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         invalid_gesture(false)
  16 {
  17         name = "Gesture";
  18
  19         touchscreen.signal_button_press.connect(sigc::bind_return(sigc::mem_fun(this, &GestureDetector::touch_down), false));
  20         touchscreen.signal_button_release.connect(sigc::bind_return(sigc::mem_fun(this, &GestureDetector::touch_up), false));
  21         touchscreen.signal_axis_motion.connect(sigc::bind_return(sigc::mem_fun(this, &GestureDetector::touch_move), false));
  22         Graphics::Window &window = touchscreen.get_window();
  23         window.signal_resize.connect(sigc::mem_fun(this, &GestureDetector::window_resized));
  24         window_resized(window.get_width(), window.get_height());
  25 }
  26
  27 string GestureDetector::get_button_name(unsigned btn) const
  28 {
  29         if(btn==GESTURE_DRAG)
  30                 return "Drag";
  31         else if(btn==GESTURE_DRAG_2)
  32                 return "Two-finger drag";
  33         else if(btn==GESTURE_PINCH)
  34                 return "Pinch";
  35         else if(btn==GESTURE_ROTATE)
  36                 return "Rotate";
  37         else
  38                 return Device::get_button_name(btn);
  39 }
  40
  41 string GestureDetector::get_axis_name(unsigned axis) const
  42 {
  43         if(axis==0)
  44                 return "X";
  45         else if(axis==1)
  46                 return "Y";
  47         else if(axis==2)
  48                 return "Progress";
  49         else
  50                 return Device::get_axis_name(axis);
  51 }
  52
  53 void GestureDetector::touch_down(unsigned btn)
  54 {
  55         if(btn>=MAX_POINTS)
  56                 return;
  57
  58         TouchPoint &p = points[btn];
  59         p.down = true;
  60         p.down_x = p.x;
  61         p.down_y = p.y;
  62         p.x = 0;
  63         p.y = 0;
  64         p.threshold_exceeded = false;
  65 }
  66
  67 void GestureDetector::touch_up(unsigned btn)
  68 {
  69         if(btn>=MAX_POINTS)
  70                 return;
  71
  72         TouchPoint &p = points[btn];
  73         p.x += p.down_x;
  74         p.y += p.down_y;
  75         p.down = false;
  76
  77         if(active_points&(1<<btn))
  78                 end_gesture();
  79
  80         if(current_gesture==GESTURE_NONE)
  81         {
  82                 // New gesture can't start until all points have been released.
  83                 invalid_gesture = false;
  84                 for(unsigned i=0; (i<MAX_POINTS && !invalid_gesture); ++i)
  85                         invalid_gesture = points[i].down;
  86         }
  87 }
  88
  89 void GestureDetector::touch_move(unsigned axis, float value, float)
  90 {
  91         if(axis>=MAX_POINTS*2)
  92                 return;
  93
  94         unsigned i = axis>>1;
  95         TouchPoint &p = points[i];
  96         // Track relative position when pressed, absolute when not.
  97         if(axis&1)
  98                 p.y = (p.down ? value-p.down_y : value);
  99         else
 100                 p.x = (p.down ? value-p.down_x : value);
 101
 102         if(p.down)
 103         {
 104                 if(p.x*p.x/threshold_x_sq+p.y*p.y/threshold_y_sq>=1)
 105                         p.threshold_exceeded = true;
 106
 107                 if(current_gesture==GESTURE_NONE && !invalid_gesture)
 108                         start_gesture();
 109                 else if(active_points&(1<<i))
 110                         update_progress();
 111         }
 112 }
 113
 114 void GestureDetector::start_gesture()
 115 {
 116         TouchPoint &p = points[0];
 117         if(!p.down)
 118                 return;
 119
 120         /* At least one point needs to have moved more than the threshold to start
 121         the gesture. */
 122         bool threshold_exceeded = false;
 123         for(unsigned i=0; (i<MAX_POINTS && !threshold_exceeded); ++i)
 124                 threshold_exceeded = (points[i].down && points[i].threshold_exceeded);
 125         if(!threshold_exceeded)
 126                 return;
 127
 128         invalid_gesture = false;
 129         if(points[1].down)
 130         {
 131                 TouchPoint &p2 = points[1];
 132                 float ddx = p.down_x-p2.down_x;
 133                 float ddy = p.down_y-p2.down_y;
 134                 float away = p.x*ddx+p.y*ddy;
 135                 float turn = p.y*ddx-p.x*ddy;
 136                 float away2 = -(p2.x*ddx+p2.y*ddy);
 137                 float turn2 = -(p2.y*ddx-p2.x*ddy);
 138                 if(away*away2>0 && abs(away)>abs(turn) && abs(away2)>abs(turn2))
 139                         /* If the points moved away from or towards each other without rotating
 140                         significantly, it's a pinch gesture. */
 141                         current_gesture = GESTURE_PINCH;
 142                 else if(turn*turn2>0 && abs(turn)>abs(away) && abs(turn2)>abs(away2))
 143                         /* If the points both turned in the same direction without significant
 144                         changes in distance, it's a rotate gesture. */
 145                         current_gesture = GESTURE_ROTATE;
 146                 else if((p.x*p2.x+p.y*p2.y)>2*abs(p.x*p2.y-p.y*p2.x))
 147                         // If both points moved in the same direction, it's a two-finger drag.
 148                         current_gesture = GESTURE_DRAG_2;
 149
 150                 if(current_gesture!=GESTURE_NONE)
 151                 {
 152                         active_points = 3;
 153                         set_axis_value(0, (p.down_x+p2.down_x)/2, true);
 154                         set_axis_value(1, (p.down_y+p2.down_y)/2, true);
 155                 }
 156         }
 157         else
 158         {
 159                 current_gesture = GESTURE_DRAG;
 160                 active_points = 1;
 161                 set_axis_value(0, p.down_x, true);
 162                 set_axis_value(1, p.down_y, true);
 163         }
 164
 165         update_progress();
 166
 167         if(current_gesture!=GESTURE_NONE)
 168                 set_button_state(current_gesture, true, true);
 169         else
 170                 invalid_gesture = true;
 171 }
 172
 173 void GestureDetector::update_progress()
 174 {
 175         TouchPoint &p = points[0];
 176
 177         if(current_gesture==GESTURE_DRAG)
 178         {
 179                 set_axis_value(2, p.x, true);
 180                 set_axis_value(3, p.y, true);
 181         }
 182         else if(current_gesture==GESTURE_DRAG_2)
 183         {
 184                 TouchPoint &p2 = points[1];
 185                 set_axis_value(2, (p.x+p2.x)/2, true);
 186                 set_axis_value(3, (p.y+p2.y)/2, true);
 187         }
 188         else if(current_gesture==GESTURE_PINCH || current_gesture==GESTURE_ROTATE)
 189         {
 190                 TouchPoint &p2 = points[1];
 191                 /* Pinch progress is the ratio between the current distance of the points
 192                 and their distance when they were pressed. */
 193                 float ddx = p.down_x-p2.down_x;
 194                 float ddy = p.down_y-p2.down_y;
 195                 float dx = ddx+p.x-p2.x;
 196                 float dy = ddy+p.y-p2.y;
 197                 if(current_gesture==GESTURE_PINCH)
 198                 {
 199                         set_axis_value(2, sqrt(dx*dx+dy*dy)/sqrt(ddx*ddx+ddy*ddy)-1, true);
 200                         set_axis_value(3, 0, true);
 201                 }
 202                 else if(current_gesture==GESTURE_ROTATE)
 203                 {
 204                         set_axis_value(2, atan2(dy*ddx-dx*ddy, dx*ddx+dy*ddy)/M_PI/2, true);
 205                         set_axis_value(3, 0, true);
 206                 }
 207         }
 208 }
 209
 210 void GestureDetector::end_gesture()
 211 {
 212         set_button_state(current_gesture, false, true);
 213         set_axis_value(2, 0, false);
 214         current_gesture = GESTURE_NONE;
 215         active_points = 0;
 216 }
 217
 218 void GestureDetector::window_resized(unsigned w, unsigned h)
 219 {
 220         threshold_x_sq = 2500.0/(w*w);
 221         threshold_y_sq = 2500.0/(h*h);
 222 }
 223
 224
 225 GestureDetector::TouchPoint::TouchPoint():
 226         down(false),
 227         down_x(0),
 228         down_y(0),
 229         x(0),
 230         y(0)
 231 { }
 232
 233 } // namespace Input
 234 } // namespace Msp