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82 lines
1.5 KiB
C++
82 lines
1.5 KiB
C++
/*
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* \brief Fading class
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* \date 2005-11-10
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* \author Norman Feske <norman.feske@genode-labs.com>
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*/
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/*
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* Copyright (C) 2005-2017 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU Affero General Public License version 3.
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*/
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#ifndef _INCLUDE__SCOUT__FADER_H_
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#define _INCLUDE__SCOUT__FADER_H_
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#include <scout/misc_math.h>
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#include <scout/tick.h>
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namespace Scout { class Fader; }
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/**
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* Class that manages the fading of a derived class.
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*/
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class Scout::Fader : public Tick
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{
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protected:
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int _curr_value = 0; /* current value */
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int _dst_value = 0; /* desired final value */
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int _step = 0;
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public:
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virtual ~Fader() { }
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/**
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* Fade to specified alpha value
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*/
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void fade_to(int dst_value, int step = -1)
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{
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if (step > 0) _step = step;
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_dst_value = dst_value;
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schedule(20);
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}
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/**
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* Set fading speed
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*/
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void step(int step) { _step = step; }
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/**
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* Assign new current fading value
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*/
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void curr(int curr)
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{
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if (curr == _curr_value) return;
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_curr_value = curr;
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schedule(20);
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}
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/**
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* Tick interface
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*/
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int on_tick() override
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{
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if (_curr_value == _dst_value)
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return 0;
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if (_curr_value < _dst_value)
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_curr_value = min(_curr_value + _step, _dst_value);
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if (_curr_value > _dst_value)
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_curr_value = max(_curr_value - _step, _dst_value);
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return 1;
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}
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};
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#endif /* _INCLUDE__SCOUT__FADER_H_ */
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