executor/src/qScale.c

/* Copyright 1994, 1995 by Abacus Research and
 * Development, Inc.  All rights reserved.
 */

#if !defined (OMIT_RCSID_STRINGS)
char ROMlib_rcsid_qScale[] =
		"$Id: qScale.c 87 2005-05-25 01:57:33Z ctm $";
#endif

#include "rsys/common.h"
#include "QuickDraw.h"
#include "CQuickDraw.h"

#include "rsys/cquick.h"

/* This routine scales old_bitmap and stores the result in dst_bitmap.
 * The only field of dst_bitmap that needs to be valid on entry is
 * baseAddr, which should point to enough information to hold the
 * resulting scaled bitmap, with rowBytes evenly divisble by 4.
 * dst_bitmap's bounds will be filled in such that "new_rect" will refer
 * to the newly scaled bits in that coordinate system.
 */
void
scale_blt_bitmap (const blt_bitmap_t *src_bitmap, blt_bitmap_t *dst_bitmap,
		  const Rect *old_rect, const Rect *new_rect,
		  int log2_bits_per_pixel)
{
  long old_width, new_width, old_height, new_height;
  long y, dx, dy, left_x, src_rowbytes, dst_rowbytes, dst_byte_width, old_v;
  long rows_left;
  const uint8 *src_base;
  uint8 *dst_row_base;

  /* Fetch the sizes of the two bitmaps. */
  old_width  = RECT_WIDTH (old_rect);
  new_width  = RECT_WIDTH (new_rect);
  old_height = RECT_HEIGHT (old_rect);
  new_height = RECT_HEIGHT (new_rect);

  /* If the old bitmap was empty, just create a new, empty bitmap.  We
   * do this to avoid dividing by zero.
   */
  if (new_width == 0 || new_height == 0)
    {
      dst_bitmap->bounds.left = dst_bitmap->bounds.right
	= dst_bitmap->bounds.top = dst_bitmap->bounds.bottom = CWC (0);
/*->*/return;
    }

  /* Compute the scale ratio as a fixed-point number. */
  dx = (old_width  << 16) / new_width;
  dy = (old_height << 16) / new_height;

  /* Compute some parameters for the main loop. */
  dst_byte_width = ((new_width << log2_bits_per_pixel) + 7) / 8;
  dst_rowbytes = (dst_byte_width + 3) & ~3;  /* Divisible by 4. */
  src_rowbytes = BITMAP_ROWBYTES (src_bitmap);
  dst_row_base = (uint8 *) MR (dst_bitmap->baseAddr);
  src_base = (uint8 *) (MR (src_bitmap->baseAddr)
	      + ((CW (old_rect->top) - CW (src_bitmap->bounds.top)) * src_rowbytes));
  left_x = (CW (old_rect->left) - CW (src_bitmap->bounds.left)) << 16;
  old_v = -1;

/* This macro expresses the main horizontal scaling loop.  The bits
 * for each byte in the destination bitmap are grabbed and ORed together,
 * and then written out.
 */
#define SCALE_LOOP(x_count, scale_code)					      \
  for (rows_left = new_height, y = 0; rows_left > 0; y += dy, rows_left--)    \
    {									      \
      long v = y >> 16;							      \
      if (v == old_v)							      \
	{								      \
	  memcpy (dst_row_base, dst_row_base - dst_rowbytes, dst_byte_width); \
	}								      \
      else								      \
	{								      \
	  long x, h;							      \
	  const unsigned char *src_row_base;				      \
									      \
	  /* Loop across this row. */					      \
	  src_row_base = &src_base[src_rowbytes * v];			      \
	  for (h = 0, x = left_x; h < (x_count); h++)			      \
	    {								      \
	      scale_code;						      \
	    }								      \
									      \
	  old_v = v;							      \
	}								      \
      dst_row_base += dst_rowbytes;					      \
    }

/* This helper macro grabs the bits corresponding to the x / 65536th pixel
 * from src_row_base on the current line, assuming the specified number of
 * bits per pixel.  FIXME: this code can read beyond the end of src_bitmap's
 * memory when collecting unneeded boundary pixels.
 */

#undef BITS
#define BITS(log2_bpp) \
  ((src_row_base[x >> (19 - (log2_bpp))]   /* This is the containing byte.  */\
    >> (((~(x >> 16)) & (7 >> (log2_bpp))) /* Pixel # within that byte.     */\
	<< (log2_bpp)))                    /* Scale by pixel size.          */\
   & ((1 << (1 << (log2_bpp))) - 1))       /* Mask out all but wanted bits. */

/* #warning "Can look too far into memory for the boundary pixels" */


  switch (log2_bits_per_pixel)
    {
    case 0:  /* 1 bpp */
      SCALE_LOOP (dst_byte_width,
		  {
	            unsigned char new;
		    new = BITS (0) << 7;
		    x += dx;
		    new |= BITS (0) << 6;
		    x += dx;
		    new |= BITS (0) << 5;
		    x += dx;
		    new |= BITS (0) << 4;
		    x += dx;
		    new |= BITS (0) << 3;
		    x += dx;
		    new |= BITS (0) << 2;
		    x += dx;
		    new |= BITS (0) << 1;
		    x += dx;
		    new |= BITS (0);
		    x += dx;
		    dst_row_base[h] = new;
		  });
      break;
    case 1:  /* 2 bpp */
      SCALE_LOOP (dst_byte_width,
		  {
	            unsigned char new;
		    new = BITS (1) << 6;
		    x += dx;
		    new |= BITS (1) << 4;
		    x += dx;
		    new |= BITS (1) << 2;
		    x += dx;
		    new |= BITS (1);
		    x += dx;
		    dst_row_base[h] = new;
		  });
      break;
    case 2:  /* 4 bpp */
      SCALE_LOOP (dst_byte_width,
		  {
	            unsigned char new;
		    new = BITS (2) << 4;
		    x += dx;
		    new |= BITS (2);
		    x += dx;
		    dst_row_base[h] = new;
		  });
      break;
    case 3:  /* 8 bpp */
      SCALE_LOOP (dst_byte_width,
		  {
	            dst_row_base[h] = BITS (3);
		    x += dx;
		  });
      break;
    case 4:
      SCALE_LOOP
	(new_width,
	 {
	  ((uint16 *) dst_row_base)[h]
	    = ((uint16 *) src_row_base)[x >> 16];
	  x += dx;
	});
      break;
    case 5:
      SCALE_LOOP
	(new_width,
	 {
	  ((uint32 *) dst_row_base)[h]
	    = ((uint32 *) src_row_base)[x >> 16];
	  x += dx;
	});
      break;
    default:
      gui_fatal ("invalid target depth %d",
		   (1 << log2_bits_per_pixel));
    }

  BITMAP_SET_ROWBYTES_X (dst_bitmap, CW (dst_rowbytes));
  dst_bitmap->bounds = *new_rect;
}