1 /* 2 * Copyright (C) 2015 Nicolas Bonnefon and other contributors 3 * 4 * This file is part of glogg. 5 * 6 * glogg is free software: you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License as published by 8 * the Free Software Foundation, either version 3 of the License, or 9 * (at your option) any later version. 10 * 11 * glogg is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 * 16 * You should have received a copy of the GNU General Public License 17 * along with glogg. If not, see <http://www.gnu.org/licenses/>. 18 */ 19 20 #ifndef VIEWTOOLS_H 21 #define VIEWTOOLS_H 22 23 #include <chrono> 24 25 #include <QObject> 26 27 // This class is a controller for an elastic hook manipulated with 28 // the mouse wheel or touchpad. 29 // It is used for the "follow" line at the end of the file. 30 class ElasticHook : public QObject { 31 Q_OBJECT 32 33 public: 34 ElasticHook( int hook_threshold ) { 35 hook_threshold_ = hook_threshold; 36 } 37 38 // Instruct the elastic to move by the passed pixels 39 // (a positive value increase the elastic tension) 40 void move( int value ); 41 42 int length() const { return position_; } 43 44 protected: 45 void timerEvent( QTimerEvent *event ); 46 47 signals: 48 // Sent when the length has changed 49 void lengthChanged(); 50 // Sent when the hooked status has changed 51 void hooked( bool is_hooked ); 52 53 private: 54 void decreasePosition(); 55 56 static constexpr int TIMER_PERIOD_MS = 10; 57 static constexpr int DECREASE_RATE = 4; 58 int hook_threshold_; 59 int position_ = 0; 60 int timer_id_ = 0; 61 std::chrono::time_point<std::chrono::steady_clock> last_update_; 62 }; 63 64 #endif 65