From 014e800e8ac5687b19f9061da87935c5495a7ffe Mon Sep 17 00:00:00 2001
From: Norman Feske <norman.feske@genode-labs.com>
Date: Wed, 6 Mar 2019 10:20:22 +0100
Subject: [PATCH] menu view: immediate hover update on dialog change

This patch improves the hover handling in situations where the dialog
changes under the pointer. Previously, hover changes were reported
as response to user input only, which failed to cover this case. This
became a problem with Sculpt CE's '+' menu, which changes on the fly
when entering/leaving sub menus.

The patch also cleanly separates the hover handling from the focus
handling. Originally, the hovering was reset when the menu view got
unfocused. In situations like Sculpt's '+' menu where the menu view
receives a transient focus only while clicked and gets unfocused on the
button-release event (aka clack), each clack would invalidate the hover
information until a new input event comes in.

Finally, the patch introduces the clear distinction between situations
where the entire dialog is hovered or not. Previously, this state was
somehow implicitly kept by issuing an invalid hover report whenever a
leave event was observed.

Issue #3209
---
 repos/gems/src/app/menu_view/main.cc | 75 ++++++++++++++++++++--------
 1 file changed, 53 insertions(+), 22 deletions(-)

diff --git a/repos/gems/src/app/menu_view/main.cc b/repos/gems/src/app/menu_view/main.cc
index 9ceb4cb0ae..40c2c5604a 100644
--- a/repos/gems/src/app/menu_view/main.cc
+++ b/repos/gems/src/app/menu_view/main.cc
@@ -43,8 +43,19 @@ struct Menu_view::Main
 
 	Nitpicker::Session::View_handle _view_handle = _nitpicker.create_view();
 
+	/**
+	 * Dialog position in screen coordinate space
+	 */
 	Point _position { };
 
+	/**
+	 * Last pointer position at the time of the most recent hovering report,
+	 * in screen coordinate space.
+	 */
+	Point _hovered_position { };
+
+	bool _dialog_hovered = false;
+
 	Area _configured_size { };
 	Area _visible_size { };
 
@@ -120,7 +131,7 @@ struct Menu_view::Main
 
 	Attached_dataspace _input_ds { _env.rm(), _nitpicker.input()->dataspace() };
 
-	Widget::Unique_id _hovered { };
+	Widget::Unique_id _last_reported_hovered { };
 
 	void _handle_config();
 
@@ -154,6 +165,8 @@ struct Menu_view::Main
 
 	Genode::Reporter _hover_reporter = { _env, "hover" };
 
+	void _update_hover_report();
+
 	bool _schedule_redraw = false;
 
 	/**
@@ -190,6 +203,28 @@ struct Menu_view::Main
 };
 
 
+void Menu_view::Main::_update_hover_report()
+{
+	if (!_hover_reporter.enabled())
+		return;
+
+	if (!_dialog_hovered) {
+		Genode::Reporter::Xml_generator xml(_hover_reporter, [&] () { });
+		return;
+	}
+
+	Widget::Unique_id const new_hovered = _root_widget.hovered(_hovered_position);
+
+	if (_last_reported_hovered != new_hovered) {
+
+		Genode::Reporter::Xml_generator xml(_hover_reporter, [&] () {
+			_root_widget.gen_hover_model(xml, _hovered_position); });
+
+		_last_reported_hovered = new_hovered;
+	}
+}
+
+
 void Menu_view::Main::_handle_dialog_update()
 {
 	try {
@@ -204,12 +239,15 @@ void Menu_view::Main::_handle_dialog_update()
 	_dialog_rom.update();
 
 	Xml_node dialog = _dialog_rom.xml();
+
 	if (dialog.has_type("empty"))
 		return;
 
 	_root_widget.update(dialog);
 	_root_widget.size(_root_widget_size());
 
+	_update_hover_report();
+
 	_schedule_redraw = true;
 
 	/*
@@ -247,35 +285,29 @@ void Menu_view::Main::_handle_config()
 
 void Menu_view::Main::_handle_input()
 {
+	Point const orig_hovered_position = _hovered_position;
+	bool  const orig_dialog_hovered   = _dialog_hovered;
+
 	_nitpicker.input()->for_each_event([&] (Input::Event const &ev) {
 		ev.handle_absolute_motion([&] (int x, int y) {
-
-			Point const at = Point(x, y) - _position;
-			Widget::Unique_id const new_hovered = _root_widget.hovered(at);
-
-			if (_hovered != new_hovered) {
-
-				if (_hover_reporter.enabled()) {
-					Genode::Reporter::Xml_generator xml(_hover_reporter, [&] () {
-						_root_widget.gen_hover_model(xml, at);
-					});
-				}
-
-				_hovered = new_hovered;
-			}
+			_dialog_hovered   = true;
+			_hovered_position = Point(x, y) - _position;
 		});
 
 		/*
 		 * Reset hover model when losing the focus
 		 */
-		if (ev.focus_leave() || ev.hover_leave()) {
-			_hovered = Widget::Unique_id();
-
-			if (_hover_reporter.enabled()) {
-				Genode::Reporter::Xml_generator xml(_hover_reporter, [&] () { });
-			}
+		if (ev.hover_leave()) {
+			_dialog_hovered   = false;
+			_hovered_position = Point();
 		}
 	});
+
+	bool const hover_changed = orig_dialog_hovered   != _dialog_hovered
+	                        || orig_hovered_position != _hovered_position;
+
+	if (hover_changed)
+		_update_hover_report();
 }
 
 
@@ -319,7 +351,6 @@ void Menu_view::Main::_handle_frame_timer()
 		else
 			_buffer->reset_surface();
 
-		_root_widget.size(size);
 		_root_widget.position(Point(0, 0));
 
 		// XXX restrict redraw to dirty regions