1 files changed, 141 insertions, 0 deletions
diff --git a/srcs/juloo.keyboard2/Gesture.java b/srcs/juloo.keyboard2/Gesture.java
new file mode 100644
index 0000000..5ee666b
--- /dev/null
+++ b/srcs/juloo.keyboard2/Gesture.java
@@ -0,0 +1,141 @@
+package juloo.keyboard2;
+
+public final class Gesture
+{
+  /** The pointer direction that caused the last state change.
+      Integer from 0 to 15 (included). */
+  int current_dir;
+
+  State state;
+
+  public Gesture(int starting_direction)
+  {
+    current_dir = starting_direction;
+    state = State.Swiped;
+  }
+
+  enum State
+  {
+    Cancelled,
+    Swiped,
+    Rotating_clockwise,
+    Rotating_anticlockwise,
+    Ended_swipe,
+    Ended_center,
+    Ended_clockwise,
+    Ended_anticlockwise
+  }
+
+  enum Name
+  {
+    None,
+    Swipe,
+    Roundtrip,
+    Circle,
+    Anticircle
+  }
+
+  /** Angle to travel before a rotation gesture starts. A threshold too low
+      would be too easy to reach while doing back and forth gestures, as the
+      quadrants are very small. In the same unit as [current_dir] */
+  static final int ROTATION_THRESHOLD = 2;
+
+  /** Return the currently recognized gesture. Return [null] if no gesture is
+      recognized. Might change everytime [changed_direction] return [true]. */
+  public Name get_gesture()
+  {
+    switch (state)
+    {
+      case Cancelled:
+        return Name.None;
+      case Swiped:
+      case Ended_swipe:
+        return Name.Swipe;
+      case Ended_center:
+        return Name.Roundtrip;
+      case Rotating_clockwise:
+      case Ended_clockwise:
+        return Name.Circle;
+      case Rotating_anticlockwise:
+      case Ended_anticlockwise:
+          return Name.Anticircle;
+    }
+    return Name.None; // Unreachable
+  }
+
+  public boolean is_in_progress()
+  {
+    switch (state)
+    {
+      case Swiped:
+      case Rotating_clockwise:
+      case Rotating_anticlockwise:
+        return true;
+    }
+    return false;
+  }
+
+  public int current_direction() { return current_dir; }
+
+  /** The pointer changed direction. Return [true] if the gesture changed
+      state and [get_gesture] return a different value. */
+  public boolean changed_direction(int direction)
+  {
+    int d = dir_diff(current_dir, direction);
+    boolean clockwise = d > 0;
+    switch (state)
+    {
+      case Swiped:
+        if (Math.abs(d) < ROTATION_THRESHOLD)
+          return false;
+        // Start a rotation
+        state = (clockwise) ?
+          State.Rotating_clockwise : State.Rotating_anticlockwise;
+        current_dir = direction;
+        return true;
+      // Check that rotation is not reversing
+      case Rotating_clockwise:
+      case Rotating_anticlockwise:
+        current_dir = direction;
+        if ((state == State.Rotating_clockwise) == clockwise)
+          return false;
+        state = State.Cancelled;
+        return true;
+    }
+    return false;
+  }
+
+  /** Return [true] if [get_gesture] will return a different value. */
+  public boolean moved_to_center()
+  {
+    switch (state)
+    {
+      case Swiped: state = State.Ended_center; return true;
+      case Rotating_clockwise: state = State.Ended_clockwise; return false;
+      case Rotating_anticlockwise: state = State.Ended_anticlockwise; return false;
+    }
+    return false;
+  }
+
+  /** Will not change the gesture state. */
+  public void pointer_up()
+  {
+    switch (state)
+    {
+      case Swiped: state = State.Ended_swipe; break;
+      case Rotating_clockwise: state = State.Ended_clockwise; break;
+      case Rotating_anticlockwise: state = State.Ended_anticlockwise; break;
+    }
+  }
+
+  static int dir_diff(int d1, int d2)
+  {
+    final int n = 16;
+    // Shortest-path in modulo arithmetic
+    if (d1 == d2)
+      return 0;
+    int left = (d1 - d2 + n) % n;
+    int right = (d2 - d1 + n) % n;
+    return (left < right) ? -left : right;
+  }
+}