From 329915ac1bf45f21e5f2ea27b05ba30ccd78915e Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Wed, 18 May 2022 22:45:35 +0300
Subject: [PATCH] Rich text label wip: store cached label state as a series of
 batches of texture views (NB: transparent labels are broken)

---
 libs/ui/include/psemek/ui/label.hpp | 15 +++++++--
 libs/ui/source/label.cpp            | 51 ++++++++++++++++++++---------
 2 files changed, 48 insertions(+), 18 deletions(-)

diff --git a/libs/ui/include/psemek/ui/label.hpp b/libs/ui/include/psemek/ui/label.hpp
index 1c866f06..1ea6c44c 100644
--- a/libs/ui/include/psemek/ui/label.hpp
+++ b/libs/ui/include/psemek/ui/label.hpp
@@ -95,8 +95,19 @@ namespace psemek::ui
 
 		struct cached_state
 		{
-			struct font const * font = nullptr;
-			std::vector<glyph> glyphs;
+			struct image
+			{
+				geom::box<std::size_t, 2> texcoords;
+				geom::box<float, 2> position;
+			};
+
+			struct batch
+			{
+				gfx::texture_2d const * texture;
+				std::vector<image> images;
+			};
+
+			std::vector<batch> batches;
 			geom::vector<float, 2> size{0.f, 0.f};
 		};
 
diff --git a/libs/ui/source/label.cpp b/libs/ui/source/label.cpp
index e3c85cd9..67400fc4 100644
--- a/libs/ui/source/label.cpp
+++ b/libs/ui/source/label.cpp
@@ -103,17 +103,20 @@ namespace psemek::ui
 		if (!cached_state_)
 			update_cached_state();
 
-		if (!cached_state_->font) return;
-
 		auto st = merged_own_style();
 		if (!st) return;
 
 		if (st->text_shadow_offset != geom::vector{0, 0})
-			for (auto & g : cached_state_->glyphs)
-				p.draw_glyph(*(cached_state_->font), g.character, g.position + geom::cast<float>(*st->text_shadow_offset), *st->shadow_color);
+		{
+			auto const offset = geom::cast<float>(*st->text_shadow_offset);
+			for (auto const & batch : cached_state_->batches)
+				for (auto const & image : batch.images)
+					p.draw_image(image.position + offset, gfx::texture_view_2d{batch.texture, image.texcoords}, *st->shadow_color);
+		}
 
-		for (auto & g : cached_state_->glyphs)
-			p.draw_glyph(*(cached_state_->font), g.character, g.position, *st->text_color);
+		for (auto const & batch : cached_state_->batches)
+			for (auto const & image : batch.images)
+				p.draw_image(image.position, gfx::texture_view_2d{batch.texture, image.texcoords}, *st->text_color);
 	}
 
 	void label::on_state_changed()
@@ -142,13 +145,13 @@ namespace psemek::ui
 		auto st = merged_own_style();
 		if (!st) return state;
 
-		state.font = (font_ == font_type::normal) ? st->font.get() : st->bold_font.get();
+		auto font = (font_ == font_type::normal) ? st->font.get() : st->bold_font.get();
 
-		if (!state.font) return state;
+		if (!font) return state;
 
 		shape_options opts;
 		opts.scale = *st->text_scale;
-		auto glyphs = state.font->shape(text_, opts);
+		auto glyphs = font->shape(text_, opts);
 
 		geom::box<float, 2> raw_bbox;
 		for (auto const & g : glyphs)
@@ -159,7 +162,7 @@ namespace psemek::ui
 		if (wrap_)
 		{
 			max_lines = std::isfinite(bbox[1].length())
-				? std::max<std::size_t>(1, std::floor(bbox[1].length() / state.font->size()[1] / (*st->text_scale)))
+				? std::max<std::size_t>(1, std::floor(bbox[1].length() / font->size()[1] / (*st->text_scale)))
 				: std::numeric_limits<std::size_t>::max();
 		}
 
@@ -224,7 +227,7 @@ namespace psemek::ui
 							x_offset = glyphs[el_start - 1].position[0].max;
 
 						char const el_str[] = "...";
-						auto els = state.font->shape(el_str, opts);
+						auto els = font->shape(el_str, opts);
 						for (std::size_t i = el_start; i < line_end; ++i)
 						{
 							glyphs[i] = els[i - el_start];
@@ -283,13 +286,13 @@ namespace psemek::ui
 			switch (valign_)
 			{
 			case valignment::top:
-				offset[1] = bbox[1].min + l * (*st->text_scale) * state.font->size()[1];
+				offset[1] = bbox[1].min + l * (*st->text_scale) * font->size()[1];
 				break;
 			case valignment::center:
-				offset[1] = bbox[1].center() + (l - lines.size() / 2.f) * (*st->text_scale) * state.font->size()[1];
+				offset[1] = bbox[1].center() + (l - lines.size() / 2.f) * (*st->text_scale) * font->size()[1];
 				break;
 			case valignment::bottom:
-				offset[1] = bbox[1].max + (l - lines.size() * 1.f) * (*st->text_scale) * state.font->size()[1];
+				offset[1] = bbox[1].max + (l - lines.size() * 1.f) * (*st->text_scale) * font->size()[1];
 				break;
 			}
 
@@ -301,9 +304,25 @@ namespace psemek::ui
 			}
 		}
 
-		state.glyphs = std::move(glyphs);
+		{
+			auto & batch = state.batches.emplace_back();
+			batch.texture = &font->atlas();
+
+			for (auto const & g : glyphs)
+			{
+				auto tc = font->texcoords(g.character);
+				if (!tc) continue;
+
+				auto & image = batch.images.emplace_back();
+				image.position = g.position;
+				image.position[0] += (std::round(image.position[0].min) - image.position[0].min);
+				image.position[1] += (std::round(image.position[1].min) - image.position[1].min);
+				image.texcoords = geom::cast<std::size_t>(*tc);
+			}
+		}
+
 		state.size[0] = max_line_size;
-		state.size[1] = lines.size() * (*st->text_scale) * state.font->size()[1];
+		state.size[1] = lines.size() * (*st->text_scale) * font->size()[1];
 
 		return state;
 	}