Circle and round trip gestures (#640)

This implements clockwise/anticlockwise circle and round trip gestures
inspired by Messagease.

The circle gestures start after a small threshold to avoid making the
regular swipe too hard to aim.

The gestures do:

- circle: The center symbol with Shift applied, with a fallback on Fn
- round trip: Same as the circle gesture but applied to a side symbol
- anticlockwise circle: Nothing currently. It is intended to be made
  configurable per-layout in the future.

The new Gesture class keeps track of what the pointer is doing while it moves
on a key. It replaces the 'selected_direction' integer.

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;
+  }
+}

srcs/juloo.keyboard2/KeyModifier.java

@@ -33,7 +33,6 @@ public final class KeyModifier
     if (r == null)
     {
       r = k;
-      /* Order: Fn, Shift, accents */
       for (int i = 0; i < n_mods; i++)
         r = modify(r, mods.get(i));
       ks.put(mods, r);
@@ -70,6 +69,7 @@ public final class KeyModifier
       case ALT:
       case META: return turn_into_keyevent(k);
       case FN: return apply_fn(k);
+      case GESTURE: return apply_gesture(k);
       case SHIFT: return apply_shift(k);
       case GRAVE: return apply_map_char(k, map_char_grave);
       case AIGU: return apply_map_char(k, map_char_aigu);
@@ -139,11 +139,10 @@ public final class KeyModifier
       case Char:
         char kc = k.getChar();
         String modified = map.apply(kc);
-        if (modified == null)
-          return k;
-        return KeyValue.makeStringKey(modified, k.getFlags());
-      default: return k;
+        if (modified != null)
+          return KeyValue.makeStringKey(modified, k.getFlags());
     }
+    return k;
   }
 
   private static KeyValue apply_shift(KeyValue k)
@@ -482,6 +481,15 @@ public final class KeyModifier
     return k.withKeyevent(e);
   }
 
+  /** Modify a key affected by a round-trip or a clockwise circle gesture. */
+  private static KeyValue apply_gesture(KeyValue k)
+  {
+    KeyValue shifted = apply_shift(k);
+    if (shifted == null || shifted.equals(k))
+      return apply_fn(k);
+    return shifted;
+  }
+
   /* Lookup the cache entry for a key. Create it needed. */
   private static HashMap<Pointers.Modifiers, KeyValue> cacheEntry(KeyValue k)
   {

srcs/juloo.keyboard2/KeyValue.java

@@ -27,6 +27,7 @@ public final class KeyValue implements Comparable<KeyValue>
   public static enum Modifier
   {
     SHIFT,
+    GESTURE,
     CTRL,
     ALT,
     META,
@@ -54,8 +55,8 @@ public final class KeyValue implements Comparable<KeyValue>
     ARROW_RIGHT,
     BREVE,
     BAR,
-    FN, // Must be placed last to be applied first
-  }
+    FN,
+  } // Last is be applied first
 
   public static enum Editing
   {
@@ -404,6 +405,12 @@ public final class KeyValue implements Comparable<KeyValue>
       return new KeyValue(str, Kind.String, 0, flags | FLAG_SMALLER_FONT);
   }
 
+  /** Make a modifier key for passing to [KeyModifier]. */
+  public static KeyValue makeInternalModifier(Modifier mod)
+  {
+    return new KeyValue("", Kind.Modifier, mod.ordinal(), 0);
+  }
+
   public static KeyValue getKeyByName(String name)
   {
     switch (name)

srcs/juloo.keyboard2/Pointers.java

@@ -143,6 +143,12 @@ public final class Pointers implements Handler.Callback
       return;
     }
     stopKeyRepeat(ptr);
+    KeyValue ptr_value = ptr.value;
+    if (ptr.gesture != null && ptr.gesture.is_in_progress())
+    {
+      // A gesture was in progress
+      ptr.gesture.pointer_up();
+    }
     Pointer latched = getLatched(ptr);
     if (latched != null) // Already latched
     {
@@ -152,7 +158,7 @@ public final class Pointers implements Handler.Callback
       else // Otherwise, unlatch
       {
         removePtr(latched);
-        _handler.onPointerUp(ptr.value, ptr.modifiers);
+        _handler.onPointerUp(ptr_value, ptr.modifiers);
       }
     }
     else if ((ptr.flags & FLAG_P_LATCHABLE) != 0)
@@ -168,7 +174,7 @@ public final class Pointers implements Handler.Callback
     {
       clearLatched();
       removePtr(ptr);
-      _handler.onPointerUp(ptr.value, ptr.modifiers);
+      _handler.onPointerUp(ptr_value, ptr.modifiers);
     }
   }
 
@@ -217,18 +223,15 @@ public final class Pointers implements Handler.Callback
     return k.keys[DIRECTION_TO_INDEX[direction]];
   }
 
-  /*
-   * Get the KeyValue at the given direction. In case of swipe (direction !=
-   * null), get the nearest KeyValue that is not key0.
-   * Take care of applying [_handler.onPointerSwipe] to the selected key, this
-   * must be done at the same time to be sure to treat removed keys correctly.
-   * Return [null] if no key could be found in the given direction or if the
-   * selected key didn't change.
+  /**
+   * Get the key nearest to [direction] that is not key0. Take care
+   * of applying [_handler.modifyKey] to the selected key in the same
+   * operation to be sure to treat removed keys correctly.
+   * Return [null] if no key could be found in the given direction or
+   * if the selected key didn't change.
    */
-  private KeyValue getNearestKeyAtDirection(Pointer ptr, Integer direction)
+  private KeyValue getNearestKeyAtDirection(Pointer ptr, int direction)
   {
-    if (direction == null)
-      return _handler.modifyKey(ptr.key.keys[0], ptr.modifiers);
     KeyValue k;
     // [i] is [0, -1, 1, -2, 2, ...]
     for (int i = 0; i > -4; i = (~i>>31) - i)
@@ -261,37 +264,59 @@ public final class Pointers implements Handler.Callback
     float dy = y - ptr.downY;
 
     float dist = Math.abs(dx) + Math.abs(dy);
-    Integer direction;
     if (dist < _config.swipe_dist_px)
     {
-      direction = null;
+      // Pointer is still on the center.
+      if (ptr.gesture == null || !ptr.gesture.is_in_progress())
+        return;
+      // Gesture ended
+      ptr.gesture.moved_to_center();
+      ptr.value = apply_gesture(ptr, ptr.gesture.get_gesture());
+      ptr.flags = 0;
+
     }
     else
-    {
+    { // Pointer is on a quadrant.
       // See [getKeyAtDirection()] for the meaning. The starting point on the
       // circle is the top direction.
       double a = Math.atan2(dy, dx) + Math.PI;
       // a is between 0 and 2pi, 0 is pointing to the left
       // add 12 to align 0 to the top
-      direction = ((int)(a * 8 / Math.PI) + 12) % 16;
-    }
+      int direction = ((int)(a * 8 / Math.PI) + 12) % 16;
+      if (ptr.gesture == null)
+      { // Gesture starts
 
-    if (direction != ptr.selected_direction)
-    {
-      ptr.selected_direction = direction;
-      KeyValue newValue = getNearestKeyAtDirection(ptr, direction);
-      if (newValue != null && !newValue.equals(ptr.value))
-      {
-        ptr.value = newValue;
-        ptr.flags = pointer_flags_of_kv(newValue);
-        // Sliding mode is entered when key5 or key6 is down on a slider key.
-        if (ptr.key.slider &&
-            (newValue.equals(ptr.key.getKeyValue(5))
-             || newValue.equals(ptr.key.getKeyValue(6))))
-        {
-          startSliding(ptr, x);
+        ptr.gesture = new Gesture(direction);
+        KeyValue new_value = getNearestKeyAtDirection(ptr, direction);
+        if (new_value != null)
+        { // Pointer is swiping into a side key.
+
+          ptr.value = new_value;
+          ptr.flags = pointer_flags_of_kv(new_value);
+          // Sliding mode is entered when key5 or key6 is down on a slider key.
+          if (ptr.key.slider &&
+              (new_value.equals(ptr.key.getKeyValue(5))
+               || new_value.equals(ptr.key.getKeyValue(6))))
+          {
+            startSliding(ptr, x);
+          }
+          _handler.onPointerDown(new_value, true);
+        }
+
+      }
+      else if (ptr.gesture.changed_direction(direction))
+      { // Gesture changed state
+        if (!ptr.gesture.is_in_progress())
+        { // Gesture ended
+          stopKeyRepeat(ptr);
+          _handler.onPointerFlagsChanged(true);
+        }
+        else
+        {
+          ptr.value = apply_gesture(ptr, ptr.gesture.get_gesture());
+          restartKeyRepeat(ptr);
+          ptr.flags = 0; // Special behaviors are ignored during a gesture.
         }
-        _handler.onPointerDown(newValue, true);
       }
     }
   }
@@ -395,6 +420,12 @@ public final class Pointers implements Handler.Callback
     }
   }
 
+  private void restartKeyRepeat(Pointer ptr)
+  {
+    stopKeyRepeat(ptr);
+    startKeyRepeat(ptr);
+  }
+
   /** A pointer is repeating. Returns [true] if repeat should continue. */
   private boolean handleKeyRepeat(Pointer ptr)
   {
@@ -447,14 +478,51 @@ public final class Pointers implements Handler.Callback
     return flags;
   }
 
+  // Gestures
+
+  /** Apply a gesture to the current key. */
+  KeyValue apply_gesture(Pointer ptr, Gesture.Name gesture)
+  {
+    switch (gesture)
+    {
+      case None:
+        return ptr.value;
+      case Swipe:
+        return ptr.value;
+      case Roundtrip:
+        return
+          modify_key_with_extra_modifier(
+              ptr,
+              getNearestKeyAtDirection(ptr, ptr.gesture.current_direction()),
+              KeyValue.Modifier.GESTURE);
+      case Circle:
+        return
+          modify_key_with_extra_modifier(ptr, ptr.key.keys[0],
+              KeyValue.Modifier.GESTURE);
+      case Anticircle:
+        return _handler.modifyKey(ptr.key.keys[0], ptr.modifiers);
+    }
+    return ptr.value; // Unreachable
+  }
+
+  KeyValue modify_key_with_extra_modifier(Pointer ptr, KeyValue kv,
+      KeyValue.Modifier extra_mod)
+  {
+    return
+      _handler.modifyKey(kv,
+        ptr.modifiers.with_extra_mod(KeyValue.makeInternalModifier(extra_mod)));
+  }
+
+  // Pointers
+
   private static final class Pointer
   {
     /** -1 when latched. */
     public int pointerId;
     /** The Key pressed by this Pointer */
     public final KeyboardData.Key key;
-    /** Current direction. [null] means not swiping. */
-    public Integer selected_direction;
+    /** Gesture state, see [Gesture]. [null] means the pointer has not moved out of the center region. */
+    public Gesture gesture;
     /** Selected value with [modifiers] applied. */
     public KeyValue value;
     public float downX;
@@ -472,7 +540,7 @@ public final class Pointers implements Handler.Callback
     {
       pointerId = p;
       key = k;
-      selected_direction = null;
+      gesture = null;
       value = v;
       downX = x;
       downY = y;
@@ -602,6 +670,14 @@ public final class Pointers implements Handler.Callback
       return false;
     }
 
+    /** Return a copy of this object with an extra modifier added. */
+    public Modifiers with_extra_mod(KeyValue m)
+    {
+      KeyValue[] newmods = Arrays.copyOf(_mods, _size + 1);
+      newmods[_size] = m;
+      return ofArray(newmods, newmods.length);
+    }
+
     /** Returns the activated modifiers that are not in [m2]. */
     public Iterator<KeyValue> diff(Modifiers m2)
     {