Highlight hovered GraphEdit connection by widening the line

Currently, GraphEdit connections are highlighted by tinting the color.
With this change the connections are highlighted by widening the line
by a configurable factor.

doc/classes/GraphEdit.xml

@@ -501,9 +501,6 @@
 		<theme_item name="activity" data_type="color" type="Color" default="Color(1, 1, 1, 1)">
 			Color the connection line is interpolated to based on the activity value of a connection (see [method set_connection_activity]).
 		</theme_item>
-		<theme_item name="connection_hover_tint_color" data_type="color" type="Color" default="Color(0, 0, 0, 0.3)">
-			Color which is blended with the connection line when the mouse is hovering over it.
-		</theme_item>
 		<theme_item name="connection_rim_color" data_type="color" type="Color" default="Color(0.1, 0.1, 0.1, 0.6)">
 			Color of the rim around each connection line used for making intersecting lines more distinguishable.
 		</theme_item>
@@ -522,6 +519,9 @@
 		<theme_item name="selection_stroke" data_type="color" type="Color" default="Color(1, 1, 1, 0.8)">
 			The outline color of the selection rectangle.
 		</theme_item>
+		<theme_item name="connection_hover_thickness" data_type="constant" type="int" default="80">
+			Widen the line of the connection when the mouse is hovering over it by a percentage factor. A value of [code]0[/code] disables the highlight. A value of [code]100[/code] doubles the line width.
+		</theme_item>
 		<theme_item name="port_hotzone_inner_extent" data_type="constant" type="int" default="22">
 			The horizontal range within which a port can be grabbed (inner side).
 		</theme_item>

editor/themes/editor_theme_manager.cpp

@@ -1556,7 +1556,7 @@ void EditorThemeManager::_populate_standard_styles(const Ref<EditorTheme> &p_the
 		p_theme->set_color("selection_stroke", "GraphEdit", p_theme->get_color(SNAME("box_selection_stroke_color"), EditorStringName(Editor)));
 		p_theme->set_color("activity", "GraphEdit", p_config.dark_theme ? Color(1, 1, 1) : Color(0, 0, 0));
 
-		p_theme->set_color("connection_hover_tint_color", "GraphEdit", p_config.dark_theme ? Color(0, 0, 0, 0.3) : Color(1, 1, 1, 0.3));
+		p_theme->set_constant("connection_hover_thickness", "GraphEdit", 80);
 		p_theme->set_color("connection_valid_target_tint_color", "GraphEdit", p_config.dark_theme ? Color(1, 1, 1, 0.4) : Color(0, 0, 0, 0.4));
 		p_theme->set_color("connection_rim_color", "GraphEdit", p_config.tree_panel_style->get_bg_color());
 

scene/gui/graph_edit.cpp

@@ -1436,15 +1436,14 @@ void GraphEdit::_update_connections() {
 			to_color = to_color.lerp(theme_cache.activity_color, c->activity);
 		}
 
-		if (c == hovered_connection) {
-			from_color = from_color.blend(theme_cache.connection_hover_tint_color);
-			to_color = to_color.blend(theme_cache.connection_hover_tint_color);
-		}
-
 		// Update Line2D node.
 		Ref<Gradient> line_gradient = memnew(Gradient);
 
 		float line_width = _get_shader_line_width();
+		if (c == hovered_connection) {
+			line_width *= 1.0f + ((float)theme_cache.connection_hover_thickness / 100.0f);
+		}
+
 		c->_cache.line->set_width(line_width);
 		line_gradient->set_color(0, from_color);
 		line_gradient->set_color(1, to_color);
@@ -2816,7 +2815,7 @@ void GraphEdit::_bind_methods() {
 	BIND_THEME_ITEM(Theme::DATA_TYPE_COLOR, GraphEdit, grid_minor);
 
 	BIND_THEME_ITEM_CUSTOM(Theme::DATA_TYPE_COLOR, GraphEdit, activity_color, "activity");
-	BIND_THEME_ITEM(Theme::DATA_TYPE_COLOR, GraphEdit, connection_hover_tint_color);
+	BIND_THEME_ITEM(Theme::DATA_TYPE_CONSTANT, GraphEdit, connection_hover_thickness);
 	BIND_THEME_ITEM(Theme::DATA_TYPE_COLOR, GraphEdit, connection_valid_target_tint_color);
 	BIND_THEME_ITEM(Theme::DATA_TYPE_COLOR, GraphEdit, connection_rim_color);
 	BIND_THEME_ITEM(Theme::DATA_TYPE_COLOR, GraphEdit, selection_fill);

scene/gui/graph_edit.h

@@ -273,7 +273,7 @@ class GraphEdit : public Control {
 		Color grid_minor;
 
 		Color activity_color;
-		Color connection_hover_tint_color;
+		int connection_hover_thickness;
 		Color connection_valid_target_tint_color;
 		Color connection_rim_color;
 

scene/theme/default_theme.cpp

@@ -1252,7 +1252,7 @@ void fill_default_theme(Ref<Theme> &theme, const Ref<Font> &default_font, const
 	theme->set_color("selection_fill", "GraphEdit", Color(1, 1, 1, 0.3));
 	theme->set_color("selection_stroke", "GraphEdit", Color(1, 1, 1, 0.8));
 	theme->set_color("activity", "GraphEdit", Color(1, 1, 1));
-	theme->set_color("connection_hover_tint_color", "GraphEdit", Color(0, 0, 0, 0.3));
+	theme->set_constant("connection_hover_thickness", "GraphEdit", 80);
 	theme->set_color("connection_valid_target_tint_color", "GraphEdit", Color(1, 1, 1, 0.4));
 	theme->set_color("connection_rim_color", "GraphEdit", style_normal_color);