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 ) : hook_threshold_( hook_threshold ) {} 35 36 // Instruct the elastic to move by the passed pixels 37 // (a positive value increase the elastic tension) 38 void move( int value ); 39 40 // Programmatically force the hook hooked or not. 41 void hook( bool hooked ) 42 { hooked_ = hooked; } 43 44 // Return the "length" of the elastic hook. 45 int length() const { return position_; } 46 bool isHooked() const { return hooked_; } 47 48 protected: 49 void timerEvent( QTimerEvent *event ); 50 51 signals: 52 // Sent when the length has changed 53 void lengthChanged(); 54 // Sent when the hooked status has changed 55 void hooked( bool is_hooked ); 56 57 private: 58 void decreasePosition(); 59 60 static constexpr int TIMER_PERIOD_MS = 10; 61 static constexpr int DECREASE_RATE = 4; 62 const int hook_threshold_; 63 bool hooked_ = false; 64 int position_ = 0; 65 int timer_id_ = 0; 66 std::chrono::time_point<std::chrono::steady_clock> last_update_; 67 }; 68 69 #endif 70