From a9de6232de810b21ab6344990761be396faeff08 Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Fri, 20 May 2022 17:05:51 +0300
Subject: [PATCH] Implement underline & strikethrough in ui::label

---
 libs/ui/include/psemek/ui/label.hpp |  3 ++
 libs/ui/source/label.cpp            | 67 +++++++++++++++++++++++++++++
 2 files changed, 70 insertions(+)

diff --git a/libs/ui/include/psemek/ui/label.hpp b/libs/ui/include/psemek/ui/label.hpp
index f998de65..f1adff0e 100644
--- a/libs/ui/include/psemek/ui/label.hpp
+++ b/libs/ui/include/psemek/ui/label.hpp
@@ -106,6 +106,9 @@ namespace psemek::ui
 
 		void update_cached_state() const;
 		cached_state cached_state_for(geom::box<float, 2> const & bbox) const;
+
+		mutable std::shared_ptr<gfx::texture_2d> single_white_pixel_texture_;
+		std::shared_ptr<gfx::texture_2d> single_white_pixel_texture() const;
 	};
 
 }
diff --git a/libs/ui/source/label.cpp b/libs/ui/source/label.cpp
index b11c3e4b..c0e001fe 100644
--- a/libs/ui/source/label.cpp
+++ b/libs/ui/source/label.cpp
@@ -141,6 +141,9 @@ namespace psemek::ui
 
 		auto font = st->text_style->is_set(text_style_flag::bold) ? st->bold_font.get() : st->font.get();
 
+		bool const underline = st->text_style->is_set(text_style_flag::underline);
+		bool const strikethrough = st->text_style->is_set(text_style_flag::strikethrough);
+
 		if (!font) return state;
 
 		shape_options opts;
@@ -242,6 +245,12 @@ namespace psemek::ui
 
 		float max_line_size = 0.f;
 
+		float const underline_width = *(st->text_scale);
+		float const strikethrough_width = *(st->text_scale);
+
+		std::vector<geom::box<float, 2>> underline_box(lines.size());
+		std::vector<geom::box<float, 2>> strikethrough_box(lines.size());
+
 		for (std::size_t l = 0; l < lines.size(); ++l)
 		{
 			geom::interval<float> x_range;
@@ -290,6 +299,14 @@ namespace psemek::ui
 				break;
 			}
 
+			underline_box[l][0] = x_range + offset[0];
+			underline_box[l][1].min = offset[1] + font->size()[1] * (*st->text_scale);
+			underline_box[l][1].max = underline_box[l][1].min + underline_width;
+
+			strikethrough_box[l][0] = x_range + offset[0];
+			strikethrough_box[l][1].min = offset[1] + font->size()[1] * (*st->text_scale) / 2.f;
+			strikethrough_box[l][1].max = strikethrough_box[l][1].min + strikethrough_width;
+
 			for (std::size_t i = lines[l].first; i < lines[l].second; ++i)
 			{
 				glyphs[i].position += offset;
@@ -315,10 +332,60 @@ namespace psemek::ui
 			}
 		}
 
+		if (underline)
+		{
+			auto & batch = state.batches.emplace_back();
+			batch.texture = single_white_pixel_texture().get();
+
+			for (auto const & u : underline_box)
+			{
+				auto & image = batch.images.emplace_back();
+				image.position = u;
+				image.texcoords = {{{0.f, 1.f}, {0.f, 1.f}}};
+			}
+		}
+
+		if (strikethrough)
+		{
+			auto & batch = state.batches.emplace_back();
+			batch.texture = single_white_pixel_texture().get();
+
+			for (auto const & u : strikethrough_box)
+			{
+				auto & image = batch.images.emplace_back();
+				image.position = u;
+				image.texcoords = {{{0.f, 1.f}, {0.f, 1.f}}};
+			}
+		}
+
 		state.size[0] = max_line_size;
 		state.size[1] = lines.size() * (*st->text_scale) * font->size()[1];
 
 		return state;
 	}
 
+	std::shared_ptr<gfx::texture_2d> label::single_white_pixel_texture() const
+	{
+		static std::weak_ptr<gfx::texture_2d> texture;
+
+		if (!single_white_pixel_texture_)
+		{
+			std::shared_ptr<gfx::texture_2d> ptr;
+
+			if (!(ptr = texture.lock()))
+			{
+				ptr = std::make_shared<gfx::texture_2d>();
+
+				gfx::pixmap_rgba pm({1, 1}, {255, 255, 255, 255});
+				ptr->load(pm);
+				ptr->nearest_filter();
+				texture = ptr;
+			}
+
+			single_white_pixel_texture_ = ptr;
+		}
+
+		return single_white_pixel_texture_;
+	}
+
 }