1 // Copyright 2012 The ChromiumOS Authors 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #include <map> 6 #include <memory> 7 #include <gtest/gtest.h> // for FRIEND_TEST 8 9 #include "include/filter_interpreter.h" 10 #include "include/finger_metrics.h" 11 #include "include/gestures.h" 12 #include "include/prop_registry.h" 13 #include "include/tracer.h" 14 15 #ifndef GESTURES_BOX_FILTER_INTERPRETER_H_ 16 #define GESTURES_BOX_FILTER_INTERPRETER_H_ 17 18 namespace gestures { 19 20 // This filter interpreter applies simple "box" algorithm to fingers as they 21 // pass through the filter. The purpose is to filter noisy input. 22 // The algorithm is: For each axis: 23 // - For each input point, compare X distance to previous output point for 24 // the finger. 25 // - If the X distance is under box_width_ / 2, report the old location. 26 // - Report the new point shifted box_width_ / 2 toward the previous 27 // output point. 28 // - Apply box_height_ to Y distance. 29 // 30 // The way to think about this is that there is a box around the previous 31 // output point with a width and height of box_width_. If a new point is 32 // within that box, report the old location (don't move the box). If the new 33 // point is outside, shift the box over to include the new point, then report 34 // the new center of the box. 35 36 class BoxFilterInterpreter : public FilterInterpreter, public PropertyDelegate { 37 FRIEND_TEST(BoxFilterInterpreterTest, SimpleTest); 38 FRIEND_TEST(BoxFilterInterpreterTest, ZeroSizeBoxTest); 39 public: 40 // Takes ownership of |next|: 41 BoxFilterInterpreter(PropRegistry* prop_reg, Interpreter* next, 42 Tracer* tracer); ~BoxFilterInterpreter()43 virtual ~BoxFilterInterpreter() {} 44 45 protected: 46 virtual void SyncInterpretImpl(HardwareState& hwstate, stime_t* timeout); 47 48 private: 49 std::map<short, FingerState> previous_output_; 50 51 DoubleProperty box_width_; 52 DoubleProperty box_height_; 53 }; 54 55 } // namespace gestures 56 57 #endif // GESTURES_BOX_FILTER_INTERPRETER_H_ 58