint8_t t;
  } s;
} ogt_yuvt_t;

/** An undefined or invalid colormap index. */
#define INVALID_CMAP_ENTRY -1

/** Type of a palette/colormap index*/
typedef int16_t cmap_t;

/** Number of entries in RGB palette/colormap*/
#define CMAP_RGB2_SIZE 256

/**
   Force v in the range 0..255. In video_chroma/i420_rgb.c, this
   is macro is called CLIP. FIXME: Combine with that.
*/
#define clip_8_bit(v) \
  ((v < 0) ? 0 : (v > 255) ? 255 : v)

/**
   Color conversion from
    http://www.inforamp.net/~poynton/notes/colour_and_gamma/ColorFAQ.html#RTFToC30
    http://people.ee.ethz.ch/~buc/brechbuehler/mirror/color/ColorFAQ.html
 
    Thanks to Billy Biggs <[e-mail]> for the pointer and
    the following conversion.
 
    R' = [ 1.1644         0    1.5960 ]   ([ Y' ]   [  16 ])
    G' = [ 1.1644   -0.3918   -0.8130 ] * ([ Cb ] - [ 128 ])
    B' = [ 1.1644    2.0172         0 ]   ([ Cr ]   [ 128 ])

  See also vlc/modules/video_chroma/i420_rgb.h and
  vlc/modules/video_chroma/i420_rgb_c.h for a way to do this in a way
  more optimized for integer arithmetic. Would be nice to merge the
  two routines.
 
*/

/**
   Convert a YUV pixel into an RGB pixel.
 */
static inline void
yuv2rgb(const ogt_yuvt_t *p_yuv, uint8_t *p_rgb_out )
{
  
  int i_Y  = p_yuv->s.y - 16;
  int i_Cb = p_yuv->s.v - 128;
  int i_Cr = p_yuv->s.u - 128;
  
  int i_red   = (1.1644 * i_Y) + (1.5960 * i_Cr);
  int i_green = (1.1644 * i_Y) - (0.3918 * i_Cb) - (0.8130 * i_Cr);
  int i_blue  = (1.1644 * i_Y) + (2.0172 * i_Cb);
  
  i_red   = clip_8_bit( i_red );
  i_green = clip_8_bit( i_green );
  i_blue  = clip_8_bit( i_blue );
  
#ifdef WORDS_BIGENDIAN
  *p_rgb_out++ = i_red;
  *p_rgb_out++ = i_green;
  *p_rgb_out++ = i_blue;
#else
  *p_rgb_out++ = i_blue;
  *p_rgb_out++ = i_green;
  *p_rgb_out++ = i_red;
#endif
  
}

/* The byte storage of an RGB pixel. */ 
#define RGB_SIZE 3

#define GREEN_PIXEL 1
#ifdef WORDS_BIGENDIAN
#define RED_PIXEL   0
#define BLUE_PIXEL  2
#else
#define RED_PIXEL   2
#define BLUE_PIXEL  0
#endif

/**
   Store an RGB pixel into the location of p_pixel, taking into
   account the "Endian"-ness of the underlying machine.

   (N.B. Not sure if I've got this right or this is the right thing
   to do.)
 */
static inline void
put_rgb24_pixel(const uint8_t *rgb, /*out*/ uint8_t *p_pixel)
{
#ifdef WORDS_BIGENDIAN
  *p_pixel++;
#endif
  *p_pixel++ = rgb[RED_PIXEL];
  *p_pixel++ = rgb[GREEN_PIXEL];
  *p_pixel++ = rgb[BLUE_PIXEL];
}

/**
   Find the nearest colormap entry in p_vout (assumed to have RGB2
   chroma, i.e. 256 RGB 8bpp entries) that is closest in color to p_rgb.  Set
   out_rgb to the color found and return the colormap index. 
   INVALID_CMAP_ENTRY is returned if there is some error.
*/
cmap_t
find_cmap_rgb8_nearest(const vout_thread_t *p_vout, const uint8_t *p_rgb,
                       /*out*/ uint8_t *out_rgb);

/**
   Get the the rgb value for a given colormap entry for p_vout (which is'
   assumed to have RGB2 chroma). 
   
   VLC_FALSE is returned if there was some error.
*/
vlc_bool_t
query_color(const vout_thread_t *p_vout, cmap_t i_cmap,
            /*out*/ uint8_t *rgb);

#endif /* PIXMAP_H */


/* 
 * Local variables:
 *  c-file-style: "gnu"
 *  tab-width: 8
 *  indent-tabs-mode: nil
 * End:
 */