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