mirror of
https://github.com/brl/mutter.git
synced 2024-11-23 08:30:42 -05:00
314 lines
9.8 KiB
C
314 lines
9.8 KiB
C
/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
|
||
/*
|
||
* Utilities for region manipulation
|
||
*
|
||
* Copyright (C) 2010 Red Hat, Inc.
|
||
*
|
||
* This program is free software; you can redistribute it and/or
|
||
* modify it under the terms of the GNU General Public License as
|
||
* published by the Free Software Foundation; either version 2 of the
|
||
* License, or (at your option) any later version.
|
||
*
|
||
* 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, USA.
|
||
*/
|
||
|
||
#include "region-utils.h"
|
||
|
||
#include <math.h>
|
||
|
||
/* MetaRegionBuilder */
|
||
|
||
/* Various algorithms in this file require unioning together a set of rectangles
|
||
* that are unsorted or overlap; unioning such a set of rectangles 1-by-1
|
||
* using cairo_region_union_rectangle() produces O(N^2) behavior (if the union
|
||
* adds or removes rectangles in the middle of the region, then it has to
|
||
* move all the rectangles after that.) To avoid this behavior, MetaRegionBuilder
|
||
* creates regions for small groups of rectangles and merges them together in
|
||
* a binary tree.
|
||
*
|
||
* Possible improvement: From a glance at the code, accumulating all the rectangles
|
||
* into a flat array and then calling the (not usefully documented)
|
||
* cairo_region_create_rectangles() would have the same behavior and would be
|
||
* simpler and a bit more efficient.
|
||
*/
|
||
|
||
/* Optimium performance seems to be with MAX_CHUNK_RECTANGLES=4; 8 is about 10% slower.
|
||
* But using 8 may be more robust to systems with slow malloc(). */
|
||
#define MAX_CHUNK_RECTANGLES 8
|
||
|
||
void
|
||
meta_region_builder_init (MetaRegionBuilder *builder)
|
||
{
|
||
int i;
|
||
for (i = 0; i < META_REGION_BUILDER_MAX_LEVELS; i++)
|
||
builder->levels[i] = NULL;
|
||
builder->n_levels = 1;
|
||
}
|
||
|
||
void
|
||
meta_region_builder_add_rectangle (MetaRegionBuilder *builder,
|
||
int x,
|
||
int y,
|
||
int width,
|
||
int height)
|
||
{
|
||
cairo_rectangle_int_t rect;
|
||
int i;
|
||
|
||
if (builder->levels[0] == NULL)
|
||
builder->levels[0] = cairo_region_create ();
|
||
|
||
rect.x = x;
|
||
rect.y = y;
|
||
rect.width = width;
|
||
rect.height = height;
|
||
|
||
cairo_region_union_rectangle (builder->levels[0], &rect);
|
||
if (cairo_region_num_rectangles (builder->levels[0]) >= MAX_CHUNK_RECTANGLES)
|
||
{
|
||
for (i = 1; i < builder->n_levels + 1; i++)
|
||
{
|
||
if (builder->levels[i] == NULL)
|
||
{
|
||
if (i < META_REGION_BUILDER_MAX_LEVELS)
|
||
{
|
||
builder->levels[i] = builder->levels[i - 1];
|
||
builder->levels[i - 1] = NULL;
|
||
if (i == builder->n_levels)
|
||
builder->n_levels++;
|
||
}
|
||
|
||
break;
|
||
}
|
||
else
|
||
{
|
||
cairo_region_union (builder->levels[i], builder->levels[i - 1]);
|
||
cairo_region_destroy (builder->levels[i - 1]);
|
||
builder->levels[i - 1] = NULL;
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
cairo_region_t *
|
||
meta_region_builder_finish (MetaRegionBuilder *builder)
|
||
{
|
||
cairo_region_t *result = NULL;
|
||
int i;
|
||
|
||
for (i = 0; i < builder->n_levels; i++)
|
||
{
|
||
if (builder->levels[i])
|
||
{
|
||
if (result == NULL)
|
||
result = builder->levels[i];
|
||
else
|
||
{
|
||
cairo_region_union(result, builder->levels[i]);
|
||
cairo_region_destroy (builder->levels[i]);
|
||
}
|
||
}
|
||
}
|
||
|
||
if (result == NULL)
|
||
result = cairo_region_create ();
|
||
|
||
return result;
|
||
}
|
||
|
||
|
||
/* MetaRegionIterator */
|
||
|
||
void
|
||
meta_region_iterator_init (MetaRegionIterator *iter,
|
||
cairo_region_t *region)
|
||
{
|
||
iter->region = region;
|
||
iter->i = 0;
|
||
iter->n_rectangles = cairo_region_num_rectangles (region);
|
||
iter->line_start = TRUE;
|
||
|
||
if (iter->n_rectangles > 1)
|
||
{
|
||
cairo_region_get_rectangle (region, 0, &iter->rectangle);
|
||
cairo_region_get_rectangle (region, 1, &iter->next_rectangle);
|
||
|
||
iter->line_end = iter->next_rectangle.y != iter->rectangle.y;
|
||
}
|
||
else if (iter->n_rectangles > 0)
|
||
{
|
||
cairo_region_get_rectangle (region, 0, &iter->rectangle);
|
||
iter->line_end = TRUE;
|
||
}
|
||
}
|
||
|
||
gboolean
|
||
meta_region_iterator_at_end (MetaRegionIterator *iter)
|
||
{
|
||
return iter->i >= iter->n_rectangles;
|
||
}
|
||
|
||
void
|
||
meta_region_iterator_next (MetaRegionIterator *iter)
|
||
{
|
||
iter->i++;
|
||
iter->rectangle = iter->next_rectangle;
|
||
iter->line_start = iter->line_end;
|
||
|
||
if (iter->i + 1 < iter->n_rectangles)
|
||
{
|
||
cairo_region_get_rectangle (iter->region, iter->i + 1, &iter->next_rectangle);
|
||
iter->line_end = iter->next_rectangle.y != iter->rectangle.y;
|
||
}
|
||
else
|
||
{
|
||
iter->line_end = TRUE;
|
||
}
|
||
}
|
||
|
||
static void
|
||
add_expanded_rect (MetaRegionBuilder *builder,
|
||
int x,
|
||
int y,
|
||
int width,
|
||
int height,
|
||
int x_amount,
|
||
int y_amount,
|
||
gboolean flip)
|
||
{
|
||
if (flip)
|
||
meta_region_builder_add_rectangle (builder,
|
||
y - y_amount, x - x_amount,
|
||
height + 2 * y_amount, width + 2 * x_amount);
|
||
else
|
||
meta_region_builder_add_rectangle (builder,
|
||
x - x_amount, y - y_amount,
|
||
width + 2 * x_amount, height + 2 * y_amount);
|
||
}
|
||
|
||
static cairo_region_t *
|
||
expand_region (cairo_region_t *region,
|
||
int x_amount,
|
||
int y_amount,
|
||
gboolean flip)
|
||
{
|
||
MetaRegionBuilder builder;
|
||
int n;
|
||
int i;
|
||
|
||
meta_region_builder_init (&builder);
|
||
|
||
n = cairo_region_num_rectangles (region);
|
||
for (i = 0; i < n; i++)
|
||
{
|
||
cairo_rectangle_int_t rect;
|
||
|
||
cairo_region_get_rectangle (region, i, &rect);
|
||
add_expanded_rect (&builder,
|
||
rect.x, rect.y, rect.width, rect.height,
|
||
x_amount, y_amount, flip);
|
||
}
|
||
|
||
return meta_region_builder_finish (&builder);
|
||
}
|
||
|
||
/* This computes a (clipped version) of the inverse of the region
|
||
* and expands it by the given amount */
|
||
static cairo_region_t *
|
||
expand_region_inverse (cairo_region_t *region,
|
||
int x_amount,
|
||
int y_amount,
|
||
gboolean flip)
|
||
{
|
||
MetaRegionBuilder builder;
|
||
MetaRegionIterator iter;
|
||
cairo_rectangle_int_t extents;
|
||
|
||
int last_x;
|
||
|
||
meta_region_builder_init (&builder);
|
||
|
||
cairo_region_get_extents (region, &extents);
|
||
add_expanded_rect (&builder,
|
||
extents.x, extents.y - 1, extents.width, 1,
|
||
x_amount, y_amount, flip);
|
||
add_expanded_rect (&builder,
|
||
extents.x - 1, extents.y, 1, extents.height,
|
||
x_amount, y_amount, flip);
|
||
add_expanded_rect (&builder,
|
||
extents.x + extents.width, extents.y, 1, extents.height,
|
||
x_amount, y_amount, flip);
|
||
add_expanded_rect (&builder,
|
||
extents.x, extents.y + extents.height, extents.width, 1,
|
||
x_amount, y_amount, flip);
|
||
|
||
last_x = extents.x;
|
||
for (meta_region_iterator_init (&iter, region);
|
||
!meta_region_iterator_at_end (&iter);
|
||
meta_region_iterator_next (&iter))
|
||
{
|
||
if (iter.rectangle.x > last_x)
|
||
add_expanded_rect (&builder,
|
||
last_x, iter.rectangle.y,
|
||
iter.rectangle.x - last_x, iter.rectangle.height,
|
||
x_amount, y_amount, flip);
|
||
|
||
if (iter.line_end)
|
||
{
|
||
if (extents.x + extents.width > iter.rectangle.x + iter.rectangle.width)
|
||
add_expanded_rect (&builder,
|
||
iter.rectangle.x + iter.rectangle.width, iter.rectangle.y,
|
||
(extents.x + extents.width) - (iter.rectangle.x + iter.rectangle.width), iter.rectangle.height,
|
||
x_amount, y_amount, flip);
|
||
last_x = extents.x;
|
||
}
|
||
else
|
||
last_x = iter.rectangle.x + iter.rectangle.width;
|
||
}
|
||
|
||
return meta_region_builder_finish (&builder);
|
||
}
|
||
|
||
/**
|
||
* meta_make_border_region:
|
||
* @region: a #cairo_region_t
|
||
* @x_amount: distance from the border to extend horizontally
|
||
* @y_amount: distance from the border to extend vertically
|
||
* @flip: if true, the result is computed with x and y interchanged
|
||
*
|
||
* Computes the "border region" of a given region, which is roughly
|
||
* speaking the set of points near the boundary of the region. If we
|
||
* define the operation of growing a region as computing the set of
|
||
* points within a given manhattan distance of the region, then the
|
||
* border is 'grow(region) intersect grow(inverse(region))'.
|
||
*
|
||
* If we create an image by filling the region with a solid color,
|
||
* the border is the region affected by blurring the region.
|
||
*
|
||
* Return value: a new region which is the border of the given region
|
||
*/
|
||
cairo_region_t *
|
||
meta_make_border_region (cairo_region_t *region,
|
||
int x_amount,
|
||
int y_amount,
|
||
gboolean flip)
|
||
{
|
||
cairo_region_t *border_region;
|
||
cairo_region_t *inverse_region;
|
||
|
||
border_region = expand_region (region, x_amount, y_amount, flip);
|
||
inverse_region = expand_region_inverse (region, x_amount, y_amount, flip);
|
||
cairo_region_intersect (border_region, inverse_region);
|
||
cairo_region_destroy (inverse_region);
|
||
|
||
return border_region;
|
||
}
|