/*
   Copyright (C) 2002 Free Software Foundation, Inc.

   Author:  Alexander Malmberg <alexander@malmberg.org>

   This file is part of GNUstep.

   This 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.
   
   This 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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include <math.h>

#include <AppKit/NSAffineTransform.h>

#include "ARTGState.h"

#ifndef RDS
#include "x11/XWindowBuffer.h"
#endif
#include "blit.h"


@implementation ARTGState (composite)


/* Figure out what blit function we should use. If one or both of the
windows are known to be totally opaque, we can optimize in many ways
(see big table at the end of blit.m). Will set dst_need_alpha and blit_func
if necessary. Returns new operation, or -1 it it's a noop. */
-(int) _composite_func: (BOOL)src_opaque : (BOOL)src_transparent
	: (BOOL)dst_opaque : (BOOL *)dst_needs_alpha
	: (int)op : (void (**)(composite_run_t *c, int num))blit_func_r
{
  void (*blit_func)(composite_run_t *c, int num);

  *dst_needs_alpha = NO;
  *blit_func_r = blit_func = NULL;

  if (src_transparent) /* only happens with compositerect */
    {
      switch (op)
	{
	case NSCompositeCopy:
	case NSCompositeSourceIn:
	case NSCompositeSourceOut:
	case NSCompositeDestinationIn:
	case NSCompositeDestinationAtop:
	case NSCompositePlusDarker:
	  return NSCompositeClear;

	case NSCompositeSourceOver:
	case NSCompositeSourceAtop:
	case NSCompositeDestinationOver:
	case NSCompositeDestinationOut:
	case NSCompositeXOR:
	case NSCompositePlusLighter:
	  return -1; /* noop */
	}
    }
  else
    if (src_opaque && dst_opaque)
      { /* both source and destination are totally opaque */
	switch (op)
	  {
	  case NSCompositeSourceOver:
	  case NSCompositeSourceIn:
	  case NSCompositeSourceAtop:
	    return NSCompositeCopy;

	  case NSCompositeSourceOut:
	  case NSCompositeDestinationOut:
	  case NSCompositeXOR:
	    return NSCompositeClear;

	  case NSCompositeDestinationOver:
	  case NSCompositeDestinationIn:
	  case NSCompositeDestinationAtop:
	    return -1; /* noop */

	  case NSCompositePlusLighter:
	    blit_func = DI.composite_plusl_oo;
	    break;
	  case NSCompositePlusDarker:
	    blit_func = DI.composite_plusd_oo;
	    break;
	  }
      }
    else if (src_opaque)
      { /* source is opaque, destination has alpha */
	switch (op)
	  {
	  case NSCompositeSourceOver:
	    return NSCompositeCopy;

	  case NSCompositeSourceIn:
	  case NSCompositeSourceAtop:
	    blit_func = DI.composite_sin_oa;
	    break;

	  case NSCompositeSourceOut:
	  case NSCompositeXOR:
	    blit_func = DI.composite_sout_oa;
	    break;

	  case NSCompositeDestinationOver:
	  case NSCompositeDestinationAtop:
	    blit_func = DI.composite_dover_oa;
	    break;

	  case NSCompositeDestinationIn:
	    return -1; /* noop */

	  case NSCompositeDestinationOut:
	    return NSCompositeClear;

	  case NSCompositePlusLighter:
	    blit_func = DI.composite_plusl_oa;
	    break;
	  case NSCompositePlusDarker:
	    blit_func = DI.composite_plusd_oa;
	    break;
	  }
      }
    else if (dst_opaque)
      { /* source has alpha, destination is opaque */
	switch (op)
	  {
	  case NSCompositeCopy:
	    *dst_needs_alpha = YES;
	    break;

	  case NSCompositeSourceOver:
	  case NSCompositeSourceAtop:
	    blit_func = DI.composite_sover_ao;
	    break;

	  case NSCompositeSourceIn:
	    return NSCompositeCopy;

	  case NSCompositeSourceOut:
	    return NSCompositeClear;

	  case NSCompositeDestinationOver:
	    return -1; /* noop */

	  case NSCompositeDestinationIn:
	  case NSCompositeDestinationOut:
	  case NSCompositeDestinationAtop:
	  case NSCompositeXOR:
	    *dst_needs_alpha = YES;
	    goto both_have_alpha;

	  case NSCompositePlusLighter:
	    blit_func = DI.composite_plusl_ao;
	    break;
	  case NSCompositePlusDarker:
	    blit_func = DI.composite_plusd_ao;
	    break;
	  }
      }
    else
      { /* both source and destination have alpha */
      both_have_alpha:
	switch (op)
	  {
	  case NSCompositeSourceOver:
	    blit_func = DI.composite_sover_aa;
	    break;
	  case NSCompositeSourceIn:
	    blit_func = DI.composite_sin_aa;
	    break;
	  case NSCompositeSourceOut:
	    blit_func = DI.composite_sout_aa;
	    break;
	  case NSCompositeSourceAtop:
	    blit_func = DI.composite_satop_aa;
	    break;
	  case NSCompositeDestinationOver:
	    blit_func = DI.composite_dover_aa;
	    break;
	  case NSCompositeDestinationIn:
	    blit_func = DI.composite_din_aa;
	    break;
	  case NSCompositeDestinationOut:
	    blit_func = DI.composite_dout_aa;
	    break;
	  case NSCompositeDestinationAtop:
	    blit_func = DI.composite_datop_aa;
	    break;
	  case NSCompositeXOR:
	    blit_func = DI.composite_xor_aa;
	    break;
	  case NSCompositePlusLighter:
	    blit_func = DI.composite_plusl_aa;
	    break;
	  case NSCompositePlusDarker:
	    blit_func = DI.composite_plusd_aa;
	    break;
	  }
      }
  *blit_func_r = blit_func;
  return op;
}


static void copy_oo(composite_run_t *c, int num)
{
	memcpy(c->dst,c->src,num*DI.bytes_per_pixel);
}

static void copy_oa(composite_run_t *c, int num)
{
	memcpy(c->dst,c->src,num*DI.bytes_per_pixel);
	if (DI.inline_alpha)
	{
		unsigned char *dsta=c->dst+DI.inline_alpha_ofs;
		for (;num;num--,dsta+=4)
			*dsta=0xff;
	}
	else
		memset(c->dsta,0xff,num);
}

static void copy_aa(composite_run_t *c, int num)
{
	memcpy(c->dst,c->src,num*DI.bytes_per_pixel);
	if (!DI.inline_alpha)
		memcpy(c->dsta,c->srca,num);
}


/*
Handle compositing in transformed coordinate spaces. _rect_setup sets up
the a rect_trace_t structure, and each call to _rect_advance returns YES
and the left and right points on the next row, or NO if all rows are done.
*/
typedef struct
{
  int x[4], y[4];
  int cy, ey;

  int left_delta;
  int lx, lx_frac, ldx, ldx_frac, l_de, le;
  int rx, rx_frac, rdx, rdx_frac, r_de, re;

  int cx0, cx1;
} rect_trace_t;

static void _rect_setup(rect_trace_t *t, NSRect r, int cx0, int cx1,
		 NSAffineTransform *ctm, int up, int *y0, int wi_sy)
{
  float fx[4], fy[4];
  NSPoint p;

  t->cx0 = cx0;
  t->cx1 = cx1;

  p = r.origin;
  p = [ctm pointInMatrixSpace: p];
  fx[0] = p.x; fy[0] = p.y;
  p = r.origin; p.x += r.size.width;
  p = [ctm pointInMatrixSpace: p];
  fx[1] = p.x; fy[1] = p.y;
  p = r.origin; p.x += r.size.width; p.y += r.size.height;
  p = [ctm pointInMatrixSpace: p];
  fx[2] = p.x; fy[2] = p.y;
  p = r.origin; p.y += r.size.height;
  p = [ctm pointInMatrixSpace: p];
  fx[3] = p.x; fy[3] = p.y;

  if (fabs(fx[0] - floor(fx[0] + .5)) < 0.001) fx[0] = floor(fx[0] + .5);
  if (fabs(fx[1] - floor(fx[1] + .5)) < 0.001) fx[1] = floor(fx[1] + .5);
  if (fabs(fx[2] - floor(fx[2] + .5)) < 0.001) fx[2] = floor(fx[2] + .5);
  if (fabs(fx[3] - floor(fx[3] + .5)) < 0.001) fx[3] = floor(fx[3] + .5);
  if (fabs(fy[0] - floor(fy[0] + .5)) < 0.001) fy[0] = floor(fy[0] + .5);
  if (fabs(fy[1] - floor(fy[1] + .5)) < 0.001) fy[1] = floor(fy[1] + .5);
  if (fabs(fy[2] - floor(fy[2] + .5)) < 0.001) fy[2] = floor(fy[2] + .5);
  if (fabs(fy[3] - floor(fy[3] + .5)) < 0.001) fy[3] = floor(fy[3] + .5);

  t->x[0] = floor(fx[0]); t->y[0] = wi_sy - floor(fy[0]);
  t->x[1] = floor(fx[1]); t->y[1] = wi_sy - floor(fy[1]);
  t->x[2] = floor(fx[2]); t->y[2] = wi_sy - floor(fy[2]);
  t->x[3] = floor(fx[3]); t->y[3] = wi_sy - floor(fy[3]);

  /* If we're tracing the 'other way', we just flip the y-coordinates
  and unflip when returning them */
  if (up)
    {
      t->y[0] = -t->y[0];
      t->y[1] = -t->y[1];
      t->y[2] = -t->y[2];
      t->y[3] = -t->y[3];
    }

  t->cy = t->y[t->le = 0];
  if (t->y[1] < t->cy) t->cy = t->y[t->le = 1];
  if (t->y[2] < t->cy) t->cy = t->y[t->le = 2];
  if (t->y[3] < t->cy) t->cy = t->y[t->le = 3];
  t->re = t->le;

  t->ey = t->y[0];
  if (t->y[1] > t->ey) t->ey = t->y[1];
  if (t->y[2] > t->ey) t->ey = t->y[2];
  if (t->y[3] > t->ey) t->ey = t->y[3];

  if (t->x[(t->le + 1) & 3] < t->x[(t->le - 1) & 3])
    t->left_delta = 1;
  else
    t->left_delta = -1;

  /* silence the compiler */
  t->lx = t->lx_frac = t->ldx = t->ldx_frac = t->l_de = 0;
  t->rx = t->rx_frac = t->rdx = t->rdx_frac = t->r_de = 0;

  if (up)
    *y0 = -t->cy;
  else
    *y0 = t->cy;
}

static BOOL _rect_advance(rect_trace_t *t, int *x0, int *x1)
{
  int next;

  if (t->cy > t->ey)
    return NO;

      if (t->cy == t->y[t->le])
	{
	  next = (t->le + t->left_delta) & 3;
	  if (t->y[t->le] == t->y[next])
	    {
	      t->le = next;
	      next = (t->le + t->left_delta) & 3;
	    }
	  t->l_de = t->y[next] - t->y[t->le];
	  if (!t->l_de)
	    return NO;
	  t->lx = t->x[t->le];
	  t->lx_frac = 0;
	  t->ldx = (t->x[next] - t->x[t->le]) / t->l_de;
	  t->ldx_frac = (t->x[next] - t->x[t->le]) % t->l_de;

	  t->le = next;
	}
      else
	{
	  t->lx += t->ldx;
	  t->lx_frac += t->ldx_frac;
	  if (t->lx_frac < 0)
	    t->lx--, t->lx_frac += t->l_de;
	  if (t->lx_frac > t->l_de)
	    t->lx++, t->lx_frac -= t->l_de;
	}

      if (t->cy == t->y[t->re])
	{
	  next = (t->re - t->left_delta) & 3;
	  if (t->y[t->re] == t->y[next])
	    {
	      t->re = next;
	      next = (t->re - t->left_delta) & 3;
	    }
	  t->r_de = t->y[next] - t->y[t->re];
	  if (!t->r_de)
	    return NO;
	  t->rx = t->x[t->re];
	  t->rx_frac = t->r_de - 1; /* TODO? */
	  t->rdx = (t->x[next] - t->x[t->re]) / t->r_de;
	  t->rdx_frac = (t->x[next] - t->x[t->re]) % t->r_de;

	  t->re = next;
	}
      else
	{
	  t->rx += t->rdx;
	  t->rx_frac += t->rdx_frac;
	  if (t->rx_frac < 0)
	    t->rx--, t->rx_frac += t->r_de;
	  if (t->rx_frac > t->r_de)
	    t->rx++, t->rx_frac -= t->r_de;
	}

      if (t->rx > t->lx && t->rx >= t->cx0 && t->lx < t->cx1)
	{
	  *x0 = t->lx - t->cx0;
	  if (*x0 < 0)
	    *x0 = 0;
	  *x1 = t->rx - t->cx0;
	  if (*x1 > t->cx1 - t->cx0)
	    *x1 = t->cx1 - t->cx0;
	}
      else
	{
	  *x0 = *x1 = 0;
	}

      t->cy++;

  return YES;
}


- (void) compositeGState: (GSGState *)source
                fromRect: (NSRect)aRect
                 toPoint: (NSPoint)aPoint
                      op: (NSCompositingOperation)composite_op
{
  ARTGState *ags = (ARTGState *)source;
  unsigned char *dst, *dst_alpha, *src, *src_alpha;

  int op;
  void (*blit_func)(composite_run_t *c, int num) = NULL;

  NSPoint sp, dp;

  int cx0,cy0,cx1,cy1;
  int sx0,sy0;

  int sbpl, dbpl;
  int asbpl, adbpl;

  rect_trace_t state;

  /* 0 = top->down, 1 = bottom->up */
  /*
    TODO: this does not handle the horizontal case
    either 0=top->down, left->right, 2=top->down, right->left
    or keep 0 and add 2=top->down, make temporary copy of source
    could allocate a temporary array on the stack large enough to hold
    one row and do the operations on it
  */
  /* currently 2=top->down, be careful with overlapping rows */
  /* order=1 is handled generically by flipping sbpl and dbpl and
     adjusting the pointers. order=2 is handled specially */
  int order;

  int delta;


  if (!wi || !wi->data || !ags->wi || !ags->wi->data) return;
  if (all_clipped) return;


  {
    BOOL dst_needs_alpha;
    op = [self _composite_func: !ags->wi->has_alpha : NO
	     : !wi->has_alpha : &dst_needs_alpha
	     : composite_op : &blit_func];
    if (op == -1)
      return;

    if (dst_needs_alpha)
      {
	[wi needsAlpha];
	if (!wi->has_alpha)
	  return;
      }
  }


  /* these ignore the source window, so we send them off to
     compositerect: op: */
  if (op == NSCompositeClear || op == NSCompositeHighlight)
    {
      [self compositerect: NSMakeRect(aPoint.x, aPoint.y,
				      aRect.size.width, aRect.size.height)
	    op: op];
      return;
    }


  /* Set up all the pointers and clip things */

  dbpl = wi->bytes_per_line;
  sbpl = ags->wi->bytes_per_line;

  cx0 = clip_x0;
  cy0 = clip_y0;
  cx1 = clip_x1;
  cy1 = clip_y1;

  sp = [ags->ctm pointInMatrixSpace: aRect.origin];
  sp.x = floor(sp.x);
  sp.y = floor(ags->wi->sy - sp.y);
  dp = [ctm pointInMatrixSpace: aPoint];
  dp.x = floor(dp.x);
  dp.y = floor(wi->sy - dp.y);

  if (dp.x - cx0 > sp.x)
    cx0 = dp.x - sp.x;
  if (dp.y - cy0 > sp.y)
    cy0 = dp.y - sp.y;

  if (cx1 - dp.x > ags->wi->sx - sp.x)
    cx1 = dp.x + ags->wi->sx - sp.x;
  if (cy1 - dp.y > ags->wi->sy - sp.y)
    cy1 = dp.y + ags->wi->sy - sp.y;

  sx0 = sp.x - dp.x + cx0;
  sy0 = sp.y - dp.y + cy0;

  dst = wi->data + cx0 * DI.bytes_per_pixel + cy0 * dbpl;
  src = ags->wi->data + sx0 * DI.bytes_per_pixel + sy0 * sbpl;

  if (ags->wi->has_alpha && op == NSCompositeCopy)
    {
      [wi needsAlpha];
      if (!wi->has_alpha)
	return;
    }

  if (ags->wi->has_alpha)
    {
      if (DI.inline_alpha)
	src_alpha = src;
      else
	src_alpha = ags->wi->alpha + sx0 + sy0 * ags->wi->sx;
      asbpl = ags->wi->sx;
    }
  else
    {
      src_alpha = NULL;
      asbpl = 0;
    }

  if (wi->has_alpha)
    {
      if (DI.inline_alpha)
	dst_alpha = dst;
      else
	dst_alpha = wi->alpha + cx0 + cy0 * wi->sx;
      adbpl = wi->sx;
    }
  else
    {
      dst_alpha = NULL;
      adbpl = 0;
    }

  cy1 -= cy0;
  cx1 -= cx0;

  if (cx0<0 || cy0<0 || cx0+cx1>wi->sx || cy0+cy1>wi->sy ||
      sx0<0 || sy0<0 || sx0+cx1>ags->wi->sx || sy0+cy1>ags->wi->sy)
  {
    NSLog(@"Warning: invalid coordinates in composite: (%g %g)+(%g %g) -> (%g %g) got (%i %i) (%i %i) +(%i %i)",
	  aRect.origin.x,aRect.origin.x,aRect.size.width,aRect.size.height,aPoint.x,aPoint.y,
	  cx0,cy0,sx0,sy0,cx1,cy1);
    return;
  }

  if (cx1<=0 || cy1<=0)
    return;

  /* To handle overlapping areas properly, we sometimes need to do
     things bottom-up instead of top-down. If so, we flip the
     coordinates here. */
  order = 0;
  if (ags->wi == self->wi && sy0 <= cy0)
    {
      order = 1;
      dst += dbpl * (cy1 - 1);
      src += sbpl * (cy1 - 1);
      dst_alpha += adbpl * (cy1 - 1);
      src_alpha += asbpl * (cy1 - 1);
      dbpl = -dbpl;
      sbpl = -sbpl;
      adbpl = -adbpl;
      asbpl = -asbpl;
      if (sy0 == cy0)
	{
	  if ((sx0 >= cx0 && sx0 <= cx0 + cx1) || (cx0 >= sx0 && cx0 <= sx0 + cx1))
	    {
	      order = 2;
	    }
	}
    }

  if (op == NSCompositeCopy)
    {
      if (ags->wi->has_alpha)
	blit_func = copy_aa;
      else if (wi->has_alpha)
	blit_func = copy_oa;
      else
	blit_func = copy_oo;
    }

  if (!blit_func)
    {
      NSLog(@"unimplemented: compositeGState: %p fromRect: (%g %g)+(%g %g) toPoint: (%g %g)  op: %i",
	    source,
	    aRect.origin.x, aRect.origin.y,
	    aRect.size.width, aRect.size.height,
	    aPoint.x, aPoint.y,
	    op);
      return;
    }

  {
    int ry;
    int x0, x1;
    _rect_setup(&state, aRect, sx0, sx0 + cx1, ags->ctm, order, &ry, ags->wi->sy);
    if (order)
      {
	if (ry < sy0)
	  return;
	delta = sy0 + cy1 - ry;
      }
    else
      {
	if (ry >= sy0 + cy1)
	  return;
	delta = ry - sy0;
      }

    if (delta > 0)
      {
	src += sbpl * delta;
	src_alpha += asbpl * delta;
	dst += dbpl * delta;
	dst_alpha += adbpl * delta;
      }
    else if (delta < 0)
      {
	delta = -delta;
	while (delta)
	  {
	    if (!_rect_advance(&state,&x0,&x1))
	      {
	        break;
	      }
	    delta--;
	  }
	if (delta)
	  return;
      }
  }

  /* this breaks the alpha pointer in some, but that's ok since in
     all those cases, the alpha pointer isn't used (inline alpha or
     no alpha) */
  if (order == 2)
    {
      unsigned char tmpbuf[cx1 * DI.bytes_per_pixel];
      unsigned char tmpbufa[cx1];
      int y;
      composite_run_t c;
      int x0, x1;

      c.dst = dst;
      c.dsta = dst_alpha;
      c.src = tmpbuf;
      c.srca = tmpbufa;
      for (y = cy1 - delta - 1; y >= 0; y--)
	{
	  if (!_rect_advance(&state,&x0,&x1))
	    break;
	  x1 -= x0;

	  c.dst += x0 * DI.bytes_per_pixel;
	  c.dsta += x0;
	  /* TODO: update c.dst and c.dsta properly when x1==0 */

	  if (x1)
	    {
	      memcpy(tmpbuf, src + x0 * DI.bytes_per_pixel, x1 * DI.bytes_per_pixel);
	      if (ags->wi->has_alpha && !DI.inline_alpha)
		memcpy(tmpbufa, src_alpha + x0, x1);

	      if (!clip_span)
		{
		  blit_func(&c, x1);
		  c.dst += dbpl - x0 * DI.bytes_per_pixel;
		  c.dsta += adbpl - x0;
		}
	      else
		{
		  unsigned int *span, *end;
		  BOOL state = NO;

		  span = &clip_span[clip_index[y + cy0 - clip_y0]];
		  end = &clip_span[clip_index[y + cy0 - clip_y0 + 1]];

		  x0 = x0 + cx0 - clip_x0;
		  x1 += x0;
		  while (span != end && *span < x0)
		    {
		      state = !state;
		      span++;
		      if (span == end)
			break;
		    }
		  if (span != end)
		    {
		      while (span != end && *span < x1)
			{
			  if (state)
			    blit_func(&c, *span - x0);
			  c.dst += (*span - x0) * DI.bytes_per_pixel;
			  c.dsta += (*span - x0);
			  c.src += (*span - x0) * DI.bytes_per_pixel;
			  c.srca += (*span - x0);
			  x0 = *span;

			  state = !state;
			  span++;
			  if (span == end)
			    break;
			}
		      if (state)
			blit_func(&c, x1 - x0);
		    }
		  x0 = x0 - cx0 + clip_x0;
		  c.dst += dbpl - x0 * DI.bytes_per_pixel;
		  c.dsta += adbpl - x0;
		  c.src = tmpbuf;
		  c.srca = tmpbufa;
		}
	    }

	  src += sbpl;
	  src_alpha += asbpl;
	}
    }
  else
    {
      int y;
      composite_run_t c;
      int x0, x1;

      c.dst = dst;
      c.dsta = dst_alpha;
      c.src = src;
      c.srca = src_alpha;
      if (order)
	y = cy1 - delta - 1;
      else
	y = delta;
      for (; y < cy1 && y >= 0; order? y-- : y++)
	{
	  if (!_rect_advance(&state,&x0,&x1))
	      break;
	  x1 -= x0;
	  if (x1 <= 0)
	    {
	      c.dst += dbpl;
	      c.dsta += adbpl;
	      c.src += sbpl;
	      c.srca += asbpl;
	      continue;
	    }
	  c.dst += x0 * DI.bytes_per_pixel;
	  c.dsta += x0;
	  c.src += x0 * DI.bytes_per_pixel;
	  c.srca += x0;
	  if (!clip_span)
	    {
	      blit_func(&c, x1);
	      c.dst += dbpl - x0 * DI.bytes_per_pixel;
	      c.dsta += adbpl - x0;
	      c.src += sbpl - x0 * DI.bytes_per_pixel;
	      c.srca += asbpl - x0;
	    }
	  else
	    {
	      unsigned int *span, *end;
	      BOOL state = NO;

	      span = &clip_span[clip_index[y + cy0 - clip_y0]];
	      end = &clip_span[clip_index[y + cy0 - clip_y0 + 1]];

	      x0 = x0 + cx0 - clip_x0;
	      x1 += x0;
	      while (span != end && *span < x0)
		{
		  state = !state;
		  span++;
		  if (span == end)
		    break;
		}
	      if (span != end)
		{
		  while (span != end && *span < x1)
		    {
		      if (state)
		        blit_func(&c, *span - x0);
		      c.dst += (*span - x0) * DI.bytes_per_pixel;
		      c.dsta += (*span - x0);
		      c.src += (*span - x0) * DI.bytes_per_pixel;
		      c.srca += (*span - x0);
		      x0 = *span;

		      state = !state;
		      span++;
		      if (span == end)
			break;
		    }
		  if (state)
		    blit_func(&c, x1 - x0);
		}
	      x0 = x0 - cx0 + clip_x0;
	      c.dst += dbpl - x0 * DI.bytes_per_pixel;
	      c.dsta += adbpl - x0;
	      c.src += sbpl -  x0 * DI.bytes_per_pixel;
	      c.srca += asbpl - x0;
	    }
	}
    }
  UPDATE_UNBUFFERED
}


- (void) dissolveGState: (GSGState *)source
               fromRect: (NSRect)aRect
                toPoint: (NSPoint)aPoint
                  delta: (float)fraction
{
/* much setup code shared with compositeGState:... */
  ARTGState *ags = (ARTGState *)source;
  unsigned char *dst, *dst_alpha, *src, *src_alpha;

  void (*blit_func)(composite_run_t *c, int num) = NULL;

  NSPoint sp, dp;

  int cx0,cy0,cx1,cy1;
  int sx0,sy0;

  int sbpl, dbpl;
  int asbpl, adbpl;

  rect_trace_t state;

  /* 0 = top->down, 1 = bottom->up */
  /*
    TODO: this does not handle the horizontal case
    either 0=top->down, left->right, 2=top->down, right->left
    or keep 0 and add 2=top->down, make temporary copy of source
    could allocate a temporary array on the stack large enough to hold
    one row and do the operations on it
  */
  /* currently 2=top->down, be careful with overlapping rows */
  /* order=1 is handled generically by flipping sbpl and dbpl and
     adjusting the pointers. order=2 is handled specially */
  int order;

  int delta;


  if (!wi || !wi->data || !ags->wi || !ags->wi->data) return;
  if (all_clipped) return;

  /* Set up all the pointers and clip things */

  dbpl = wi->bytes_per_line;
  sbpl = ags->wi->bytes_per_line;

  cx0 = clip_x0;
  cy0 = clip_y0;
  cx1 = clip_x1;
  cy1 = clip_y1;

  sp = [ags->ctm pointInMatrixSpace: aRect.origin];
  sp.x = floor(sp.x);
  sp.y = floor(ags->wi->sy - sp.y);
  dp = [ctm pointInMatrixSpace: aPoint];
  dp.x = floor(dp.x);
  dp.y = floor(wi->sy - dp.y);

  if (dp.x - cx0 > sp.x)
    cx0 = dp.x - sp.x;
  if (dp.y - cy0 > sp.y)
    cy0 = dp.y - sp.y;

  if (cx1 - dp.x > ags->wi->sx - sp.x)
    cx1 = dp.x + ags->wi->sx - sp.x;
  if (cy1 - dp.y > ags->wi->sy - sp.y)
    cy1 = dp.y + ags->wi->sy - sp.y;

  sx0 = sp.x - dp.x + cx0;
  sy0 = sp.y - dp.y + cy0;

  dst = wi->data + cx0 * DI.bytes_per_pixel + cy0 * dbpl;
  src = ags->wi->data + sx0 * DI.bytes_per_pixel + sy0 * sbpl;

  if (ags->wi->has_alpha)
    {
      if (DI.inline_alpha)
	src_alpha = src;
      else
	src_alpha = ags->wi->alpha + sx0 + sy0 * ags->wi->sx;
      asbpl = ags->wi->sx;
    }
  else
    {
      src_alpha = NULL;
      asbpl = 0;
    }

  if (wi->has_alpha)
    {
      if (DI.inline_alpha)
	dst_alpha = dst;
      else
	dst_alpha = wi->alpha + cx0 + cy0 * wi->sx;
      adbpl = wi->sx;
    }
  else
    {
      dst_alpha = NULL;
      adbpl = 0;
    }

  cy1 -= cy0;
  cx1 -= cx0;

  if (cx0<0 || cy0<0 || cx0+cx1>wi->sx || cy0+cy1>wi->sy ||
      sx0<0 || sy0<0 || sx0+cx1>ags->wi->sx || sy0+cy1>ags->wi->sy)
  {
    NSLog(@"Warning: invalid coordinates in dissolve: (%g %g)+(%g %g) -> (%g %g) got (%i %i) (%i %i) +(%i %i)",
	  aRect.origin.x,aRect.origin.x,aRect.size.width,aRect.size.height,aPoint.x,aPoint.y,
	  cx0,cy0,sx0,sy0,cx1,cy1);
    return;
  }

  if (cx1<=0 || cy1<=0)
    return;

  /* To handle overlapping areas properly, we sometimes need to do
     things bottom-up instead of top-down. If so, we flip the
     coordinates here. */
  order = 0;
  if (ags->wi == self->wi && sy0 <= cy0)
    {
      order = 1;
      dst += dbpl * (cy1 - 1);
      src += sbpl * (cy1 - 1);
      dst_alpha += adbpl * (cy1 - 1);
      src_alpha += asbpl * (cy1 - 1);
      dbpl = -dbpl;
      sbpl = -sbpl;
      adbpl = -adbpl;
      asbpl = -asbpl;
      if (sy0 == cy0)
	{
	  if ((sx0 >= cx0 && sx0 <= cx0 + cx1) || (cx0 >= sx0 && cx0 <= sx0 + cx1))
	    {
	      order = 2;
	    }
	}
    }

  if (ags->wi->has_alpha && wi->has_alpha)
    blit_func = DI.dissolve_aa;
  else if (wi->has_alpha)
    blit_func = DI.dissolve_oa;
  else if (ags->wi->has_alpha)
    blit_func = DI.dissolve_ao;
  else
    blit_func = DI.dissolve_oo;

  if (!blit_func)
    {
      NSLog(@"unimplemented: dissolveGState: %p fromRect: (%g %g)+(%g %g) toPoint: (%g %g)  delta: %g",
	    source,
	    aRect.origin.x, aRect.origin.y,
	    aRect.size.width, aRect.size.height,
	    aPoint.x, aPoint.y,
	    fraction);
      return;
    }

  {
    int ry;
    int x0, x1;
    _rect_setup(&state, aRect, sx0, sx0 + cx1, ags->ctm, order, &ry, ags->wi->sy);
    if (order)
      {
	if (ry < sy0)
	  return;
	delta = sy0 + cy1 - ry;
      }
    else
      {
	if (ry >= sy0 + cy1)
	  return;
	delta = ry - sy0;
      }

    if (delta > 0)
      {
	src += sbpl * delta;
	src_alpha += asbpl * delta;
	dst += dbpl * delta;
	dst_alpha += adbpl * delta;
      }
    else if (delta < 0)
      {
	delta = -delta;
	while (delta)
	  {
	    if (!_rect_advance(&state,&x0,&x1))
	      {
	        break;
	      }
	    delta--;
	  }
	if (delta)
	  return;
      }
  }

  /* this breaks the alpha pointer in some cases, but that's ok since in
     all those cases, the alpha pointer isn't used (inline alpha or
     no alpha) */
  if (order == 2)
    {
      unsigned char tmpbuf[cx1 * DI.bytes_per_pixel];
      unsigned char tmpbufa[cx1];
      int y;
      composite_run_t c;
      int x0, x1;

      c.dst = dst;
      c.dsta = dst_alpha;
      c.src = tmpbuf;
      c.srca = tmpbufa;
      c.fraction = fraction * 255;
      for (y = cy1 - delta - 1; y >= 0; y--)
	{
	  if (!_rect_advance(&state,&x0,&x1))
	    break;
	  x1 -= x0;

	  c.dst += x0 * DI.bytes_per_pixel;
	  c.dsta += x0;

	  if (x1)
	    {
	      memcpy(tmpbuf, src + x0 * DI.bytes_per_pixel, x1 * DI.bytes_per_pixel);
	      if (ags->wi->has_alpha && !DI.inline_alpha)
		memcpy(tmpbufa, src_alpha + x0, x1);

	      if (!clip_span)
		{
		  blit_func(&c, x1);
		  c.dst += dbpl - x0 * DI.bytes_per_pixel;
		  c.dsta += adbpl - x0;
		}
	      else
		{
		  unsigned int *span, *end;
		  BOOL state = NO;

		  span = &clip_span[clip_index[y + cy0 - clip_y0]];
		  end = &clip_span[clip_index[y + cy0 - clip_y0 + 1]];

		  x0 = x0 + cx0 - clip_x0;
		  x1 += x0;
		  while (span != end && *span < x0)
		    {
		      state = !state;
		      span++;
		      if (span == end)
			break;
		    }
		  if (span != end)
		    {
		      while (span != end && *span < x1)
			{
			  if (state)
			    blit_func(&c, *span - x0);
			  c.dst += (*span - x0) * DI.bytes_per_pixel;
			  c.dsta += (*span - x0);
			  c.src += (*span - x0) * DI.bytes_per_pixel;
			  c.srca += (*span - x0);
			  x0 = *span;

			  state = !state;
			  span++;
			  if (span == end)
			    break;
			}
		      if (state)
			blit_func(&c, x1 - x0);
		    }
		  x0 = x0 - cx0 + clip_x0;
		  c.dst += dbpl - x0 * DI.bytes_per_pixel;
		  c.dsta += adbpl - x0;
		  c.src = tmpbuf;
		  c.srca = tmpbufa;
		}
	    }

	  src += sbpl;
	  src_alpha += asbpl;
	}
    }
  else
    {
      int y;
      composite_run_t c;
      int x0, x1;

      c.dst = dst;
      c.dsta = dst_alpha;
      c.src = src;
      c.srca = src_alpha;
      c.fraction = fraction * 255;
      if (order)
	y = cy1 - delta - 1;
      else
	y = delta;
      for (; y < cy1 && y >= 0; order? y-- : y++)
	{
	  if (!_rect_advance(&state,&x0,&x1))
	      break;
	  x1 -= x0;
	  if (x1 <= 0)
	    {
	      c.dst += dbpl;
	      c.dsta += adbpl;
	      c.src += sbpl;
	      c.srca += asbpl;
	      continue;
	    }
	  c.dst += x0 * DI.bytes_per_pixel;
	  c.dsta += x0;
	  c.src += x0 * DI.bytes_per_pixel;
	  c.srca += x0;
	  if (!clip_span)
	    {
	      blit_func(&c, x1);
	      c.dst += dbpl - x0 * DI.bytes_per_pixel;
	      c.dsta += adbpl - x0;
	      c.src += sbpl - x0 * DI.bytes_per_pixel;
	      c.srca += asbpl - x0;
	    }
	  else
	    {
	      unsigned int *span, *end;
	      BOOL state = NO;

	      span = &clip_span[clip_index[y + cy0 - clip_y0]];
	      end = &clip_span[clip_index[y + cy0 - clip_y0 + 1]];

	      x0 = x0 + cx0 - clip_x0;
	      x1 += x0;
	      while (span != end && *span < x0)
		{
		  state = !state;
		  span++;
		  if (span == end)
		    break;
		}
	      if (span != end)
		{
		  while (span != end && *span < x1)
		    {
		      if (state)
		        blit_func(&c, *span - x0);
		      c.dst += (*span - x0) * DI.bytes_per_pixel;
		      c.dsta += (*span - x0);
		      c.src += (*span - x0) * DI.bytes_per_pixel;
		      c.srca += (*span - x0);
		      x0 = *span;

		      state = !state;
		      span++;
		      if (span == end)
			break;
		    }
		  if (state)
		    blit_func(&c, x1 - x0);
		}
	      x0 = x0 - cx0 + clip_x0;
	      c.dst += dbpl - x0 * DI.bytes_per_pixel;
	      c.dsta += adbpl - x0;
	      c.src += sbpl -  x0 * DI.bytes_per_pixel;
	      c.srca += asbpl - x0;
	    }
	}
    }
  UPDATE_UNBUFFERED
}


- (void) compositerect: (NSRect)aRect
                    op: (NSCompositingOperation)op
{
/* much setup code shared with compositeGState:... */
  unsigned char *dst, *dst_alpha;
  int dbpl, adbpl;

  int cx0, cy0, cx1, cy1;

  void (*blit_func)(composite_run_t *c, int num);

  rect_trace_t state;

  int delta;


  if (!wi || !wi->data) return;
  if (all_clipped) return;


  {
    BOOL dest_needs_alpha;

    /* TODO: which color? using fill_color for now */
    op = [self _composite_func: fill_color[3] == 255 : fill_color[3] == 0
	     : !wi->has_alpha : &dest_needs_alpha
	     : op : &blit_func];

    if (op == -1)
      return;

    if (dest_needs_alpha || op == NSCompositeClear)
      {
	[wi needsAlpha];
	if (!wi->has_alpha)
	  return;
      }
  }


  dbpl = wi->bytes_per_line;
  adbpl = wi->sx;

  cx0 = clip_x0; cy0 = clip_y0;
  cx1 = clip_x1; cy1 = clip_y1;

  dst = wi->data + cx0 * DI.bytes_per_pixel + cy0 * dbpl;
  dst_alpha = wi->alpha + cx0 + cy0 * wi->sx;

  cx1 -= cx0;
  cy1 -= cy0;

  {
    int ry;
    int x0, x1;
    _rect_setup(&state, aRect, cx0, cx0 + cx1, ctm, 0, &ry, wi->sy);
    if (ry >= cy0 + cy1)
      return;
    delta = ry - cy0;

    if (delta > 0)
      {
	dst += dbpl * delta;
	dst_alpha += adbpl * delta;
      }
    else if (delta < 0)
      {
	delta = -delta;
	while (delta)
	  {
	    if (!_rect_advance(&state,&x0,&x1))
	        break;
	    delta--;
	  }
	if (delta)
	  return;
      }
  }


#define DO_STUFF(HANDLE_SPAN) \
{ \
  int y; \
  int x0, x1; \
  int n; \
 \
  if (clip_span) \
    { \
      for (y = delta; y < cy1; y++) \
	{ \
	  unsigned int *span, *end; \
	  BOOL clip_state = NO; \
 \
	  if (!_rect_advance(&state,&x0,&x1)) \
	    break; \
 \
	  x1 -= x0; \
	  if (!x1) \
	    { \
	      dst += dbpl; \
	      dst_alpha += adbpl; \
	      continue; \
	    } \
 \
	  dst += x0 * DI.bytes_per_pixel; \
	  dst_alpha += x0; \
 \
	  span = &clip_span[clip_index[y + cy0 - clip_y0]]; \
	  end = &clip_span[clip_index[y + cy0 - clip_y0 + 1]]; \
 \
	  x0 = x0 + cx0 - clip_x0; \
	  x1 += x0; \
	  while (span != end && *span < x0) \
	    { \
	      clip_state = !clip_state; \
	      span++; \
	      if (span == end) \
		break; \
	    } \
	  if (span != end) \
	    { \
	      while (span != end && *span < x1) \
		{ \
		  if (clip_state) \
		    { \
		      n = (*span - x0); \
		      HANDLE_SPAN \
		    } \
		  dst += (*span - x0) * DI.bytes_per_pixel; \
		  dst_alpha += (*span - x0); \
		  x0 = *span; \
 \
		  clip_state = !clip_state; \
		  span++; \
		  if (span == end) \
		    break; \
		} \
	      if (clip_state) \
		{ \
		  n = x1 - x0; \
		  HANDLE_SPAN \
		} \
	    } \
	  x0 = x0 - cx0 + clip_x0; \
 \
	  dst += dbpl - x0 * DI.bytes_per_pixel; \
	  dst_alpha += adbpl - x0; \
	} \
    } \
  else \
    { \
      for (y = delta; y < cy1; y++) \
	{ \
	  if (!_rect_advance(&state,&x0,&x1)) \
	    break; \
 \
	  x1 -= x0; \
	  if (!x1) \
	    { \
	      dst += dbpl; \
	      dst_alpha += adbpl; \
	      continue; \
	    } \
 \
	  dst += x0 * DI.bytes_per_pixel; \
	  dst_alpha += x0; \
 \
	  n = x1; \
	  HANDLE_SPAN \
 \
	  dst += dbpl - x0 * DI.bytes_per_pixel; \
	  dst_alpha += adbpl - x0; \
	} \
    } \
}

  if (op == NSCompositeClear)
    {
      DO_STUFF(
	memset(dst, 0, n * DI.bytes_per_pixel);
	if (!DI.inline_alpha)
	  memset(dst_alpha, 0, n);
)
    }
  else if (op == NSCompositeHighlight)
    {
      DO_STUFF(
	{
	  unsigned char *d = dst;
	  n *= DI.bytes_per_pixel;
	  for (; n; n--, d++)
	    (*d) ^= 0xff;
	}
)
    }
  else if (op == NSCompositeCopy)
    {
      render_run_t ri;
      ri.dst = dst;
      /* We don't want to blend, so we premultiply and fill the
	 alpha channel manually. */
      ri.a = fill_color[3];
      ri.r = (fill_color[0] * ri.a + 0xff) >> 8;
      ri.g = (fill_color[1] * ri.a + 0xff) >> 8;
      ri.b = (fill_color[2] * ri.a + 0xff) >> 8;
      if (ri.a != 255 && !wi->has_alpha)
	return;

      DO_STUFF(
	ri.dst = dst;
	DI.render_run_opaque(&ri, n);
	if (ri.a != 255)
	  {
	    if (DI.inline_alpha)
	      {
		/* TODO: needs to change to support inline
		   alpha for non-32-bit modes */
		unsigned char *p;
		for (p = dst; n; n--, p += 4)
		  p[DI.inline_alpha_ofs] = ri.a;
	      }
	    else
	      {
		memset(dst_alpha, ri.a, n);
	      }
	  }
)
    }
  else if (blit_func)
    {
      /* this is slightly ugly, but efficient */
      unsigned char buf[DI.bytes_per_pixel * cx1];
      unsigned char abuf[fill_color[3] == 255? 1 : cx1];
      composite_run_t c;

      c.src = buf;
      if (fill_color[3] != 255)
	c.srca = abuf;
      else
	c.srca = NULL;

      {
	render_run_t ri;
	ri.dst = buf;
	ri.dsta = NULL;
	/* Note that we premultiply _here_ and set the alpha
	   channel manually (for speed; no reason to do slow
	   blending when we just want a straight blit of all
	   channels). */
	ri.a = fill_color[3];
	ri.r = (fill_color[0] * ri.a + 0xff) >> 8;
	ri.g = (fill_color[1] * ri.a + 0xff) >> 8;
	ri.b = (fill_color[2] * ri.a + 0xff) >> 8;
	DI.render_run_opaque(&ri, cx1);
	if (fill_color[3] != 255)
	  {
	    if (DI.inline_alpha)
	      {
		int i;
		unsigned char *s;
		/* TODO: needs to change to support inline
		   alpha for non-32-bit modes */
		for (i = 0, s = buf + DI.inline_alpha_ofs; i < cx1; i++, s += 4)
		  *s = ri.a;
	      }
	    else
	      memset(abuf, ri.a, cx1);
	  }
      }

      DO_STUFF(
	c.dst = dst;
	c.dsta = dst_alpha;
	blit_func(&c, n);
)
    }
  else
    {
      NSLog(@"unimplemented compositerect: (%g %g)+(%g %g)  op: %i",
	    aRect.origin.x, aRect.origin.y,
	    aRect.size.width, aRect.size.height,
	    op);
    }
  UPDATE_UNBUFFERED
}

@end