moving from https://github.com/perberos/mate-desktop-environment

1 files changed, 426 insertions, 0 deletions

diff --git a/eel/eel-canvas-util.c b/eel/eel-canvas-util.c
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+/*
+ * Copyright (C) 1997, 1998, 1999, 2000 Free Software Foundation
+ * All rights reserved.
+ *
+ * This file is part of the Mate Library.
+ *
+ * The Mate 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 Mate 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 Mate 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 EelCanvas widget
+ *
+ * EelCanvas 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 <[email protected]>
+ */
+
+#include <config.h>
+
+#include <sys/types.h>
+#include <glib.h>
+#include <math.h>
+
+#include "eel-canvas.h"
+#include "eel-canvas-util.h"
+
+/*
+ * Ok, so some systems require magic incantations for M_PI to be defined.
+ * It's not important enough to worry about.
+ */
+#ifndef M_PI
+#define M_PI 3.141592653589793238462643383279502884197169399375105820974944592307816406286208998628034825342117
+#endif
+
+/**
+ * eel_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.
+ **/
+EelCanvasPoints *
+eel_canvas_points_new (int num_points)
+{
+    EelCanvasPoints *points;
+
+    g_return_val_if_fail (num_points > 1, NULL);
+
+    points = g_new (EelCanvasPoints, 1);
+    points->num_points = num_points;
+    points->coords = g_new (double, 2 * num_points);
+    points->ref_count = 1;
+
+    return points;
+}
+
+/**
+ * eel_canvas_points_ref:
+ * @points: A canvas points structure.
+ *
+ * Increases the reference count of the specified points structure.
+ *
+ * Return value: The canvas points structure itself.
+ **/
+EelCanvasPoints *
+eel_canvas_points_ref (EelCanvasPoints *points)
+{
+    g_return_val_if_fail (points != NULL, NULL);
+
+    points->ref_count += 1;
+    return points;
+}
+
+/**
+ * eel_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
+eel_canvas_points_free (EelCanvasPoints *points)
+{
+    g_return_if_fail (points != NULL);
+
+    points->ref_count -= 1;
+    if (points->ref_count == 0)
+    {
+        g_free (points->coords);
+        g_free (points);
+    }
+}
+
+/**
+ * eel_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.
+ **/
+int
+eel_canvas_get_miter_points (double x1, double y1, double x2, double y2, double x3, double y3,
+                             double width,
+                             double *mx1, double *my1, double *mx2, double *my2)
+{
+    double theta1;		/* angle of segment p2-p1 */
+    double theta2;		/* angle of segment p2-p3 */
+    double theta;		/* angle between line segments */
+    double theta3;		/* angle that bisects theta1 and theta2 and points to p1 */
+    double dist;		/* distance of miter points from p2 */
+    double dx, dy;		/* x and y offsets corresponding to dist */
+
+    double ELEVEN_DEGREES = 11.0 * M_PI / 180.0;
+
+    /* Degenerate cases.  */
+    if ((x1 == x2 && y1 == y2) || (x2 == x3 && y2 == y3))
+        return FALSE;
+
+    theta1 = atan2 (y1 - y2, x1 - x2);
+    theta2 = atan2 (y3 - y2, x3 - x2);
+    theta = theta1 - theta2;
+
+    /* Normalize to (-pi; pi].  */
+    if (theta > M_PI)
+        theta -= 2.0 * M_PI;
+    else if (theta <= -M_PI)
+        theta += 2.0 * M_PI;
+
+    if (fabs (theta) < ELEVEN_DEGREES)
+        return FALSE;
+
+    dist = fabs (0.5 * width / sin (0.5 * theta));
+
+    theta3 = (theta1 + theta2) / 2.0;
+    if (sin (theta3 - theta1) > 0.0)
+        theta3 += M_PI;
+
+    dx = dist * cos (theta3);
+    dy = dist * sin (theta3);
+
+    *mx1 = x2 + dx;
+    *mx2 = x2 - dx;
+    *my1 = y2 + dy;
+    *my2 = y2 - dy;
+
+    return TRUE;
+}
+
+/**
+ * eel_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
+eel_canvas_get_butt_points (double x1, double y1, double x2, double y2,
+                            double width, int project,
+                            double *bx1, double *by1, double *bx2, double *by2)
+{
+    double length;
+    double dx, dy;
+
+    width *= 0.5;
+    dx = x2 - x1;
+    dy = y2 - y1;
+    length = sqrt (dx * dx + dy * dy);
+
+    if (length < EEL_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;
+        }
+    }
+}
+
+/**
+ * eel_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.
+ **/
+double
+eel_canvas_polygon_to_point (double *poly, int num_points, double x, double y)
+{
+    double best;
+    int intersections;
+    int i;
+    double *p;
+    double 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;
+    if (poly == NULL)
+        return best;
+
+    intersections = 0;
+
+    for (i = num_points, p = poly; i > 1; i--, p += 2)
+    {
+        double 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
+        {
+            double m1, b1, m2, b2;
+            int 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;
+}
+
+/**
+ * eel_canvas_item_reset_bounds:
+ * @item: A canvas item
+ *
+ * Resets the bounding box of a canvas item to an empty rectangle.
+ **/
+void
+eel_canvas_item_reset_bounds (EelCanvasItem *item)
+{
+    item->x1 = 0.0;
+    item->y1 = 0.0;
+    item->x2 = 0.0;
+    item->y2 = 0.0;
+}
+
+/**
+ * eel_canvas_update_bbox:
+ * @canvas: the canvas 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
+eel_canvas_update_bbox (EelCanvasItem *item, int x1, int y1, int x2, int y2)
+{
+    eel_canvas_item_request_redraw (item);
+    item->x1 = x1;
+    item->y1 = y1;
+    item->x2 = x2;
+    item->y2 = y2;
+    eel_canvas_item_request_redraw (item);
+}
+