source/input/gesturedetector.cpp

   1 #include <cmath>
   2 #include <sigc++/bind_return.h>
   3 #include "gesturedetector.h"
   4 #include "touchscreen.h"
   5
   6 using namespace std;
   7
   8 namespace Msp {
   9 namespace Input {
  10
  11 GestureDetector::GestureDetector(Touchscreen &ts):
  12         touchscreen(ts),
  13         current_gesture(GESTURE_NONE),
  14         active_points(0),
  15         invalid_gesture(false)
  16 {
  17         name = "Gesture";
  18
  19         touchscreen.signal_button_press.connect(sigc::bind_return(sigc::mem_fun(this, &GestureDetector::touch_down), false));
  20         touchscreen.signal_button_release.connect(sigc::bind_return(sigc::mem_fun(this, &GestureDetector::touch_up), false));
  21         touchscreen.signal_axis_motion.connect(sigc::bind_return(sigc::mem_fun(this, &GestureDetector::touch_move), false));
  22         Graphics::Window &window = touchscreen.get_window();
  23         window.signal_resize.connect(sigc::mem_fun(this, &GestureDetector::window_resized));
  24         window_resized(window.get_width(), window.get_height());
  25 }
  26
  27 string GestureDetector::get_button_name(unsigned btn) const
  28 {
  29         if(btn==GESTURE_SWIPE_DOWN)
  30                 return "Swipe down";
  31         else if(btn==GESTURE_SWIPE_UP)
  32                 return "Swipe up";
  33         else if(btn==GESTURE_SWIPE_LEFT)
  34                 return "Swipe left";
  35         else if(btn==GESTURE_SWIPE_RIGHT)
  36                 return "Swipe right";
  37         else if(btn==GESTURE_PINCH)
  38                 return "Pinch";
  39         else
  40                 return Device::get_button_name(btn);
  41 }
  42
  43 string GestureDetector::get_axis_name(unsigned axis) const
  44 {
  45         if(axis==0)
  46                 return "X";
  47         else if(axis==1)
  48                 return "Y";
  49         else if(axis==2)
  50                 return "Progress";
  51         else
  52                 return Device::get_axis_name(axis);
  53 }
  54
  55 void GestureDetector::touch_down(unsigned btn)
  56 {
  57         if(btn>=MAX_POINTS)
  58                 return;
  59
  60         TouchPoint &p = points[btn];
  61         p.down = true;
  62         p.down_x = p.x;
  63         p.down_y = p.y;
  64         p.x = 0;
  65         p.y = 0;
  66         p.threshold_exceeded = false;
  67 }
  68
  69 void GestureDetector::touch_up(unsigned btn)
  70 {
  71         if(btn>=MAX_POINTS)
  72                 return;
  73
  74         TouchPoint &p = points[btn];
  75         p.x += p.down_x;
  76         p.y += p.down_y;
  77         p.down = false;
  78
  79         if(active_points&(1<<btn))
  80                 end_gesture();
  81
  82         if(current_gesture==GESTURE_NONE)
  83         {
  84                 // New gesture can't start until all points have been released.
  85                 invalid_gesture = false;
  86                 for(unsigned i=0; (i<MAX_POINTS && !invalid_gesture); ++i)
  87                         invalid_gesture = points[i].down;
  88         }
  89 }
  90
  91 void GestureDetector::touch_move(unsigned axis, float value, float)
  92 {
  93         if(axis>=MAX_POINTS*2)
  94                 return;
  95
  96         unsigned i = axis>>1;
  97         TouchPoint &p = points[i];
  98         // Track relative position when pressed, absolute when not.
  99         if(axis&1)
 100                 p.y = (p.down ? value-p.down_y : value);
 101         else
 102                 p.x = (p.down ? value-p.down_x : value);
 103
 104         if(p.down)
 105         {
 106                 if(p.x*p.x/threshold_x_sq+p.y*p.y/threshold_y_sq>=1)
 107                         p.threshold_exceeded = true;
 108
 109                 if(current_gesture==GESTURE_NONE && !invalid_gesture)
 110                         start_gesture();
 111                 else if(active_points&(1<<i))
 112                         update_progress();
 113         }
 114 }
 115
 116 void GestureDetector::start_gesture()
 117 {
 118         TouchPoint &p = points[0];
 119         if(!p.down)
 120                 return;
 121
 122         /* At least one point needs to have moved more than the threshold to start
 123         the gesture. */
 124         bool threshold_exceeded = false;
 125         for(unsigned i=0; (i<MAX_POINTS && !threshold_exceeded); ++i)
 126                 threshold_exceeded = (points[i].down && points[i].threshold_exceeded);
 127         if(!threshold_exceeded)
 128                 return;
 129
 130         invalid_gesture = false;
 131         if(points[1].down)
 132         {
 133                 TouchPoint &p2 = points[1];
 134                 float ddx = p.down_x-p2.down_x;
 135                 float ddy = p.down_y-p2.down_y;
 136                 float away = p.x*ddx+p.y*ddy;
 137                 float turn = p.y*ddx-p.x*ddy;
 138                 float away2 = -(p2.x*ddx+p2.y*ddy);
 139                 float turn2 = -(p2.y*ddx-p2.x*ddy);
 140                 if(away*away2>0 && abs(away)>abs(turn) && abs(away2)>abs(turn2))
 141                         /* If the points moved away from or towards each other without rotating
 142                         significantly, it's a pinch gesture. */
 143                         current_gesture = GESTURE_PINCH;
 144                 else
 145                         invalid_gesture = true;
 146
 147                 if(current_gesture!=GESTURE_NONE)
 148                 {
 149                         active_points = 3;
 150                         set_axis_value(0, (p.down_x+p2.down_x)/2, true);
 151                         set_axis_value(1, (p.down_y+p2.down_y)/2, true);
 152                 }
 153         }
 154         else
 155         {
 156                 // Allow a maximum deviation of about 26° to recognize a swipe gesture.
 157                 if(abs(p.x)>2*abs(p.y))
 158                         current_gesture = (p.x>0 ? GESTURE_SWIPE_RIGHT : GESTURE_SWIPE_LEFT);
 159                 else if(abs(p.y)>2*abs(p.x))
 160                         current_gesture = (p.y>0 ? GESTURE_SWIPE_UP : GESTURE_SWIPE_DOWN);
 161                 else
 162                         invalid_gesture = true;
 163
 164                 if(current_gesture!=GESTURE_NONE)
 165                 {
 166                         active_points = 1;
 167                         set_axis_value(0, p.down_x, true);
 168                         set_axis_value(1, p.down_y, true);
 169                 }
 170         }
 171
 172         update_progress();
 173
 174         if(current_gesture!=GESTURE_NONE)
 175                 set_button_state(current_gesture, true, true);
 176 }
 177
 178 void GestureDetector::update_progress()
 179 {
 180         TouchPoint &p = points[0];
 181
 182         if(current_gesture==GESTURE_SWIPE_DOWN)
 183                 set_axis_value(2, -p.y, true);
 184         else if(current_gesture==GESTURE_SWIPE_UP)
 185                 set_axis_value(2, p.y, true);
 186         else if(current_gesture==GESTURE_SWIPE_LEFT)
 187                 set_axis_value(2, -p.x, true);
 188         else if(current_gesture==GESTURE_SWIPE_RIGHT)
 189                 set_axis_value(2, p.x, true);
 190         else if(current_gesture==GESTURE_PINCH)
 191         {
 192                 TouchPoint &p2 = points[1];
 193                 /* Pinch progress is the ratio between the current distance of the points
 194                 and their distance when they were pressed. */
 195                 float ddx = p.down_x-p2.down_x;
 196                 float ddy = p.down_y-p2.down_y;
 197                 float dx = ddx+p.x-p2.x;
 198                 float dy = ddy+p.y-p2.y;
 199                 set_axis_value(2, sqrt(dx*dx+dy*dy)/sqrt(ddx*ddx+ddy*ddy)-1, true);
 200         }
 201 }
 202
 203 void GestureDetector::end_gesture()
 204 {
 205         set_button_state(current_gesture, false, true);
 206         set_axis_value(2, 0, false);
 207         current_gesture = GESTURE_NONE;
 208         active_points = 0;
 209 }
 210
 211 void GestureDetector::window_resized(unsigned w, unsigned h)
 212 {
 213         threshold_x_sq = 2500.0/(w*w);
 214         threshold_y_sq = 2500.0/(h*h);
 215 }
 216
 217
 218 GestureDetector::TouchPoint::TouchPoint():
 219         down(false),
 220         down_x(0),
 221         down_y(0),
 222         x(0),
 223         y(0)
 224 { }
 225
 226 } // namespace Input
 227 } // namespace Msp