Learning_GTK4_tree/gsk/gskpathparser.c

824 lines
21 KiB
C

/*
* Copyright © 2020 Benjamin Otte
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see <http://www.gnu.org/licenses/>.
*
* Authors: Benjamin Otte <otte@gnome.org>
*/
#include "config.h"
#include "gskpathprivate.h"
#include "gskcurveprivate.h"
#include "gskpathbuilder.h"
#include "gskpathpoint.h"
#include "gskcontourprivate.h"
static void
skip_whitespace (const char **p)
{
while (g_ascii_isspace (**p))
(*p)++;
}
static void
skip_optional_comma (const char **p)
{
skip_whitespace (p);
if (**p == ',')
(*p)++;
}
static gboolean
parse_number (const char **p,
double *c)
{
char *e;
*c = g_ascii_strtod (*p, &e);
if (e == *p)
return FALSE;
*p = e;
skip_optional_comma (p);
return TRUE;
}
static gboolean
parse_coordinate (const char **p,
double *c)
{
return parse_number (p, c);
}
static gboolean
parse_coordinate_pair (const char **p,
double *x,
double *y)
{
double xx, yy;
const char *o = *p;
if (!parse_coordinate (p, &xx))
{
*p = o;
return FALSE;
}
if (!parse_coordinate (p, &yy))
{
*p = o;
return FALSE;
}
*x = xx;
*y = yy;
return TRUE;
}
static gboolean
parse_nonnegative_number (const char **p,
double *x)
{
const char *o = *p;
double n;
if (!parse_number (p, &n))
return FALSE;
if (n < 0)
{
*p = o;
return FALSE;
}
*x = n;
return TRUE;
}
/* This fixes a flaw in our use of strchr() below:
*
* If p already points at the end of the string,
* we misinterpret strchr ("xyz", *p) returning
* non-NULL to mean that we can increment p.
*
* But strchr() will return a pointer to the
* final NUL byte in this case, and we walk off
* the end of the string. Oops
*/
static inline char *
_strchr (const char *str,
int c)
{
if (c == 0)
return NULL;
else
return strchr (str, c);
}
static gboolean
parse_flag (const char **p,
gboolean *f)
{
skip_whitespace (p);
if (_strchr ("01", **p))
{
*f = **p == '1';
(*p)++;
skip_optional_comma (p);
return TRUE;
}
return FALSE;
}
static gboolean
parse_command (const char **p,
char *cmd)
{
char *s;
const char *allowed;
if (*cmd == 'X')
allowed = "mM";
else
allowed = "mMhHvVzZlLcCsStTqQaAoO";
skip_whitespace (p);
s = _strchr (allowed, **p);
if (s)
{
*cmd = *s;
(*p)++;
return TRUE;
}
return FALSE;
}
static gboolean
parse_string (const char **p,
const char *s)
{
int len = strlen (s);
if (strncmp (*p, s, len) != 0)
return FALSE;
(*p) += len;
return TRUE;
}
#define NEAR(x, y) (fabs ((x) - (y)) < 0.001)
static gboolean
is_rect (double x0, double y0,
double x1, double y1,
double x2, double y2,
double x3, double y3)
{
return NEAR (x0, x3) && NEAR (x1, x2) &&
NEAR (y0, y1) && NEAR (y2, y3) &&
x0 < x1 && y1 < y2;
}
static gboolean
is_line (double x0, double y0,
double x1, double y1,
double x2, double y2,
double x3, double y3)
{
if (NEAR (y0, y3))
return x0 <= x1 && x1 <= x2 && x2 <= x3 &&
NEAR (y0, y1) && NEAR (y0, y2) && NEAR (y0, y3);
else
return y0 <= y1 && y1 <= y2 && y2 <= y3 &&
NEAR (x0, x1) && NEAR (x0, x2) && NEAR (x0, x3);
}
static gboolean
parse_rectangle (const char **p,
double *x,
double *y,
double *w,
double *h)
{
const char *o = *p;
double w2;
if (parse_coordinate_pair (p, x, y) &&
parse_string (p, "h") &&
parse_coordinate (p, w) &&
parse_string (p, "v") &&
parse_coordinate (p, h) &&
parse_string (p, "h") &&
parse_coordinate (p, &w2) &&
parse_string (p, "z") &&
w2 == -*w && *w >= 0 && *h >= 0)
{
skip_whitespace (p);
return TRUE;
}
*p = o;
return FALSE;
}
static gboolean
parse_circle (const char **p,
double *cx,
double *cy,
double *r)
{
const char *o = *p;
double x0, y0, x1, y1, x2, y2, x3, y3;
double x4, y4, x5, y5, x6, y6, x7, y7;
double x8, y8, w0, w1, w2, w3;
double rr;
if (parse_coordinate_pair (p, &x0, &y0) &&
parse_string (p, "o") &&
parse_coordinate_pair (p, &x1, &y1) &&
parse_coordinate_pair (p, &x2, &y2) &&
parse_nonnegative_number (p, &w0) &&
parse_string (p, "o") &&
parse_coordinate_pair (p, &x3, &y3) &&
parse_coordinate_pair (p, &x4, &y4) &&
parse_nonnegative_number (p, &w1) &&
parse_string (p, "o") &&
parse_coordinate_pair (p, &x5, &y5) &&
parse_coordinate_pair (p, &x6, &y6) &&
parse_nonnegative_number (p, &w2) &&
parse_string (p, "o") &&
parse_coordinate_pair (p, &x7, &y7) &&
parse_coordinate_pair (p, &x8, &y8) &&
parse_nonnegative_number (p, &w3) &&
parse_string (p, "z"))
{
rr = y1;
if (x1 == 0 && y1 == rr &&
x2 == -rr && y2 == rr &&
x3 == -rr && y3 == 0 &&
x4 == -rr && y4 == -rr &&
x5 == 0 && y5 == -rr &&
x6 == rr && y6 == -rr &&
x7 == rr && y7 == 0 &&
x8 == rr && y8 == rr &&
NEAR (w0, M_SQRT1_2) && NEAR (w1, M_SQRT1_2) &&
NEAR (w2, M_SQRT1_2) && NEAR (w3, M_SQRT1_2))
{
*cx = x0 - rr;
*cy = y0;
*r = rr;
skip_whitespace (p);
return TRUE;
}
}
*p = o;
return FALSE;
}
static gboolean
parse_rounded_rect (const char **p,
GskRoundedRect *rr)
{
const char *o = *p;
double x0, y0, x1, y1, x2, y2, x3, y3;
double x4, y4, x5, y5, x6, y6, x7, y7;
double x8, y8, x9, y9, x10, y10, x11, y11;
double x12, y12, w0, w1, w2, w3;
if (parse_coordinate_pair (p, &x0, &y0) &&
parse_string (p, "L") &&
parse_coordinate_pair (p, &x1, &y1) &&
parse_string (p, "O") &&
parse_coordinate_pair (p, &x2, &y2) &&
parse_coordinate_pair (p, &x3, &y3) &&
parse_nonnegative_number (p, &w0) &&
parse_string (p, "L") &&
parse_coordinate_pair (p, &x4, &y4) &&
parse_string (p, "O") &&
parse_coordinate_pair (p, &x5, &y5) &&
parse_coordinate_pair (p, &x6, &y6) &&
parse_nonnegative_number (p, &w1) &&
parse_string (p, "L") &&
parse_coordinate_pair (p, &x7, &y7) &&
parse_string (p, "O") &&
parse_coordinate_pair (p, &x8, &y8) &&
parse_coordinate_pair (p, &x9, &y9) &&
parse_nonnegative_number (p, &w2) &&
parse_string (p, "L") &&
parse_coordinate_pair (p, &x10, &y10) &&
parse_string (p, "O") &&
parse_coordinate_pair (p, &x11, &y11) &&
parse_coordinate_pair (p, &x12, &y12) &&
parse_nonnegative_number (p, &w3) &&
parse_string (p, "Z"))
{
if (NEAR (x0, x12) && NEAR (y0, y12) &&
is_rect (x11, y11, x2, y2, x5, y5, x8, y8) &&
is_line (x11, y11, x0, y0, x1, y1, x2, y2) &&
is_line (x2, y2, x3, y3, x4, y4, x5, y5) &&
is_line (x8, y8, x7, y7, x6, y6, x5, y5) &&
is_line (x11, y11, x10, y10, x9, y9, x8, y8) &&
NEAR (w0, M_SQRT1_2) && NEAR (w1, M_SQRT1_2) &&
NEAR (w2, M_SQRT1_2) && NEAR (w3, M_SQRT1_2))
{
rr->bounds = GRAPHENE_RECT_INIT (x11, y11, x5 - x11, y5 - y11);
rr->corner[GSK_CORNER_TOP_LEFT] = GRAPHENE_SIZE_INIT (x12 - x11, y10 - y11);
rr->corner[GSK_CORNER_TOP_RIGHT] = GRAPHENE_SIZE_INIT (x2 - x1, y3 - y2);
rr->corner[GSK_CORNER_BOTTOM_RIGHT] = GRAPHENE_SIZE_INIT (x5 - x6, y5 - y4);
rr->corner[GSK_CORNER_BOTTOM_LEFT] = GRAPHENE_SIZE_INIT (x7 - x8, y8 - y9);
skip_whitespace (p);
return TRUE;
}
}
*p = o;
return FALSE;
}
#undef NEAR
/**
* gsk_path_parse:
* @string: a string
*
* This is a convenience function that constructs a `GskPath`
* from a serialized form.
*
* The string is expected to be in (a superset of)
* [SVG path syntax](https://www.w3.org/TR/SVG11/paths.html#PathData),
* as e.g. produced by [method@Gsk.Path.to_string].
*
* A high-level summary of the syntax:
*
* - `M x y` Move to `(x, y)`
* - `L x y` Add a line from the current point to `(x, y)`
* - `Q x1 y1 x2 y2` Add a quadratic Bézier from the current point to `(x2, y2)`, with control point `(x1, y1)`
* - `C x1 y1 x2 y2 x3 y3` Add a cubic Bézier from the current point to `(x3, y3)`, with control points `(x1, y1)` and `(x2, y2)`
* - `Z` Close the contour by drawing a line back to the start point
* - `H x` Add a horizontal line from the current point to the given x value
* - `V y` Add a vertical line from the current point to the given y value
* - `T x2 y2` Add a quadratic Bézier, using the reflection of the previous segments' control point as control point
* - `S x2 y2 x3 y3` Add a cubic Bézier, using the reflection of the previous segments' second control point as first control point
* - `A rx ry r l s x y` Add an elliptical arc from the current point to `(x, y)` with radii rx and ry. See the SVG documentation for how the other parameters influence the arc.
* - `O x1 y1 x2 y2 w` Add a rational quadratic Bézier from the current point to `(x2, y2)` with control point `(x1, y1)` and weight `w`.
*
* All the commands have lowercase variants that interpret coordinates
* relative to the current point.
*
* The `O` command is an extension that is not supported in SVG.
*
* Returns: (nullable): a new `GskPath`, or `NULL` if @string could not be parsed
*
* Since: 4.14
*/
GskPath *
gsk_path_parse (const char *string)
{
GskPathBuilder *builder;
double x, y;
double prev_x1, prev_y1;
double path_x, path_y;
const char *p;
char cmd;
char prev_cmd;
gboolean after_comma;
gboolean repeat;
builder = gsk_path_builder_new ();
cmd = 'X';
path_x = path_y = 0;
x = y = 0;
prev_x1 = prev_y1 = 0;
after_comma = FALSE;
p = string;
while (*p)
{
prev_cmd = cmd;
repeat = !parse_command (&p, &cmd);
if (after_comma && !repeat)
goto error;
switch (cmd)
{
case 'X':
goto error;
case 'Z':
case 'z':
if (repeat)
goto error;
else
{
gsk_path_builder_close (builder);
x = path_x;
y = path_y;
}
break;
case 'M':
case 'm':
{
double x1, y1, w, h, r;
GskRoundedRect rr;
/* Look for special contours */
if (parse_rectangle (&p, &x1, &y1, &w, &h))
{
gsk_path_builder_add_rect (builder, &GRAPHENE_RECT_INIT (x1, y1, w, h));
if (_strchr ("zZX", prev_cmd))
{
path_x = x1;
path_y = y1;
}
x = x1;
y = y1;
}
else if (parse_circle (&p, &x1, &y1, &r))
{
gsk_path_builder_add_circle (builder, &GRAPHENE_POINT_INIT (x1, y1), r);
if (_strchr ("zZX", prev_cmd))
{
path_x = x1 + r;
path_y = y1;
}
x = x1 + r;
y = y1;
}
else if (parse_rounded_rect (&p, &rr))
{
gsk_path_builder_add_rounded_rect (builder, &rr);
if (_strchr ("zZX", prev_cmd))
{
path_x = rr.bounds.origin.x + rr.corner[GSK_CORNER_TOP_LEFT].width;
path_y = rr.bounds.origin.y;
}
x = rr.bounds.origin.x + rr.corner[GSK_CORNER_TOP_LEFT].width;
y = rr.bounds.origin.y;
}
else if (parse_coordinate_pair (&p, &x1, &y1))
{
if (cmd == 'm')
{
x1 += x;
y1 += y;
}
if (repeat)
gsk_path_builder_line_to (builder, x1, y1);
else
{
gsk_path_builder_move_to (builder, x1, y1);
if (_strchr ("zZX", prev_cmd))
{
path_x = x1;
path_y = y1;
}
}
x = x1;
y = y1;
}
else
goto error;
}
break;
case 'L':
case 'l':
{
double x1, y1;
if (parse_coordinate_pair (&p, &x1, &y1))
{
if (cmd == 'l')
{
x1 += x;
y1 += y;
}
if (_strchr ("zZ", prev_cmd))
{
gsk_path_builder_move_to (builder, x, y);
path_x = x;
path_y = y;
}
gsk_path_builder_line_to (builder, x1, y1);
x = x1;
y = y1;
}
else
goto error;
}
break;
case 'H':
case 'h':
{
double x1;
if (parse_coordinate (&p, &x1))
{
if (cmd == 'h')
x1 += x;
if (_strchr ("zZ", prev_cmd))
{
gsk_path_builder_move_to (builder, x, y);
path_x = x;
path_y = y;
}
gsk_path_builder_line_to (builder, x1, y);
x = x1;
}
else
goto error;
}
break;
case 'V':
case 'v':
{
double y1;
if (parse_coordinate (&p, &y1))
{
if (cmd == 'v')
y1 += y;
if (_strchr ("zZ", prev_cmd))
{
gsk_path_builder_move_to (builder, x, y);
path_x = x;
path_y = y;
}
gsk_path_builder_line_to (builder, x, y1);
y = y1;
}
else
goto error;
}
break;
case 'C':
case 'c':
{
double x0, y0, x1, y1, x2, y2;
if (parse_coordinate_pair (&p, &x0, &y0) &&
parse_coordinate_pair (&p, &x1, &y1) &&
parse_coordinate_pair (&p, &x2, &y2))
{
if (cmd == 'c')
{
x0 += x;
y0 += y;
x1 += x;
y1 += y;
x2 += x;
y2 += y;
}
if (_strchr ("zZ", prev_cmd))
{
gsk_path_builder_move_to (builder, x, y);
path_x = x;
path_y = y;
}
gsk_path_builder_cubic_to (builder, x0, y0, x1, y1, x2, y2);
prev_x1 = x1;
prev_y1 = y1;
x = x2;
y = y2;
}
else
goto error;
}
break;
case 'S':
case 's':
{
double x0, y0, x1, y1, x2, y2;
if (parse_coordinate_pair (&p, &x1, &y1) &&
parse_coordinate_pair (&p, &x2, &y2))
{
if (cmd == 's')
{
x1 += x;
y1 += y;
x2 += x;
y2 += y;
}
if (_strchr ("CcSs", prev_cmd))
{
x0 = 2 * x - prev_x1;
y0 = 2 * y - prev_y1;
}
else
{
x0 = x;
y0 = y;
}
if (_strchr ("zZ", prev_cmd))
{
gsk_path_builder_move_to (builder, x, y);
path_x = x;
path_y = y;
}
gsk_path_builder_cubic_to (builder, x0, y0, x1, y1, x2, y2);
prev_x1 = x1;
prev_y1 = y1;
x = x2;
y = y2;
}
else
goto error;
}
break;
case 'Q':
case 'q':
{
double x1, y1, x2, y2;
if (parse_coordinate_pair (&p, &x1, &y1) &&
parse_coordinate_pair (&p, &x2, &y2))
{
if (cmd == 'q')
{
x1 += x;
y1 += y;
x2 += x;
y2 += y;
}
if (_strchr ("zZ", prev_cmd))
{
gsk_path_builder_move_to (builder, x, y);
path_x = x;
path_y = y;
}
gsk_path_builder_quad_to (builder, x1, y1, x2, y2);
prev_x1 = x1;
prev_y1 = y1;
x = x2;
y = y2;
}
else
goto error;
}
break;
case 'T':
case 't':
{
double x1, y1, x2, y2;
if (parse_coordinate_pair (&p, &x2, &y2))
{
if (cmd == 't')
{
x2 += x;
y2 += y;
}
if (_strchr ("QqTt", prev_cmd))
{
x1 = 2 * x - prev_x1;
y1 = 2 * y - prev_y1;
}
else
{
x1 = x;
y1 = y;
}
if (_strchr ("zZ", prev_cmd))
{
gsk_path_builder_move_to (builder, x, y);
path_x = x;
path_y = y;
}
gsk_path_builder_quad_to (builder, x1, y1, x2, y2);
prev_x1 = x1;
prev_y1 = y1;
x = x2;
y = y2;
}
else
goto error;
}
break;
case 'O':
case 'o':
{
double x1, y1, x2, y2, weight;
if (parse_coordinate_pair (&p, &x1, &y1) &&
parse_coordinate_pair (&p, &x2, &y2) &&
parse_nonnegative_number (&p, &weight))
{
if (cmd == 'o')
{
x1 += x;
y1 += y;
x2 += x;
y2 += y;
}
if (_strchr ("zZ", prev_cmd))
{
gsk_path_builder_move_to (builder, x, y);
path_x = x;
path_y = y;
}
gsk_path_builder_conic_to (builder, x1, y1, x2, y2, weight);
x = x2;
y = y2;
}
else
goto error;
}
break;
case 'A':
case 'a':
{
double rx, ry;
double x_axis_rotation;
int large_arc, sweep;
double x1, y1;
if (parse_nonnegative_number (&p, &rx) &&
parse_nonnegative_number (&p, &ry) &&
parse_number (&p, &x_axis_rotation) &&
parse_flag (&p, &large_arc) &&
parse_flag (&p, &sweep) &&
parse_coordinate_pair (&p, &x1, &y1))
{
if (cmd == 'a')
{
x1 += x;
y1 += y;
}
if (_strchr ("zZ", prev_cmd))
{
gsk_path_builder_move_to (builder, x, y);
path_x = x;
path_y = y;
}
gsk_path_builder_svg_arc_to (builder,
rx, ry, x_axis_rotation,
large_arc, sweep,
x1, y1);
x = x1;
y = y1;
}
else
goto error;
}
break;
default:
goto error;
}
after_comma = (p > string) && p[-1] == ',';
}
if (after_comma)
goto error;
return gsk_path_builder_free_to_path (builder);
error:
//g_warning ("Can't parse string '%s' as GskPath, error at %ld", string, p - string);
gsk_path_builder_unref (builder);
return NULL;
}
/* vim:set foldmethod=marker expandtab: */