SSL cairo-analysis-surface.c   Interaktion und
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/* -*- Mode: c; tab-width: 8; c-basic-offset: 4; indent-tabs-mode: t; -*- */
/*
 * Copyright © 2006 Keith Packard
 * Copyright © 2007 Adrian Johnson
 *
 * 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., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, 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 Keith Packard
 *
 * Contributor(s):
 *      Keith Packard <keithp@keithp.com>
 *      Adrian Johnson <ajohnson@redneon.com>
 */

#include "cairoint.h"

#include "cairo-analysis-surface-private.h"
#include "cairo-box-inline.h"
#include "cairo-default-context-private.h"
#include "cairo-error-private.h"
#include "cairo-paginated-private.h"
#include "cairo-recording-surface-inline.h"
#include "cairo-surface-snapshot-inline.h"
#include "cairo-surface-subsurface-inline.h"
#include "cairo-region-private.h"

typedef struct {
    cairo_surface_t base;

    cairo_surface_t *target;

    cairo_bool_t first_op;
    cairo_bool_t has_supported;
    cairo_bool_t has_unsupported;

    cairo_region_t supported_region;
    cairo_region_t fallback_region;
    cairo_box_t page_bbox;

    cairo_bool_t create_region_ids;
    unsigned source_region_id;
    unsigned mask_region_id;

    cairo_bool_t has_ctm;
    cairo_matrix_t ctm;

} cairo_analysis_surface_t;

cairo_int_status_t
_cairo_analysis_surface_merge_status (cairo_int_status_t status_a,
          cairo_int_status_t status_b)
{
    /* fatal errors should be checked and propagated at source */
    assert (! _cairo_int_status_is_error (status_a));
    assert (! _cairo_int_status_is_error (status_b));

    /* return the most important status */
    if (status_a == CAIRO_INT_STATUS_UNSUPPORTED ||
 status_b == CAIRO_INT_STATUS_UNSUPPORTED)
 return CAIRO_INT_STATUS_UNSUPPORTED;

    if (status_a == CAIRO_INT_STATUS_IMAGE_FALLBACK ||
 status_b == CAIRO_INT_STATUS_IMAGE_FALLBACK)
 return CAIRO_INT_STATUS_IMAGE_FALLBACK;

    if (status_a == CAIRO_INT_STATUS_ANALYZE_RECORDING_SURFACE_PATTERN ||
 status_b == CAIRO_INT_STATUS_ANALYZE_RECORDING_SURFACE_PATTERN)
 return CAIRO_INT_STATUS_ANALYZE_RECORDING_SURFACE_PATTERN;

    if (status_a == CAIRO_INT_STATUS_FLATTEN_TRANSPARENCY ||
 status_b == CAIRO_INT_STATUS_FLATTEN_TRANSPARENCY)
 return CAIRO_INT_STATUS_FLATTEN_TRANSPARENCY;

    /* at this point we have checked all the valid internal codes, so... */
    assert (status_a == CAIRO_INT_STATUS_SUCCESS &&
     status_b == CAIRO_INT_STATUS_SUCCESS);

    return CAIRO_INT_STATUS_SUCCESS;
}

struct proxy {
    cairo_surface_t base;
    cairo_surface_t *target;
};

static cairo_status_t
proxy_finish (void *abstract_surface)
{
    return CAIRO_STATUS_SUCCESS;
}

static const cairo_surface_backend_t proxy_backend  = {
    CAIRO_INTERNAL_SURFACE_TYPE_NULL,
    proxy_finish,
};

static cairo_surface_t *
attach_proxy (cairo_surface_t *source,
       cairo_surface_t *target)
{
    struct proxy *proxy;

    proxy = _cairo_malloc (sizeof (*proxy));
    if (unlikely (proxy == NULL))
 return _cairo_surface_create_in_error (CAIRO_STATUS_NO_MEMORY);

    _cairo_surface_init (&proxy->base, &proxy_backend, NULL, target->content, target->is_vector);

    proxy->target = target;
    _cairo_surface_attach_snapshot (source, &proxy->base, NULL);

    return &proxy->base;
}

static void
detach_proxy (cairo_surface_t *proxy)
{
    cairo_surface_finish (proxy);
    cairo_surface_destroy (proxy);
}

static cairo_int_status_t
_add_operation (cairo_analysis_surface_t *surface,
  cairo_rectangle_int_t    *rect,
  cairo_int_status_t        backend_status)
{
    cairo_int_status_t status;
    cairo_box_t bbox;

    if (rect->width == 0 || rect->height == 0) {
 /* Even though the operation is not visible we must be careful
 * to not allow unsupported operations to be replayed to the
 * backend during CAIRO_PAGINATED_MODE_RENDER */
 if (backend_status == CAIRO_INT_STATUS_SUCCESS ||
     backend_status == CAIRO_INT_STATUS_FLATTEN_TRANSPARENCY ||
     backend_status == CAIRO_INT_STATUS_NOTHING_TO_DO)
 {
     return CAIRO_INT_STATUS_SUCCESS;
 }
 else
 {
     return CAIRO_INT_STATUS_IMAGE_FALLBACK;
 }
    }

    _cairo_box_from_rectangle (&bbox, rect);

    if (surface->has_ctm) {
 int tx, ty;

 if (_cairo_matrix_is_integer_translation (&surface->ctm, &tx, &ty)) {
     rect->x += tx;
     rect->y += ty;

     tx = _cairo_fixed_from_int (tx);
     bbox.p1.x += tx;
     bbox.p2.x += tx;

     ty = _cairo_fixed_from_int (ty);
     bbox.p1.y += ty;
     bbox.p2.y += ty;
 } else {
     _cairo_matrix_transform_bounding_box_fixed (&surface->ctm,
       &bbox, NULL);

     if (bbox.p1.x == bbox.p2.x || bbox.p1.y == bbox.p2.y) {
  /* Even though the operation is not visible we must be
 * careful to not allow unsupported operations to be
 * replayed to the backend during
 * CAIRO_PAGINATED_MODE_RENDER */
  if (backend_status == CAIRO_INT_STATUS_SUCCESS ||
      backend_status == CAIRO_INT_STATUS_FLATTEN_TRANSPARENCY ||
      backend_status == CAIRO_INT_STATUS_NOTHING_TO_DO)
  {
      return CAIRO_INT_STATUS_SUCCESS;
  }
  else
  {
      return CAIRO_INT_STATUS_IMAGE_FALLBACK;
  }
     }

     _cairo_box_round_to_rectangle (&bbox, rect);
 }
    }

    if (surface->first_op) {
 surface->first_op = FALSE;
 surface->page_bbox = bbox;
    } else
 _cairo_box_add_box(&surface->page_bbox, &bbox);

    /* If the operation is completely enclosed within the fallback
     * region there is no benefit in emitting a native operation as
     * the fallback image will be painted on top.
     */
    if (cairo_region_contains_rectangle (&surface->fallback_region, rect) == CAIRO_REGION_OVERLAP_IN)
 return CAIRO_INT_STATUS_IMAGE_FALLBACK;

    if (backend_status == CAIRO_INT_STATUS_FLATTEN_TRANSPARENCY) {
 /* A status of CAIRO_INT_STATUS_FLATTEN_TRANSPARENCY indicates
 * that the backend only supports this operation if the
 * transparency removed. If the extents of this operation does
 * not intersect any other native operation, the operation is
 * natively supported and the backend will blend the
 * transparency into the white background.
 */
 if (cairo_region_contains_rectangle (&surface->supported_region, rect) == CAIRO_REGION_OVERLAP_OUT)
     backend_status = CAIRO_INT_STATUS_SUCCESS;
    }

    if (backend_status == CAIRO_INT_STATUS_SUCCESS) {
 /* Add the operation to the supported region. Operations in
 * this region will be emitted as native operations.
 */
 surface->has_supported = TRUE;
 return cairo_region_union_rectangle (&surface->supported_region, rect);
    }

    /* Add the operation to the unsupported region. This region will
     * be painted as an image after all native operations have been
     * emitted.
     */
    surface->has_unsupported = TRUE;
    status = cairo_region_union_rectangle (&surface->fallback_region, rect);

    /* The status CAIRO_INT_STATUS_IMAGE_FALLBACK is used to indicate
     * unsupported operations to the recording surface as using
     * CAIRO_INT_STATUS_UNSUPPORTED would cause cairo-surface to
     * invoke the cairo-surface-fallback path then return
     * CAIRO_STATUS_SUCCESS.
     */
    if (status == CAIRO_INT_STATUS_SUCCESS)
 return CAIRO_INT_STATUS_IMAGE_FALLBACK;
    else
 return status;
}

static cairo_int_status_t
_analyze_recording_surface_pattern (cairo_analysis_surface_t *surface,
        const cairo_pattern_t    *pattern,
        cairo_rectangle_int_t    *extents,
        unsigned int             *regions_id,
        cairo_analysis_source_t   source_type)
{
    const cairo_surface_pattern_t *surface_pattern;
    cairo_analysis_surface_t *tmp;
    cairo_surface_t *source, *proxy;
    cairo_matrix_t p2d;
    cairo_int_status_t status;
    cairo_int_status_t analysis_status = CAIRO_INT_STATUS_SUCCESS;
    cairo_bool_t surface_is_unbounded;
    cairo_bool_t unused;
    cairo_bool_t replay_all;

    assert (pattern->type == CAIRO_PATTERN_TYPE_SURFACE);
    surface_pattern = (const cairo_surface_pattern_t *) pattern;
    assert (surface_pattern->surface->type == CAIRO_SURFACE_TYPE_RECORDING);
    source = surface_pattern->surface;

    proxy = _cairo_surface_has_snapshot (source, &proxy_backend);
    if (proxy != NULL) {
 /* nothing untoward found so far */
 return CAIRO_STATUS_SUCCESS;
    }

    tmp = (cairo_analysis_surface_t *)
 _cairo_analysis_surface_create (surface->target, surface->create_region_ids);
    if (unlikely (tmp->base.status)) {
 status = tmp->base.status;
 goto cleanup1;
    }
    proxy = attach_proxy (source, &tmp->base);

    p2d = pattern->matrix;
    status = cairo_matrix_invert (&p2d);
    assert (status == CAIRO_INT_STATUS_SUCCESS);
    _cairo_analysis_surface_set_ctm (&tmp->base, &p2d);

    source = _cairo_surface_get_source (source, NULL);
    surface_is_unbounded = (pattern->extend == CAIRO_EXTEND_REPEAT
       || pattern->extend == CAIRO_EXTEND_REFLECT);

    if (surface->create_region_ids) {
 status = _cairo_recording_surface_region_array_attach (source, regions_id);
 if (unlikely (status))
     goto cleanup2;
    }

    replay_all = FALSE;
    if (surface->target->backend->analyze_recording_surface) {
 status = surface->target->backend->analyze_recording_surface (
     surface->target,
     surface_pattern,
     surface->create_region_ids ? *regions_id : 0,
     source_type,
     TRUE);
        if (status == CAIRO_INT_STATUS_ANALYZE_RECORDING_SURFACE_PATTERN) {
     /* Ensure all commands are replayed even if previously
     * replayed and assigned to a region.*/
            replay_all = TRUE;
            status = CAIRO_INT_STATUS_SUCCESS;
        }
        if (unlikely (status))
            goto cleanup3;
    }

    if (surface->create_region_ids) {
 status = _cairo_recording_surface_replay_and_create_regions (source,
             *regions_id,
             &pattern->matrix,
             &tmp->base,
             surface_is_unbounded,
             replay_all);
 if (unlikely (status))
     goto cleanup3;
    } else {
 status = _cairo_recording_surface_replay_with_transform (source,
         &pattern->matrix,
         &tmp->base,
         surface_is_unbounded,
         replay_all);
 if (unlikely (status))
     goto cleanup3;
    }

    if (surface->target->backend->analyze_recording_surface) {
 status = surface->target->backend->analyze_recording_surface (
     surface->target,
     surface_pattern,
     surface->create_region_ids ? *regions_id : 0,
     source_type,
     FALSE);
        if (unlikely (status))
            goto cleanup3;
    }

    /* black background or mime data fills entire extents */
    if (!(source->content & CAIRO_CONTENT_ALPHA) || _cairo_surface_has_mime_image (source)) {
 cairo_rectangle_int_t rect;

 if (_cairo_surface_get_extents (source, &rect)) {
     cairo_box_t bbox;

     _cairo_box_from_rectangle (&bbox, &rect);
     _cairo_matrix_transform_bounding_box_fixed (&p2d, &bbox, NULL);
     _cairo_box_round_to_rectangle (&bbox, &rect);
     status = _add_operation (tmp, &rect, CAIRO_INT_STATUS_SUCCESS);
     if (status == CAIRO_INT_STATUS_IMAGE_FALLBACK)
  status = CAIRO_INT_STATUS_SUCCESS;
     if (unlikely (status))
  goto cleanup3;
 }
    }

    if (tmp->has_supported) {
 surface->has_supported = TRUE;
 unused = cairo_region_union (&surface->supported_region, &tmp->supported_region);
    }

    if (tmp->has_unsupported) {
 surface->has_unsupported = TRUE;
 unused = cairo_region_union (&surface->fallback_region, &tmp->fallback_region);
    }

    analysis_status = tmp->has_unsupported ? CAIRO_INT_STATUS_IMAGE_FALLBACK : CAIRO_INT_STATUS_SUCCESS;
    if (pattern->extend != CAIRO_EXTEND_NONE) {
 _cairo_unbounded_rectangle_init (extents);
    } else {
 status = cairo_matrix_invert (&tmp->ctm);
 _cairo_matrix_transform_bounding_box_fixed (&tmp->ctm,
          &tmp->page_bbox, NULL);
 _cairo_box_round_to_rectangle (&tmp->page_bbox, extents);
    }

  cleanup3:
    if (surface->create_region_ids && unlikely (status)) {
 _cairo_recording_surface_region_array_remove (source, *regions_id);
    }
  cleanup2:
    detach_proxy (proxy);
  cleanup1:
    cairo_surface_destroy (&tmp->base);

    if (unlikely (status))
 return status;
    else
 return analysis_status;
}

static cairo_status_t
_cairo_analysis_surface_finish (void *abstract_surface)
{
    cairo_analysis_surface_t *surface = (cairo_analysis_surface_t *) abstract_surface;

    _cairo_region_fini (&surface->supported_region);
    _cairo_region_fini (&surface->fallback_region);

    cairo_surface_destroy (surface->target);

    return CAIRO_STATUS_SUCCESS;
}

static cairo_bool_t
_cairo_analysis_surface_get_extents (void   *abstract_surface,
         cairo_rectangle_int_t *rectangle)
{
    cairo_analysis_surface_t *surface = abstract_surface;

    return _cairo_surface_get_extents (surface->target, rectangle);
}

static void
_rectangle_intersect_clip (cairo_rectangle_int_t *extents, const cairo_clip_t *clip)
{
    if (clip != NULL)
 _cairo_rectangle_intersect (extents, _cairo_clip_get_extents (clip));
}

static void
_cairo_analysis_surface_operation_extents (cairo_analysis_surface_t *surface,
        cairo_operator_t op,
        const cairo_pattern_t *source,
        const cairo_clip_t *clip,
        cairo_rectangle_int_t *extents)
{
    cairo_bool_t is_empty;

    is_empty = _cairo_surface_get_extents (&surface->base, extents);

    if (_cairo_operator_bounded_by_source (op)) {
 cairo_rectangle_int_t source_extents;

 _cairo_pattern_get_extents (source, &source_extents, surface->target->is_vector);
 _cairo_rectangle_intersect (extents, &source_extents);
    }

    _rectangle_intersect_clip (extents, clip);
}

static cairo_int_status_t
_cairo_analysis_surface_paint (void   *abstract_surface,
          cairo_operator_t  op,
          const cairo_pattern_t *source,
          const cairo_clip_t *clip)
{
    cairo_analysis_surface_t *surface = abstract_surface;
    cairo_int_status_t      backend_status;
    cairo_rectangle_int_t  extents;

    surface->source_region_id = 0;
    surface->mask_region_id = 0;
    if (surface->target->backend->paint == NULL) {
 backend_status = CAIRO_INT_STATUS_UNSUPPORTED;
    } else {
 backend_status =
     surface->target->backend->paint (surface->target,
          op, source, clip);
 if (_cairo_int_status_is_error (backend_status))
     return backend_status;
    }

    _cairo_analysis_surface_operation_extents (surface,
            op, source, clip,
            &extents);
    if (backend_status == CAIRO_INT_STATUS_ANALYZE_RECORDING_SURFACE_PATTERN) {
 cairo_rectangle_int_t rec_extents;
 backend_status = _analyze_recording_surface_pattern (surface,
            source,
            &rec_extents,
            &surface->source_region_id,
            CAIRO_ANALYSIS_SOURCE_PAINT);
 _cairo_rectangle_intersect (&extents, &rec_extents);
    }

    return _add_operation (surface, &extents, backend_status);
}

static cairo_int_status_t
_cairo_analysis_surface_mask (void   *abstract_surface,
         cairo_operator_t   op,
         const cairo_pattern_t *source,
         const cairo_pattern_t *mask,
         const cairo_clip_t *clip)
{
    cairo_analysis_surface_t *surface = abstract_surface;
    cairo_int_status_t       backend_status;
    cairo_rectangle_int_t   extents;

    surface->source_region_id = 0;
    surface->mask_region_id = 0;
    if (surface->target->backend->mask == NULL) {
 backend_status = CAIRO_INT_STATUS_UNSUPPORTED;
    } else {
 backend_status =
     surface->target->backend->mask (surface->target,
         op, source, mask, clip);
 if (_cairo_int_status_is_error (backend_status))
     return backend_status;
    }

    _cairo_analysis_surface_operation_extents (surface,
            op, source, clip,
            &extents);
    if (backend_status == CAIRO_INT_STATUS_ANALYZE_RECORDING_SURFACE_PATTERN) {
 cairo_int_status_t backend_source_status = CAIRO_STATUS_SUCCESS;
 cairo_int_status_t backend_mask_status = CAIRO_STATUS_SUCCESS;
 cairo_rectangle_int_t rec_extents;

 if (source->type == CAIRO_PATTERN_TYPE_SURFACE) {
     cairo_surface_t *src_surface = ((cairo_surface_pattern_t *)source)->surface;
     src_surface = _cairo_surface_get_source (src_surface, NULL);
     if (_cairo_surface_is_recording (src_surface)) {
  backend_source_status =
      _analyze_recording_surface_pattern (surface,
       source,
       &rec_extents,
       &surface->source_region_id,
       CAIRO_ANALYSIS_SOURCE_MASK);
  if (_cairo_int_status_is_error (backend_source_status))
      return backend_source_status;

  _cairo_rectangle_intersect (&extents, &rec_extents);
     }
 }

 if (mask->type == CAIRO_PATTERN_TYPE_SURFACE) {
     cairo_surface_t *mask_surface = ((cairo_surface_pattern_t *)mask)->surface;
     mask_surface = _cairo_surface_get_source (mask_surface, NULL);
     if (_cairo_surface_is_recording (mask_surface)) {
  backend_mask_status =
      _analyze_recording_surface_pattern (surface,
       mask,
       &rec_extents,
       &surface->mask_region_id,
       CAIRO_ANALYSIS_MASK_MASK);
  if (_cairo_int_status_is_error (backend_mask_status))
      return backend_mask_status;

  _cairo_rectangle_intersect (&extents, &rec_extents);
     }
 }

 backend_status =
     _cairo_analysis_surface_merge_status (backend_source_status,
        backend_mask_status);
    }

    if (_cairo_operator_bounded_by_mask (op)) {
 cairo_rectangle_int_t mask_extents;

 _cairo_pattern_get_extents (mask, &mask_extents, surface->target->is_vector);
 _cairo_rectangle_intersect (&extents, &mask_extents);
    }

    return _add_operation (surface, &extents, backend_status);
}

static cairo_int_status_t
_cairo_analysis_surface_stroke (void      *abstract_surface,
    cairo_operator_t     op,
    const cairo_pattern_t    *source,
    const cairo_path_fixed_t   *path,
    const cairo_stroke_style_t *style,
    const cairo_matrix_t    *ctm,
    const cairo_matrix_t    *ctm_inverse,
    double       tolerance,
    cairo_antialias_t     antialias,
    const cairo_clip_t    *clip)
{
    cairo_analysis_surface_t *surface = abstract_surface;
    cairo_int_status_t      backend_status;
    cairo_rectangle_int_t    extents;

    surface->source_region_id = 0;
    surface->mask_region_id = 0;
    if (surface->target->backend->stroke == NULL) {
 backend_status = CAIRO_INT_STATUS_UNSUPPORTED;
    } else {
 backend_status =
     surface->target->backend->stroke (surface->target, op,
           source, path, style,
           ctm, ctm_inverse,
           tolerance, antialias,
           clip);
 if (_cairo_int_status_is_error (backend_status))
     return backend_status;
    }

    _cairo_analysis_surface_operation_extents (surface,
            op, source, clip,
            &extents);
    if (backend_status == CAIRO_INT_STATUS_ANALYZE_RECORDING_SURFACE_PATTERN) {
 cairo_rectangle_int_t rec_extents;
 backend_status = _analyze_recording_surface_pattern (surface,
            source,
            &rec_extents,
            &surface->source_region_id,
            CAIRO_ANALYSIS_SOURCE_STROKE);
 _cairo_rectangle_intersect (&extents, &rec_extents);
    }

    if (_cairo_operator_bounded_by_mask (op)) {
 cairo_rectangle_int_t mask_extents;
 cairo_int_status_t status;

 status = _cairo_path_fixed_stroke_extents (path, style,
         ctm, ctm_inverse,
         tolerance,
         &mask_extents);
 if (unlikely (status))
     return status;

 _cairo_rectangle_intersect (&extents, &mask_extents);
    }

    return _add_operation (surface, &extents, backend_status);
}

static cairo_int_status_t
_cairo_analysis_surface_fill (void   *abstract_surface,
         cairo_operator_t   op,
         const cairo_pattern_t *source,
         const cairo_path_fixed_t *path,
         cairo_fill_rule_t   fill_rule,
         double    tolerance,
         cairo_antialias_t   antialias,
         const cairo_clip_t *clip)
{
    cairo_analysis_surface_t *surface = abstract_surface;
    cairo_int_status_t      backend_status;
    cairo_rectangle_int_t    extents;

    if (surface->target->backend->fill == NULL) {
 backend_status = CAIRO_INT_STATUS_UNSUPPORTED;
    } else {
 backend_status =
     surface->target->backend->fill (surface->target, op,
         source, path, fill_rule,
         tolerance, antialias,
         clip);
 if (_cairo_int_status_is_error (backend_status))
     return backend_status;
    }

    _cairo_analysis_surface_operation_extents (surface,
            op, source, clip,
            &extents);
    if (backend_status == CAIRO_INT_STATUS_ANALYZE_RECORDING_SURFACE_PATTERN) {
 cairo_rectangle_int_t rec_extents;
 backend_status = _analyze_recording_surface_pattern (surface,
            source,
            &rec_extents,
            &surface->source_region_id,
            CAIRO_ANALYSIS_SOURCE_FILL);
 _cairo_rectangle_intersect (&extents, &rec_extents);
    }

    if (_cairo_operator_bounded_by_mask (op)) {
 cairo_rectangle_int_t mask_extents;

 _cairo_path_fixed_fill_extents (path, fill_rule, tolerance,
     &mask_extents);

 _cairo_rectangle_intersect (&extents, &mask_extents);
    }

    return _add_operation (surface, &extents, backend_status);
}

static cairo_int_status_t
_cairo_analysis_surface_show_glyphs (void    *abstract_surface,
         cairo_operator_t    op,
         const cairo_pattern_t *source,
         cairo_glyph_t   *glyphs,
         int     num_glyphs,
         cairo_scaled_font_t  *scaled_font,
         const cairo_clip_t         *clip)
{
    cairo_analysis_surface_t *surface = abstract_surface;
    cairo_int_status_t      status, backend_status;
    cairo_rectangle_int_t    extents, glyph_extents;

    surface->source_region_id = 0;
    surface->mask_region_id = 0;

    /* Adapted from _cairo_surface_show_glyphs */
    if (surface->target->backend->show_glyphs != NULL) {
 backend_status =
     surface->target->backend->show_glyphs (surface->target, op,
         source,
         glyphs, num_glyphs,
         scaled_font,
         clip);
 if (_cairo_int_status_is_error (backend_status))
     return backend_status;
    }
    else if (surface->target->backend->show_text_glyphs != NULL)
    {
 backend_status =
     surface->target->backend->show_text_glyphs (surface->target, op,
       source,
       NULL, 0,
       glyphs, num_glyphs,
       NULL, 0,
       FALSE,
       scaled_font,
       clip);
 if (_cairo_int_status_is_error (backend_status))
     return backend_status;
    }
    else
    {
 backend_status = CAIRO_INT_STATUS_UNSUPPORTED;
    }

    _cairo_analysis_surface_operation_extents (surface,
            op, source, clip,
            &extents);
    if (backend_status == CAIRO_INT_STATUS_ANALYZE_RECORDING_SURFACE_PATTERN) {
 cairo_rectangle_int_t rec_extents;
 backend_status = _analyze_recording_surface_pattern (surface,
            source,
            &rec_extents,
            &surface->source_region_id,
            CAIRO_ANALYSIS_SOURCE_SHOW_GLYPHS);
 _cairo_rectangle_intersect (&extents, &rec_extents);
    }

    if (_cairo_operator_bounded_by_mask (op)) {
 status = _cairo_scaled_font_glyph_device_extents (scaled_font,
         glyphs,
         num_glyphs,
         &glyph_extents,
         NULL);
 if (unlikely (status))
     return status;

 _cairo_rectangle_intersect (&extents, &glyph_extents);
    }

    return _add_operation (surface, &extents, backend_status);
}

static cairo_bool_t
_cairo_analysis_surface_has_show_text_glyphs (void *abstract_surface)
{
    cairo_analysis_surface_t *surface = abstract_surface;

    return cairo_surface_has_show_text_glyphs (surface->target);
}

static cairo_int_status_t
_cairo_analysis_surface_show_text_glyphs (void       *abstract_surface,
       cairo_operator_t      op,
       const cairo_pattern_t     *source,
       const char      *utf8,
       int        utf8_len,
       cairo_glyph_t      *glyphs,
       int        num_glyphs,
       const cairo_text_cluster_t *clusters,
       int        num_clusters,
       cairo_text_cluster_flags_t cluster_flags,
       cairo_scaled_font_t     *scaled_font,
       const cairo_clip_t      *clip)
{
    cairo_analysis_surface_t *surface = abstract_surface;
    cairo_int_status_t      status, backend_status;
    cairo_rectangle_int_t    extents, glyph_extents;

    surface->source_region_id = 0;
    surface->mask_region_id = 0;

    /* Adapted from _cairo_surface_show_glyphs */
    backend_status = CAIRO_INT_STATUS_UNSUPPORTED;
    if (surface->target->backend->show_text_glyphs != NULL) {
 backend_status =
     surface->target->backend->show_text_glyphs (surface->target, op,
       source,
       utf8, utf8_len,
       glyphs, num_glyphs,
       clusters, num_clusters,
       cluster_flags,
       scaled_font,
       clip);
 if (_cairo_int_status_is_error (backend_status))
     return backend_status;
    }
    if (backend_status == CAIRO_INT_STATUS_UNSUPPORTED &&
 surface->target->backend->show_glyphs != NULL)
    {
 backend_status =
     surface->target->backend->show_glyphs (surface->target, op,
         source,
         glyphs, num_glyphs,
         scaled_font,
         clip);
 if (_cairo_int_status_is_error (backend_status))
     return backend_status;
    }

    _cairo_analysis_surface_operation_extents (surface,
            op, source, clip,
            &extents);
    if (backend_status == CAIRO_INT_STATUS_ANALYZE_RECORDING_SURFACE_PATTERN) {
 cairo_rectangle_int_t rec_extents;
 _analyze_recording_surface_pattern (surface,
         source,
         &rec_extents,
         &surface->source_region_id,
         CAIRO_ANALYSIS_SOURCE_SHOW_GLYPHS);
 _cairo_rectangle_intersect (&extents, &rec_extents);
    }

    if (_cairo_operator_bounded_by_mask (op)) {
 status = _cairo_scaled_font_glyph_device_extents (scaled_font,
         glyphs,
         num_glyphs,
         &glyph_extents,
         NULL);
 if (unlikely (status))
     return status;

 _cairo_rectangle_intersect (&extents, &glyph_extents);
    }

    return _add_operation (surface, &extents, backend_status);
}

static cairo_int_status_t
_cairo_analysis_surface_tag (void                 *abstract_surface,
        cairo_bool_t                begin,
        const char                 *tag_name,
        const char                 *attributes)
{
    cairo_analysis_surface_t *surface = abstract_surface;
    cairo_int_status_t      backend_status;

    surface->source_region_id = 0;
    surface->mask_region_id = 0;
    backend_status = CAIRO_INT_STATUS_SUCCESS;
    if (surface->target->backend->tag != NULL) {
 backend_status =
     surface->target->backend->tag (surface->target,
        begin,
        tag_name,
        attributes);
        if (backend_status == CAIRO_INT_STATUS_SUCCESS)
            surface->has_supported = TRUE;
    }

    return backend_status;
}

static cairo_bool_t
_cairo_analysis_surface_supports_color_glyph (void                 *abstract_surface,
                                              cairo_scaled_font_t  *scaled_font,
                                              unsigned long         glyph_index)
{
    return TRUE;
}

static cairo_int_status_t
_cairo_analysis_surface_command_id (void                 *abstract_surface,
        unsigned int          recording_id,
        unsigned int          command_id)
{
    cairo_analysis_surface_t *surface = abstract_surface;
    cairo_int_status_t backend_status;

    backend_status = CAIRO_INT_STATUS_SUCCESS;
    if (surface->target->backend->command_id != NULL) {
 backend_status =
     surface->target->backend->command_id (surface->target,
        recording_id,
        command_id);
    }

    return backend_status;
}

static const cairo_surface_backend_t cairo_analysis_surface_backend = {
    CAIRO_INTERNAL_SURFACE_TYPE_ANALYSIS,

    _cairo_analysis_surface_finish,
    NULL,

    NULL, /* create_similar */
    NULL, /* create_similar_image */
    NULL, /* map_to_image */
    NULL, /* unmap */

    NULL, /* source */
    NULL, /* acquire_source_image */
    NULL, /* release_source_image */
    NULL, /* snapshot */

    NULL, /* copy_page */
    NULL, /* show_page */

    _cairo_analysis_surface_get_extents,
    NULL, /* get_font_options */

    NULL, /* flush */
    NULL, /* mark_dirty_rectangle */

    _cairo_analysis_surface_paint,
    _cairo_analysis_surface_mask,
    _cairo_analysis_surface_stroke,
    _cairo_analysis_surface_fill,
    NULL, /* fill_stroke */
    _cairo_analysis_surface_show_glyphs,
    _cairo_analysis_surface_has_show_text_glyphs,
    _cairo_analysis_surface_show_text_glyphs,
    NULL, /* get_supported_mime_types */
    _cairo_analysis_surface_tag,
    _cairo_analysis_surface_supports_color_glyph,
    NULL, /* analyze_recording_surface */
    _cairo_analysis_surface_command_id,
};

cairo_surface_t *
_cairo_analysis_surface_create (cairo_surface_t  *target,
    cairo_bool_t             create_region_ids)
{
    cairo_analysis_surface_t *surface;
    cairo_status_t status;

    status = target->status;
    if (unlikely (status))
 return _cairo_surface_create_in_error (status);

    surface = _cairo_malloc (sizeof (cairo_analysis_surface_t));
    if (unlikely (surface == NULL))
 return _cairo_surface_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));

    /* I believe the content type here is truly arbitrary. I'm quite
     * sure nothing will ever use this value. */
    _cairo_surface_init (&surface->base,
    &cairo_analysis_surface_backend,
    NULL, /* device */
    CAIRO_CONTENT_COLOR_ALPHA,
    target->is_vector);

    cairo_matrix_init_identity (&surface->ctm);
    surface->has_ctm = FALSE;

    surface->target = cairo_surface_reference (target);
    surface->first_op  = TRUE;
    surface->has_supported = FALSE;
    surface->has_unsupported = FALSE;

    surface->create_region_ids = create_region_ids;
    surface->source_region_id = 0;
    surface->mask_region_id = 0;

    _cairo_region_init (&surface->supported_region);
    _cairo_region_init (&surface->fallback_region);

    surface->page_bbox.p1.x = 0;
    surface->page_bbox.p1.y = 0;
    surface->page_bbox.p2.x = 0;
    surface->page_bbox.p2.y = 0;

    return &surface->base;
}

void
_cairo_analysis_surface_set_ctm (cairo_surface_t *abstract_surface,
     const cairo_matrix_t  *ctm)
{
    cairo_analysis_surface_t *surface;

    if (abstract_surface->status)
 return;

    surface = (cairo_analysis_surface_t *) abstract_surface;

    surface->ctm = *ctm;
    surface->has_ctm = ! _cairo_matrix_is_identity (&surface->ctm);
}

void
_cairo_analysis_surface_get_ctm (cairo_surface_t *abstract_surface,
     cairo_matrix_t  *ctm)
{
    cairo_analysis_surface_t *surface = (cairo_analysis_surface_t *) abstract_surface;

    *ctm = surface->ctm;
}


cairo_region_t *
_cairo_analysis_surface_get_supported (cairo_surface_t *abstract_surface)
{
    cairo_analysis_surface_t *surface = (cairo_analysis_surface_t *) abstract_surface;

    return &surface->supported_region;
}

cairo_region_t *
_cairo_analysis_surface_get_unsupported (cairo_surface_t *abstract_surface)
{
    cairo_analysis_surface_t *surface = (cairo_analysis_surface_t *) abstract_surface;

    return &surface->fallback_region;
}

cairo_bool_t
_cairo_analysis_surface_has_supported (cairo_surface_t *abstract_surface)
{
    cairo_analysis_surface_t *surface = (cairo_analysis_surface_t *) abstract_surface;

    return surface->has_supported;
}

cairo_bool_t
_cairo_analysis_surface_has_unsupported (cairo_surface_t *abstract_surface)
{
    cairo_analysis_surface_t *surface = (cairo_analysis_surface_t *) abstract_surface;

    return surface->has_unsupported;
}

void
_cairo_analysis_surface_get_bounding_box (cairo_surface_t *abstract_surface,
       cairo_box_t     *bbox)
{
    cairo_analysis_surface_t *surface = (cairo_analysis_surface_t *) abstract_surface;

    *bbox = surface->page_bbox;
}

unsigned int
_cairo_analysis_surface_get_source_region_id (cairo_surface_t *abstract_surface)
{
    cairo_analysis_surface_t *surface = (cairo_analysis_surface_t *) abstract_surface;

    return surface->source_region_id;
}

unsigned int
_cairo_analysis_surface_get_mask_region_id (cairo_surface_t *abstract_surface)
{
    cairo_analysis_surface_t *surface = (cairo_analysis_surface_t *) abstract_surface;

    return surface->mask_region_id;
}


/* null surface type: a surface that does nothing (has no side effects, yay!) */

static cairo_int_status_t
_paint_return_success (void   *surface,
         cairo_operator_t   op,
         const cairo_pattern_t *source,
         const cairo_clip_t *clip)
{
    if (source->type == CAIRO_PATTERN_TYPE_SURFACE) {
        cairo_surface_pattern_t *surface_pattern = (cairo_surface_pattern_t *) source;
        if (surface_pattern->surface->type == CAIRO_SURFACE_TYPE_RECORDING)
            return CAIRO_INT_STATUS_ANALYZE_RECORDING_SURFACE_PATTERN;
    }

    return CAIRO_INT_STATUS_SUCCESS;
}

static cairo_int_status_t
_mask_return_success (void   *surface,
        cairo_operator_t   op,
        const cairo_pattern_t *source,
        const cairo_pattern_t *mask,
        const cairo_clip_t *clip)
{
    if (source->type == CAIRO_PATTERN_TYPE_SURFACE) {
        cairo_surface_pattern_t *surface_pattern = (cairo_surface_pattern_t *) source;
        if (surface_pattern->surface->type == CAIRO_SURFACE_TYPE_RECORDING)
            return CAIRO_INT_STATUS_ANALYZE_RECORDING_SURFACE_PATTERN;
    }

    if (mask->type == CAIRO_PATTERN_TYPE_SURFACE) {
        cairo_surface_pattern_t *surface_pattern = (cairo_surface_pattern_t *) mask;
        if (surface_pattern->surface->type == CAIRO_SURFACE_TYPE_RECORDING)
            return CAIRO_INT_STATUS_ANALYZE_RECORDING_SURFACE_PATTERN;
    }

    return CAIRO_INT_STATUS_SUCCESS;
}

static cairo_int_status_t
_stroke_return_success (void    *surface,
   cairo_operator_t   op,
   const cairo_pattern_t  *source,
   const cairo_path_fixed_t *path,
   const cairo_stroke_style_t *style,
   const cairo_matrix_t  *ctm,
   const cairo_matrix_t  *ctm_inverse,
   double     tolerance,
   cairo_antialias_t   antialias,
   const cairo_clip_t  *clip)
{
    if (source->type == CAIRO_PATTERN_TYPE_SURFACE) {
        cairo_surface_pattern_t *surface_pattern = (cairo_surface_pattern_t *) source;
        if (surface_pattern->surface->type == CAIRO_SURFACE_TYPE_RECORDING)
            return CAIRO_INT_STATUS_ANALYZE_RECORDING_SURFACE_PATTERN;
    }

    return CAIRO_INT_STATUS_SUCCESS;
}

static cairo_int_status_t
_fill_return_success (void   *surface,
        cairo_operator_t   op,
        const cairo_pattern_t *source,
        const cairo_path_fixed_t *path,
        cairo_fill_rule_t   fill_rule,
        double    tolerance,
        cairo_antialias_t   antialias,
        const cairo_clip_t *clip)
{
    if (source->type == CAIRO_PATTERN_TYPE_SURFACE) {
        cairo_surface_pattern_t *surface_pattern = (cairo_surface_pattern_t *) source;
        if (surface_pattern->surface->type == CAIRO_SURFACE_TYPE_RECORDING)
            return CAIRO_INT_STATUS_ANALYZE_RECORDING_SURFACE_PATTERN;
    }

    return CAIRO_INT_STATUS_SUCCESS;
}

static cairo_int_status_t
_show_glyphs_return_success (void   *surface,
        cairo_operator_t   op,
        const cairo_pattern_t *source,
        cairo_glyph_t  *glyphs,
        int    num_glyphs,
        cairo_scaled_font_t *scaled_font,
        const cairo_clip_t  *clip)
{
    if (source->type == CAIRO_PATTERN_TYPE_SURFACE) {
        cairo_surface_pattern_t *surface_pattern = (cairo_surface_pattern_t *) source;
        if (surface_pattern->surface->type == CAIRO_SURFACE_TYPE_RECORDING)
            return CAIRO_INT_STATUS_ANALYZE_RECORDING_SURFACE_PATTERN;
    }

    return CAIRO_INT_STATUS_SUCCESS;
}

static const cairo_surface_backend_t cairo_null_surface_backend = {
    CAIRO_INTERNAL_SURFACE_TYPE_NULL,
    NULL, /* finish */

    NULL, /* only accessed through the surface functions */

    NULL, /* create_similar */
    NULL, /* create similar image */
    NULL, /* map to image */
    NULL, /* unmap image*/

    NULL, /* source */
    NULL, /* acquire_source_image */
    NULL, /* release_source_image */
    NULL, /* snapshot */

    NULL, /* copy_page */
    NULL, /* show_page */

    NULL, /* get_extents */
    NULL, /* get_font_options */

    NULL, /* flush */
    NULL, /* mark_dirty_rectangle */

    _paint_return_success,     /* paint */
    _mask_return_success,     /* mask */
    _stroke_return_success,     /* stroke */
    _fill_return_success,     /* fill */
    NULL, /* fill_stroke */
    _show_glyphs_return_success,    /* show_glyphs */
    NULL, /* has_show_text_glyphs */
    NULL, /* show_text_glyphs */
    NULL, /* get_supported_mime_types */
    NULL, /* tag */
    NULL, /* supports_color_glyph */
    NULL, /* analyze_recording_surface */
    NULL, /* command_id*/
};

cairo_surface_t *
_cairo_null_surface_create (cairo_content_t content)
{
    cairo_surface_t *surface;

    surface = _cairo_malloc (sizeof (cairo_surface_t));
    if (unlikely (surface == NULL)) {
 return _cairo_surface_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
    }

    _cairo_surface_init (surface,
    &cairo_null_surface_backend,
    NULL, /* device */
    content,
    TRUE); /* is_vector */

    return surface;
}