/* Copyright (C) 1989, 1996, 1997, 1998, 1999 Aladdin Enterprises.  All rights reserved.
  
  This program is free software; you can redistribute it and/or modify it
  under the terms of the GNU General Public License version 2
  as published by the Free Software Foundation.


  This software is provided AS-IS with no warranty, either express or
  implied. That is, 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, 02111-1307.
  
  For more information about licensing, please refer to
  http://www.ghostscript.com/licensing/. For information on
  commercial licensing, go to http://www.artifex.com/licensing/ or
  contact Artifex Software, Inc., 101 Lucas Valley Road #110,
  San Rafael, CA  94903, U.S.A., +1(415)492-9861.
*/

/* $Id: gspaint.c,v 1.6 2002/10/07 08:28:56 ghostgum Exp $ */
/* Painting procedures for Ghostscript library */
#include "math_.h"		/* for fabs */
#include "gx.h"
#include "gpcheck.h"
#include "gserrors.h"
#include "gsropt.h"		/* for gxpaint.h */
#include "gxfixed.h"
#include "gxmatrix.h"		/* for gs_state */
#include "gspaint.h"
#include "gspath.h"
#include "gzpath.h"
#include "gxpaint.h"
#include "gzstate.h"
#include "gxdevice.h"
#include "gxdevmem.h"
#include "gzcpath.h"

/* Define the nominal size for alpha buffers. */
#define abuf_nominal_SMALL 500
#define abuf_nominal_LARGE 2000
#if arch_small_memory
#  define abuf_nominal abuf_nominal_SMALL
#else
#  define abuf_nominal\
     (gs_debug_c('.') ? abuf_nominal_SMALL : abuf_nominal_LARGE)
#endif

/* Erase the page */
int
gs_erasepage(gs_state * pgs)
{
    /*
     * We can't just fill with device white; we must take the
     * transfer function into account.
     */
    int code;

    if ((code = gs_gsave(pgs)) < 0)
	return code;
    if ((code = gs_setgray(pgs, 1.0)) >= 0) {
	/* Fill the page directly, ignoring clipping. */
	code = gs_fillpage(pgs);
    }
    gs_grestore(pgs);
    return code;
}

/* Fill the page with the current color. */
int
gs_fillpage(gs_state * pgs)
{
    gx_device *dev;
    int code;
    gs_logical_operation_t save_lop;

    gx_set_dev_color(pgs);
    dev = gs_currentdevice(pgs);
    /* Fill the page directly, ignoring clipping. */
    /* Use the default RasterOp. */
    save_lop = pgs->log_op;
    gs_init_rop(pgs);
    code = gx_fill_rectangle(0, 0, dev->width, dev->height,
			     pgs->dev_color, pgs);
    pgs->log_op = save_lop;
    if (code < 0)
	return code;
    return (*dev_proc(dev, sync_output)) (dev);
}

/*
 * Determine the number of bits of alpha buffer for a stroke or fill.
 * We should do alpha buffering iff this value is >1.
 */
private int
alpha_buffer_bits(gs_state * pgs)
{
    gx_device *dev;

    if (!color_is_pure(pgs->dev_color))
	return 0;
    dev = gs_currentdevice_inline(pgs);
    if (gs_device_is_abuf(dev)) {
	/* We're already writing into an alpha buffer. */
	return 0;
    }
    return (*dev_proc(dev, get_alpha_bits))
	(dev, (pgs->in_cachedevice ? go_text : go_graphics));
}
/*
 * Set up an alpha buffer for a stroke or fill operation.  Return 0
 * if no buffer could be allocated, 1 if a buffer was installed,
 * or the usual negative error code.
 *
 * The fill/stroke code sets up a clipping device if needed; however,
 * since we scale up all the path coordinates, we either need to scale up
 * the clipping region, or do clipping after, rather than before,
 * alpha buffering.  Either of these is a little inconvenient, but
 * the former is less inconvenient.
 */
private int
scale_paths(gs_state * pgs, int log2_scale_x, int log2_scale_y, bool do_path)
{
    /*
     * Because of clip and clippath, any of path, clip_path, and view_clip
     * may be aliases for each other.  The only reliable way to detect
     * this is by comparing the segments pointers.  Note that we must
     * scale the non-segment parts of the paths even if the segments are
     * aliased.
     */
    const gx_path_segments *seg_clip =
	(pgs->clip_path->path_valid ? pgs->clip_path->path.segments : 0);
    const gx_clip_rect_list *list_clip = pgs->clip_path->rect_list;
    const gx_path_segments *seg_view_clip;
    const gx_clip_rect_list *list_view_clip;
    const gx_path_segments *seg_effective_clip =
	(pgs->effective_clip_path->path_valid ?
	 pgs->effective_clip_path->path.segments : 0);
    const gx_clip_rect_list *list_effective_clip =
	pgs->effective_clip_path->rect_list;

    gx_cpath_scale_exp2_shared(pgs->clip_path, log2_scale_x, log2_scale_y,
			       false, false);
    if (pgs->view_clip != 0 && pgs->view_clip != pgs->clip_path) {
	seg_view_clip =
	    (pgs->view_clip->path_valid ? pgs->view_clip->path.segments : 0);
	list_view_clip = pgs->view_clip->rect_list;
	gx_cpath_scale_exp2_shared(pgs->view_clip, log2_scale_x, log2_scale_y,
				   list_view_clip == list_clip,
				   seg_view_clip && seg_view_clip == seg_clip);
    } else
	seg_view_clip = 0, list_view_clip = 0;
    if (pgs->effective_clip_path != pgs->clip_path &&
	pgs->effective_clip_path != pgs->view_clip
	)
	gx_cpath_scale_exp2_shared(pgs->effective_clip_path, log2_scale_x,
				   log2_scale_y,
				   list_effective_clip == list_clip ||
				   list_effective_clip == list_view_clip,
				   seg_effective_clip &&
				   (seg_effective_clip == seg_clip ||
				    seg_effective_clip == seg_view_clip));
    if (do_path) {
	const gx_path_segments *seg_path = pgs->path->segments;

	gx_path_scale_exp2_shared(pgs->path, log2_scale_x, log2_scale_y,
				  seg_path == seg_clip ||
				  seg_path == seg_view_clip ||
				  seg_path == seg_effective_clip);
    }
    return 0;
}
private void
scale_dash_pattern(gs_state * pgs, floatp scale)
{
    int i;

    for (i = 0; i < pgs->line_params.dash.pattern_size; ++i)
	pgs->line_params.dash.pattern[i] *= scale;
    pgs->line_params.dash.offset *= scale;
    pgs->line_params.dash.pattern_length *= scale;
    pgs->line_params.dash.init_dist_left *= scale;
    if (pgs->line_params.dot_length_absolute)
	pgs->line_params.dot_length *= scale;
}
private int
alpha_buffer_init(gs_state * pgs, fixed extra_x, fixed extra_y, int alpha_bits)
{
    gx_device *dev = gs_currentdevice_inline(pgs);
    int log2_alpha_bits = ilog2(alpha_bits);
    gs_fixed_rect bbox;
    gs_int_rect ibox;
    uint width, raster, band_space;
    uint height;
    gs_log2_scale_point log2_scale;
    gs_memory_t *mem;
    gx_device_memory *mdev;

    log2_scale.x = log2_scale.y = log2_alpha_bits;
    gx_path_bbox(pgs->path, &bbox);
    ibox.p.x = fixed2int(bbox.p.x - extra_x) - 1;
    ibox.p.y = fixed2int(bbox.p.y - extra_y) - 1;
    ibox.q.x = fixed2int_ceiling(bbox.q.x + extra_x) + 1;
    ibox.q.y = fixed2int_ceiling(bbox.q.y + extra_y) + 1;
    width = (ibox.q.x - ibox.p.x) << log2_scale.x;
    raster = bitmap_raster(width);
    band_space = raster << log2_scale.y;
    height = (abuf_nominal / band_space) << log2_scale.y;
    if (height == 0)
	height = 1 << log2_scale.y;
    mem = pgs->memory;
    mdev = gs_alloc_struct(mem, gx_device_memory, &st_device_memory,
			   "alpha_buffer_init");
    if (mdev == 0)
	return 0;		/* if no room, don't buffer */
    gs_make_mem_abuf_device(mdev, mem, dev, &log2_scale,
			    alpha_bits, ibox.p.x << log2_scale.x);
    mdev->width = width;
    mdev->height = height;
    mdev->bitmap_memory = mem;
    if ((*dev_proc(mdev, open_device)) ((gx_device *) mdev) < 0) {
	/* No room for bits, punt. */
	gs_free_object(mem, mdev, "alpha_buffer_init");
	return 0;
    }
    gx_set_device_only(pgs, (gx_device *) mdev);
    scale_paths(pgs, log2_scale.x, log2_scale.y, true);
    return 1;
}

/* Release an alpha buffer. */
private void
alpha_buffer_release(gs_state * pgs, bool newpath)
{
    gx_device_memory *mdev =
    (gx_device_memory *) gs_currentdevice_inline(pgs);

    (*dev_proc(mdev, close_device)) ((gx_device *) mdev);
    scale_paths(pgs, -mdev->log2_scale.x, -mdev->log2_scale.y,
		!(newpath && !gx_path_is_shared(pgs->path)));
    /* Reference counting will free mdev. */
    gx_set_device_only(pgs, mdev->target);
}

/* Fill the current path using a specified rule. */
private int
fill_with_rule(gs_state * pgs, int rule)
{
    int code;

    /* If we're inside a charpath, just merge the current path */
    /* into the parent's path. */
    if (pgs->in_charpath)
	code = gx_path_add_char_path(pgs->show_gstate->path, pgs->path,
				     pgs->in_charpath);
    else {
	int abits, acode;

	gx_set_dev_color(pgs);
	code = gs_state_color_load(pgs);
	if (code < 0)
	    return code;
	abits = alpha_buffer_bits(pgs);
	if (abits > 1) {
	    acode = alpha_buffer_init(pgs, pgs->fill_adjust.x,
				      pgs->fill_adjust.y, abits);
	    if (acode < 0)
		return acode;
	} else
	    acode = 0;
	code = gx_fill_path(pgs->path, pgs->dev_color, pgs, rule,
			    pgs->fill_adjust.x, pgs->fill_adjust.y);
	if (acode > 0)
	    alpha_buffer_release(pgs, code >= 0);
	if (code >= 0)
	    gs_newpath(pgs);

    }
    return code;
}
/* Fill using the winding number rule */
int
gs_fill(gs_state * pgs)
{
    return fill_with_rule(pgs, gx_rule_winding_number);
}
/* Fill using the even/odd rule */
int
gs_eofill(gs_state * pgs)
{
    return fill_with_rule(pgs, gx_rule_even_odd);
}

/* Stroke the current path */
int
gs_stroke(gs_state * pgs)
{
    int code;

    /*
     * If we're inside a charpath, just merge the current path
     * into the parent's path.
     */
    if (pgs->in_charpath) {
	if (pgs->in_charpath == cpm_true_charpath) {
	    /*
	     * A stroke inside a true charpath should do the
	     * equivalent of strokepath.
	     */
	    code = gs_strokepath(pgs);
	    if (code < 0)
		return code;
	}
	code = gx_path_add_char_path(pgs->show_gstate->path, pgs->path,
				     pgs->in_charpath);
    } else {
	int abits, acode;

	gx_set_dev_color(pgs);
	code = gs_state_color_load(pgs);
	if (code < 0)
	    return code;
	abits = alpha_buffer_bits(pgs);
	if (abits > 1) {
	    /*
	     * Expand the bounding box by the line width.
	     * This is expensive to compute, so we only do it
	     * if we know we're going to buffer.
	     */
	    float xxyy = fabs(pgs->ctm.xx) + fabs(pgs->ctm.yy);
	    float xyyx = fabs(pgs->ctm.xy) + fabs(pgs->ctm.yx);
	    float scale = (float)(1 << (abits / 2));
	    float orig_width = gs_currentlinewidth(pgs);
	    float new_width = orig_width * scale;
	    fixed extra_adjust =
		float2fixed(max(xxyy, xyyx) * new_width / 2);
	    float orig_flatness = gs_currentflat(pgs);
	    gx_path spath;

	    /* Scale up the line width, dash pattern, and flatness. */
	    if (extra_adjust < fixed_1)
		extra_adjust = fixed_1;
	    acode = alpha_buffer_init(pgs,
				      pgs->fill_adjust.x + extra_adjust,
				      pgs->fill_adjust.y + extra_adjust,
				      abits);
	    if (acode < 0)
		return acode;
	    gs_setlinewidth(pgs, new_width);
	    scale_dash_pattern(pgs, scale);
	    gs_setflat(pgs, orig_flatness * scale);
	    /*
	     * The alpha-buffer device requires that we fill the
	     * entire path as a single unit.
	     */
	    gx_path_init_local(&spath, pgs->memory);
	    code = gx_stroke_add(pgs->path, &spath, pgs);
	    gs_setlinewidth(pgs, orig_width);
	    scale_dash_pattern(pgs, 1.0 / scale);
	    if (code >= 0)
		code = gx_fill_path(&spath, pgs->dev_color, pgs,
				    gx_rule_winding_number,
				    pgs->fill_adjust.x,
				    pgs->fill_adjust.y);
	    gs_setflat(pgs, orig_flatness);
	    gx_path_free(&spath, "gs_stroke");
	    if (acode > 0)
		alpha_buffer_release(pgs, code >= 0);
	} else
	    code = gx_stroke_fill(pgs->path, pgs);
	if (code >= 0)
	    gs_newpath(pgs);
    }
    return code;
}

/* Compute the stroked outline of the current path */
int
gs_strokepath(gs_state * pgs)
{
    gx_path spath;
    int code;

    gx_path_init_local(&spath, pgs->path->memory);
    code = gx_stroke_add(pgs->path, &spath, pgs);
    if (code < 0) {
	gx_path_free(&spath, "gs_strokepath");
	return code;
    }
    return gx_path_assign_free(pgs->path, &spath);
}
