source/input/gesturedetector.cpp

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