/*
* Copyright (C) 1997, 1998, 1999, 2000 Free Software Foundation
* All rights reserved.
*
* This file is part of the Gnome Library.
*
* The Gnome Library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* The Gnome 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with the Gnome Library; see the file COPYING.LIB. If not,
* write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
/*
@NOTATION@
*/
/* Miscellaneous utility functions for the GnomeCanvas widget
*
* GnomeCanvas is basically a port of the Tk toolkit's most excellent canvas
* widget. Tk is copyrighted by the Regents of the University of California,
* Sun Microsystems, and other parties.
*
*
* Author: Federico Mena <federico@nuclecu.unam.mx>
*/
#include <config.h>
/* needed for M_PI_2 under 'gcc -ansi -predantic' on GNU/Linux */
#ifndef _BSD_SOURCE
# define _BSD_SOURCE 1
#endif
#include <sys/types.h>
#include <glib.h>
#include <math.h>
#include "gnome-canvas.h"
#include "gnome-canvas-util.h"
#include <libart_lgpl/art_uta.h>
#include <libart_lgpl/art_svp.h>
#include <libart_lgpl/art_svp_ops.h>
#include <libart_lgpl/art_rgb.h>
#include <libart_lgpl/art_rgb_svp.h>
#include <libart_lgpl/art_uta_svp.h>
#include <libart_lgpl/art_rect_svp.h>
/**
* gnome_canvas_points_new:
* @num_points: The number of points to allocate space for in the array.
*
* Creates a structure that should be used to pass an array of points to
* items.
*
* Return value: A newly-created array of points. It should be filled in
* by the user.
**/
GnomeCanvasPoints *
gnome_canvas_points_new (gint num_points)
{
GnomeCanvasPoints *points;
g_return_val_if_fail (num_points > 1, NULL);
points = g_new (GnomeCanvasPoints, 1);
points->num_points = num_points;
points->coords = g_new (double, 2 * num_points);
points->ref_count = 1;
return points;
}
/**
* gnome_canvas_points_ref:
* @points: A canvas points structure.
*
* Increases the reference count of the specified points structure.
*
* Return value: The canvas points structure itself.
**/
GnomeCanvasPoints *
gnome_canvas_points_ref (GnomeCanvasPoints *points)
{
g_return_val_if_fail (points != NULL, NULL);
points->ref_count += 1;
return points;
}
/**
* gnome_canvas_points_free:
* @points: A canvas points structure.
*
* Decreases the reference count of the specified points structure. If it
* reaches zero, then the structure is freed.
**/
void
gnome_canvas_points_free (GnomeCanvasPoints *points)
{
g_return_if_fail (points != NULL);
points->ref_count -= 1;
if (points->ref_count == 0) {
g_free (points->coords);
g_free (points);
}
}
/**
* gnome_canvas_get_miter_points:
* @x1: X coordinate of the first point
* @y1: Y coordinate of the first point
* @x2: X coordinate of the second (angle) point
* @y2: Y coordinate of the second (angle) point
* @x3: X coordinate of the third point
* @y3: Y coordinate of the third point
* @width: Width of the line
* @mx1: The X coordinate of the first miter point is returned here.
* @my1: The Y coordinate of the first miter point is returned here.
* @mx2: The X coordinate of the second miter point is returned here.
* @my2: The Y coordinate of the second miter point is returned here.
*
* Given three points forming an angle, computes the coordinates of the inside
* and outside points of the mitered corner formed by a line of a given width at
* that angle.
*
* Return value: FALSE if the angle is less than 11 degrees (this is the same
* threshold as X uses. If this occurs, the return points are not modified.
* Otherwise, returns TRUE.
**/
gint
gnome_canvas_get_miter_points (gdouble x1,
gdouble y1,
gdouble x2,
gdouble y2,
gdouble x3,
gdouble y3,
gdouble width,
gdouble *mx1,
gdouble *my1,
gdouble *mx2,
gdouble *my2)
{
gdouble theta1; /* angle of segment p2-p1 */
gdouble theta2; /* angle of segment p2-p3 */
gdouble theta; /* angle between line segments */
gdouble theta3; /* angle that bisects theta1 and theta2 and points to p1 */
gdouble dist; /* distance of miter points from p2 */
gdouble dx, dy; /* x and y offsets corresponding to dist */
#define ELEVEN_DEGREES (11.0 * G_PI / 180.0)
if (y2 == y1)
theta1 = (x2 < x1) ? 0.0 : G_PI;
else if (x2 == x1)
theta1 = (y2 < y1) ? G_PI_2 : -G_PI_2;
else
theta1 = atan2 (y1 - y2, x1 - x2);
if (y3 == y2)
theta2 = (x3 > x2) ? 0 : G_PI;
else if (x3 == x2)
theta2 = (y3 > y2) ? G_PI_2 : -G_PI_2;
else
theta2 = atan2 (y3 - y2, x3 - x2);
theta = theta1 - theta2;
if (theta > G_PI)
theta -= 2.0 * G_PI;
else if (theta < -G_PI)
theta += 2.0 * G_PI;
if ((theta < ELEVEN_DEGREES) && (theta > -ELEVEN_DEGREES))
return FALSE;
dist = 0.5 * width / sin (0.5 * theta);
if (dist < 0.0)
dist = -dist;
theta3 = (theta1 + theta2) / 2.0;
if (sin (theta3 - (theta1 + G_PI)) < 0.0)
theta3 += G_PI;
dx = dist * cos (theta3);
dy = dist * sin (theta3);
*mx1 = x2 + dx;
*mx2 = x2 - dx;
*my1 = y2 + dy;
*my2 = y2 - dy;
return TRUE;
}
/**
* gnome_canvas_get_butt_points:
* @x1: X coordinate of first point in the line
* @y1: Y cooordinate of first point in the line
* @x2: X coordinate of second point (endpoint) of the line
* @y2: Y coordinate of second point (endpoint) of the line
* @width: Width of the line
* @project: Whether the butt points should project out by width/2 distance
* @bx1: X coordinate of first butt point is returned here
* @by1: Y coordinate of first butt point is returned here
* @bx2: X coordinate of second butt point is returned here
* @by2: Y coordinate of second butt point is returned here
*
* Computes the butt points of a line segment.
**/
void
gnome_canvas_get_butt_points (gdouble x1, gdouble y1, gdouble x2, gdouble y2,
gdouble width, gint project,
gdouble *bx1, gdouble *by1, gdouble *bx2, gdouble *by2)
{
gdouble length;
gdouble dx, dy;
width *= 0.5;
dx = x2 - x1;
dy = y2 - y1;
length = sqrt (dx * dx + dy * dy);
if (length < GNOME_CANVAS_EPSILON) {
*bx1 = *bx2 = x2;
*by1 = *by2 = y2;
} else {
dx = -width * (y2 - y1) / length;
dy = width * (x2 - x1) / length;
*bx1 = x2 + dx;
*bx2 = x2 - dx;
*by1 = y2 + dy;
*by2 = y2 - dy;
if (project) {
*bx1 += dy;
*bx2 += dy;
*by1 -= dx;
*by2 -= dx;
}
}
}
/**
* gnome_canvas_polygon_to_point:
* @poly: Vertices of the polygon. X coordinates are in the even indices, and Y
* coordinates are in the odd indices
* @num_points: Number of points in the polygon
* @x: X coordinate of the point
* @y: Y coordinate of the point
*
* Computes the distance between a point and a polygon.
*
* Return value: The distance from the point to the polygon, or zero if the
* point is inside the polygon.
**/
gdouble
gnome_canvas_polygon_to_point (gdouble *poly, gint num_points, gdouble x, gdouble y)
{
gdouble best;
gint intersections;
gint i;
gdouble *p;
gdouble dx, dy;
/* Iterate through all the edges in the polygon, updating best and
* intersections.
*
* When computing intersections, include left X coordinate of line
* within its range, but not Y coordinate. Otherwise if the point
* lies exactly below a vertex we'll count it as two intersections. */
best = 1.0e36;
intersections = 0;
for (i = num_points, p = poly; i > 1; i--, p += 2) {
gdouble px, py, dist;
/* Compute the point on the current edge closest to the
* point and update the intersection count. This must be
* done separately for vertical edges, horizontal edges,
* and others. */
if (p[2] == p[0]) {
/* Vertical edge */
px = p[0];
if (p[1] >= p[3]) {
py = MIN (p[1], y);
py = MAX (py, p[3]);
} else {
py = MIN (p[3], y);
py = MAX (py, p[1]);
}
} else if (p[3] == p[1]) {
/* Horizontal edge */
py = p[1];
if (p[0] >= p[2]) {
px = MIN (p[0], x);
px = MAX (px, p[2]);
if ((y < py) && (x < p[0]) && (x >= p[2]))
intersections++;
} else {
px = MIN (p[2], x);
px = MAX (px, p[0]);
if ((y < py) && (x < p[2]) && (x >= p[0]))
intersections++;
}
} else {
gdouble m1, b1, m2, b2;
gint lower;
/* Diagonal edge. Convert the edge to a line equation (y = m1*x + b1), then
* compute a line perpendicular to this edge but passing through the point,
* (y = m2*x + b2).
*/
m1 = (p[3] - p[1]) / (p[2] - p[0]);
b1 = p[1] - m1 * p[0];
m2 = -1.0 / m1;
b2 = y - m2 * x;
px = (b2 - b1) / (m1 - m2);
py = m1 * px + b1;
if (p[0] > p[2]) {
if (px > p[0]) {
px = p[0];
py = p[1];
} else if (px < p[2]) {
px = p[2];
py = p[3];
}
} else {
if (px > p[2]) {
px = p[2];
py = p[3];
} else if (px < p[0]) {
px = p[0];
py = p[1];
}
}
lower = (m1 * x + b1) > y;
if (lower && (x >= MIN (p[0], p[2])) && (x < MAX (p[0], p[2])))
intersections++;
}
/* Compute the distance to the closest point, and see if that is the best so far */
dx = x - px;
dy = y - py;
dist = sqrt (dx * dx + dy * dy);
if (dist < best)
best = dist;
}
/* We've processed all the points. If the number of
* intersections is odd, the point is inside the polygon. */
if (intersections & 0x1)
return 0.0;
else
return best;
}
/* Here are some helper functions for aa rendering: */
/**
* gnome_canvas_update_svp:
* @canvas: the canvas containing the svp that needs updating.
* @p_svp: a pointer to the existing svp
* @new_svp: the new svp
*
* Sets the svp to the new value, requesting repaint on what's changed. This
* function takes responsibility for freeing new_svp.
**/
void
gnome_canvas_update_svp (GnomeCanvas *canvas, ArtSVP **p_svp, ArtSVP *new_svp)
{
ArtSVP *old_svp;
ArtSVP *diff G_GNUC_UNUSED;
ArtUta *repaint_uta;
old_svp = *p_svp;
if (old_svp != NULL) {
ArtDRect bb;
art_drect_svp (&bb, old_svp);
if ((bb.x1 - bb.x0) * (bb.y1 - bb.y0) > (64 * 64)) {
repaint_uta = art_uta_from_svp (old_svp);
gnome_canvas_request_redraw_uta (canvas, repaint_uta);
} else {
ArtIRect ib;
art_drect_to_irect (&ib, &bb);
gnome_canvas_request_redraw (canvas, ib.x0, ib.y0, ib.x1, ib.y1);
}
art_svp_free (old_svp);
}
if (new_svp != NULL) {
ArtDRect bb;
art_drect_svp (&bb, new_svp);
if ((bb.x1 - bb.x0) * (bb.y1 - bb.y0) > (64 * 64)) {
repaint_uta = art_uta_from_svp (new_svp);
gnome_canvas_request_redraw_uta (canvas, repaint_uta);
} else {
ArtIRect ib;
art_drect_to_irect (&ib, &bb);
gnome_canvas_request_redraw (canvas, ib.x0, ib.y0, ib.x1, ib.y1);
}
}
*p_svp = new_svp;
}
/**
* gnome_canvas_update_svp_clip:
* @canvas: the canvas containing the svp that needs updating.
* @p_svp: a pointer to the existing svp
* @new_svp: the new svp
* @clip_svp: a clip path, if non-null
*
* Sets the svp to the new value, clipping if necessary, and requesting repaint
* on what's changed. This function takes responsibility for freeing new_svp.
**/
void
gnome_canvas_update_svp_clip (GnomeCanvas *canvas,
ArtSVP **p_svp,
ArtSVP *new_svp,
ArtSVP *clip_svp)
{
ArtSVP *clipped_svp;
if (clip_svp != NULL) {
clipped_svp = art_svp_intersect (new_svp, clip_svp);
art_svp_free (new_svp);
} else {
clipped_svp = new_svp;
}
gnome_canvas_update_svp (canvas, p_svp, clipped_svp);
}
/**
* gnome_canvas_item_reset_bounds:
* @item: A canvas item
*
* Resets the bounding box of a canvas item to an empty rectangle.
**/
void
gnome_canvas_item_reset_bounds (GnomeCanvasItem *item)
{
item->x1 = 0.0;
item->y1 = 0.0;
item->x2 = 0.0;
item->y2 = 0.0;
}
/**
* gnome_canvas_item_update_svp:
* @item: the canvas item containing the svp that needs updating.
* @p_svp: a pointer to the existing svp
* @new_svp: the new svp
*
* Sets the svp to the new value, requesting repaint on what's changed. This
* function takes responsibility for freeing new_svp. This routine also adds the
* svp's bbox to the item's.
**/
void
gnome_canvas_item_update_svp (GnomeCanvasItem *item, ArtSVP **p_svp, ArtSVP *new_svp)
{
ArtDRect bbox;
gnome_canvas_update_svp (item->canvas, p_svp, new_svp);
if (new_svp) {
bbox.x0 = item->x1;
bbox.y0 = item->y1;
bbox.x1 = item->x2;
bbox.y1 = item->y2;
art_drect_svp_union (&bbox, new_svp);
item->x1 = bbox.x0;
item->y1 = bbox.y0;
item->x2 = bbox.x1;
item->y2 = bbox.y1;
}
}
/**
* gnome_canvas_item_update_svp_clip:
* @item: the canvas item containing the svp that needs updating.
* @p_svp: a pointer to the existing svp
* @new_svp: the new svp
* @clip_svp: a clip path, if non-null
*
* Sets the svp to the new value, clipping if necessary, and requesting repaint
* on what's changed. This function takes responsibility for freeing new_svp.
**/
void
gnome_canvas_item_update_svp_clip (GnomeCanvasItem *item,
ArtSVP **p_svp,
ArtSVP *new_svp,
ArtSVP *clip_svp)
{
ArtSVP *clipped_svp;
if (clip_svp != NULL) {
clipped_svp = art_svp_intersect (new_svp, clip_svp);
art_svp_free (new_svp);
} else {
clipped_svp = new_svp;
}
gnome_canvas_item_update_svp (item, p_svp, clipped_svp);
}
/**
* gnome_canvas_item_request_redraw_svp
* @item: the item containing the svp
* @svp: the svp that needs to be redrawn
*
* Request redraw of the svp if in aa mode, or the entire item in in xlib mode.
**/
void
gnome_canvas_item_request_redraw_svp (GnomeCanvasItem *item, const ArtSVP *svp)
{
gnome_canvas_request_redraw (item->canvas, item->x1, item->y1, item->x2, item->y2);
}
/**
* gnome_canvas_update_bbox:
* @item: the canvas item needing update
* @x1: Left coordinate of the new bounding box
* @y1: Top coordinate of the new bounding box
* @x2: Right coordinate of the new bounding box
* @y2: Bottom coordinate of the new bounding box
*
* Sets the bbox to the new value, requesting full repaint.
**/
void
gnome_canvas_update_bbox (GnomeCanvasItem *item, gint x1, gint y1, gint x2, gint y2)
{
gnome_canvas_request_redraw (item->canvas, item->x1, item->y1, item->x2, item->y2);
item->x1 = x1;
item->y1 = y1;
item->x2 = x2;
item->y2 = y2;
gnome_canvas_request_redraw (item->canvas, item->x1, item->y1, item->x2, item->y2);
}
/**
* gnome_canvas_join_gdk_to_art
* @gdk_join: a join type, represented in GDK format
*
* Convert from GDK line join specifier to libart.
*
* Return value: The line join specifier in libart format.
**/
ArtPathStrokeJoinType
gnome_canvas_join_gdk_to_art (GdkJoinStyle gdk_join)
{
switch (gdk_join) {
case GDK_JOIN_MITER:
return ART_PATH_STROKE_JOIN_MITER;
case GDK_JOIN_ROUND:
return ART_PATH_STROKE_JOIN_ROUND;
case GDK_JOIN_BEVEL:
return ART_PATH_STROKE_JOIN_BEVEL;
default:
g_assert_not_reached ();
return ART_PATH_STROKE_JOIN_MITER; /* shut up the compiler */
}
}
/**
* gnome_canvas_cap_gdk_to_art
* @gdk_cap: a cap type, represented in GDK format
*
* Convert from GDK line cap specifier to libart.
*
* Return value: The line cap specifier in libart format.
**/
ArtPathStrokeCapType
gnome_canvas_cap_gdk_to_art (GdkCapStyle gdk_cap)
{
switch (gdk_cap) {
case GDK_CAP_BUTT:
case GDK_CAP_NOT_LAST:
return ART_PATH_STROKE_CAP_BUTT;
case GDK_CAP_ROUND:
return ART_PATH_STROKE_CAP_ROUND;
case GDK_CAP_PROJECTING:
return ART_PATH_STROKE_CAP_SQUARE;
default:
g_assert_not_reached ();
return ART_PATH_STROKE_CAP_BUTT; /* shut up the compiler */
}
}
