From 48be0b4b07fbdeb9a6b43c8bdf0066e8fdf3db55 Mon Sep 17 00:00:00 2001
From: Jinhao <cnjinhao@hotmail.com>
Date: Sat, 13 Jan 2018 10:49:37 +0800
Subject: [PATCH] improve visualization of group caption

---
 include/nana/gui/programming_interface.hpp |  2 ++
 source/gui/programming_interface.cpp       |  9 +++++++++
 source/gui/widgets/group.cpp               | 23 +++++++++++++++++++---
 3 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/include/nana/gui/programming_interface.hpp b/include/nana/gui/programming_interface.hpp
index 8c0d85fe..814a98b7 100644
--- a/include/nana/gui/programming_interface.hpp
+++ b/include/nana/gui/programming_interface.hpp
@@ -301,6 +301,8 @@ namespace API
 	void window_size(window, const size&);
 	size window_outline_size(window);
 	void window_outline_size(window, const size&);
+
+	nana::optional<rectangle> window_rectangle(window);
 	bool get_window_rectangle(window, rectangle&);
 	bool track_window_size(window, const size&, bool true_for_max);   ///< Sets the minimum or maximum tracking size of a window.
 	void window_enabled(window, bool);
diff --git a/source/gui/programming_interface.cpp b/source/gui/programming_interface.cpp
index 22e22cac..626803d3 100644
--- a/source/gui/programming_interface.cpp
+++ b/source/gui/programming_interface.cpp
@@ -821,6 +821,15 @@ namespace API
 		}
 	}
 
+	nana::optional<rectangle> window_rectangle(window wd)
+	{
+		auto iwd = reinterpret_cast<basic_window*>(wd);
+		internal_scope_guard lock;
+		if (restrict::wd_manager().available(iwd))
+			return rectangle(iwd->pos_owner, iwd->dimension);
+		return{};
+	}
+
 	bool get_window_rectangle(window wd, rectangle& r)
 	{
 		auto iwd = reinterpret_cast<basic_window*>(wd);
diff --git a/source/gui/widgets/group.cpp b/source/gui/widgets/group.cpp
index ab8e9e73..74d76575 100644
--- a/source/gui/widgets/group.cpp
+++ b/source/gui/widgets/group.cpp
@@ -208,8 +208,8 @@ namespace nana{
 		outter[field_title] << impl_->caption;
 		outter.collocate();
 
+		impl_->caption.transparent(true);
 		color pbg = API::bgcolor(this->parent());
-
 		impl_->caption.bgcolor(pbg.blend(colors::black, 0.025));
 
 		this->bgcolor(pbg.blend(colors::black, 0.05));
@@ -222,10 +222,27 @@ namespace nana{
 			auto gap_px = impl_->gap - 1;
 
 			graph.rectangle(true, API::bgcolor(this->parent()));
-			graph.round_rectangle(rectangle(point(gap_px, impl_->caption_dimension.height / 2),
-				nana::size(graph.width() - 2 * gap_px, graph.height() - impl_->caption_dimension.height / 2 - gap_px)
+
+			auto const top_round_line = static_cast<int>(impl_->caption_dimension.height) / 2;
+
+			graph.round_rectangle(rectangle(point(gap_px, top_round_line),
+				nana::size(graph.width() - 2 * gap_px, graph.height() - top_round_line - gap_px)
 				),
 				3, 3, colors::gray_border, true, this->bgcolor());
+
+			auto opt_r = API::window_rectangle(impl_->caption);
+			if (opt_r)
+			{
+				rectangle grad_r{ opt_r->position(), nana::size{ opt_r->width, static_cast<unsigned>(top_round_line - opt_r->y) } };
+
+				grad_r.y += top_round_line / 2;
+				grad_r.x -= 2;
+				grad_r.width += 4;
+
+				graph.gradual_rectangle(grad_r,
+					API::bgcolor(this->parent()), this->bgcolor(), true
+					);
+			}
 		});
 	}