workbench/classes/zune/nlist/nbitmap_mcc/WritePixelArrayAlpha.c

   1 /***************************************************************************
   2
   3  NBitmap.mcc - New Bitmap MUI Custom Class
   4  Copyright (C) 2006 by Daniel Allsopp
   5  Copyright (C) 2007-2013 by NList Open Source Team
   6
   7  This library is free software; you can redistribute it and/or
   8  modify it under the terms of the GNU Lesser General Public
   9  License as published by the Free Software Foundation; either
  10  version 2.1 of the License, or (at your option) any later version.
  11
  12  This library is distributed in the hope that it will be useful,
  13  but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  Lesser General Public License for more details.
  16
  17  NList classes Support Site:  http://www.sf.net/projects/nlist-classes
  18
  19  $Id$
  20
  21 ***************************************************************************/
  22
  23 #include <proto/exec.h>
  24 #include <proto/cybergraphics.h>
  25 #include <proto/graphics.h>
  26 #include <cybergraphx/cybergraphics.h>
  27
  28 #include "private.h"
  29
  30 static LONG do_alpha(LONG a, LONG v)
  31 {
  32   LONG tmp  = (a*v);
  33   return ((tmp<<8) + tmp + 32768)>>16;
  34 }
  35
  36 ULONG _WPAA(APTR src, UWORD srcx, UWORD srcy, UWORD srcmod, struct RastPort *rp, UWORD destx, UWORD desty, UWORD width, UWORD height, ULONG globalalpha)
  37 {
  38   ULONG pixels = 0;
  39
  40   ENTER();
  41
  42   if(width > 0 && height > 0)
  43   {
  44     ULONG *buf;
  45
  46     if((buf = AllocVecShared(width * 4, MEMF_ANY)) != NULL)
  47     {
  48       ULONG x, y;
  49
  50       // Incorrect but cant bother with alpha channel math for now
  51       globalalpha = 255 - (globalalpha >> 24);
  52
  53       for(y = 0; y < height; y++)
  54       {
  55         ULONG *spix;
  56         ULONG *dpix;
  57
  58         ReadPixelArray(buf, 0, 0, width * 4, rp, destx, desty + y, width, 1, RECTFMT_ARGB);
  59
  60         spix = (ULONG *)((ULONG)src + (srcy + y) * srcmod + srcx * sizeof(ULONG));
  61         dpix = buf;
  62
  63         for(x = 0; x < width; x++)
  64         {
  65           ULONG srcpix, dstpix, a, r, g, b;
  66
  67           srcpix = *spix++;
  68           dstpix = *dpix;
  69
  70           a = (srcpix >> 24) & 0xff;
  71           r = (srcpix >> 16) & 0xff;
  72           g = (srcpix >> 8) & 0xff;
  73           b = (srcpix >> 0) & 0xff;
  74
  75           a = a - globalalpha;
  76
  77           if(a > 0)
  78           {
  79             ULONG dest_r, dest_g, dest_b;
  80
  81             dest_r = (dstpix >> 16) & 0xff;
  82             dest_g = (dstpix >> 8) & 0xff;
  83             dest_b = (dstpix >> 0) & 0xff;
  84
  85             dest_r += do_alpha(a, r - dest_r);
  86             dest_g += do_alpha(a, g - dest_g);
  87             dest_b += do_alpha(a, b - dest_b);
  88
  89             dstpix = 0xff000000 | dest_r << 16 | dest_g << 8 | dest_b;
  90           }
  91
  92           *dpix++ = dstpix;
  93           pixels++;
  94         }
  95
  96         WritePixelArray(buf, 0, 0, width * 4, rp, destx, desty + y, width, 1, RECTFMT_ARGB);
  97       }
  98
  99       FreeVec(buf);
 100     }
 101   }
 102
 103   RETURN(pixels);
 104   return pixels;
 105 }