Selection mode (#913)

* Selection mode: Space to cancel the selection

This adds the "selection mode", which is activated when text is selected
in the text box. The selection mode is exited when the selection is
cleared.

While the selection mode is activated, the Space and Esc keys are
modified into the "selection cancel" key, which remove the selection
without changing the text.
The space bar is otherwise easy to type by accident during a selection
and causes the selected text to be deleted.

* Selection mode: Move each ends of selection separately with slider

When the selection mode is activated, the space bar sliders change how
they affect the selection:

- The left side of the slider moves the left position of the selection.
  To shrink the selection from the left side, the slider must be
  activated by sliding to the left, extending the selection
  temporarilly, then by sliding to the right.

- The right side of the slider affects the right position if the
  selection.

1 files changed, 62 insertions, 13 deletions

diff --git a/srcs/juloo.keyboard2/KeyEventHandler.java b/srcs/juloo.keyboard2/KeyEventHandler.java
index 30282c7..0dd7f87 100644
--- a/srcs/juloo.keyboard2/KeyEventHandler.java
+++ b/srcs/juloo.keyboard2/KeyEventHandler.java
@@ -242,6 +242,7 @@ public final class KeyEventHandler
       case AUTOFILL: send_context_menu_action(android.R.id.autofill); break;
       case DELETE_WORD: send_key_down_up(KeyEvent.KEYCODE_DEL, KeyEvent.META_CTRL_ON | KeyEvent.META_CTRL_LEFT_ON); break;
       case FORWARD_DELETE_WORD: send_key_down_up(KeyEvent.KEYCODE_FORWARD_DEL, KeyEvent.META_CTRL_ON | KeyEvent.META_CTRL_LEFT_ON); break;
+      case SELECTION_CANCEL: cancel_selection(); break;
     }
   }
 
@@ -259,15 +260,17 @@ public final class KeyEventHandler
     return conn.getExtractedText(_move_cursor_req, 0);
   }
 
-  /** [repeatition] might be negative, in which case the direction is reversed. */
-  void handle_slider(KeyValue.Slider s, int repeatition)
+  /** [r] might be negative, in which case the direction is reversed. */
+  void handle_slider(KeyValue.Slider s, int r)
   {
     switch (s)
     {
-      case Cursor_left: move_cursor(-repeatition); break;
-      case Cursor_right: move_cursor(repeatition); break;
-      case Cursor_up: move_cursor_vertical(-repeatition); break;
-      case Cursor_down: move_cursor_vertical(repeatition); break;
+      case Cursor_left: move_cursor(-r); break;
+      case Cursor_right: move_cursor(r); break;
+      case Cursor_up: move_cursor_vertical(-r); break;
+      case Cursor_down: move_cursor_vertical(r); break;
+      case Selection_cursor_left: move_cursor_sel(r, true); break;
+      case Selection_cursor_right: move_cursor_sel(r, false); break;
     }
   }
 
@@ -281,12 +284,7 @@ public final class KeyEventHandler
     if (conn == null)
       return;
     ExtractedText et = get_cursor_pos(conn);
-    int system_mods =
-      KeyEvent.META_CTRL_ON | KeyEvent.META_ALT_ON | KeyEvent.META_META_ON;
-    // Fallback to sending key events if system modifiers are activated or
-    // ExtractedText is not supported, for example on Termux.
-    if (!_move_cursor_force_fallback && et != null
-        && (_meta_state & system_mods) == 0)
+    if (et != null && can_set_selection(conn))
     {
       int sel_start = et.selectionStart;
       int sel_end = et.selectionEnd;
@@ -305,8 +303,45 @@ public final class KeyEventHandler
           sel_start = sel_end;
       }
       if (conn.setSelection(sel_start, sel_end))
-        return; // [setSelection] succeeded, don't fallback to key events
+        return; // Fallback to sending key events if [setSelection] failed
+    }
+    move_cursor_fallback(d);
+  }
+
+  /** Move one of the two side of a selection. If [sel_left] is true, the left
+      position is moved, otherwise the right position is moved. */
+  void move_cursor_sel(int d, boolean sel_left)
+  {
+    InputConnection conn = _recv.getCurrentInputConnection();
+    if (conn == null)
+      return;
+    ExtractedText et = get_cursor_pos(conn);
+    if (et != null && can_set_selection(conn))
+    {
+      int sel_start = et.selectionStart;
+      int sel_end = et.selectionEnd;
+      if (sel_left == (sel_start <= sel_end))
+        sel_start += d;
+      else
+        sel_end += d;
+      if (conn.setSelection(sel_start, sel_end))
+        return; // Fallback to sending key events if [setSelection] failed
     }
+    move_cursor_fallback(d);
+  }
+
+  /** Returns whether the selection can be set using [conn.setSelection()].
+      This can happen on Termux or when system modifiers are activated for
+      example. */
+  boolean can_set_selection(InputConnection conn)
+  {
+    final int system_mods =
+      KeyEvent.META_CTRL_ON | KeyEvent.META_ALT_ON | KeyEvent.META_META_ON;
+    return !_move_cursor_force_fallback && (_meta_state & system_mods) == 0;
+  }
+
+  void move_cursor_fallback(int d)
+  {
     if (d < 0)
       send_key_down_up_repeat(KeyEvent.KEYCODE_DPAD_LEFT, -d);
     else
@@ -400,11 +435,25 @@ public final class KeyEventHandler
       send_key_down_up(event_code);
   }
 
+  void cancel_selection()
+  {
+    InputConnection conn = _recv.getCurrentInputConnection();
+    if (conn == null)
+      return;
+    ExtractedText et = get_cursor_pos(conn);
+    if (et == null) return;
+    final int curs = et.selectionStart;
+    // Notify the receiver as Android's [onUpdateSelection] is not triggered.
+    if (conn.setSelection(curs, curs));
+      _recv.selection_state_changed(false);
+  }
+
   public static interface IReceiver
   {
     public void handle_event_key(KeyValue.Event ev);
     public void set_shift_state(boolean state, boolean lock);
     public void set_compose_pending(boolean pending);
+    public void selection_state_changed(boolean selection_is_ongoing);
     public InputConnection getCurrentInputConnection();
     public Handler getHandler();
   }