source/input/gesturedetector.cpp

   1 #include "gesturedetector.h"
   2 #define _USE_MATH_DEFINES
   3 #include <cmath>
   4 #include <sigc++/bind_return.h>
   5 #include "touchscreen.h"
   6
   7 using namespace std;
   8
   9 namespace Msp {
  10 namespace Input {
  11
  12 GestureDetector::GestureDetector(Touchscreen &ts):
  13         Device(UNSPECIFIED),
  14         touchscreen(ts),
  15         current_gesture(GESTURE_NONE),
  16         pending_tap(GESTURE_NONE),
  17         invalid_gesture(false)
  18 {
  19         name = "Gesture";
  20
  21         touchscreen.signal_button_press.connect(sigc::bind_return(sigc::mem_fun(this, &GestureDetector::touch_down), false));
  22         touchscreen.signal_button_release.connect(sigc::bind_return(sigc::mem_fun(this, &GestureDetector::touch_up), false));
  23         touchscreen.signal_axis_motion.connect(sigc::bind_return(sigc::mem_fun(this, &GestureDetector::touch_move), false));
  24         Graphics::Window &window = touchscreen.get_window();
  25         window.signal_resize.connect(sigc::mem_fun(this, &GestureDetector::window_resized));
  26         window_resized(window.get_width(), window.get_height());
  27 }
  28
  29 string GestureDetector::get_button_name(unsigned btn) const
  30 {
  31         if(btn==GESTURE_TAP)
  32                 return "Tap";
  33         else if(btn==GESTURE_TAP_2)
  34                 return "Two-finger tap";
  35         else if(btn==GESTURE_TAP_3)
  36                 return "Three-finger tap";
  37         else if(btn==GESTURE_DRAG)
  38                 return "Drag";
  39         else if(btn==GESTURE_DRAG_2)
  40                 return "Two-finger drag";
  41         else if(btn==GESTURE_DRAG_3)
  42                 return "Three-finger drag";
  43         else if(btn==GESTURE_PINCH)
  44                 return "Pinch";
  45         else if(btn==GESTURE_ROTATE)
  46                 return "Rotate";
  47         else
  48                 return Device::get_button_name(btn);
  49 }
  50
  51 string GestureDetector::get_axis_name(unsigned axis) const
  52 {
  53         if(axis==0)
  54                 return "X";
  55         else if(axis==1)
  56                 return "Y";
  57         else if(axis==2)
  58                 return "Delta X";
  59         else if(axis==3)
  60                 return "Delta Y";
  61         else
  62                 return Device::get_axis_name(axis);
  63 }
  64
  65 void GestureDetector::touch_down(unsigned btn)
  66 {
  67         if(btn>=MAX_POINTS)
  68                 return;
  69
  70         TouchPoint &p = points[btn];
  71         p.down = true;
  72         p.down_x = p.x;
  73         p.down_y = p.y;
  74         p.x = 0;
  75         p.y = 0;
  76         p.threshold_exceeded = false;
  77
  78         if(current_gesture==GESTURE_NONE && !invalid_gesture)
  79         {
  80                 if(btn==0)
  81                         pending_tap = GESTURE_TAP;
  82                 else if(btn==1)
  83                         pending_tap = GESTURE_TAP_2;
  84                 else if(btn==2)
  85                         pending_tap = GESTURE_TAP_3;
  86         }
  87 }
  88
  89 void GestureDetector::touch_up(unsigned btn)
  90 {
  91         if(btn>=MAX_POINTS)
  92                 return;
  93
  94         TouchPoint &p = points[btn];
  95         p.x += p.down_x;
  96         p.y += p.down_y;
  97         p.down = false;
  98
  99         if(btn<gesture_points(current_gesture))
 100                 end_gesture();
 101
 102         if(current_gesture==GESTURE_NONE)
 103         {
 104                 // New gesture can't start until all points have been released.
 105                 invalid_gesture = false;
 106                 for(unsigned i=0; (i<MAX_POINTS && !invalid_gesture); ++i)
 107                         invalid_gesture = points[i].down;
 108
 109                 if(!invalid_gesture && pending_tap!=GESTURE_NONE)
 110                 {
 111                         set_gesture_location(gesture_points(pending_tap));
 112                         set_button_state(pending_tap, true, true);
 113                         set_button_state(pending_tap, false, true);
 114
 115                         pending_tap = GESTURE_NONE;
 116                 }
 117         }
 118 }
 119
 120 void GestureDetector::touch_move(unsigned axis, float value, float)
 121 {
 122         if(axis>=MAX_POINTS*2)
 123                 return;
 124
 125         unsigned i = axis>>1;
 126         TouchPoint &p = points[i];
 127         // Track relative position when pressed, absolute when not.
 128         if(axis&1)
 129                 p.y = (p.down ? value-p.down_y : value);
 130         else
 131                 p.x = (p.down ? value-p.down_x : value);
 132
 133         if(p.down)
 134         {
 135                 if(p.x*p.x/threshold_x_sq+p.y*p.y/threshold_y_sq>=1)
 136                 {
 137                         p.threshold_exceeded = true;
 138                         pending_tap = GESTURE_NONE;
 139                 }
 140
 141                 if(current_gesture==GESTURE_NONE && !invalid_gesture)
 142                         start_gesture();
 143                 else if(i<gesture_points(current_gesture))
 144                         update_progress();
 145         }
 146 }
 147
 148 void GestureDetector::start_gesture()
 149 {
 150         TouchPoint &p = points[0];
 151         if(!p.down)
 152                 return;
 153
 154         /* All held points need to have moved more than the threshold to start the
 155         gesture. */
 156         bool threshold_exceeded = true;
 157         for(unsigned i=0; (i<MAX_POINTS && threshold_exceeded); ++i)
 158                 if(points[i].down && !points[i].threshold_exceeded)
 159                         threshold_exceeded = false;
 160         if(!threshold_exceeded)
 161                 return;
 162
 163         invalid_gesture = false;
 164         if(points[2].down)
 165         {
 166                 bool same_direction = true;
 167                 for(unsigned i=0; (same_direction && i<2); ++i)
 168                         for(unsigned j=i+1; (same_direction && j<3); ++j)
 169                         {
 170                                 TouchPoint &pi = points[i];
 171                                 TouchPoint &pj = points[j];
 172                                 same_direction = ((pi.x*pj.x+pi.y*pj.y)>2*abs(pi.x*pj.y-pi.y*pj.x));
 173                         }
 174
 175                 if(same_direction)
 176                         current_gesture = GESTURE_DRAG_3;
 177         }
 178         else if(points[1].down)
 179         {
 180                 TouchPoint &p2 = points[1];
 181                 float ddx = p.down_x-p2.down_x;
 182                 float ddy = p.down_y-p2.down_y;
 183                 float away = p.x*ddx+p.y*ddy;
 184                 float turn = p.y*ddx-p.x*ddy;
 185                 float away2 = -(p2.x*ddx+p2.y*ddy);
 186                 float turn2 = -(p2.y*ddx-p2.x*ddy);
 187                 if(away*away2>0 && abs(away)>abs(turn) && abs(away2)>abs(turn2))
 188                         /* If the points moved away from or towards each other without rotating
 189                         significantly, it's a pinch gesture. */
 190                         current_gesture = GESTURE_PINCH;
 191                 else if(turn*turn2>0 && abs(turn)>abs(away) && abs(turn2)>abs(away2))
 192                         /* If the points both turned in the same direction without significant
 193                         changes in distance, it's a rotate gesture. */
 194                         current_gesture = GESTURE_ROTATE;
 195                 else if((p.x*p2.x+p.y*p2.y)>2*abs(p.x*p2.y-p.y*p2.x))
 196                         // If both points moved in the same direction, it's a two-finger drag.
 197                         current_gesture = GESTURE_DRAG_2;
 198         }
 199         else
 200                 current_gesture = GESTURE_DRAG;
 201
 202         if(current_gesture!=GESTURE_NONE)
 203         {
 204                 set_gesture_location(gesture_points(current_gesture));
 205                 update_progress();
 206                 set_button_state(current_gesture, true, true);
 207         }
 208         else
 209                 invalid_gesture = true;
 210 }
 211
 212 void GestureDetector::set_gesture_location(unsigned n_points)
 213 {
 214         float x = 0;
 215         float y = 0;
 216         for(unsigned i=0; i<n_points; ++i)
 217         {
 218                 x += points[i].down_x;
 219                 y += points[i].down_y;
 220         }
 221
 222         set_axis_value(0, x/n_points, true);
 223         set_axis_value(1, y/n_points, true);
 224 }
 225
 226 void GestureDetector::set_gesture_delta(unsigned n_points)
 227 {
 228         float x = 0;
 229         float y = 0;
 230         for(unsigned i=0; i<n_points; ++i)
 231         {
 232                 x += points[i].x;
 233                 y += points[i].y;
 234         }
 235
 236         set_axis_value(2, x/n_points, true);
 237         set_axis_value(3, y/n_points, true);
 238 }
 239
 240 void GestureDetector::update_progress()
 241 {
 242         if(current_gesture>=GESTURE_DRAG && current_gesture<=GESTURE_DRAG_3)
 243                 set_gesture_delta(gesture_points(current_gesture));
 244         else if(current_gesture==GESTURE_PINCH || current_gesture==GESTURE_ROTATE)
 245         {
 246                 TouchPoint &p = points[0];
 247                 TouchPoint &p2 = points[1];
 248                 /* Pinch progress is the ratio between the current distance of the points
 249                 and their distance when they were pressed. */
 250                 float ddx = p.down_x-p2.down_x;
 251                 float ddy = p.down_y-p2.down_y;
 252                 float dx = ddx+p.x-p2.x;
 253                 float dy = ddy+p.y-p2.y;
 254                 if(current_gesture==GESTURE_PINCH)
 255                 {
 256                         set_axis_value(2, sqrt(dx*dx+dy*dy)/sqrt(ddx*ddx+ddy*ddy)-1, true);
 257                         set_axis_value(3, 0, true);
 258                 }
 259                 else if(current_gesture==GESTURE_ROTATE)
 260                 {
 261                         set_axis_value(2, atan2(dy*ddx-dx*ddy, dx*ddx+dy*ddy)/M_PI/2, true);
 262                         set_axis_value(3, 0, true);
 263                 }
 264         }
 265 }
 266
 267 void GestureDetector::end_gesture()
 268 {
 269         set_button_state(current_gesture, false, true);
 270         set_axis_value(2, 0, false);
 271         current_gesture = GESTURE_NONE;
 272         pending_tap = GESTURE_NONE;
 273 }
 274
 275 void GestureDetector::window_resized(unsigned w, unsigned h)
 276 {
 277         threshold_x_sq = 2500.0/(w*w);
 278         threshold_y_sq = 2500.0/(h*h);
 279 }
 280
 281
 282 GestureDetector::TouchPoint::TouchPoint():
 283         down(false),
 284         down_x(0),
 285         down_y(0),
 286         x(0),
 287         y(0),
 288         threshold_exceeded(false)
 289 { }
 290
 291
 292 unsigned gesture_points(Gesture gesture)
 293 {
 294         switch(gesture)
 295         {
 296         case GESTURE_NONE: return 0;
 297         case GESTURE_TAP: return 1;
 298         case GESTURE_TAP_2: return 2;
 299         case GESTURE_TAP_3: return 3;
 300         case GESTURE_DRAG: return 1;
 301         case GESTURE_DRAG_2: return 2;
 302         case GESTURE_DRAG_3: return 3;
 303         case GESTURE_PINCH: return 2;
 304         case GESTURE_ROTATE: return 2;
 305         default: throw invalid_argument("gesture_points");
 306         }
 307 }
 308
 309 } // namespace Input
 310 } // namespace Msp