Add skeleton of TextRenderer

Signed-off-by: Slendi <slendi@socopon.com>

src/TextRenderer.cpp

@@ -0,0 +1,104 @@
+#include "TextRenderer.hpp"
+
+#include <cassert>
+#include <cstdlib>
+#include <mutex>
+#include <optional>
+#include <string>
+#include <string_view>
+#include <unordered_map>
+
+#include <fontconfig/fontconfig.h>
+
+#include <raylib.h>
+
+TextRenderer::TextRenderer()
+{
+	static char const msdf_fs_data[] {
+#embed "msdf.fs"
+		, 0
+	};
+	m_msdf_shader = LoadShaderFromMemory(nullptr, msdf_fs_data);
+	assert(IsShaderValid(m_msdf_shader));
+}
+
+TextRenderer::~TextRenderer() { UnloadShader(m_msdf_shader); }
+
+auto TextRenderer::measure_text(FontHandle const font,
+    std::string_view const text, int const size) -> Vector2
+{
+	// FIXME: Implement.
+	return {};
+}
+
+auto TextRenderer::draw_text(FontHandle const font, std::string_view const text,
+    Vector2 const pos, int const size, Color const color) -> void
+{
+	int const pos_x = pos.x;
+	int const pos_y = pos.y;
+	// Don't use pos from here on out!
+	// FIXME: Implement.
+	(void)pos_x, (void)pos_y;
+}
+
+auto TextRenderer::load_font(std::filesystem::path const &path)
+    -> std::optional<FontHandle>
+{
+	// FIXME: Implement.
+	return std::nullopt;
+}
+
+auto TextRenderer::unload_font(FontHandle const font)
+{
+	// FIXME: Implement.
+}
+
+auto find_font_path(std::string_view path)
+    -> std::optional<std::filesystem::path>
+{
+	static std::once_flag fc_once;
+	std::call_once(fc_once, []() {
+		if (FcInit())
+			std::atexit([] { FcFini(); });
+	});
+
+	static std::mutex m;
+	static std::unordered_map<std::string, std::optional<std::string>> cache;
+
+	std::string const key(path);
+
+	{
+		std::scoped_lock lock(m);
+		if (auto it = cache.find(key); it != cache.end())
+			return it->second;
+	}
+
+	FcPattern *pattern
+	    = FcNameParse(reinterpret_cast<FcChar8 const *>(key.c_str()));
+	if (!pattern) {
+		std::scoped_lock lock(m);
+		return cache[key] = std::nullopt;
+	}
+
+	FcConfigSubstitute(nullptr, pattern, FcMatchPattern);
+	FcDefaultSubstitute(pattern);
+
+	FcResult result;
+	FcPattern *font = FcFontMatch(nullptr, pattern, &result);
+
+	std::optional<std::string> final_path;
+	if (font) {
+		FcChar8 *file;
+		if (FcPatternGetString(font, FC_FILE, 0, &file) == FcResultMatch)
+			final_path = reinterpret_cast<char *>(file);
+		FcPatternDestroy(font);
+	}
+
+	FcPatternDestroy(pattern);
+
+	{
+		std::scoped_lock lock(m);
+		cache[key] = final_path;
+	}
+	return final_path;
+}