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65 lines
1.6 KiB
C++
65 lines
1.6 KiB
C++
// vim: set tabstop=4 shiftwidth=4 expandtab:
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/*
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Gwenview: an image viewer
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Copyright 2008 Aurélien Gâteau <agateau@kde.org>
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; either version 2
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of the License, or (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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#ifndef RAMP_H
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#define RAMP_H
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namespace Gwenview
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{
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/**
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* This class maps values on a linear ramp.
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* It's useful to do mappings like this:
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*
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* x | -oo x1 x2 +oo
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* --+--------------------------------------
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* y | y1 y1 (linear ramp) y2 y2
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*
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* Note that y1 can be greater than y2 if necessary
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*/
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class Ramp
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{
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public:
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Ramp(qreal x1, qreal x2, qreal y1, qreal y2)
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: mX1(x1)
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, mX2(x2)
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, mY1(y1)
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, mY2(y2) {
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mK = (y2 - y1) / (x2 - x1);
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}
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qreal operator()(qreal x) const
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{
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if (x < mX1) {
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return mY1;
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}
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if (x > mX2) {
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return mY2;
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}
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return mY1 + (x - mX1) * mK;
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}
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private:
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qreal mX1, mX2, mY1, mY2, mK;
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};
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} // namespace
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#endif /* RAMP_H */
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