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