Re-implement Cairo-based rendering.
This commit is contained in:
Daiki Ueno
230
eek/eek-keyboard-drawing.c
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230
eek/eek-keyboard-drawing.c
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/*
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* Copyright (C) 2006 Sergey V. Udaltsov <svu@gnome.org>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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#include <math.h>
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#include <pango/pangocairo.h>
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif /* HAVE_CONFIG_H */
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#include "eek-types.h"
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static gdouble
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length (gdouble x, gdouble y)
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{
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return sqrt (x * x + y * y);
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}
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static gdouble
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point_line_distance (gdouble ax, gdouble ay, gdouble nx, gdouble ny)
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{
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return ax * nx + ay * ny;
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}
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static void
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normal_form (gdouble ax, gdouble ay,
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gdouble bx, gdouble by,
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gdouble * nx, gdouble * ny, gdouble * d)
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{
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gdouble l;
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*nx = by - ay;
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*ny = ax - bx;
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l = length (*nx, *ny);
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*nx /= l;
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*ny /= l;
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*d = point_line_distance (ax, ay, *nx, *ny);
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}
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static void
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inverse (gdouble a, gdouble b, gdouble c, gdouble d,
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gdouble * e, gdouble * f, gdouble * g, gdouble * h)
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{
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gdouble det;
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det = a * d - b * c;
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*e = d / det;
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*f = -b / det;
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*g = -c / det;
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*h = a / det;
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}
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static void
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multiply (gdouble a, gdouble b, gdouble c, gdouble d,
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gdouble e, gdouble f, gdouble * x, gdouble * y)
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{
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*x = a * e + b * f;
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*y = c * e + d * f;
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}
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static void
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intersect (gdouble n1x, gdouble n1y, gdouble d1,
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gdouble n2x, gdouble n2y, gdouble d2, gdouble * x, gdouble * y)
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{
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gdouble e, f, g, h;
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inverse (n1x, n1y, n2x, n2y, &e, &f, &g, &h);
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multiply (e, f, g, h, d1, d2, x, y);
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}
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/* draw an angle from the current point to b and then to c,
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* with a rounded corner of the given radius.
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*/
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static void
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rounded_corner (cairo_t * cr,
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gdouble bx, gdouble by,
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gdouble cx, gdouble cy, gdouble radius)
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{
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gdouble ax, ay;
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gdouble n1x, n1y, d1;
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gdouble n2x, n2y, d2;
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gdouble pd1, pd2;
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gdouble ix, iy;
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gdouble dist1, dist2;
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gdouble nx, ny, d;
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gdouble a1x, a1y, c1x, c1y;
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gdouble phi1, phi2;
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cairo_get_current_point (cr, &ax, &ay);
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#ifdef KBDRAW_DEBUG
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printf (" current point: (%f, %f), radius %f:\n", ax, ay,
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radius);
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#endif
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/* make sure radius is not too large */
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dist1 = length (bx - ax, by - ay);
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dist2 = length (cx - bx, cy - by);
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radius = MIN (radius, MIN (dist1, dist2));
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/* construct normal forms of the lines */
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normal_form (ax, ay, bx, by, &n1x, &n1y, &d1);
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normal_form (bx, by, cx, cy, &n2x, &n2y, &d2);
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/* find which side of the line a,b the point c is on */
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if (point_line_distance (cx, cy, n1x, n1y) < d1)
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pd1 = d1 - radius;
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else
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pd1 = d1 + radius;
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/* find which side of the line b,c the point a is on */
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if (point_line_distance (ax, ay, n2x, n2y) < d2)
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pd2 = d2 - radius;
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else
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pd2 = d2 + radius;
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/* intersect the parallels to find the center of the arc */
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intersect (n1x, n1y, pd1, n2x, n2y, pd2, &ix, &iy);
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nx = (bx - ax) / dist1;
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ny = (by - ay) / dist1;
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d = point_line_distance (ix, iy, nx, ny);
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/* a1 is the point on the line a-b where the arc starts */
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intersect (n1x, n1y, d1, nx, ny, d, &a1x, &a1y);
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nx = (cx - bx) / dist2;
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ny = (cy - by) / dist2;
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d = point_line_distance (ix, iy, nx, ny);
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/* c1 is the point on the line b-c where the arc ends */
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intersect (n2x, n2y, d2, nx, ny, d, &c1x, &c1y);
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/* determine the first angle */
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if (a1x - ix == 0)
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phi1 = (a1y - iy > 0) ? M_PI_2 : 3 * M_PI_2;
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else if (a1x - ix > 0)
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phi1 = atan ((a1y - iy) / (a1x - ix));
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else
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phi1 = M_PI + atan ((a1y - iy) / (a1x - ix));
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/* determine the second angle */
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if (c1x - ix == 0)
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phi2 = (c1y - iy > 0) ? M_PI_2 : 3 * M_PI_2;
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else if (c1x - ix > 0)
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phi2 = atan ((c1y - iy) / (c1x - ix));
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else
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phi2 = M_PI + atan ((c1y - iy) / (c1x - ix));
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/* compute the difference between phi2 and phi1 mod 2pi */
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d = phi2 - phi1;
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while (d < 0)
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d += 2 * M_PI;
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while (d > 2 * M_PI)
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d -= 2 * M_PI;
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#ifdef KBDRAW_DEBUG
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printf (" line 1 to: (%f, %f):\n", a1x, a1y);
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#endif
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if (!(isnan (a1x) || isnan (a1y)))
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cairo_line_to (cr, a1x, a1y);
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/* pick the short arc from phi1 to phi2 */
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if (d < M_PI)
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cairo_arc (cr, ix, iy, radius, phi1, phi2);
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else
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cairo_arc_negative (cr, ix, iy, radius, phi1, phi2);
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#ifdef KBDRAW_DEBUG
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printf (" line 2 to: (%f, %f):\n", cx, cy);
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#endif
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cairo_line_to (cr, cx, cy);
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}
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/* renamed from rounded_polygon, use EekPoint instead of GdkPoint not
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to depend on GTK+, and exported */
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void
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_eek_rounded_polygon (cairo_t *cr,
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gdouble radius,
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EekPoint *points,
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gint num_points)
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{
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gint i, j;
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cairo_move_to (cr,
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(gdouble) (points[num_points - 1].x +
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points[0].x) / 2,
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(gdouble) (points[num_points - 1].y +
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points[0].y) / 2);
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#ifdef KBDRAW_DEBUG
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printf (" rounded polygon of radius %f:\n", radius);
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#endif
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for (i = 0; i < num_points; i++) {
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j = (i + 1) % num_points;
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rounded_corner (cr, (gdouble) points[i].x,
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(gdouble) points[i].y,
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(gdouble) (points[i].x + points[j].x) / 2,
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(gdouble) (points[i].y + points[j].y) / 2,
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radius);
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#ifdef KBDRAW_DEBUG
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printf (" corner (%d, %d) -> (%d, %d):\n",
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points[i].x, points[i].y, points[j].x,
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points[j].y);
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#endif
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};
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cairo_close_path (cr);
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}
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