/work/workdir/UnpackedTarball/cairo/src/cairo-rectangular-scan-converter.c

Source
/* cairo - a vector graphics library with display and print output
 *
 * Copyright © 2009 Intel Corporation
 *
 * 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.
 *
 * Contributor(s):
 *  Chris Wilson <chris@chris-wilson.co.uk>
 */

#include "cairoint.h"

#include "cairo-combsort-inline.h"
#include "cairo-error-private.h"
#include "cairo-freelist-private.h"
#include "cairo-list-private.h"
#include "cairo-spans-private.h"

#include <setjmp.h>

typedef struct _rectangle {
    struct _rectangle *next, *prev;
    cairo_fixed_t left, right;
    cairo_fixed_t top, bottom;
    int32_t top_y, bottom_y;
    int dir;
} rectangle_t;

#define UNROLL3(x) x x x

/* the parent is always given by index/2 */
#define PQ_PARENT_INDEX(i) ((i) >> 1)
#define PQ_FIRST_ENTRY 1

/* left and right children are index * 2 and (index * 2) +1 respectively */
#define PQ_LEFT_CHILD_INDEX(i) ((i) << 1)

typedef struct _pqueue {
    int size, max_size;

    rectangle_t **elements;
    rectangle_t *elements_embedded[1024];
} pqueue_t;

typedef struct {
    rectangle_t **start;
    pqueue_t stop;
    rectangle_t head, tail;
    rectangle_t *insert_cursor;
    int32_t current_y;
    int32_t xmin, xmax;

    struct coverage {
  struct cell {
      struct cell *prev, *next;
      int x, covered, uncovered;
  } head, tail, *cursor;
  unsigned int count;
  cairo_freepool_t pool;
    } coverage;

    cairo_half_open_span_t spans_stack[CAIRO_STACK_ARRAY_LENGTH (cairo_half_open_span_t)];
    cairo_half_open_span_t *spans;
    unsigned int num_spans;
    unsigned int size_spans;

    jmp_buf jmpbuf;
} sweep_line_t;

static inline int
rectangle_compare_start (const rectangle_t *a,
       const rectangle_t *b)
{
    int cmp;

    cmp = a->top_y - b->top_y;
    if (cmp)
  return cmp;

    return a->left - b->left;
}

static inline int
rectangle_compare_stop (const rectangle_t *a,
      const rectangle_t *b)
{
    return a->bottom_y - b->bottom_y;
}

static inline void
pqueue_init (pqueue_t *pq)
{
    pq->max_size = ARRAY_LENGTH (pq->elements_embedded);
    pq->size = 0;

    pq->elements = pq->elements_embedded;
    pq->elements[PQ_FIRST_ENTRY] = NULL;
}

static inline void
pqueue_fini (pqueue_t *pq)
{
    if (pq->elements != pq->elements_embedded)
  free (pq->elements);
}

static cairo_bool_t
pqueue_grow (pqueue_t *pq)
{
    rectangle_t **new_elements;
    pq->max_size *= 2;

    if (pq->elements == pq->elements_embedded) {
  new_elements = _cairo_malloc_ab (pq->max_size,
           sizeof (rectangle_t *));
  if (unlikely (new_elements == NULL))
      return FALSE;

  memcpy (new_elements, pq->elements_embedded,
    sizeof (pq->elements_embedded));
    } else {
  new_elements = _cairo_realloc_ab (pq->elements,
            pq->max_size,
            sizeof (rectangle_t *));
  if (unlikely (new_elements == NULL))
      return FALSE;
    }

    pq->elements = new_elements;
    return TRUE;
}

static inline void
pqueue_push (sweep_line_t *sweep, rectangle_t *rectangle)
{
    rectangle_t **elements;
    int i, parent;

    if (unlikely (sweep->stop.size + 1 == sweep->stop.max_size)) {
  if (unlikely (! pqueue_grow (&sweep->stop)))
      longjmp (sweep->jmpbuf,
         _cairo_error (CAIRO_STATUS_NO_MEMORY));
    }

    elements = sweep->stop.elements;
    for (i = ++sweep->stop.size;
   i != PQ_FIRST_ENTRY &&
   rectangle_compare_stop (rectangle,
         elements[parent = PQ_PARENT_INDEX (i)]) < 0;
   i = parent)
    {
  elements[i] = elements[parent];
    }

    elements[i] = rectangle;
}

static inline void
pqueue_pop (pqueue_t *pq)
{
    rectangle_t **elements = pq->elements;
    rectangle_t *tail;
    int child, i;

    tail = elements[pq->size--];
    if (pq->size == 0) {
  elements[PQ_FIRST_ENTRY] = NULL;
  return;
    }

    for (i = PQ_FIRST_ENTRY;
   (child = PQ_LEFT_CHILD_INDEX (i)) <= pq->size;
   i = child)
    {
  if (child != pq->size &&
      rectangle_compare_stop (elements[child+1],
            elements[child]) < 0)
  {
      child++;
  }

  if (rectangle_compare_stop (elements[child], tail) >= 0)
      break;

  elements[i] = elements[child];
    }
    elements[i] = tail;
}

static inline rectangle_t *
peek_stop (sweep_line_t *sweep)
{
    return sweep->stop.elements[PQ_FIRST_ENTRY];
}

CAIRO_COMBSORT_DECLARE (rectangle_sort, rectangle_t *, rectangle_compare_start)

static void
sweep_line_init (sweep_line_t *sweep)
{
    sweep->head.left = INT_MIN;
    sweep->head.next = &sweep->tail;
    sweep->tail.left = INT_MAX;
    sweep->tail.prev = &sweep->head;
    sweep->insert_cursor = &sweep->tail;

    _cairo_freepool_init (&sweep->coverage.pool, sizeof (struct cell));

    sweep->spans = sweep->spans_stack;
    sweep->size_spans = ARRAY_LENGTH (sweep->spans_stack);

    sweep->coverage.head.prev = NULL;
    sweep->coverage.head.x = INT_MIN;
    sweep->coverage.tail.next = NULL;
    sweep->coverage.tail.x = INT_MAX;

    pqueue_init (&sweep->stop);
}

static void
sweep_line_fini (sweep_line_t *sweep)
{
    _cairo_freepool_fini (&sweep->coverage.pool);
    pqueue_fini (&sweep->stop);

    if (sweep->spans != sweep->spans_stack)
  free (sweep->spans);
}

static inline void
add_cell (sweep_line_t *sweep, int x, int covered, int uncovered)
{
    struct cell *cell;

    cell = sweep->coverage.cursor;
    if (cell->x > x) {
  do {
      UNROLL3({
    if (cell->prev->x < x)
        break;
    cell = cell->prev;
      })
  } while (TRUE);
    } else {
  if (cell->x == x)
      goto found;

  do {
      UNROLL3({
    cell = cell->next;
    if (cell->x >= x)
        break;
      })
  } while (TRUE);
    }

    if (x != cell->x) {
  struct cell *c;

  sweep->coverage.count++;

  c = _cairo_freepool_alloc (&sweep->coverage.pool);
  if (unlikely (c == NULL)) {
      longjmp (sweep->jmpbuf,
         _cairo_error (CAIRO_STATUS_NO_MEMORY));
  }

  cell->prev->next = c;
  c->prev = cell->prev;
  c->next = cell;
  cell->prev = c;

  c->x = x;
  c->covered = 0;
  c->uncovered = 0;

  cell = c;
    }

found:
    cell->covered += covered;
    cell->uncovered += uncovered;
    sweep->coverage.cursor = cell;
}

static inline void
_active_edges_to_spans (sweep_line_t  *sweep)
{
    int32_t y = sweep->current_y;
    rectangle_t *rectangle;
    int coverage, prev_coverage;
    int prev_x;
    struct cell *cell;

    sweep->num_spans = 0;
    if (sweep->head.next == &sweep->tail)
  return;

    sweep->coverage.head.next = &sweep->coverage.tail;
    sweep->coverage.tail.prev = &sweep->coverage.head;
    sweep->coverage.cursor = &sweep->coverage.tail;
    sweep->coverage.count = 0;

    /* XXX cell coverage only changes when a rectangle appears or
     * disappears. Try only modifying coverage at such times.
     */
    for (rectangle = sweep->head.next;
   rectangle != &sweep->tail;
   rectangle = rectangle->next)
    {
  int height;
  int frac, i;

  if (y == rectangle->bottom_y) {
      height = rectangle->bottom & CAIRO_FIXED_FRAC_MASK;
      if (height == 0)
    continue;
  } else
      height = CAIRO_FIXED_ONE;
  if (y == rectangle->top_y)
      height -= rectangle->top & CAIRO_FIXED_FRAC_MASK;
  height *= rectangle->dir;

  i = _cairo_fixed_integer_part (rectangle->left),
  frac = _cairo_fixed_fractional_part (rectangle->left);
  add_cell (sweep, i,
      (CAIRO_FIXED_ONE-frac) * height,
      frac * height);

  i = _cairo_fixed_integer_part (rectangle->right),
  frac = _cairo_fixed_fractional_part (rectangle->right);
  add_cell (sweep, i,
      -(CAIRO_FIXED_ONE-frac) * height,
      -frac * height);
    }

    if (2*sweep->coverage.count >= sweep->size_spans) {
  unsigned size;

  size = sweep->size_spans;
  while (size <= 2*sweep->coverage.count)
      size <<= 1;

  if (sweep->spans != sweep->spans_stack)
      free (sweep->spans);

  sweep->spans = _cairo_malloc_ab (size, sizeof (cairo_half_open_span_t));
  if (unlikely (sweep->spans == NULL))
      longjmp (sweep->jmpbuf, _cairo_error (CAIRO_STATUS_NO_MEMORY));

  sweep->size_spans = size;
    }

    prev_coverage = coverage = 0;
    prev_x = INT_MIN;
    for (cell = sweep->coverage.head.next; cell != &sweep->coverage.tail; cell = cell->next) {
  if (cell->x != prev_x && coverage != prev_coverage) {
      int n = sweep->num_spans++;
      int c = coverage >> (CAIRO_FIXED_FRAC_BITS * 2 - 8);
      sweep->spans[n].x = prev_x;
      sweep->spans[n].inverse = 0;
      sweep->spans[n].coverage = c - (c >> 8);
      prev_coverage = coverage;
  }

  coverage += cell->covered;
  if (coverage != prev_coverage) {
      int n = sweep->num_spans++;
      int c = coverage >> (CAIRO_FIXED_FRAC_BITS * 2 - 8);
      sweep->spans[n].x = cell->x;
      sweep->spans[n].inverse = 0;
      sweep->spans[n].coverage = c - (c >> 8);
      prev_coverage = coverage;
  }
  coverage += cell->uncovered;
  prev_x = cell->x + 1;
    }
    _cairo_freepool_reset (&sweep->coverage.pool);

    if (sweep->num_spans) {
  if (prev_x <= sweep->xmax) {
      int n = sweep->num_spans++;
      int c = coverage >> (CAIRO_FIXED_FRAC_BITS * 2 - 8);
      sweep->spans[n].x = prev_x;
      sweep->spans[n].inverse = 0;
      sweep->spans[n].coverage = c - (c >> 8);
  }

  if (coverage && prev_x < sweep->xmax) {
      int n = sweep->num_spans++;
      sweep->spans[n].x = sweep->xmax;
      sweep->spans[n].inverse = 1;
      sweep->spans[n].coverage = 0;
  }
    }
}

static inline void
sweep_line_delete (sweep_line_t *sweep,
           rectangle_t  *rectangle)
{
    if (sweep->insert_cursor == rectangle)
  sweep->insert_cursor = rectangle->next;

    rectangle->prev->next = rectangle->next;
    rectangle->next->prev = rectangle->prev;

    pqueue_pop (&sweep->stop);
}

static inline void
sweep_line_insert (sweep_line_t *sweep,
       rectangle_t  *rectangle)
{
    rectangle_t *pos;

    pos = sweep->insert_cursor;
    if (pos->left != rectangle->left) {
  if (pos->left > rectangle->left) {
      do {
    UNROLL3({
        if (pos->prev->left < rectangle->left)
      break;
        pos = pos->prev;
    })
      } while (TRUE);
  } else {
      do {
    UNROLL3({
        pos = pos->next;
        if (pos->left >= rectangle->left)
      break;
    });
      } while (TRUE);
  }
    }

    pos->prev->next = rectangle;
    rectangle->prev = pos->prev;
    rectangle->next = pos;
    pos->prev = rectangle;
    sweep->insert_cursor = rectangle;

    pqueue_push (sweep, rectangle);
}

static void
render_rows (sweep_line_t *sweep_line,
       cairo_span_renderer_t *renderer,
       int height)
{
    cairo_status_t status;

    _active_edges_to_spans (sweep_line);

    status = renderer->render_rows (renderer,
            sweep_line->current_y, height,
            sweep_line->spans,
            sweep_line->num_spans);
    if (unlikely (status))
  longjmp (sweep_line->jmpbuf, status);
}

static cairo_status_t
generate (cairo_rectangular_scan_converter_t *self,
    cairo_span_renderer_t *renderer,
    rectangle_t **rectangles)
{
    sweep_line_t sweep_line;
    rectangle_t *start, *stop;
    cairo_status_t status;

    sweep_line_init (&sweep_line);
    sweep_line.xmin = _cairo_fixed_integer_part (self->extents.p1.x);
    sweep_line.xmax = _cairo_fixed_integer_part (self->extents.p2.x);
    sweep_line.start = rectangles;
    if ((status = setjmp (sweep_line.jmpbuf)))
  goto out;

    sweep_line.current_y = _cairo_fixed_integer_part (self->extents.p1.y);
    start = *sweep_line.start++;
    do {
  if (start->top_y != sweep_line.current_y) {
      render_rows (&sweep_line, renderer,
       start->top_y - sweep_line.current_y);
      sweep_line.current_y = start->top_y;
  }

  do {
      sweep_line_insert (&sweep_line, start);
      start = *sweep_line.start++;
      if (start == NULL)
    goto end;
      if (start->top_y != sweep_line.current_y)
    break;
  } while (TRUE);

  render_rows (&sweep_line, renderer, 1);

  stop = peek_stop (&sweep_line);
  while (stop->bottom_y == sweep_line.current_y) {
      sweep_line_delete (&sweep_line, stop);
      stop = peek_stop (&sweep_line);
      if (stop == NULL)
    break;
  }

  sweep_line.current_y++;

  while (stop != NULL && stop->bottom_y < start->top_y) {
      if (stop->bottom_y != sweep_line.current_y) {
    render_rows (&sweep_line, renderer,
           stop->bottom_y - sweep_line.current_y);
    sweep_line.current_y = stop->bottom_y;
      }

      render_rows (&sweep_line, renderer, 1);

      do {
    sweep_line_delete (&sweep_line, stop);
    stop = peek_stop (&sweep_line);
      } while (stop != NULL && stop->bottom_y == sweep_line.current_y);

      sweep_line.current_y++;
  }
    } while (TRUE);

  end:
    render_rows (&sweep_line, renderer, 1);

    stop = peek_stop (&sweep_line);
    while (stop->bottom_y == sweep_line.current_y) {
  sweep_line_delete (&sweep_line, stop);
  stop = peek_stop (&sweep_line);
  if (stop == NULL)
      goto out;
    }

    while (++sweep_line.current_y < _cairo_fixed_integer_part (self->extents.p2.y)) {
  if (stop->bottom_y != sweep_line.current_y) {
      render_rows (&sweep_line, renderer,
       stop->bottom_y - sweep_line.current_y);
      sweep_line.current_y = stop->bottom_y;
  }

  render_rows (&sweep_line, renderer, 1);

  do {
      sweep_line_delete (&sweep_line, stop);
      stop = peek_stop (&sweep_line);
      if (stop == NULL)
    goto out;
  } while (stop->bottom_y == sweep_line.current_y);

    }

  out:
    sweep_line_fini (&sweep_line);

    return status;
}
static void generate_row(cairo_span_renderer_t *renderer,
       const rectangle_t *r,
       int y, int h,
       uint16_t coverage)
{
    cairo_half_open_span_t spans[4];
    unsigned int num_spans = 0;
    int x1 = _cairo_fixed_integer_part (r->left);
    int x2 = _cairo_fixed_integer_part (r->right);
    if (x2 > x1) {
  if (! _cairo_fixed_is_integer (r->left)) {
      spans[num_spans].x = x1;
      spans[num_spans].coverage =
    coverage * (256 - _cairo_fixed_fractional_part (r->left)) >> 8;
      num_spans++;
      x1++;
  }

  if (x2 > x1) {
      spans[num_spans].x = x1;
      spans[num_spans].coverage = coverage - (coverage >> 8);
      num_spans++;
  }

  if (! _cairo_fixed_is_integer (r->right)) {
      spans[num_spans].x = x2++;
      spans[num_spans].coverage =
    coverage * _cairo_fixed_fractional_part (r->right) >> 8;
      num_spans++;
  }
    } else {
  spans[num_spans].x = x2++;
  spans[num_spans].coverage = coverage * (r->right - r->left) >> 8;
  num_spans++;
    }

    spans[num_spans].x = x2;
    spans[num_spans].coverage = 0;
    num_spans++;

    renderer->render_rows (renderer, y, h, spans, num_spans);
}

static cairo_status_t
generate_box (cairo_rectangular_scan_converter_t *self,
        cairo_span_renderer_t *renderer)
{
    const rectangle_t *r = self->chunks.base;
    int y1 = _cairo_fixed_integer_part (r->top);
    int y2 = _cairo_fixed_integer_part (r->bottom);
    if (y2 > y1) {
  if (! _cairo_fixed_is_integer (r->top)) {
      generate_row(renderer, r, y1, 1,
       256 - _cairo_fixed_fractional_part (r->top));
      y1++;
  }

  if (y2 > y1)
      generate_row(renderer, r, y1, y2-y1, 256);

  if (! _cairo_fixed_is_integer (r->bottom))
      generate_row(renderer, r, y2, 1,
       _cairo_fixed_fractional_part (r->bottom));
    } else
  generate_row(renderer, r, y1, 1, r->bottom - r->top);

    return CAIRO_STATUS_SUCCESS;
}

static cairo_status_t
_cairo_rectangular_scan_converter_generate (void      *converter,
              cairo_span_renderer_t *renderer)
{
    cairo_rectangular_scan_converter_t *self = converter;
    rectangle_t *rectangles_stack[CAIRO_STACK_ARRAY_LENGTH (rectangle_t *)];
    rectangle_t **rectangles;
    struct _cairo_rectangular_scan_converter_chunk *chunk;
    cairo_status_t status;
    int i, j;

    if (unlikely (self->num_rectangles == 0)) {
  return renderer->render_rows (renderer,
              _cairo_fixed_integer_part (self->extents.p1.y),
              _cairo_fixed_integer_part (self->extents.p2.y - self->extents.p1.y),
              NULL, 0);
    }

    if (self->num_rectangles == 1)
  return generate_box (self, renderer);

    rectangles = rectangles_stack;
    if (unlikely (self->num_rectangles >= ARRAY_LENGTH (rectangles_stack))) {
  rectangles = _cairo_malloc_ab (self->num_rectangles + 1,
               sizeof (rectangle_t *));
  if (unlikely (rectangles == NULL))
      return _cairo_error (CAIRO_STATUS_NO_MEMORY);
    }

    j = 0;
    for (chunk = &self->chunks; chunk != NULL; chunk = chunk->next) {
  rectangle_t *rectangle;

  rectangle = chunk->base;
  for (i = 0; i < chunk->count; i++)
      rectangles[j++] = &rectangle[i];
    }
    rectangle_sort (rectangles, j);
    rectangles[j] = NULL;

    status = generate (self, renderer, rectangles);

    if (rectangles != rectangles_stack)
  free (rectangles);

    return status;
}

static rectangle_t *
_allocate_rectangle (cairo_rectangular_scan_converter_t *self)
{
    rectangle_t *rectangle;
    struct _cairo_rectangular_scan_converter_chunk *chunk;

    chunk = self->tail;
    if (chunk->count == chunk->size) {
  int size;

  size = chunk->size * 2;
  chunk->next = _cairo_malloc_ab_plus_c (size,
                 sizeof (rectangle_t),
                 sizeof (struct _cairo_rectangular_scan_converter_chunk));

  if (unlikely (chunk->next == NULL))
      return NULL;

  chunk = chunk->next;
  chunk->next = NULL;
  chunk->count = 0;
  chunk->size = size;
  chunk->base = chunk + 1;
  self->tail = chunk;
    }

    rectangle = chunk->base;
    return rectangle + chunk->count++;
}

cairo_status_t
_cairo_rectangular_scan_converter_add_box (cairo_rectangular_scan_converter_t *self,
             const cairo_box_t *box,
             int dir)
{
    rectangle_t *rectangle;

    rectangle = _allocate_rectangle (self);
    if (unlikely (rectangle == NULL))
  return _cairo_error (CAIRO_STATUS_NO_MEMORY);

    rectangle->dir = dir;
    rectangle->left  = MAX (box->p1.x, self->extents.p1.x);
    rectangle->right = MIN (box->p2.x, self->extents.p2.x);
    if (unlikely (rectangle->right <= rectangle->left)) {
  self->tail->count--;
  return CAIRO_STATUS_SUCCESS;
    }

    rectangle->top = MAX (box->p1.y, self->extents.p1.y);
    rectangle->top_y  = _cairo_fixed_integer_floor (rectangle->top);
    rectangle->bottom = MIN (box->p2.y, self->extents.p2.y);
    rectangle->bottom_y = _cairo_fixed_integer_floor (rectangle->bottom);
    if (likely (rectangle->bottom > rectangle->top))
  self->num_rectangles++;
    else
  self->tail->count--;

    return CAIRO_STATUS_SUCCESS;
}

static void
_cairo_rectangular_scan_converter_destroy (void *converter)
{
    cairo_rectangular_scan_converter_t *self = converter;
    struct _cairo_rectangular_scan_converter_chunk *chunk, *next;

    for (chunk = self->chunks.next; chunk != NULL; chunk = next) {
  next = chunk->next;
  free (chunk);
    }
}

void
_cairo_rectangular_scan_converter_init (cairo_rectangular_scan_converter_t *self,
          const cairo_rectangle_int_t *extents)
{
    self->base.destroy = _cairo_rectangular_scan_converter_destroy;
    self->base.generate = _cairo_rectangular_scan_converter_generate;

    _cairo_box_from_rectangle (&self->extents, extents);

    self->chunks.base = self->buf;
    self->chunks.next = NULL;
    self->chunks.count = 0;
    self->chunks.size = sizeof (self->buf) / sizeof (rectangle_t);
    self->tail = &self->chunks;

    self->num_rectangles = 0;
}

Coverage Report

Created: 2025-11-16 09:57