headers/private/shared/ShakeTrackingFilter.h

   1 /*
   2  * Copyright 2009, Alexandre Deckner, alex@zappotek.com
   3  * Distributed under the terms of the MIT License.
   4  */
   5 #ifndef SHAKE_TRACKING_FILTER_H
   6 #define SHAKE_TRACKING_FILTER_H
   7
   8
   9 #include <MessageFilter.h>
  10 #include <Point.h>
  11
  12 class BView;
  13 class BHandler;
  14 class BMessageRunner;
  15
  16 namespace BPrivate {
  17
  18 class LowPassFilter {
  19 public:
  20                                                 LowPassFilter(uint32 size);
  21                                                 ~LowPassFilter();
  22
  23                         void        Input(const BPoint& p);
  24                         BPoint          Output() const;
  25 private:
  26         BPoint* fPoints;
  27         uint32  fSize;
  28         BPoint  fSum;
  29 };
  30
  31
  32 class ShakeTrackingFilter : public BMessageFilter {
  33 public:
  34                                                                 ShakeTrackingFilter(
  35                                                                         BView* targetView,
  36                                                                         uint32 messageWhat,
  37                                                                         uint32 countThreshold = 2,
  38                                                                         bigtime_t timeTreshold = 400000);
  39
  40                                                                 ~ShakeTrackingFilter();
  41
  42                         filter_result           Filter(BMessage* message, BHandler** _target);
  43
  44 private:
  45                         BView*                          fTargetView;
  46                         uint32                          fMessageWhat;
  47
  48                         BMessageRunner*         fCancelRunner;
  49                         LowPassFilter           fLowPass;
  50                         BPoint                          fLastDelta;
  51                         BPoint                          fLastPosition;
  52                         uint32                          fCounter;
  53                         uint32                          fCountThreshold;
  54                         bigtime_t                       fTimeThreshold;
  55 };
  56
  57 }       // namespace BPrivate
  58
  59 using BPrivate::ShakeTrackingFilter;
  60 using BPrivate::LowPassFilter;
  61
  62 #endif  // SHAKE_TRACKING_FILTER_H