223 lines
6.5 KiB
C++
223 lines
6.5 KiB
C++
/*
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Copyright (C) 2011-2013 Paul Davis
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Author: Carl Hetherington <cth@carlh.net>
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program 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
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <algorithm>
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#include <cmath>
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#include <stdint.h>
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#include <cairomm/context.h>
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#include "canvas/utils.h"
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using std::max;
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using std::min;
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void
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ArdourCanvas::color_to_hsv (Color color, double& h, double& s, double& v)
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{
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double r, g, b, a;
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double cmax;
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double cmin;
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double delta;
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color_to_rgba (color, r, g, b, a);
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if (r > g) {
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cmax = max (r, b);
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} else {
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cmax = max (g, b);
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}
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if (r < g) {
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cmin = min (r, b);
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} else {
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cmin = min (g, b);
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}
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v = cmax;
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delta = cmax - cmin;
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if (cmax == 0) {
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// r = g = b == 0 ... v is undefined, s = 0
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s = 0.0;
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h = -1.0;
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}
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if (delta != 0.0) {
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if (cmax == r) {
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h = fmod ((g - b)/delta, 6.0);
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} else if (cmax == g) {
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h = ((b - r)/delta) + 2;
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} else {
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h = ((r - g)/delta) + 4;
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}
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h *= 60.0;
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}
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if (delta == 0 || cmax == 0) {
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s = 0;
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} else {
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s = delta / cmax;
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}
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}
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ArdourCanvas::Color
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ArdourCanvas::hsv_to_color (double h, double s, double v, double a)
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{
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s = min (1.0, max (0.0, s));
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v = min (1.0, max (0.0, v));
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if (s == 0) {
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// achromatic (grey)
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return rgba_to_color (v, v, v, a);
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}
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h = min (360.0, max (0.0, h));
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double c = v * s;
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double x = c * (1.0 - fabs(fmod(h / 60.0, 2) - 1.0));
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double m = v - c;
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if (h >= 0.0 && h < 60.0) {
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return rgba_to_color (c + m, x + m, m, a);
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} else if (h >= 60.0 && h < 120.0) {
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return rgba_to_color (x + m, c + m, m, a);
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} else if (h >= 120.0 && h < 180.0) {
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return rgba_to_color (m, c + m, x + m, a);
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} else if (h >= 180.0 && h < 240.0) {
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return rgba_to_color (m, x + m, c + m, a);
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} else if (h >= 240.0 && h < 300.0) {
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return rgba_to_color (x + m, m, c + m, a);
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} else if (h >= 300.0 && h < 360.0) {
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return rgba_to_color (c + m, m, x + m, a);
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}
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return rgba_to_color (m, m, m, a);
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}
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void
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ArdourCanvas::color_to_rgba (Color color, double& r, double& g, double& b, double& a)
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{
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r = ((color >> 24) & 0xff) / 255.0;
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g = ((color >> 16) & 0xff) / 255.0;
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b = ((color >> 8) & 0xff) / 255.0;
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a = ((color >> 0) & 0xff) / 255.0;
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}
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ArdourCanvas::Color
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ArdourCanvas::rgba_to_color (double r, double g, double b, double a)
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{
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/* clamp to [0 .. 1] range */
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r = min (1.0, max (0.0, r));
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g = min (1.0, max (0.0, g));
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b = min (1.0, max (0.0, b));
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a = min (1.0, max (0.0, a));
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/* convert to [0..255] range */
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unsigned int rc, gc, bc, ac;
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rc = rint (r * 255.0);
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gc = rint (g * 255.0);
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bc = rint (b * 255.0);
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ac = rint (a * 255.0);
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/* build-an-integer */
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return (rc << 24) | (gc << 16) | (bc << 8) | ac;
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}
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void
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ArdourCanvas::set_source_rgba (Cairo::RefPtr<Cairo::Context> context, Color color)
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{
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context->set_source_rgba (
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((color >> 24) & 0xff) / 255.0,
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((color >> 16) & 0xff) / 255.0,
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((color >> 8) & 0xff) / 255.0,
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((color >> 0) & 0xff) / 255.0
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);
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}
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ArdourCanvas::Distance
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ArdourCanvas::distance_to_segment_squared (Duple const & p, Duple const & p1, Duple const & p2, double& t, Duple& at)
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{
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static const double kMinSegmentLenSquared = 0.00000001; // adjust to suit. If you use float, you'll probably want something like 0.000001f
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static const double kEpsilon = 1.0E-14; // adjust to suit. If you use floats, you'll probably want something like 1E-7f
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double dx = p2.x - p1.x;
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double dy = p2.y - p1.y;
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double dp1x = p.x - p1.x;
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double dp1y = p.y - p1.y;
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const double segLenSquared = (dx * dx) + (dy * dy);
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if (segLenSquared >= -kMinSegmentLenSquared && segLenSquared <= kMinSegmentLenSquared) {
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// segment is a point.
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at = p1;
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t = 0.0;
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return ((dp1x * dp1x) + (dp1y * dp1y));
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}
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// Project a line from p to the segment [p1,p2]. By considering the line
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// extending the segment, parameterized as p1 + (t * (p2 - p1)),
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// we find projection of point p onto the line.
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// It falls where t = [(p - p1) . (p2 - p1)] / |p2 - p1|^2
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t = ((dp1x * dx) + (dp1y * dy)) / segLenSquared;
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if (t < kEpsilon) {
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// intersects at or to the "left" of first segment vertex (p1.x, p1.y). If t is approximately 0.0, then
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// intersection is at p1. If t is less than that, then there is no intersection (i.e. p is not within
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// the 'bounds' of the segment)
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if (t > -kEpsilon) {
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// intersects at 1st segment vertex
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t = 0.0;
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}
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// set our 'intersection' point to p1.
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at = p1;
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// Note: If you wanted the ACTUAL intersection point of where the projected lines would intersect if
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// we were doing PointLineDistanceSquared, then qx would be (p1.x + (t * dx)) and qy would be (p1.y + (t * dy)).
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} else if (t > (1.0 - kEpsilon)) {
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// intersects at or to the "right" of second segment vertex (p2.x, p2.y). If t is approximately 1.0, then
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// intersection is at p2. If t is greater than that, then there is no intersection (i.e. p is not within
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// the 'bounds' of the segment)
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if (t < (1.0 + kEpsilon)) {
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// intersects at 2nd segment vertex
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t = 1.0;
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}
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// set our 'intersection' point to p2.
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at = p2;
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// Note: If you wanted the ACTUAL intersection point of where the projected lines would intersect if
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// we were doing PointLineDistanceSquared, then qx would be (p1.x + (t * dx)) and qy would be (p1.y + (t * dy)).
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} else {
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// The projection of the point to the point on the segment that is perpendicular succeeded and the point
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// is 'within' the bounds of the segment. Set the intersection point as that projected point.
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at = Duple (p1.x + (t * dx), p1.y + (t * dy));
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}
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// return the squared distance from p to the intersection point. Note that we return the squared distance
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// as an optimization because many times you just need to compare relative distances and the squared values
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// works fine for that. If you want the ACTUAL distance, just take the square root of this value.
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double dpqx = p.x - at.x;
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double dpqy = p.y - at.y;
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return ((dpqx * dpqx) + (dpqy * dpqy));
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}
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