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PIKApp/app/operations/pikaoperationflood.c

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/* PIKA - Photo and Image Kooker Application
* a rebranding of The GNU Image Manipulation Program (created with heckimp)
* A derived work which may be trivial. However, any changes may be (C)2023 by Aldercone Studio
*
* Original copyright, applying to most contents (license remains unchanged):
* Copyright (C) 1995 Spencer Kimball and Peter Mattis
*
* pikaoperationflood.c
* Copyright (C) 2016 Ell
*
* 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 3 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, see <https://www.gnu.org/licenses/>.
*/
/* Implementation of the Flood algorithm.
* See https://wiki.pika.org/wiki/Algorithms:Flood for details.
*/
#include "config.h"
#include <string.h> /* For `memcpy()`. */
#include <cairo.h>
#include <gegl.h>
#include <gdk-pixbuf/gdk-pixbuf.h>
#include "libpikabase/pikabase.h"
#include "operations-types.h"
#include "pikaoperationflood.h"
/* Maximal gap, in pixels, between consecutive dirty ranges, below (and
* including) which they are coalesced, at the beginning of the distribution
* step.
*/
#define PIKA_OPERATION_FLOOD_COALESCE_MAX_GAP 32
typedef struct _PikaOperationFloodSegment PikaOperationFloodSegment;
typedef struct _PikaOperationFloodDirtyRange PikaOperationFloodDirtyRange;
typedef struct _PikaOperationFloodContext PikaOperationFloodContext;
/* A segment. */
struct _PikaOperationFloodSegment
{
/* A boolean flag indicating whether the image- and ROI-virtual coordinate
* systems should be transposed when processing this segment. TRUE iff the
* segment is vertical.
*/
guint transpose : 1;
/* The y-coordinate of the segment, in the ROI-virtual coordinate system. */
guint y : 8 * sizeof (guint) - 3;
/* The difference between the y-coordinates of the source segment and this
* segment, in the ROI-virtual coordinate system. Either -1 or +1 for
* ordinary segments, and 0 for seed segments, as a special case.
*
* Note the use of `signed` as the type specifier. The C standard doesn't
* specify the signedness of bit-fields whose type specifier is `int`, or a
* typedef-name defined as `int`, such as `gint`.
*/
signed source_y_delta : 2;
/* The x-coordinates of the first and last pixels of the segment, in the ROI-
* virtual coordinate system. Note that this is a closed range:
* [x[0], x[1]].
*/
gint x[2];
};
/* Make sure the maximal image dimension fits in
* `PikaOperationFloodSegment::y`.
*/
G_STATIC_ASSERT (PIKA_MAX_IMAGE_SIZE <= (1 << (8 * sizeof (guint) - 3)));
/* A dirty range of the current segment. */
struct _PikaOperationFloodDirtyRange
{
/* A boolean flag indicating whether the range was extended, or its existing
* pixels were modified, during the horizontal propagation step.
*/
gboolean modified;
/* The x-coordinates of the first and last pixels of the range, in the ROI-
* virtual coordinate system. Note that this is a closed range:
* [x[0], x[1]].
*/
gint x[2];
};
/* Common parameters for the various parts of the algorithm. */
struct _PikaOperationFloodContext
{
/* Input image. */
GeglBuffer *input;
/* Input image format. */
const Babl *input_format;
/* Output image. */
GeglBuffer *output;
/* Output image format. */
const Babl *output_format;
/* Region of interset. */
GeglRectangle roi;
/* Current segment. */
PikaOperationFloodSegment segment;
/* The following arrays hold the ground- and water-level of the current- and
* source-segments. The vertical- and horizontal-propagation steps don't
* generally access the input and output GEGL buffers directly, but rather
* read from, and write to, these arrays, for efficiency. These arrays are
* read-from, and written-to, the corresponding GEGL buffers before and after
* these steps.
*/
/* Ground level of the current segment, indexed by x-coordinate in the ROI-
* virtual coordinate system. Only valid inside the range
* `[segment.x[0], segment.x[1]]`.
*/
gfloat *ground;
/* Water level of the current segment, indexed by x-coordinate in the ROI-
* virtual coordinate system. Initially only valid inside the range
* `[segment.x[0], segment.x[1]]`, but may be written-to outside this range
* during horizontal propagation, if the dirty ranges are extended past the
* bounds of the segment.
*/
gfloat *water;
/* Water level of the source segment, indexed by x-coordinate in the ROI-
* virtual coordinate system. Only valid inside the range
* `[segment.x[0], segment.x[1]]`.
*/
gfloat *source_water;
/* A common buffer for the water level of the current- and source-segments.
* `water` and `source_water` are pointers into this buffer. This buffer is
* used as an optimization, in order to read the water level of both segments
* from the output GEGL buffer in a single call, and is otherwise not used
* directly (`water` and `source_water` are used to access the water level
* instead.)
*/
gfloat *water_buffer;
};
static void pika_operation_flood_prepare (GeglOperation *operation);
static GeglRectangle pika_operation_flood_get_required_for_output (GeglOperation *self,
const gchar *input_pad,
const GeglRectangle *roi);
static GeglRectangle pika_operation_flood_get_cached_region (GeglOperation *self,
const GeglRectangle *roi);
static void pika_operation_flood_process_push (GQueue *queue,
gboolean transpose,
gint y,
gint source_y_delta,
gint x0,
gint x1);
static void pika_operation_flood_process_seed (GQueue *queue,
const GeglRectangle *roi);
static void pika_operation_flood_process_transform_rect (const PikaOperationFloodContext *ctx,
GeglRectangle *dest,
const GeglRectangle *src);
static void pika_operation_flood_process_fetch (PikaOperationFloodContext *ctx);
static gint pika_operation_flood_process_propagate_vertical (PikaOperationFloodContext *ctx,
PikaOperationFloodDirtyRange *dirty_ranges);
static void pika_operation_flood_process_propagate_horizontal (PikaOperationFloodContext *ctx,
gint dir,
PikaOperationFloodDirtyRange *dirty_ranges,
gint range_count);
static gint pika_operation_flood_process_coalesce (const PikaOperationFloodContext *ctx,
PikaOperationFloodDirtyRange *dirty_ranges,
gint range_count,
gint gap);
static void pika_operation_flood_process_commit (const PikaOperationFloodContext *ctx,
const PikaOperationFloodDirtyRange *dirty_ranges,
gint range_count);
static void pika_operation_flood_process_distribute (const PikaOperationFloodContext *ctx,
GQueue *queue,
const PikaOperationFloodDirtyRange *dirty_ranges,
gint range_count);
static gboolean pika_operation_flood_process (GeglOperation *operation,
GeglBuffer *input,
GeglBuffer *output,
const GeglRectangle *roi,
gint level);
G_DEFINE_TYPE (PikaOperationFlood, pika_operation_flood,
GEGL_TYPE_OPERATION_FILTER)
#define parent_class pika_operation_flood_parent_class
/* GEGL graph for the test case. */
static const gchar* reference_xml = "<?xml version='1.0' encoding='UTF-8'?>"
"<gegl>"
"<node operation='pika:flood'> </node>"
"<node operation='gegl:load'>"
" <params>"
" <param name='path'>flood-input.png</param>"
" </params>"
"</node>"
"</gegl>";
static void
pika_operation_flood_class_init (PikaOperationFloodClass *klass)
{
GeglOperationClass *operation_class = GEGL_OPERATION_CLASS (klass);
GeglOperationFilterClass *filter_class = GEGL_OPERATION_FILTER_CLASS (klass);
/* The input and output buffers must be different, since we generally need to
* be able to access the input-image values after having written to the
* output buffer.
*/
operation_class->want_in_place = FALSE;
/* We don't want `GeglOperationFilter` to split the image across multiple
* threads, since this operation depends on, and affects, the image as a
* whole.
*/
operation_class->threaded = FALSE;
/* Note that both of these options are the default; we set them here for
* explicitness.
*/
gegl_operation_class_set_keys (operation_class,
"name", "pika:flood",
"categories", "pika",
"description", "PIKA Flood operation",
"reference", "https://wiki.pika.org/wiki/Algorithms:Flood",
"reference-image", "flood-output.png",
"reference-composition", reference_xml,
NULL);
operation_class->prepare = pika_operation_flood_prepare;
operation_class->get_required_for_output = pika_operation_flood_get_required_for_output;
operation_class->get_cached_region = pika_operation_flood_get_cached_region;
filter_class->process = pika_operation_flood_process;
}
static void
pika_operation_flood_init (PikaOperationFlood *self)
{
}
static void
pika_operation_flood_prepare (GeglOperation *operation)
{
const Babl *space = gegl_operation_get_source_space (operation, "input");
gegl_operation_set_format (operation, "input", babl_format_with_space ("Y float", space));
gegl_operation_set_format (operation, "output", babl_format_with_space ("Y float", space));
}
static GeglRectangle
pika_operation_flood_get_required_for_output (GeglOperation *self,
const gchar *input_pad,
const GeglRectangle *roi)
{
return *gegl_operation_source_get_bounding_box (self, "input");
}
static GeglRectangle
pika_operation_flood_get_cached_region (GeglOperation *self,
const GeglRectangle *roi)
{
return *gegl_operation_source_get_bounding_box (self, "input");
}
/* Pushes a single segment into the queue. */
static void
pika_operation_flood_process_push (GQueue *queue,
gboolean transpose,
gint y,
gint source_y_delta,
gint x0,
gint x1)
{
PikaOperationFloodSegment *segment;
segment = g_slice_new (PikaOperationFloodSegment);
segment->transpose = transpose;
segment->y = y;
segment->source_y_delta = source_y_delta;
segment->x[0] = x0;
segment->x[1] = x1;
g_queue_push_tail (queue, segment);
}
/* Pushes the seed segments into the queue. Recall that the seed segments are
* indicated by having their `source_y_delta` field equal 0.
*
* `roi` is given in the image-physical coordinate system.
*/
static void
pika_operation_flood_process_seed (GQueue *queue,
const GeglRectangle *roi)
{
if (roi->width == 0 || roi->height == 0)
return;
/* Top edge. */
pika_operation_flood_process_push (queue,
/* transpose = */ FALSE,
/* y = */ 0,
/* source_y_delta = */ 0,
/* x0 = */ 0,
/* x1 = */ roi->width - 1);
if (roi->height == 1)
return;
/* Bottom edge. */
pika_operation_flood_process_push (queue,
/* transpose = */ FALSE,
/* y = */ roi->height - 1,
/* source_y_delta = */ 0,
/* x0 = */ 0,
/* x1 = */ roi->width - 1);
if (roi->height == 2)
return;
/* Left edge. */
pika_operation_flood_process_push (queue,
/* transpose = */ TRUE,
/* y = */ 0,
/* source_y_delta = */ 0,
/* x0 = */ 1,
/* x1 = */ roi->height - 2);
if (roi->width == 1)
return;
/* Right edge. */
pika_operation_flood_process_push (queue,
/* transpose = */ TRUE,
/* y = */ roi->width - 1,
/* source_y_delta = */ 0,
/* x0 = */ 1,
/* x1 = */ roi->height - 2);
}
/* Transforms a `GeglRectangle` between the image-physical and image-virtual
* coordinate systems, in either direction, based on the attributes of the
* current segment (namely, its `transpose` flag.)
*
* Takes the input rectangle through `src`, and stores the result in `dest`.
* Both parameters may refer to the same object.
*/
static void
pika_operation_flood_process_transform_rect (const PikaOperationFloodContext *ctx,
GeglRectangle *dest,
const GeglRectangle *src)
{
if (! ctx->segment.transpose)
*dest = *src;
else
{
gint temp;
temp = src->x;
dest->x = src->y;
dest->y = temp;
temp = src->width;
dest->width = src->height;
dest->height = temp;
}
}
/* Reads the ground- and water-level for the current- and source-segments from
* the GEGL buffers into the corresponding arrays. Sets up the `water` and
* `source_water` pointers of `ctx` to point to the right location in
* `water_buffer`.
*/
static void
pika_operation_flood_process_fetch (PikaOperationFloodContext *ctx)
{
/* Image-virtual and image-physical rectangles, respectively. */
GeglRectangle iv_rect, ip_rect;
/* Set the horizontal extent of the rectangle to span the entire segment. */
iv_rect.x = ctx->roi.x + ctx->segment.x[0];
iv_rect.width = ctx->segment.x[1] - ctx->segment.x[0] + 1;
/* For reading the water level, we treat ordinary (non-seed) and seed
* segments differently.
*/
if (ctx->segment.source_y_delta != 0)
{
/* Ordinary segment. */
/* We set the vertical extent of the rectangle to span both the current-
* and the source-segments, and set the `water` and `source_water`
* pointers to point to two consecutive rows of the `water_buffer` array
* (the y-coordinate of the rectangle, and which row is above which,
* depends on whether the source segment is above, or below, the current
* one.)
*/
if (ctx->segment.source_y_delta < 0)
{
iv_rect.y = ctx->roi.y + ctx->segment.y - 1;
ctx->water = ctx->water_buffer + ctx->roi.width;
ctx->source_water = ctx->water_buffer;
}
else
{
iv_rect.y = ctx->roi.y + ctx->segment.y;
ctx->water = ctx->water_buffer;
ctx->source_water = ctx->water_buffer + ctx->roi.width;
}
iv_rect.height = 2;
/* Transform `iv_rect` to the image-physical coordinate system, and store
* the result in `ip_rect`.
*/
pika_operation_flood_process_transform_rect (ctx, &ip_rect, &iv_rect);
/* Read the water level from the output GEGL buffer into `water_buffer`.
*
* Notice the stride: If the current segment is horizontal, then we're
* reading a pair of rows directly into the correct locations inside
* `water_buffer` (i.e., `water` and `source_water`). On the other hand,
* if the current segment is vertical, then we're reading a pair of
* *columns*; we set the stride to 2-pixels so that the current- and
* source-water levels are interleaved in `water_buffer`, and reorder
* them below.
*/
gegl_buffer_get (ctx->output, &ip_rect, 1.0, ctx->output_format,
ctx->water_buffer + ctx->segment.x[0],
sizeof (gfloat) *
(ctx->segment.transpose ? 2 : ctx->roi.width),
GEGL_ABYSS_NONE);
/* As mentioned above, if the current segment is vertical, then the
* water levels of the current- and source-segments are interleaved in
* `water_buffer`. We deinterleave the water levels into `water` and
* `source_water`, using the yet-to-be-written-to `ground` array as a
* temporary buffer, as necessary.
*/
if (ctx->segment.transpose)
{
const gfloat *src;
gfloat *dest1, *dest2, *temp;
gint size, temp_size;
gint i;
src = ctx->water_buffer + ctx->segment.x[0];
dest1 = ctx->water_buffer + ctx->segment.x[0];
dest2 = ctx->water_buffer + ctx->roi.width + ctx->segment.x[0];
temp = ctx->ground;
size = ctx->segment.x[1] - ctx->segment.x[0] + 1;
temp_size = MAX (0, 2 * size - ctx->roi.width);
for (i = 0; i < temp_size; i++)
{
dest1[i] = src[2 * i];
temp[i] = src[2 * i + 1];
}
for (; i < size; i++)
{
dest1[i] = src[2 * i];
dest2[i] = src[2 * i + 1];
}
memcpy (dest2, temp, sizeof (gfloat) * temp_size);
}
}
else
{
/* Seed segment. */
gint x;
/* Set the `water` and `source_water` pointers to point to consecutive
* rows of the `water_buffer` array.
*/
ctx->water = ctx->water_buffer;
ctx->source_water = ctx->water_buffer + ctx->roi.width;
/* Set the vertical extent of the rectangle to span a the current
* segment's row.
*/
iv_rect.y = ctx->roi.y + ctx->segment.y;
iv_rect.height = 1;
/* Transform `iv_rect` to the image-physical coordinate system, and store
* the result in `ip_rect`.
*/
pika_operation_flood_process_transform_rect (ctx, &ip_rect, &iv_rect);
/* Read the water level of the current segment from the output GEGL
* buffer into `water`.
*/
gegl_buffer_get (ctx->output, &ip_rect, 1.0, ctx->output_format,
ctx->water + ctx->segment.x[0],
GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_NONE);
/* Initialize `source_water` to 0, as this is a seed segment. */
for (x = ctx->segment.x[0]; x <= ctx->segment.x[1]; x++)
ctx->source_water[x] = 0.0;
}
/* Set the vertical extent of the rectangle to span a the current segment's
* row.
*/
iv_rect.y = ctx->roi.y + ctx->segment.y;
iv_rect.height = 1;
/* Transform `iv_rect` to the image-physical coordinate system, and store the
* result in `ip_rect`.
*/
pika_operation_flood_process_transform_rect (ctx, &ip_rect, &iv_rect);
/* Read the ground level of the current segment from the input GEGL buffer
* into `ground`.
*/
gegl_buffer_get (ctx->input, &ip_rect, 1.0, ctx->input_format,
ctx->ground + ctx->segment.x[0],
GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_NONE);
}
/* Performs the vertical propagation step of the algorithm. Writes the dirty
* ranges to the `dirty_ranges` parameter, and returns the number of dirty
* ranges as the function's result.
*/
static gint
pika_operation_flood_process_propagate_vertical (PikaOperationFloodContext *ctx,
PikaOperationFloodDirtyRange *dirty_ranges)
{
PikaOperationFloodDirtyRange *range = dirty_ranges;
gint x;
for (x = ctx->segment.x[0]; x <= ctx->segment.x[1]; x++)
{
/* Scan the segment until we find a pixel whose water level needs to be
* updated.
*/
if (ctx->source_water[x] < ctx->water[x] &&
ctx->ground[x] < ctx->water[x])
{
/* Compute and update the water level. */
gfloat level = MAX (ctx->source_water[x], ctx->ground[x]);
ctx->water[x] = level;
/* Start a new dirty range at the current pixel. */
range->x[0] = x;
range->modified = FALSE;
for (x++; x <= ctx->segment.x[1]; x++)
{
/* Keep scanning the segment while the water level of consecutive
* pixels needs to be updated.
*/
if (ctx->source_water[x] < ctx->water[x] &&
ctx->ground[x] < ctx->water[x])
{
/* Compute and update the water level. */
gfloat other_level = MAX (ctx->source_water[x],
ctx->ground[x]);
ctx->water[x] = other_level;
/* If the water level of the current pixel, `other_level`,
* equals the water level of the current dirty range,
* `level`, we keep scanning, making the current pixel part
* of the current range. On the other hand, if the current
* pixel's water level is different than the that of the
* current range, we finalize the range, and start a new one
* at the current pixel.
*/
if (other_level != level)
{
range->x[1] = x - 1;
range++;
range->x[0] = x;
range->modified = FALSE;
level = other_level;
}
}
else
break;
}
/* Finalize the current dirty range. */
range->x[1] = x - 1;
range++;
/* Make sure we don't over-increment `x` on the continuation of the
* loop.
*/
if (x > ctx->segment.x[1])
break;
}
}
/* Return the number of dirty ranges. */
return range - dirty_ranges;
}
/* Performs a single pass of the horizontal propagation step of the algorithm.
* `dir` controls the direction of the pass: either +1 for a left-to-right
* pass, or -1 for a right-to-left pass. The dirty ranges are passed through
* the `dirty_ranges` array (and their number in `range_count`), and are
* modified in-place.
*/
static void
pika_operation_flood_process_propagate_horizontal (PikaOperationFloodContext *ctx,
gint dir,
PikaOperationFloodDirtyRange *dirty_ranges,
gint range_count)
{
/* The index of the terminal (i.e., "`dir`-most") component of the `x[]`
* array of `PikaOperationFloodSegment` and `PikaOperationFloodDirtyRange`,
* based on the scan direction. Equals 1 (i.e., the right component) when
* `dir` is +1 (i.e., left-to-right), and equals 0 (i.e., the left component)
* when `dir` is -1 (i.e., right-to-left).
*/
gint x_component;
/* One-past the final x-coordinate of the ROI, in the ROI-virtual coordinate
* system, based on the scan direction. That is, the x-coordinate of the
* pixel to the right of the rightmost pixel, for a left-to-right scan, and
* of the pixel to the left of the leftmost pixel, for a right-to-left scan.
*/
gint roi_lim;
/* One-past the final x-coordinate of the segment, in the ROI-virtual
* coordinate system, based on the scan direction, in a similar fashion to
* `roi_lim`.
*/
gint segment_lim;
/* The indices of the first, and one-past-the-last dirty ranges, based on the
* direction of the scan. Recall that when scanning right-to-left, we
* iterate over the ranges in reverse.
*/
gint first_range, last_range;
/* Index of the current dirty range. */
gint range_index;
/* Image-virtual and image-physical rectangles, respectively. */
GeglRectangle iv_rect, ip_rect;
/* Initialize the above variables based on the scan direction. */
if (dir > 0)
{
/* Left-to-right. */
x_component = 1;
roi_lim = ctx->roi.width;
first_range = 0;
last_range = range_count;
}
else
{
/* Right-to-left. */
x_component = 0;
roi_lim = -1;
first_range = range_count - 1;
last_range = -1;
}
segment_lim = ctx->segment.x[x_component] + dir;
/* We loop over the dirty ranges, in the direction of the scan. For each
* range, we iterate over the pixels, in the scan direction, starting at the
* outer edge of the range, and update the water level, considering only the
* water level of the previous and current pixels, until we arrive at a pixel
* whose water level remains the same, at which point we move to the next
* range, as described in the algorithm overview.
*/
for (range_index = first_range;
range_index != last_range;
range_index += dir)
{
/* Current dirty range. */
PikaOperationFloodDirtyRange *range;
/* Current pixel, in the ROI-virtual coordinate system. */
gint x;
/* We use `level` to compute the water level of the current pixel. At
* the beginning of each iteration, it holds the water level of the
* previous pixel.
*/
gfloat level;
/* The `inside` flag indicates whether `x` is inside the current segment.
* Recall that we may iterate past the bounds of the current segment, in
* which case we need to read the ground- and water-levels from the GEGL
* buffers directly, instead of the corresponding arrays.
*/
gboolean inside;
/* Loop limit. */
gint lim;
range = &dirty_ranges[range_index];
/* Last x-coordinate of the range, in the direction of the scan. */
x = range->x[x_component];
/* We start iterating on the pixel after `x`; initialize `level` to the
* water level of the previous pixel.
*/
level = ctx->water[x];
/* The ranges produced by the vertical propagation step are all within
* the bounds of the segment; the horizontal propagation step may only
* extend them in the direction of the scan. Therefore, on both passes
* of the horizontal propagation step, the last pixel of each range, in
* the direction of the scan, is initially inside the segment.
*/
inside = TRUE;
/* If this isn't the last range, break the loop at the beginning of the
* next range. Otherwise, break the loop at the edge of the ROI.
*/
if (range_index + dir != last_range)
lim = (range + dir)->x[1 - x_component];
else
lim = roi_lim;
/* Loop over the pixels between the edge of the current range, and the
* beginning of the next range (or the edge of the ROI).
*/
for (x += dir; x != lim; x += dir)
{
gfloat ground_level, water_level;
/* Recall that `segment_lim` is one-past the last pixel of the
* segment. If we hit it, we've gone outside the segment bounds.
*/
if (x == segment_lim)
{
inside = FALSE;
/* Initialize the rectangle to sample pixels directly from the
* GEGL buffers.
*/
iv_rect.y = ctx->roi.y + ctx->segment.y;
iv_rect.width = 1;
iv_rect.height = 1;
}
/* If we're inside the segment, read the ground- and water-levels
* from the corresponding arrays; otherwise, read them from the GEGL
* buffers directly. Note that, on each pass, we may only write to
* pixels outside the segment *in direction of the scan* (in which
* case, the new values are written to the `water` array, but not
* directly to the output GEGL buffer), hence, when reading from the
* GEGL buffers, there's no danger of reading stale values, that were
* changed on the previous pass.
*/
if (inside)
{
ground_level = ctx->ground[x];
water_level = ctx->water[x];
}
else
{
iv_rect.x = ctx->roi.x + x;
/* Transform `iv_rect` to the image-physical coordinate system,
* and store the result in `ip_rect`.
*/
pika_operation_flood_process_transform_rect (ctx,
&ip_rect, &iv_rect);
/* Read the current pixel's ground level. */
gegl_buffer_get (ctx->input, &ip_rect, 1.0, ctx->input_format,
&ground_level,
GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_NONE);
/* Read the current pixel's water level. */
gegl_buffer_get (ctx->output, &ip_rect, 1.0, ctx->output_format,
&water_level,
GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_NONE);
}
/* The new water level is the maximum of the current ground level,
* and the minimum of the current and previous water levels. Recall
* that `level` holds the previous water level, and that the current
* water level is never less than the ground level.
*/
if (level < ground_level)
level = ground_level;
if (level < water_level)
{
/* The water level changed. Update the current pixel, and set
* the `modified` flag of the current range, since it will be
* extended to include the current pixel.
*/
ctx->water[x] = level;
range->modified = TRUE;
}
else
/* The water level stayed the same. Break the loop. */
break;
}
/* Extend the current dirty range to include the last modified pixel, if
* any.
*/
range->x[x_component] = x - dir;
/* If we stopped the loop before hitting the edge of the next range, or
* if we're at the last range, continue to the next range (or quit).
*/
if (x != lim || range_index + dir == last_range)
continue;
/* If we hit the edge of the next range, we keep propagating the changes
* *inside* the next range, until we hit its other edge, or until the
* water level stays the same.
*/
range += dir;
lim = range->x[x_component] + dir;
for (; x != lim; x += dir)
{
/* Note that we're necessarily inside the segment right now, since
* the only range that could have been extended past the edge of the
* segment by the previous pass, is the first range of the current
* pass, while the range we're currently inside is at least the
* second.
*/
if (level < ctx->ground[x])
level = ctx->ground[x];
if (level < ctx->water[x])
{
ctx->water[x] = level;
/* Set the `modified` flag of the range, since the water level of
* its existing pixels changed.
*/
range->modified = TRUE;
}
else
break;
}
}
}
/* Coalesces consecutive dirty ranges that are separated by a gap less-than or
* equal-to `max_gap`, in-place, and returns the new number of ranges.
*/
static gint
pika_operation_flood_process_coalesce (const PikaOperationFloodContext *ctx,
PikaOperationFloodDirtyRange *dirty_ranges,
gint range_count,
gint max_gap)
{
/* First and last ranges to coalesce, respectively. */
const PikaOperationFloodDirtyRange *first_range, *last_range;
/* Destination range. */
PikaOperationFloodDirtyRange *range = dirty_ranges;
for (first_range = dirty_ranges;
first_range != dirty_ranges + range_count;
first_range++)
{
/* The `modified` flag of the coalesced range -- the logical-OR of the
* `modified` flags of the individual ranges.
*/
gboolean modified = first_range->modified;
/* Find all consecutive ranges with a small-enough gap. */
for (last_range = first_range;
last_range + 1 != dirty_ranges + range_count;
last_range++)
{
if ((last_range + 1)->x[0] - last_range->x[1] > max_gap)
break;
modified |= (last_range + 1)->modified;
}
/* Write the coalesced range, or copy the current range, to the
* destination range.
*/
if (first_range != last_range || first_range != range)
{
range->x[0] = first_range->x[0];
range->x[1] = last_range->x[1];
range->modified = modified;
}
first_range = last_range;
range++;
}
/* Return the new range count. */
return range - dirty_ranges;
}
/* Writes the updated water level of the dirty ranges back to the output GEGL
* buffer.
*/
static void
pika_operation_flood_process_commit (const PikaOperationFloodContext *ctx,
const PikaOperationFloodDirtyRange *dirty_ranges,
gint range_count)
{
const PikaOperationFloodDirtyRange *range;
/* Image-virtual and image-physical rectangles, respectively. */
GeglRectangle iv_rect, ip_rect;
/* Set the vertical extent of the rectangle to span a the current segment's
* row.
*/
iv_rect.y = ctx->roi.y + ctx->segment.y;
iv_rect.height = 1;
for (range = dirty_ranges; range != dirty_ranges + range_count; range++)
{
/* Set the horizontal extent of the rectangle to span the dirty range. */
iv_rect.x = ctx->roi.x + range->x[0];
iv_rect.width = range->x[1] - range->x[0] + 1;
/* Transform `iv_rect` to the image-physical coordinate system, and store
* the result in `ip_rect`.
*/
pika_operation_flood_process_transform_rect (ctx, &ip_rect, &iv_rect);
/* Write the updated water level to the output GEGL buffer. */
gegl_buffer_set (ctx->output, &ip_rect, 0, ctx->output_format,
ctx->water + range->x[0],
GEGL_AUTO_ROWSTRIDE);
}
}
/* Pushes the new segments, corresponding to the dirty ranges of the current
* segment, into the queue.
*/
static void
pika_operation_flood_process_distribute (const PikaOperationFloodContext *ctx,
GQueue *queue,
const PikaOperationFloodDirtyRange *dirty_ranges,
gint range_count)
{
const PikaOperationFloodDirtyRange *range;
static const gint y_deltas[] = {-1, +1};
gint i;
/* For each neighboring row... */
for (i = 0; i < G_N_ELEMENTS (y_deltas); i++)
{
/* The difference between the negihboring row's y-coordinate and the
* current row's y-corindate, in the ROI-virtual coordinate system.
*/
gint y_delta = y_deltas[i];
/* The negihboring row's y-coordinate in the ROI-virtual coordinate
* system.
*/
gint y = ctx->segment.y + y_delta;
/* If the neighboring row is outside the ROI, skip it. */
if (y < 0 || y >= ctx->roi.height)
continue;
/* For each dirty range... */
for (range = dirty_ranges; range != dirty_ranges + range_count; range++)
{
/* If the range was modified during horizontal propagation, or if the
* neighboring row is not the source segment's row... (note that the
* latter is always true for seed segments.)
*/
if (range->modified || y_delta != ctx->segment.source_y_delta)
{
/* Push a new segment into the queue, spanning the same pixels as
* the dirty range on the neighboring row, using the current row
* as its source segment.
*/
pika_operation_flood_process_push (queue,
ctx->segment.transpose,
y,
-y_delta,
range->x[0],
range->x[1]);
}
}
}
}
/* Main algorithm. */
static gboolean
pika_operation_flood_process (GeglOperation *operation,
GeglBuffer *input,
GeglBuffer *output,
const GeglRectangle *roi,
gint level)
{
const Babl *input_format = gegl_operation_get_format (operation, "input");
const Babl *output_format = gegl_operation_get_format (operation, "output");
GeglColor *color;
gint max_size;
PikaOperationFloodContext ctx;
PikaOperationFloodDirtyRange *dirty_ranges;
GQueue *queue;
/* Make sure the input- and output-buffers are different. */
g_return_val_if_fail (input != output, FALSE);
/* Make sure the ROI is small enough for the `PikaOperationFloodSegment::y`
* field.
*/
g_return_val_if_fail (roi->width <= PIKA_MAX_IMAGE_SIZE &&
roi->height <= PIKA_MAX_IMAGE_SIZE, FALSE);
ctx.input = input;
ctx.input_format = input_format;
ctx.output = output;
ctx.output_format = output_format;
/* All buffers need to have enough capacity to process a full row, or a full
* column, since, when processing vertical segments, we treat the image as
* transposed.
*/
max_size = MAX (roi->width, roi->height);
ctx.ground = g_new (gfloat, max_size);
/* The `water_buffer` array needs to be able to hold two rows (or columns). */
ctx.water_buffer = g_new (gfloat, 2 * max_size);
dirty_ranges = g_new (PikaOperationFloodDirtyRange, max_size);
/* Initialize the water level to 1 everywhere. */
color = gegl_color_new ("#fff");
gegl_buffer_set_color (output, roi, color);
g_object_unref (color);
/* Create the queue and push the seed segments. */
queue = g_queue_new ();
pika_operation_flood_process_seed (queue, roi);
/* While there are segments to process in the queue... */
while (! g_queue_is_empty (queue))
{
PikaOperationFloodSegment *segment;
gint range_count;
/* Pop a segment off the top of the queue, copy it to `ctx.segment`, and
* free its memory.
*/
segment = (PikaOperationFloodSegment *) g_queue_pop_head (queue);
ctx.segment = *segment;
g_slice_free (PikaOperationFloodSegment, segment);
/* Transform the ROI from the image-physical coordinate system to the
* image-virtual coordinate system, and store the result in `ctx.roi`.
*/
pika_operation_flood_process_transform_rect (&ctx, &ctx.roi, roi);
/* Read the ground- and water-levels of the current- and source-segments
* from the corresponding GEGL buffers to the corresponding arrays.
*/
pika_operation_flood_process_fetch (&ctx);
/* Perform the vertical propagation step. */
range_count = pika_operation_flood_process_propagate_vertical (&ctx,
dirty_ranges);
/* If no dirty ranges were produced during vertical propagation, then the
* water level of the current segment didn't change, and we can short-
* circuit early.
*/
if (range_count == 0)
continue;
/* Perform both passes of the horizontal propagation step. */
pika_operation_flood_process_propagate_horizontal (&ctx,
/* Left-to-right */ +1,
dirty_ranges,
range_count);
pika_operation_flood_process_propagate_horizontal (&ctx,
/* Right-to-left */ -1,
dirty_ranges,
range_count);
/* Coalesce consecutive dirty ranges separated by a gap less-than or
* equal-to `PIKA_OPERATION_FLOOD_COALESCE_MAX_GAP`.
*/
range_count = pika_operation_flood_process_coalesce (&ctx,
dirty_ranges,
range_count,
PIKA_OPERATION_FLOOD_COALESCE_MAX_GAP);
/* Write the updated water level back to the output GEGL buffer. */
pika_operation_flood_process_commit (&ctx, dirty_ranges, range_count);
/* Push the new segments into the queue. */
pika_operation_flood_process_distribute (&ctx, queue,
dirty_ranges, range_count);
}
g_queue_free (queue);
g_free (dirty_ranges);
g_free (ctx.water_buffer);
g_free (ctx.ground);
return TRUE;
}
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