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