path: root/gs/src/gspaint.c

/* Copyright (C) 1989, 1996, 1997, 1998 Aladdin Enterprises.  All rights reserved.

   This file is part of Aladdin Ghostscript.

   Aladdin Ghostscript is distributed with NO WARRANTY OF ANY KIND.  No author
   or distributor accepts any responsibility for the consequences of using it,
   or for whether it serves any particular purpose or works at all, unless he
   or she says so in writing.  Refer to the Aladdin Ghostscript Free Public
   License (the "License") for full details.

   Every copy of Aladdin Ghostscript must include a copy of the License,
   normally in a plain ASCII text file named PUBLIC.  The License grants you
   the right to copy, modify and redistribute Aladdin Ghostscript, but only
   under certain conditions described in the License.  Among other things, the
   License requires that the copyright notice and this notice be preserved on
   all copies.
 */

/*$Id$ */
/* 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 "gxcpath.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, 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)
{
    if (do_path)
	gx_path_scale_exp2(pgs->path, log2_scale_x, log2_scale_y);
    gx_cpath_scale_exp2(pgs->clip_path, log2_scale_x, log2_scale_y);
    if (pgs->view_clip != 0)
	gx_cpath_scale_exp2(pgs->view_clip, log2_scale_x, log2_scale_y);
    if (pgs->effective_clip_path != pgs->clip_path &&
	pgs->effective_clip_path != pgs->view_clip
	)
	gx_cpath_scale_exp2(pgs->effective_clip_path,
			    log2_scale_x, log2_scale_y);
    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;
    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_alpha_bits = alpha_bits >> 1;	/* works for 1,2,4 */
    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;
	float orig_width;

	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 = 1 << (abits / 2);
	    float new_width =
	    (orig_width = gs_currentlinewidth(pgs)) * scale;
	    fixed extra_adjust =
	    float2fixed(max(xxyy, xyyx) * new_width / 2);
	    gx_path spath;

	    /* Scale up the line width and dash pattern. */
	    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);
	    /*
	     * 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);
	    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->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);
}