cairo-gstate.c

按照官方的说法：Cairo is a vector graphics library with cross-device output support. 翻译过来

/* cairo - a vector graphics library with display and print output
 *
 * Copyright © 2002 University of Southern California
 * Copyright © 2005 Red Hat, Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it either under the terms of the GNU Lesser General Public
 * License version 2.1 as published by the Free Software Foundation
 * (the "LGPL") or, at your option, under the terms of the Mozilla
 * Public License Version 1.1 (the "MPL"). If you do not alter this
 * notice, a recipient may use your version of this file under either
 * the MPL or the LGPL.
 *
 * You should have received a copy of the LGPL along with this library
 * in the file COPYING-LGPL-2.1; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 * You should have received a copy of the MPL along with this library
 * in the file COPYING-MPL-1.1
 *
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.1 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
 * OF ANY KIND, either express or implied. See the LGPL or the MPL for
 * the specific language governing rights and limitations.
 *
 * The Original Code is the cairo graphics library.
 *
 * The Initial Developer of the Original Code is University of Southern
 * California.
 *
 * Contributor(s):
 *	Carl D. Worth <[e-mail]>
 */

#include <stdlib.h>

#include "cairoint.h"

#include "cairo-clip-private.h"
#include "cairo-gstate-private.h"

static cairo_status_t
_cairo_gstate_init (cairo_gstate_t  *gstate,
		    cairo_surface_t *target);

static cairo_status_t
_cairo_gstate_init_copy (cairo_gstate_t *gstate, cairo_gstate_t *other);

static void
_cairo_gstate_fini (cairo_gstate_t *gstate);

static cairo_status_t
_cairo_gstate_ensure_font_face (cairo_gstate_t *gstate);

static cairo_status_t
_cairo_gstate_ensure_scaled_font (cairo_gstate_t *gstate);

static void
_cairo_gstate_unset_scaled_font (cairo_gstate_t *gstate);

/**
 * _cairo_gstate_create:
 * @target: a #cairo_surface_t, not NULL
 *
 * Create a new #cairo_gstate_t to draw to target with all graphics
 * state parameters set to defaults. gstate->next will be set to NULL
 * and may be used by the caller to chain #cairo_gstate_t objects
 * together.
 *
 * Return value: a new #cairo_gstate_t or NULL if there is
 * insufficient memory.
 **/
cairo_gstate_t *
_cairo_gstate_create (cairo_surface_t *target)
{
    cairo_status_t status;
    cairo_gstate_t *gstate;

    assert (target != NULL);

    gstate = malloc (sizeof (cairo_gstate_t));
    if (gstate == NULL)
	return NULL;

    status = _cairo_gstate_init (gstate, target);
    if (status) {
	free (gstate);
	return NULL;
    }

    return gstate;
}

static cairo_status_t
_cairo_gstate_init (cairo_gstate_t  *gstate,
		    cairo_surface_t *target)
{
    gstate->op = CAIRO_GSTATE_OPERATOR_DEFAULT;

    gstate->tolerance = CAIRO_GSTATE_TOLERANCE_DEFAULT;
    gstate->antialias = CAIRO_ANTIALIAS_DEFAULT;

    _cairo_stroke_style_init (&gstate->stroke_style);

    gstate->fill_rule = CAIRO_GSTATE_FILL_RULE_DEFAULT;

    gstate->font_face = NULL;
    gstate->scaled_font = NULL;

    cairo_matrix_init_scale (&gstate->font_matrix,
			     CAIRO_GSTATE_DEFAULT_FONT_SIZE,
			     CAIRO_GSTATE_DEFAULT_FONT_SIZE);

    _cairo_font_options_init_default (&gstate->font_options);

    _cairo_clip_init (&gstate->clip, target);

    gstate->target = cairo_surface_reference (target);
    gstate->parent_target = NULL;
    gstate->original_target = cairo_surface_reference (target);

    _cairo_gstate_identity_matrix (gstate);
    gstate->source_ctm_inverse = gstate->ctm_inverse;

    gstate->source = _cairo_pattern_create_solid (CAIRO_COLOR_BLACK);
    if (gstate->source->status)
	return CAIRO_STATUS_NO_MEMORY;

    gstate->next = NULL;

    return CAIRO_STATUS_SUCCESS;
}

/**
 * _cairo_gstate_init_copy:
 *
 * Initialize @gstate by performing a deep copy of state fields from
 * @other. Note that gstate->next is not copied but is set to NULL by
 * this function.
 **/
static cairo_status_t
_cairo_gstate_init_copy (cairo_gstate_t *gstate, cairo_gstate_t *other)
{
    cairo_status_t status;

    gstate->op = other->op;

    gstate->tolerance = other->tolerance;
    gstate->antialias = other->antialias;

    status = _cairo_stroke_style_init_copy (&gstate->stroke_style,
					    &other->stroke_style);
    if (status)
	return status;

    gstate->fill_rule = other->fill_rule;

    gstate->font_face = cairo_font_face_reference (other->font_face);
    gstate->scaled_font = cairo_scaled_font_reference (other->scaled_font);

    gstate->font_matrix = other->font_matrix;

    _cairo_font_options_init_copy (&gstate->font_options , &other->font_options);

    _cairo_clip_init_copy (&gstate->clip, &other->clip);

    gstate->target = cairo_surface_reference (other->target);
    /* parent_target is always set to NULL; it's only ever set by redirect_target */
    gstate->parent_target = NULL;
    gstate->original_target = cairo_surface_reference (other->original_target);

    gstate->ctm = other->ctm;
    gstate->ctm_inverse = other->ctm_inverse;
    gstate->source_ctm_inverse = other->source_ctm_inverse;

    gstate->source = cairo_pattern_reference (other->source);

    gstate->next = NULL;

    return CAIRO_STATUS_SUCCESS;
}

static void
_cairo_gstate_fini (cairo_gstate_t *gstate)
{
    _cairo_stroke_style_fini (&gstate->stroke_style);

    cairo_font_face_destroy (gstate->font_face);
    gstate->font_face = NULL;

    cairo_scaled_font_destroy (gstate->scaled_font);
    gstate->scaled_font = NULL;

    _cairo_clip_fini (&gstate->clip);

    cairo_surface_destroy (gstate->target);
    gstate->target = NULL;

    cairo_surface_destroy (gstate->parent_target);
    gstate->parent_target = NULL;

    cairo_surface_destroy (gstate->original_target);
    gstate->target = NULL;

    cairo_pattern_destroy (gstate->source);
    gstate->source = NULL;
}

void
_cairo_gstate_destroy (cairo_gstate_t *gstate)
{
    if (gstate == NULL)
	return;

    _cairo_gstate_fini (gstate);
    free (gstate);
}

/**
 * _cairo_gstate_clone:
 * @other: a #cairo_gstate_t to be copied, not NULL.
 *
 * Create a new #cairo_gstate_t setting all graphics state parameters
 * to the same values as contained in @other. gstate->next will be set
 * to NULL and may be used by the caller to chain cairo_gstate_t
 * objects together.
 *
 * Return value: a new cairo_gstate_t or NULL if there is insufficient
 * memory.
 **/
cairo_gstate_t*
_cairo_gstate_clone (cairo_gstate_t *other)
{
    cairo_status_t status;
    cairo_gstate_t *gstate;

    assert (other != NULL);

    gstate = malloc (sizeof (cairo_gstate_t));
    if (gstate == NULL)
	return NULL;

    status = _cairo_gstate_init_copy (gstate, other);
    if (status) {
	free (gstate);
	return NULL;
    }

    return gstate;
}

static cairo_status_t
_cairo_gstate_recursive_apply_clip_path (cairo_gstate_t *gstate,
					 cairo_clip_path_t *cpath)
{
    cairo_status_t status;

    if (cpath == NULL)
	return CAIRO_STATUS_SUCCESS;

    status = _cairo_gstate_recursive_apply_clip_path (gstate, cpath->prev);
    if (status)
	return status;

    return _cairo_clip_clip (&gstate->clip,
			     &cpath->path,
			     cpath->fill_rule,
			     cpath->tolerance,
			     cpath->antialias,
			     gstate->target);
}

/**
 * _cairo_gstate_redirect_target:
 * @gstate: a #cairo_gstate_t
 * @child: the new child target
 *
 * Redirect @gstate rendering to a "child" target. The original
 * "parent" target with which the gstate was created will not be
 * affected. See _cairo_gstate_get_target().
 *
 * Unless the redirected target has the same device offsets as the
 * original #cairo_t target, the clip will be INVALID after this call,
 * and the caller should either recreate or reset the clip.
 **/
void
_cairo_gstate_redirect_target (cairo_gstate_t *gstate, cairo_surface_t *child)
{
    /* If this gstate is already redirected, this is an error; we need a
     * new gstate to be able to redirect */
    assert (gstate->parent_target == NULL);

    /* Set up our new parent_target based on our current target;
     * gstate->parent_target will take the ref that is held by gstate->target
     */
    cairo_surface_destroy (gstate->parent_target);
    gstate->parent_target = gstate->target;

    /* Now set up our new target; we overwrite gstate->target directly,
     * since its ref is now owned by gstate->parent_target */
    gstate->target = cairo_surface_reference (child);

    _cairo_clip_fini (&gstate->clip);
    _cairo_clip_init_deep_copy (&gstate->clip, &gstate->next->clip, child);

    /* The clip is in surface backend coordinates for the previous target;
     * translate it into the child's backend coordinates. */
    _cairo_clip_translate (&gstate->clip,
                           _cairo_fixed_from_double (child->device_transform.x0 - gstate->parent_target->device_transform.x0),
                           _cairo_fixed_from_double (child->device_transform.y0 - gstate->parent_target->device_transform.y0));
}

/**
 * _cairo_gstate_is_redirected
 * @gstate: a #cairo_gstate_t
 *
 * Return value: TRUE if the gstate is redirected to a traget
 * different than the original, FALSE otherwise.
 **/
cairo_bool_t
_cairo_gstate_is_redirected (cairo_gstate_t *gstate)
{
    return (gstate->target != gstate->original_target);
}

/**
 * _cairo_gstate_get_target:
 * @gstate: a #cairo_gstate_t
 *
 * Return the current drawing target; if drawing is not redirected,
 * this will be the same as _cairo_gstate_get_original_target().
 *
 * Return value: the current target surface
 **/
cairo_surface_t *
_cairo_gstate_get_target (cairo_gstate_t *gstate)
{
    return gstate->target;
}

/**
 * _cairo_gstate_get_parent_target:
 * @gstate: a #cairo_gstate_t
 *
 * Return the parent surface of the current drawing target surface;
 * if this particular gstate isn't a redirect gstate, this will return NULL.
 **/
cairo_surface_t *
_cairo_gstate_get_parent_target (cairo_gstate_t *gstate)
{
    return gstate->parent_target;
}

/**
 * _cairo_gstate_get_original_target:
 * @gstate: a #cairo_gstate_t
 *
 * Return the original target with which @gstate was created. This
 * function always returns the original target independent of any
 * child target that may have been set with
 * _cairo_gstate_redirect_target.
 *
 * Return value: the original target surface
 **/
cairo_surface_t *
_cairo_gstate_get_original_target (cairo_gstate_t *gstate)
{
    return gstate->original_target;
}

/**
 * _cairo_gstate_get_clip:
 * @gstate: a #cairo_gstate_t
 *
 * Return value: a pointer to the gstate's cairo_clip_t structure.
 */
cairo_clip_t *
_cairo_gstate_get_clip (cairo_gstate_t *gstate)
{
    return &gstate->clip;
}

cairo_status_t
_cairo_gstate_set_source (cairo_gstate_t  *gstate,
			  cairo_pattern_t *source)
{
    if (source->status)
	return source->status;

    cairo_pattern_reference (source);
    cairo_pattern_destroy (gstate->source);
    gstate->source = source;
    gstate->source_ctm_inverse = gstate->ctm_inverse;

    return CAIRO_STATUS_SUCCESS;
}

cairo_pattern_t *
_cairo_gstate_get_source (cairo_gstate_t *gstate)
{
    if (gstate == NULL)
	return NULL;

    return gstate->source;
}

cairo_status_t
_cairo_gstate_set_operator (cairo_gstate_t *gstate, cairo_operator_t op)
{
    gstate->op = op;

    return CAIRO_STATUS_SUCCESS;
}

cairo_operator_t
_cairo_gstate_get_operator (cairo_gstate_t *gstate)
{
    return gstate->op;
}

cairo_status_t
_cairo_gstate_set_tolerance (cairo_gstate_t *gstate, double tolerance)
{
    gstate->tolerance = tolerance;

    return CAIRO_STATUS_SUCCESS;
}

double
_cairo_gstate_get_tolerance (cairo_gstate_t *gstate)
{
    return gstate->tolerance;
}

cairo_status_t
_cairo_gstate_set_fill_rule (cairo_gstate_t *gstate, cairo_fill_rule_t fill_rule)
{
    gstate->fill_rule = fill_rule;

    return CAIRO_STATUS_SUCCESS;
}

cairo_fill_rule_t
_cairo_gstate_get_fill_rule (cairo_gstate_t *gstate)
{
    return gstate->fill_rule;
}

cairo_status_t
_cairo_gstate_set_line_width (cairo_gstate_t *gstate, double width)
{
    gstate->stroke_style.line_width = width;

    return CAIRO_STATUS_SUCCESS;
}

double
_cairo_gstate_get_line_width (cairo_gstate_t *gstate)
{
    return gstate->stroke_style.line_width;
}

cairo_status_t
_cairo_gstate_set_line_cap (cairo_gstate_t *gstate, cairo_line_cap_t line_cap)
{
    gstate->stroke_style.line_cap = line_cap;

    return CAIRO_STATUS_SUCCESS;
}

cairo_line_cap_t
_cairo_gstate_get_line_cap (cairo_gstate_t *gstate)
{
    return gstate->stroke_style.line_cap;
}

cairo_status_t
_cairo_gstate_set_line_join (cairo_gstate_t *gstate, cairo_line_join_t line_join)
{
    gstate->stroke_style.line_join = line_join;

    return CAIRO_STATUS_SUCCESS;
}

cairo_line_join_t
_cairo_gstate_get_line_join (cairo_gstate_t *gstate)
{
    return gstate->stroke_style.line_join;
}

cairo_status_t
_cairo_gstate_set_dash (cairo_gstate_t *gstate, double *dash, int num_dashes, double offset)
{
    int i;
    double dash_total;

    if (gstate->stroke_style.dash)
	free (gstate->stroke_style.dash);

    gstate->stroke_style.num_dashes = num_dashes;