Improve selection mode when selection ends cross

Emptying the selection with the spacebar slider puts the selection mode
in an unexpected state. This checks that this doesn't happen.

The selection ends can now cross each other, reversing the selection
order. Special care is made to make sure that the sliders go in the
expected direction.

Pointers is changed to send a `onPointerDown` for the first slider event
instead of a `onPointerHold`. This event is detected in
`KeyEventHandler` and the selection ends are reordered if needed when
sliding again.

srcs/juloo.keyboard2/KeyEventHandler.java

@@ -78,6 +78,11 @@ public final class KeyEventHandler
       case Compose_pending:
         _autocap.stop();
         break;
+      case Slider:
+        // Don't wait for the next key_up and move the cursor right away. This
+        // is called after the trigger distance have been travelled.
+        handle_slider(key.getSlider(), key.getSliderRepeat(), true);
+        break;
       default: break;
     }
   }
@@ -99,7 +104,7 @@ public final class KeyEventHandler
       case Modifier: break;
       case Editing: handle_editing_key(key.getEditing()); break;
       case Compose_pending: _recv.set_compose_pending(true); break;
-      case Slider: handle_slider(key.getSlider(), key.getSliderRepeat()); break;
+      case Slider: handle_slider(key.getSlider(), key.getSliderRepeat(), false); break;
       case Macro: evaluate_macro(key.getMacro()); break;
     }
     update_meta_state(old_mods);
@@ -261,7 +266,7 @@ public final class KeyEventHandler
   }
 
   /** [r] might be negative, in which case the direction is reversed. */
-  void handle_slider(KeyValue.Slider s, int r)
+  void handle_slider(KeyValue.Slider s, int r, boolean key_down)
   {
     switch (s)
     {
@@ -269,8 +274,8 @@ public final class KeyEventHandler
       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;
+      case Selection_cursor_left: move_cursor_sel(r, true, key_down); break;
+      case Selection_cursor_right: move_cursor_sel(r, false, key_down); break;
     }
   }
 
@@ -310,7 +315,7 @@ public final class KeyEventHandler
 
   /** 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)
+  void move_cursor_sel(int d, boolean sel_left, boolean key_down)
   {
     InputConnection conn = _recv.getCurrentInputConnection();
     if (conn == null)
@@ -320,10 +325,23 @@ public final class KeyEventHandler
     {
       int sel_start = et.selectionStart;
       int sel_end = et.selectionEnd;
-      if (sel_left == (sel_start <= sel_end))
-        sel_start += d;
-      else
-        sel_end += d;
+      // Reorder the selection when the slider has just been pressed. The
+      // selection might have been reversed if one end crossed the other end
+      // with a previous slider.
+      if (key_down && sel_start > sel_end)
+      {
+        sel_start = et.selectionEnd;
+        sel_end = et.selectionStart;
+      }
+      do
+      {
+        if (sel_left)
+          sel_start += d;
+        else
+          sel_end += d;
+        // Move the cursor twice if moving it once would make the selection
+        // empty and stop selection mode.
+      } while (sel_start == sel_end);
       if (conn.setSelection(sel_start, sel_end))
         return; // Fallback to sending key events if [setSelection] failed
     }

srcs/juloo.keyboard2/Pointers.java

@@ -306,7 +306,6 @@ public final class Pointers implements Handler.Callback
           // Start sliding mode
           if (new_value.getKind() == KeyValue.Kind.Slider)
             startSliding(ptr, x, y, dx, dy, new_value);
-          _handler.onPointerDown(new_value, true);
         }
 
       }
@@ -469,7 +468,7 @@ public final class Pointers implements Handler.Callback
     stopLongPress(ptr);
     ptr.flags |= FLAG_P_SLIDING;
     ptr.sliding = new Sliding(x, y, dirx, diry, kv.getSlider());
-    _handler.onPointerHold(kv, ptr.modifiers);
+    _handler.onPointerDown(kv, true);
   }
 
   /** Return the [FLAG_P_*] flags that correspond to pressing [kv]. */