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livetrax/libs/canvas/poly_line.cc
Mads Kiilerich 0b27d6e652
Fix proximity threshold for polyline
I'm not good with a mouse, so I found it hard to edit animation lines.
The mouse position has to be quite precise, with only a small threshold.

Looking at the code, AutomationLine sets the threshold for the PolyLine
to 4.0 . That seems to be a distance, and better for me than what I
experience.

The actual code in PolyLine is however comparing it directly to the
squared distance, making it more sensitive than expected.

Fixed by computing the squared threshold - also including the line
width.
2022-10-17 00:09:25 +02:00

199 lines
4.4 KiB
C++

/*
* Copyright (C) 2012 Carl Hetherington <carl@carlh.net>
* Copyright (C) 2013-2017 Paul Davis <paul@linuxaudiosystems.com>
* Copyright (C) 2015-2016 Robin Gareus <robin@gareus.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <algorithm>
#include "canvas/canvas.h"
#include "canvas/poly_line.h"
#include "canvas/utils.h"
using namespace ArdourCanvas;
PolyLine::PolyLine (Canvas* c)
: PolyItem (c)
, _threshold (1.0)
, _y1 (0)
{
}
PolyLine::PolyLine (Item* parent)
: PolyItem (parent)
, _threshold (1.0)
, _y1 (0)
{
}
void
PolyLine::compute_bounding_box () const
{
PolyItem::compute_bounding_box ();
if (_y1 > 0 && _bounding_box) {
_bounding_box.x0 = 0;
_bounding_box.x1 = COORD_MAX;
if (_y1 > _bounding_box.y1) {
_bounding_box.y1 = _y1;
}
}
}
void
PolyLine::set_fill_y1 (double y1)
{
begin_change ();
set_bbox_dirty ();
_y1 = y1;
end_change ();
}
void
PolyLine::render (Rect const& area, Cairo::RefPtr<Cairo::Context> context) const
{
if (_fill && _y1 > 0 && _points.size () > 0) {
const ArdourCanvas::Rect& vp (_canvas->visible_area ());
setup_fill_context (context);
Duple y (0, _y1);
float y1 = item_to_window (y).y;
render_path (area, context);
Duple const& c0 (left_edge ());
Duple const& c1 (right_edge ());
if (c1.x < vp.x1) {
context->line_to (vp.x1, c1.y);
context->line_to (vp.x1, y1);
} else {
context->line_to (vp.x1, y1);
}
if (c0.x > vp.x0) {
context->line_to (vp.x0, y1);
context->line_to (vp.x0, c0.y);
} else {
context->line_to (vp.x0, y1);
}
context->close_path ();
context->fill ();
}
if (_outline) {
setup_outline_context (context);
render_path (area, context);
context->stroke ();
}
}
void
PolyLine::set_steps (Points const& points, bool stepped)
{
if (!stepped) {
PolyItem::set (points);
return;
}
Points copy;
for (Points::const_iterator p = points.begin (); p != points.end ();) {
Points::const_iterator next = p;
++next;
copy.push_back (*p);
if (next != points.end () && next->x != p->x) {
copy.push_back (Duple (next->x, p->y));
}
p = next;
}
PolyItem::set (copy);
}
// Clamp x1 to xmax, and scale y1 accordingly, relative to (x0,y0)
static void
clamp2 (double& x1, double& y1, double x0, double y0, double xmax) {
if (x1 > xmax) {
double dx = x1 - x0;
double dy = y1 - y0;
double slope = 0;
// only compute slope if relevant (and safe without overflow / division by zero);
// the line is on the xmax edge, and barely visible since x1 is far out and dx is small
if (fabs(dx) > 0.1) {
slope = dy / dx;
}
x1 = xmax;
double new_dx = x1 - x0;
y1 = y0 + new_dx * slope;
}
}
bool
PolyLine::covers (Duple const& point) const
{
Duple p = window_to_item (point);
const Points::size_type npoints = _points.size ();
if (npoints < 2) {
return false;
}
Points::size_type i;
Points::size_type j;
double squared_threshold = _threshold + _outline_width;
squared_threshold *= squared_threshold;
/* repeat for each line segment */
const Rect visible (window_to_item (_canvas->visible_area ()));
for (i = 1, j = 0; i < npoints; ++i, ++j) {
Duple at;
double t;
Duple a (_points[j]);
Duple b (_points[i]);
/*
Clamp the line endpoints to the visible area of the canvas. If we do
not do this, we may have a line segment extending to COORD_MAX and our
math goes wrong.
*/
clamp2 (a.x, a.y, b.x, b.y, visible.x1);
clamp2 (a.y, a.x, b.y, b.x, visible.y1);
clamp2 (b.x, b.y, a.x, a.y, visible.x1);
clamp2 (b.y, b.x, a.y, a.x, visible.y1);
double d = distance_to_segment_squared (p, a, b, t, at);
if (t < 0.0 || t > 1.0) {
continue;
}
if (d < squared_threshold) {
return true;
}
}
return false;
}
void
PolyLine::set_covers_threshold (double t)
{
_threshold = t;
}