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* Copyright (C) 1997, 1998, 1999, 2000 Free Software Foundation
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* This file is part of the Gnome Library.
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* The Gnome Library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or (at your option) any later version.
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* The Gnome 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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* Library General Public License for more details.
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* You should have received a copy of the GNU Library General Public
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* License along with the Gnome Library; see the file COPYING.LIB. If not,
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* write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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/* Miscellaneous utility functions for the GnomeCanvas widget
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* GnomeCanvas is basically a port of the Tk toolkit's most excellent canvas widget. Tk is
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* copyrighted by the Regents of the University of California, Sun Microsystems, and other parties.
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* Author: Federico Mena <federico@nuclecu.unam.mx>
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/* needed for M_PI_2 under 'gcc -ansi -predantic' on GNU/Linux */
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# define _BSD_SOURCE 1
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#include <sys/types.h>
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#include "gnome-canvas.h"
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#include "gnome-canvas-util.h"
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#include <libart_lgpl/art_uta.h>
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#include <libart_lgpl/art_svp.h>
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#include <libart_lgpl/art_svp_ops.h>
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#include <libart_lgpl/art_rgb.h>
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#include <libart_lgpl/art_rgb_svp.h>
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#include <libart_lgpl/art_uta_svp.h>
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#include <libart_lgpl/art_rect_svp.h>
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* gnome_canvas_points_new:
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* @num_points: The number of points to allocate space for in the array.
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* Creates a structure that should be used to pass an array of points to
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* Return value: A newly-created array of points. It should be filled in
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gnome_canvas_points_new (int num_points)
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GnomeCanvasPoints *points;
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g_return_val_if_fail (num_points > 1, NULL);
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points = g_new (GnomeCanvasPoints, 1);
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points->num_points = num_points;
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points->coords = g_new (double, 2 * num_points);
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points->ref_count = 1;
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* gnome_canvas_points_ref:
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* @points: A canvas points structure.
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* Increases the reference count of the specified points structure.
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* Return value: The canvas points structure itself.
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gnome_canvas_points_ref (GnomeCanvasPoints *points)
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g_return_val_if_fail (points != NULL, NULL);
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points->ref_count += 1;
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* gnome_canvas_points_free:
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* @points: A canvas points structure.
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* Decreases the reference count of the specified points structure. If it
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* reaches zero, then the structure is freed.
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gnome_canvas_points_free (GnomeCanvasPoints *points)
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g_return_if_fail (points != NULL);
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points->ref_count -= 1;
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if (points->ref_count == 0) {
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g_free (points->coords);
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* gnome_canvas_get_miter_points:
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* @x1: X coordinate of the first point
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* @y1: Y coordinate of the first point
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* @x2: X coordinate of the second (angle) point
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* @y2: Y coordinate of the second (angle) point
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* @x3: X coordinate of the third point
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* @y3: Y coordinate of the third point
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* @width: Width of the line
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* @mx1: The X coordinate of the first miter point is returned here.
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* @my1: The Y coordinate of the first miter point is returned here.
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* @mx2: The X coordinate of the second miter point is returned here.
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* @my2: The Y coordinate of the second miter point is returned here.
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* Given three points forming an angle, computes the coordinates of the inside
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* and outside points of the mitered corner formed by a line of a given width at
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* Return value: FALSE if the angle is less than 11 degrees (this is the same
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* threshold as X uses. If this occurs, the return points are not modified.
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* Otherwise, returns TRUE.
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gnome_canvas_get_miter_points (double x1, double y1, double x2, double y2, double x3, double y3,
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double *mx1, double *my1, double *mx2, double *my2)
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double theta1; /* angle of segment p2-p1 */
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double theta2; /* angle of segment p2-p3 */
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double theta; /* angle between line segments */
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double theta3; /* angle that bisects theta1 and theta2 and points to p1 */
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double dist; /* distance of miter points from p2 */
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double dx, dy; /* x and y offsets corresponding to dist */
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#define ELEVEN_DEGREES (11.0 * G_PI / 180.0)
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theta1 = (x2 < x1) ? 0.0 : G_PI;
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theta1 = (y2 < y1) ? G_PI_2 : -G_PI_2;
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theta1 = atan2 (y1 - y2, x1 - x2);
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theta2 = (x3 > x2) ? 0 : G_PI;
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theta2 = (y3 > y2) ? G_PI_2 : -G_PI_2;
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theta2 = atan2 (y3 - y2, x3 - x2);
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theta = theta1 - theta2;
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else if (theta < -G_PI)
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if ((theta < ELEVEN_DEGREES) && (theta > -ELEVEN_DEGREES))
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dist = 0.5 * width / sin (0.5 * theta);
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theta3 = (theta1 + theta2) / 2.0;
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if (sin (theta3 - (theta1 + G_PI)) < 0.0)
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dx = dist * cos (theta3);
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dy = dist * sin (theta3);
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* gnome_canvas_get_butt_points:
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* @x1: X coordinate of first point in the line
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* @y1: Y cooordinate of first point in the line
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* @x2: X coordinate of second point (endpoint) of the line
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* @y2: Y coordinate of second point (endpoint) of the line
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* @width: Width of the line
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* @project: Whether the butt points should project out by width/2 distance
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* @bx1: X coordinate of first butt point is returned here
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* @by1: Y coordinate of first butt point is returned here
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* @bx2: X coordinate of second butt point is returned here
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* @by2: Y coordinate of second butt point is returned here
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* Computes the butt points of a line segment.
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gnome_canvas_get_butt_points (double x1, double y1, double x2, double y2,
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double width, int project,
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double *bx1, double *by1, double *bx2, double *by2)
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length = sqrt (dx * dx + dy * dy);
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if (length < GNOME_CANVAS_EPSILON) {
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dx = -width * (y2 - y1) / length;
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dy = width * (x2 - x1) / length;
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* gnome_canvas_polygon_to_point:
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* @poly: Vertices of the polygon. X coordinates are in the even indices, and Y
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* coordinates are in the odd indices
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* @num_points: Number of points in the polygon
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* @x: X coordinate of the point
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* @y: Y coordinate of the point
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* Computes the distance between a point and a polygon.
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* Return value: The distance from the point to the polygon, or zero if the
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* point is inside the polygon.
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gnome_canvas_polygon_to_point (double *poly, int num_points, double x, double y)
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/* Iterate through all the edges in the polygon, updating best and intersections.
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* When computing intersections, include left X coordinate of line within its range, but not
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* Y coordinate. Otherwise if the point lies exactly below a vertex we'll count it as two
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for (i = num_points, p = poly; i > 1; i--, p += 2) {
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/* Compute the point on the current edge closest to the point and update the
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* intersection count. This must be done separately for vertical edges, horizontal
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} else if (p[3] == p[1]) {
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/* Horizontal edge */
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if ((y < py) && (x < p[0]) && (x >= p[2]))
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if ((y < py) && (x < p[2]) && (x >= p[0]))
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double m1, b1, m2, b2;
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/* Diagonal edge. Convert the edge to a line equation (y = m1*x + b1), then
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* compute a line perpendicular to this edge but passing through the point,
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m1 = (p[3] - p[1]) / (p[2] - p[0]);
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b1 = p[1] - m1 * p[0];
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px = (b2 - b1) / (m1 - m2);
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} else if (px < p[2]) {
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} else if (px < p[0]) {
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lower = (m1 * x + b1) > y;
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if (lower && (x >= MIN (p[0], p[2])) && (x < MAX (p[0], p[2])))
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/* Compute the distance to the closest point, and see if that is the best so far */
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dist = sqrt (dx * dx + dy * dy);
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/* We've processed all the points. If the number of intersections is odd, the point is
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* inside the polygon.
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if (intersections & 0x1)
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/* Here are some helper functions for aa rendering: */
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* gnome_canvas_render_svp:
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* @buf: the canvas buffer to render over
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* @svp: the vector path to render
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* @rgba: the rgba color to render
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* Render the svp over the buf.
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gnome_canvas_render_svp (GnomeCanvasBuf *buf, ArtSVP *svp, guint32 rgba)
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guint32 fg_color, bg_color;
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bg_color = buf->bg_color;
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fg_color = rgba >> 8;
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/* composite over background color */
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int bg_r, bg_g, bg_b;
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int fg_r, fg_g, fg_b;
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bg_r = (bg_color >> 16) & 0xff;
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fg_r = (rgba >> 24) & 0xff;
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tmp = (fg_r - bg_r) * alpha;
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fg_r = bg_r + ((tmp + (tmp >> 8) + 0x80) >> 8);
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bg_g = (bg_color >> 8) & 0xff;
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fg_g = (rgba >> 16) & 0xff;
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tmp = (fg_g - bg_g) * alpha;
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fg_g = bg_g + ((tmp + (tmp >> 8) + 0x80) >> 8);
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bg_b = bg_color & 0xff;
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fg_b = (rgba >> 8) & 0xff;
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tmp = (fg_b - bg_b) * alpha;
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fg_b = bg_b + ((tmp + (tmp >> 8) + 0x80) >> 8);
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fg_color = (fg_r << 16) | (fg_g << 8) | fg_b;
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buf->rect.x0, buf->rect.y0, buf->rect.x1, buf->rect.y1,
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buf->buf, buf->buf_rowstride,
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art_rgb_svp_alpha (svp,
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buf->rect.x0, buf->rect.y0, buf->rect.x1, buf->rect.y1,
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buf->buf, buf->buf_rowstride,
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* gnome_canvas_update_svp:
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* @canvas: the canvas containing the svp that needs updating.
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* @p_svp: a pointer to the existing svp
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* @new_svp: the new svp
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* Sets the svp to the new value, requesting repaint on what's changed. This
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* function takes responsibility for freeing new_svp.
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gnome_canvas_update_svp (GnomeCanvas *canvas, ArtSVP **p_svp, ArtSVP *new_svp)
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ArtSVP *diff G_GNUC_UNUSED;
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if (old_svp != NULL) {
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art_drect_svp (&bb, old_svp);
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if ((bb.x1 - bb.x0) * (bb.y1 - bb.y0) > (64 * 64)) {
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repaint_uta = art_uta_from_svp (old_svp);
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gnome_canvas_request_redraw_uta (canvas, repaint_uta);
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art_drect_to_irect (&ib, &bb);
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gnome_canvas_request_redraw (canvas, ib.x0, ib.y0, ib.x1, ib.y1);
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art_svp_free (old_svp);
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if (new_svp != NULL) {
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art_drect_svp (&bb, new_svp);
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if ((bb.x1 - bb.x0) * (bb.y1 - bb.y0) > (64 * 64)) {
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repaint_uta = art_uta_from_svp (new_svp);
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gnome_canvas_request_redraw_uta (canvas, repaint_uta);
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art_drect_to_irect (&ib, &bb);
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gnome_canvas_request_redraw (canvas, ib.x0, ib.y0, ib.x1, ib.y1);
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* gnome_canvas_update_svp_clip:
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* @canvas: the canvas containing the svp that needs updating.
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* @p_svp: a pointer to the existing svp
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* @new_svp: the new svp
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* @clip_svp: a clip path, if non-null
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* Sets the svp to the new value, clipping if necessary, and requesting repaint
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* on what's changed. This function takes responsibility for freeing new_svp.
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gnome_canvas_update_svp_clip (GnomeCanvas *canvas, ArtSVP **p_svp, ArtSVP *new_svp, ArtSVP *clip_svp)
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if (clip_svp != NULL) {
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clipped_svp = art_svp_intersect (new_svp, clip_svp);
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art_svp_free (new_svp);
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clipped_svp = new_svp;
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gnome_canvas_update_svp (canvas, p_svp, clipped_svp);
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* gnome_canvas_item_reset_bounds:
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* @item: A canvas item
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* Resets the bounding box of a canvas item to an empty rectangle.
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gnome_canvas_item_reset_bounds (GnomeCanvasItem *item)
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* gnome_canvas_item_update_svp:
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* @item: the canvas item containing the svp that needs updating.
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* @p_svp: a pointer to the existing svp
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* @new_svp: the new svp
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* Sets the svp to the new value, requesting repaint on what's changed. This
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* function takes responsibility for freeing new_svp. This routine also adds the
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* svp's bbox to the item's.
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gnome_canvas_item_update_svp (GnomeCanvasItem *item, ArtSVP **p_svp, ArtSVP *new_svp)
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gnome_canvas_update_svp (item->canvas, p_svp, new_svp);
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art_drect_svp_union (&bbox, new_svp);
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* gnome_canvas_item_update_svp_clip:
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* @item: the canvas item containing the svp that needs updating.
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* @p_svp: a pointer to the existing svp
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* @new_svp: the new svp
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* @clip_svp: a clip path, if non-null
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* Sets the svp to the new value, clipping if necessary, and requesting repaint
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* on what's changed. This function takes responsibility for freeing new_svp.
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gnome_canvas_item_update_svp_clip (GnomeCanvasItem *item, ArtSVP **p_svp, ArtSVP *new_svp,
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if (clip_svp != NULL) {
567
clipped_svp = art_svp_intersect (new_svp, clip_svp);
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art_svp_free (new_svp);
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clipped_svp = new_svp;
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gnome_canvas_item_update_svp (item, p_svp, clipped_svp);
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* gnome_canvas_item_request_redraw_svp
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* @item: the item containing the svp
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* @svp: the svp that needs to be redrawn
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* Request redraw of the svp if in aa mode, or the entire item in in xlib mode.
584
gnome_canvas_item_request_redraw_svp (GnomeCanvasItem *item, const ArtSVP *svp)
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canvas = item->canvas;
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uta = art_uta_from_svp (svp);
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gnome_canvas_request_redraw_uta (canvas, uta);
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gnome_canvas_request_redraw (canvas, item->x1, item->y1, item->x2, item->y2);
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* gnome_canvas_update_bbox:
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* @item: the canvas item needing update
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* @x1: Left coordinate of the new bounding box
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* @y1: Top coordinate of the new bounding box
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* @x2: Right coordinate of the new bounding box
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* @y2: Bottom coordinate of the new bounding box
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* Sets the bbox to the new value, requesting full repaint.
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gnome_canvas_update_bbox (GnomeCanvasItem *item, int x1, int y1, int x2, int y2)
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gnome_canvas_request_redraw (item->canvas, item->x1, item->y1, item->x2, item->y2);
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gnome_canvas_request_redraw (item->canvas, item->x1, item->y1, item->x2, item->y2);
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* gnome_canvas_buf_ensure_buf:
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* @buf: the buf that needs to be represened in RGB format
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* Ensure that the buffer is in RGB format, suitable for compositing.
628
gnome_canvas_buf_ensure_buf (GnomeCanvasBuf *buf)
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for (y = buf->rect.y0; y < buf->rect.y1; y++) {
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art_rgb_fill_run (bufptr,
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(buf->bg_color >> 8) & 0xff,
639
buf->bg_color & 0xff,
640
buf->rect.x1 - buf->rect.x0);
641
bufptr += buf->buf_rowstride;
648
* gnome_canvas_join_gdk_to_art
649
* @gdk_join: a join type, represented in GDK format
651
* Convert from GDK line join specifier to libart.
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* Return value: The line join specifier in libart format.
655
ArtPathStrokeJoinType
656
gnome_canvas_join_gdk_to_art (GdkJoinStyle gdk_join)
660
return ART_PATH_STROKE_JOIN_MITER;
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return ART_PATH_STROKE_JOIN_ROUND;
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return ART_PATH_STROKE_JOIN_BEVEL;
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g_assert_not_reached ();
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return ART_PATH_STROKE_JOIN_MITER; /* shut up the compiler */
675
* gnome_canvas_cap_gdk_to_art
676
* @gdk_cap: a cap type, represented in GDK format
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* Convert from GDK line cap specifier to libart.
680
* Return value: The line cap specifier in libart format.
683
gnome_canvas_cap_gdk_to_art (GdkCapStyle gdk_cap)
687
case GDK_CAP_NOT_LAST:
688
return ART_PATH_STROKE_CAP_BUTT;
691
return ART_PATH_STROKE_CAP_ROUND;
693
case GDK_CAP_PROJECTING:
694
return ART_PATH_STROKE_CAP_SQUARE;
697
g_assert_not_reached ();
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return ART_PATH_STROKE_CAP_BUTT; /* shut up the compiler */
added
removed
libgnomecanvas/gnome-canvas-util.c
