1 // Adapter for interpolating string properties representing CSS colors.
3 // Copyright (C) 2013 Thomas Geymayer <tomgey@gmail.com>
5 // This library is free software; you can redistribute it and/or
6 // modify it under the terms of the GNU Library General Public
7 // License as published by the Free Software Foundation; either
8 // version 2 of the License, or (at your option) any later version.
10 // This library is distributed in the hope that it will be useful,
11 // but WITHOUT ANY WARRANTY; without even the implied warranty of
12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 // Library General Public License for more details.
15 // You should have received a copy of the GNU Library General Public
16 // License along with this library; if not, write to the Free Software
17 // Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
19 #include "ColorInterpolator.hxx"
20 #include "parse_color.hxx"
22 #include <simgear/props/props.hxx>
27 //----------------------------------------------------------------------------
28 void ColorInterpolator::setTarget(const SGPropertyNode* target)
30 if( !parseColor(target->getStringValue(), _color_end) )
33 SG_GENERAL, SG_WARN, "ColorInterpolator: failed to parse end color."
37 //----------------------------------------------------------------------------
38 void ColorInterpolator::init(const SGPropertyNode* prop)
40 osg::Vec4 color_start;
41 if( !parseColor(prop->getStringValue(), color_start) )
42 // If unable to get current color, immediately change to target color
43 color_start = _color_end;
45 _color_diff = _color_end - color_start;
48 //----------------------------------------------------------------------------
49 void ColorInterpolator::write(SGPropertyNode* prop, double t)
51 osg::Vec4 color_cur = _color_end - _color_diff * (1 - t);
52 bool has_alpha = color_cur.a() < 0.999;
54 std::ostringstream strm;
55 strm << (has_alpha ? "rgba(" : "rgb(");
57 // r, g, b (every component in [0, 255])
58 for(size_t i = 0; i < 3; ++i)
62 strm << static_cast<int>(color_cur._v[i] * 255);
65 // Write alpha if a < 1 (alpha is in [0, 1])
67 strm << ',' << color_cur.a();
71 prop->setStringValue(strm.str());
74 } // namespace simgear