/*
 *	A Picture Implementation
 *	Nana C++ Library(http://www.nanapro.org)
 *	Copyright(C) 2003-2017 Jinhao(cnjinhao@hotmail.com)
 *
 *	Distributed under the Boost Software License, Version 1.0. 
 *	(See accompanying file LICENSE_1_0.txt or copy at 
 *	http://www.boost.org/LICENSE_1_0.txt)
 *
 *	@file: nana/gui/widgets/picture.cpp
 *	@description:
 *		Used for showing a picture
 */

#include <nana/gui/widgets/picture.hpp>
#include <nana/gui/layout_utility.hpp>
#include <nana/paint/image.hpp>
#include <nana/gui/element.hpp>
#include <nana/gui/detail/widget_content_measurer_interface.hpp>

namespace nana
{
	namespace drawerbase
	{
		namespace picture
		{
			class content_measurer;

			struct implement
			{
				widget* wdg_ptr{nullptr};
				std::unique_ptr<content_measurer> measurer;

				struct gradual_bground_tag
				{
					::nana::color gradual_from;
					::nana::color gradual_to;
					bool	horizontal{true};
				}gradual_bground;

				struct back_image_tag
				{
					paint::image	image;
					rectangle		valid_area;
					::nana::align	align_horz{ ::nana::align::left };
					::nana::align_v align_vert{ ::nana::align_v::top };
					std::unique_ptr<element::bground> bground;	//If it is not a null ptr, the widget is stretchable mode
					bool			stretchable{ false };		//If it is true, the widget is stretchable mode without changing aspect ratio.
				}backimg;

				void draw_background(paint::graphics& graph, const size& dimension)
				{
					if (!API::dev::copy_transparent_background(*wdg_ptr, graph))
					{
						auto const graph_size = graph.size();
						if (dimension.width < graph_size.width || dimension.height < graph_size.height || backimg.image.alpha())
						{
							if (gradual_bground.gradual_from.invisible() || gradual_bground.gradual_to.invisible())
								graph.rectangle(true, wdg_ptr->bgcolor());
							else if (gradual_bground.gradual_from == gradual_bground.gradual_to)
								graph.rectangle(true, gradual_bground.gradual_from);
							else
								graph.gradual_rectangle(::nana::rectangle{graph_size }, gradual_bground.gradual_from, gradual_bground.gradual_to, !gradual_bground.horizontal);
						}
					}
				}
			};

			class content_measurer
				: public dev::widget_content_measurer_interface
			{
			public:
				content_measurer(implement* impl)
					: impl_{impl}
				{}

				std::optional<size> measure(graph_reference /*graph*/, unsigned limit_pixels, bool /*limit_width*/) const override
				{
					//Picture doesn't provide a support of vfit and hfit
					if (!limit_pixels)
					{
						if (impl_->backimg.valid_area.empty())
							return impl_->backimg.image.size();
					}
					return{};
				}

				size extension() const override
				{
					return{};
				}
			private:
				implement* const impl_;
			};

			//class drawer
			drawer::drawer() :impl_(new implement)
			{
				impl_->measurer.reset(new content_measurer{impl_});
			}

			drawer::~drawer()
			{
				delete impl_;
			}

			void drawer::attached(widget_reference& wdg, graph_reference)
			{
				impl_->wdg_ptr = &wdg;
				API::dev::set_measurer(wdg, impl_->measurer.get());
			}

			void drawer::refresh(graph_reference graph)
			{
				auto const graphsize = graph.size();

				auto & backimg = impl_->backimg;

				if (!backimg.bground)
				{
					if (backimg.image.empty())
					{
						impl_->draw_background(graph, {});
						return;
					}

					auto valid_area = backimg.valid_area;
					if (valid_area.empty())
						valid_area.dimension(backimg.image.size());

					//The position where the image to be drawn. 
					::nana::point pos;

					if (backimg.stretchable)
					{
						auto fit_size = fit_zoom(valid_area.dimension(), graphsize);

						if (fit_size.width != graphsize.width)
						{
							switch (backimg.align_horz)
							{
							case ::nana::align::left: break;
							case ::nana::align::center:
								pos.x = (int(graphsize.width) - int(fit_size.width)) / 2;
								break;
							case ::nana::align::right:
								pos.x = int(graphsize.width) - int(fit_size.width);
								break;
							}
						}
						else if (fit_size.height != graphsize.height)
						{
							switch (backimg.align_vert)
							{
							case ::nana::align_v::top: break;
							case ::nana::align_v::center:
								pos.y = (int(graphsize.height) - int(fit_size.height)) / 2;
								break;
							case ::nana::align_v::bottom:
								pos.y = int(graphsize.height) - int(fit_size.height);
								break;
							}
						}

						impl_->draw_background(graph, fit_size);

						backimg.image.stretch(valid_area, graph, ::nana::rectangle{ pos, fit_size });
					}
					else
					{
						switch (backimg.align_horz)
						{
						case ::nana::align::left: break;
						case ::nana::align::center:
							pos.x = (int(graphsize.width) - int(valid_area.width)) / 2;
							break;
						case ::nana::align::right:
							pos.x = int(graphsize.width) - int(valid_area.width);
							break;
						}

						switch (backimg.align_vert)
						{
						case ::nana::align_v::top: break;
						case ::nana::align_v::center:
							pos.y = (int(graphsize.height) - int(valid_area.height)) / 2;
							break;
						case ::nana::align_v::bottom:
							pos.y = int(graphsize.height) - int(valid_area.height);
							break;
						}

						impl_->draw_background(graph, valid_area.dimension());

						backimg.image.paste(valid_area, graph, pos);
					}
				}
				else
				{
					impl_->draw_background(graph, graphsize);

					color invalid_clr_for_call;
					backimg.bground->draw(graph, invalid_clr_for_call, invalid_clr_for_call, rectangle{ graphsize }, element_state::normal);
				}

				graph.setsta();
			}
			//end class drawer
		}//end namespace picture
	}//end namespace drawerbase

	//class picture
		picture::picture(window wd, bool visible)
		{
			create(wd, rectangle(), visible);
		}

		picture::picture(window wd, const nana::rectangle& r, bool visible)
		{
			create(wd, r, visible);
		}

		void picture::load(::nana::paint::image img, const ::nana::rectangle& valid_area)
		{
			internal_scope_guard lock;
			auto& backimg = get_drawer_trigger().impl_->backimg;
			backimg.image = std::move(img);
			backimg.valid_area = valid_area;

			if (backimg.bground)
				backimg.bground->image(backimg.image, true, valid_area);

			API::refresh_window(*this);
		}

		void picture::align(::nana::align horz, align_v vert)
		{
			internal_scope_guard lock;

			auto& backimg = get_drawer_trigger().impl_->backimg;

			if (backimg.align_horz == horz && backimg.align_vert == vert)
				return;

			backimg.align_horz = horz;
			backimg.align_vert = vert;

			API::refresh_window(*this);
		}

		void picture::stretchable(unsigned left, unsigned top, unsigned right, unsigned bottom)
		{
			internal_scope_guard lock;
			auto & backimg = get_drawer_trigger().impl_->backimg;
			if (!backimg.bground)
			{
				backimg.bground.reset(new element::bground);
				backimg.bground->states({ element_state::normal });
				backimg.bground->image(backimg.image, true, backimg.valid_area);
			}

			backimg.bground->stretch_parts(left, top, right, bottom);
			backimg.stretchable = false;

			API::refresh_window(*this);
		}

		void picture::stretchable(bool enables)
		{
			internal_scope_guard lock;

			auto & backimg = get_drawer_trigger().impl_->backimg;
			backimg.bground.reset();

			backimg.stretchable = enables;
			API::refresh_window(*this);
		}

		void picture::set_gradual_background(const ::nana::color& from, const ::nana::color& to, bool horizontal)
		{
			auto & bground = get_drawer_trigger().impl_->gradual_bground;
			bground.gradual_from = from;
			bground.gradual_to = to;
			bground.horizontal = horizontal;

			API::refresh_window(*this);
		}

		void picture::transparent(bool enabled)
		{
			if(enabled)
				API::effects_bground(*this, effects::bground_transparent(0), 0.0);
			else
				API::effects_bground_remove(*this);
		}

		bool picture::transparent() const
		{
			return API::is_transparent_background(*this);
		}
	//end class picture
}//end namespace nana