convert.c

这是符合Linux操作系统标准的POIXS 的pixops-2.0.5源程序

/* Copyright (C) 2004 VMware, Inc.
 * This file is part of the Pixops Library.
 *
 * The pixops library is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Library General Public License as published
 * by the Free Software Foundation; either version 2 of the License, or (at
 * your option) any later version.
 *
 * The pixops library 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 Library General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

/*
 * convert.c --
 *
 *      Implement some leaf functions for pixel format conversion.
 */

#include "pixops.h"
#include "pixops-internal.h"
#include "convert.h"


inline static boolean
support_scale_bppdepth(int bppdepth)
{
   return bppdepth == 8 ||
          bppdepth == 15 ||
          bppdepth == 16 ||
          bppdepth == 24 ||
          bppdepth == 32;
}


PixopsStatus
pixops_support_scale_formats (int dest_bytes_per_pixel,
                              int dest_depth,
                              boolean dest_has_alpha,
                              int src_bytes_per_pixel,
                              int src_depth,
                              unsigned int *src_colormap,
                              boolean src_has_alpha)
{
   if ((!dest_has_alpha && src_has_alpha) ||
       (dest_has_alpha && dest_bytes_per_pixel != 4) ||
       (src_has_alpha && src_bytes_per_pixel != 4)) {
      goto bad;
   }

   /*
    * XXX We don't support 8BGR source, for no good reason.
    */
   if (src_bytes_per_pixel == 1 && !src_colormap) {
      goto bad;
   }

   if ((src_bytes_per_pixel << 3) < src_depth ||
       (dest_bytes_per_pixel << 3) < dest_depth) {
      goto bad;
   }

   if (!(support_scale_bppdepth (BPPDEPTH(src_bytes_per_pixel << 3, src_depth)) &&
         support_scale_bppdepth (BPPDEPTH(dest_bytes_per_pixel << 3, dest_depth)))) {
      goto bad;
   }

   return PIXOPS_STATUS_SUCCESS;

bad:
   return PIXOPS_STATUS_UNSUPPORTED_FORMAT;
}


PixopsStatus
pixops_support_scale_composite_formats (int dest_channels,
                                        boolean dest_has_alpha,
                                        int src_channels,
                                        boolean src_has_alpha)
{
   /*
    * Only 24-bit depth compositing is supported
    */
   if ((src_channels != 3 && src_channels != 4) ||
       (dest_channels != 3 && dest_channels != 4)) {
      goto bad;
   }

   if (dest_has_alpha && dest_channels != 4 ||
       src_has_alpha && src_channels != 4) {
      goto bad;
   }

   return PIXOPS_STATUS_SUCCESS;

bad:
   return PIXOPS_STATUS_UNSUPPORTED_FORMAT;
}