source/input/gesturedetector.cpp

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