Allow overriding fonts via media files (#15606)

Co-authored-by: sfan5 <[email protected]>

doc/lua_api.md

@@ -194,7 +194,8 @@ Mod directory structure
     │   │   │   └── another_subfolder
     │   │   └── bar_subfolder
     │   ├── sounds
-    │   ├── media
+    │   ├── fonts
+    │   ├── media
     │   ├── locale
     │   └── <custom data>
     └── another
@@ -265,7 +266,7 @@ The main Lua script. Running this script should register everything it
 wants to register. Subsequent execution depends on Luanti calling the
 registered callbacks.
 
-### `textures`, `sounds`, `media`, `models`, `locale`
+### `textures`, `sounds`, `media`, `models`, `locale`, `fonts`
 
 Media files (textures, sounds, whatever) that will be transferred to the
 client and will be available for use by the mod and translation files for
@@ -278,6 +279,7 @@ Accepted formats are:
     images: .png, .jpg, .tga
     sounds: .ogg vorbis
     models: .x, .b3d, .obj, (since version 5.10:) .gltf, .glb
+    fonts: .ttf, .woff (both since version 5.11, see notes below)
 
 Other formats won't be sent to the client (e.g. you can store .blend files
 in a folder for convenience, without the risk that such files are transferred)
@@ -342,6 +344,28 @@ For example, if your model used an emissive material,
 you should expect that a future version of Luanti may respect this,
 and thus cause your model to render differently there.
 
+#### Custom fonts
+
+You can supply custom fonts in TrueType Font (`.ttf`) or Web Open Font Format (`.woff`) format.
+The former is supported primarily for convenience. The latter is preferred due to its compression.
+
+In the future, having multiple custom fonts and the ability to switch between them is planned,
+but for now this feature is limited to the ability to override Luanti's default fonts via mods.
+It is recommended that this only be used by game mods to set a look and feel.
+
+The stems (file names without extension) are self-explanatory:
+
+* Regular variants:
+  * `regular`
+  * `bold`
+  * `italic`
+  * `bold_italic`
+* Monospaced variants:
+  * `mono`
+  * `mono_bold`
+  * `mono_italic`
+  * `mono_bold_italic`
+
 Naming conventions
 ------------------
 

src/client/client.cpp

@@ -9,6 +9,7 @@
 #include <IFileSystem.h>
 #include <json/json.h>
 #include "client.h"
+#include "client/fontengine.h"
 #include "network/clientopcodes.h"
 #include "network/connection.h"
 #include "network/networkpacket.h"
@@ -361,6 +362,9 @@ Client::~Client()
 	for (auto &csp : m_sounds_client_to_server)
 		m_sound->freeId(csp.first);
 	m_sounds_client_to_server.clear();
+
+	// Go back to our mainmenu fonts
+	g_fontengine->clearMediaFonts();
 }
 
 void Client::connect(const Address &address, const std::string &address_name,
@@ -837,6 +841,13 @@ bool Client::loadMedia(const std::string &data, const std::string &filename,
 		return true;
 	}
 
+	const char *font_ext[] = {".ttf", ".woff", NULL};
+	name = removeStringEnd(filename, font_ext);
+	if (!name.empty()) {
+		g_fontengine->setMediaFont(name, data);
+		return true;
+	}
+
 	errorstream << "Client: Don't know how to load file \""
 		<< filename << "\"" << std::endl;
 	return false;

src/client/fontengine.cpp

@@ -3,18 +3,18 @@
 // Copyright (C) 2010-2014 sapier <sapier at gmx dot net>
 
 #include "fontengine.h"
-#include <cmath>
+
 #include "client/renderingengine.h"
-#include "config.h"
-#include "porting.h"
-#include "filesys.h"
-#include "gettext.h"
 #include "settings.h"
 #include "irrlicht_changes/CGUITTFont.h"
 #include "util/numeric.h" // rangelim
 #include <IGUIEnvironment.h>
 #include <IGUIFont.h>
 
+#include <cmath>
+#include <cstring>
+#include <unordered_set>
+
 /** reference to access font engine, has to be initialized by main */
 FontEngine *g_fontengine = nullptr;
 
@@ -35,7 +35,6 @@ static const char *settings[] = {
 	"dpi_change_notifier", "display_density_factor", "gui_scaling",
 };
 
-/******************************************************************************/
 FontEngine::FontEngine(gui::IGUIEnvironment* env) :
 	m_env(env)
 {
@@ -53,16 +52,14 @@ FontEngine::FontEngine(gui::IGUIEnvironment* env) :
 		g_settings->registerChangedCallback(name, font_setting_changed, this);
 }
 
-/******************************************************************************/
 FontEngine::~FontEngine()
 {
 	g_settings->deregisterAllChangedCallbacks(this);
 
-	cleanCache();
+	clearCache();
 }
 
-/******************************************************************************/
-void FontEngine::cleanCache()
+void FontEngine::clearCache()
 {
 	RecursiveMutexAutoLock l(m_font_mutex);
 
@@ -76,7 +73,6 @@ void FontEngine::cleanCache()
 	}
 }
 
-/******************************************************************************/
 irr::gui::IGUIFont *FontEngine::getFont(FontSpec spec)
 {
 	return getFont(spec, false);
@@ -118,15 +114,13 @@ irr::gui::IGUIFont *FontEngine::getFont(FontSpec spec, bool may_fail)
 	return font;
 }
 
-/******************************************************************************/
 unsigned int FontEngine::getTextHeight(const FontSpec &spec)
 {
 	gui::IGUIFont *font = getFont(spec);
 
 	return font->getDimension(L"Some unimportant example String").Height;
 }
 
-/******************************************************************************/
 unsigned int FontEngine::getTextWidth(const std::wstring &text, const FontSpec &spec)
 {
 	gui::IGUIFont *font = getFont(spec);
@@ -143,7 +137,6 @@ unsigned int FontEngine::getLineHeight(const FontSpec &spec)
 			+ font->getKerning(L'S').Y;
 }
 
-/******************************************************************************/
 unsigned int FontEngine::getDefaultFontSize()
 {
 	return m_default_size[m_currentMode];
@@ -157,7 +150,6 @@ unsigned int FontEngine::getFontSize(FontMode mode)
 	return m_default_size[mode];
 }
 
-/******************************************************************************/
 void FontEngine::readSettings()
 {
 	m_default_size[FM_Standard]  = rangelim(g_settings->getU16("font_size"), 5, 72);
@@ -167,12 +159,9 @@ void FontEngine::readSettings()
 	m_default_bold = g_settings->getBool("font_bold");
 	m_default_italic = g_settings->getBool("font_italic");
 
-	cleanCache();
-	updateFontCache();
-	updateSkin();
+	refresh();
 }
 
-/******************************************************************************/
 void FontEngine::updateSkin()
 {
 	gui::IGUIFont *font = getFont();
@@ -181,15 +170,50 @@ void FontEngine::updateSkin()
 	m_env->getSkin()->setFont(font);
 }
 
-/******************************************************************************/
-void FontEngine::updateFontCache()
+void FontEngine::updateCache()
 {
 	/* the only font to be initialized is default one,
 	 * all others are re-initialized on demand */
 	getFont(FONT_SIZE_UNSPECIFIED, FM_Unspecified);
 }
 
-/******************************************************************************/
+void FontEngine::refresh() {
+	clearCache();
+	updateCache();
+	updateSkin();
+}
+
+void FontEngine::setMediaFont(const std::string &name, const std::string &data)
+{
+	static std::unordered_set<std::string> valid_names {
+		"regular", "bold", "italic", "bold_italic",
+		"mono", "mono_bold", "mono_italic", "mono_bold_italic",
+	};
+	if (!valid_names.count(name)) {
+		warningstream << "Ignoring unrecognized media font: " << name << std::endl;
+		return;
+	}
+
+	constexpr char TTF_MAGIC[5] = {0, 1, 0, 0, 0};
+	if (data.size() < 5 || (memcmp(data.data(), "wOFF", 4) &&
+			memcmp(data.data(), TTF_MAGIC, 5))) {
+		warningstream << "Rejecting media font with unrecognized magic" << std::endl;
+		return;
+	}
+
+	std::string copy = data;
+	irr_ptr<gui::SGUITTFace> face(gui::SGUITTFace::createFace(std::move(copy)));
+	m_media_faces.emplace(name, face);
+	refresh();
+}
+
+void FontEngine::clearMediaFonts()
+{
+	RecursiveMutexAutoLock l(m_font_mutex);
+	m_media_faces.clear();
+	refresh();
+}
+
 gui::IGUIFont *FontEngine::initFont(const FontSpec &spec)
 {
 	assert(spec.mode != FM_Unspecified);
@@ -230,28 +254,55 @@ gui::IGUIFont *FontEngine::initFont(const FontSpec &spec)
 	else
 		path_setting = setting_prefix + "font_path" + setting_suffix;
 
-	std::string fallback_settings[] = {
-		g_settings->get(path_setting),
-		Settings::getLayer(SL_DEFAULTS)->get(path_setting)
-	};
+	std::string media_name = spec.mode == FM_Mono
+			? "mono" + setting_suffix
+			: (setting_suffix.empty() ? "" : setting_suffix.substr(1));
+	if (media_name.empty())
+		media_name = "regular";
 
-	for (const std::string &font_path : fallback_settings) {
-		gui::CGUITTFont *font = gui::CGUITTFont::createTTFont(m_env,
-				font_path.c_str(), size, true, true, font_shadow,
+	auto createFont = [&](gui::SGUITTFace *face) -> gui::CGUITTFont* {
+		auto *font = gui::CGUITTFont::createTTFont(m_env,
+				face, size, true, true, font_shadow,
 				font_shadow_alpha);
 
-		if (!font) {
-			errorstream << "FontEngine: Cannot load '" << font_path <<
-				"'. Trying to fall back to another path." << std::endl;
-			continue;
-		}
+		if (!font)
+			return nullptr;
 
 		if (spec.mode != _FM_Fallback) {
 			FontSpec spec2(spec);
 			spec2.mode = _FM_Fallback;
 			font->setFallback(getFont(spec2, true));
 		}
+
 		return font;
+	};
+
+	auto it = m_media_faces.find(media_name);
+	if (it != m_media_faces.end()) {
+		auto *face = it->second.get();
+		if (auto *font = createFont(face))
+			return font;
+		errorstream << "FontEngine: Cannot load media font '" << media_name <<
+			"'. Falling back to client settings." << std::endl;
+	}
+
+	std::string fallback_settings[] = {
+		g_settings->get(path_setting),
+		Settings::getLayer(SL_DEFAULTS)->get(path_setting)
+	};
+	for (const std::string &font_path : fallback_settings) {
+		infostream << "Creating new font: " << font_path.c_str()
+				<< " " << size << "pt" << std::endl;
+
+		// Grab the face.
+		if (auto *face = irr::gui::SGUITTFace::loadFace(font_path)) {
+			auto *font = createFont(face);
+			face->drop();
+			return font;
+		}
+
+		errorstream << "FontEngine: Cannot load '" << font_path <<
+			"'. Trying to fall back to another path." << std::endl;
 	}
 	return nullptr;
 }

src/client/fontengine.h

@@ -5,6 +5,9 @@
 #pragma once
 
 #include <map>
+#include <unordered_map>
+#include "irr_ptr.h"
+#include "irrlicht_changes/CGUITTFont.h"
 #include "util/basic_macros.h"
 #include "irrlichttypes.h"
 #include "irrString.h" // utf8_to_wide
@@ -66,7 +69,7 @@ class FontEngine
 	/** get text height for a specific font */
 	unsigned int getTextHeight(const FontSpec &spec);
 
-	/** get text width if a text for a specific font */
+	/** get text width of a text for a specific font */
 	unsigned int getTextHeight(
 			unsigned int font_size=FONT_SIZE_UNSPECIFIED,
 			FontMode mode=FM_Unspecified)
@@ -77,7 +80,7 @@ class FontEngine
 
 	unsigned int getTextWidth(const std::wstring &text, const FontSpec &spec);
 
-	/** get text width if a text for a specific font */
+	/** get text width of a text for a specific font */
 	unsigned int getTextWidth(const std::wstring& text,
 			unsigned int font_size=FONT_SIZE_UNSPECIFIED,
 			FontMode mode=FM_Unspecified)
@@ -118,20 +121,26 @@ class FontEngine
 	/** update internal parameters from settings */
 	void readSettings();
 
+	void setMediaFont(const std::string &name, const std::string &data);
+
+	void clearMediaFonts();
+
 private:
 	irr::gui::IGUIFont *getFont(FontSpec spec, bool may_fail);
 
 	/** update content of font cache in case of a setting change made it invalid */
-	void updateFontCache();
+	void updateCache();
 
 	/** initialize a new TTF font */
 	gui::IGUIFont *initFont(const FontSpec &spec);
 
 	/** update current minetest skin with font changes */
 	void updateSkin();
 
-	/** clean cache */
-	void cleanCache();
+	void clearCache();
+
+	/** refresh after fonts have been changed */
+	void refresh();
 
 	/** pointer to irrlicht gui environment */
 	gui::IGUIEnvironment* m_env = nullptr;
@@ -142,6 +151,9 @@ class FontEngine
 	/** internal storage for caching fonts of different size */
 	std::map<unsigned int, irr::gui::IGUIFont*> m_font_cache[FM_MaxMode << 2];
 
+	/** media-provided faces, indexed by filename (without extension) */
+	std::unordered_map<std::string, irr_ptr<gui::SGUITTFace>> m_media_faces;
+
 	/** default font size to use */
 	unsigned int m_default_size[FM_MaxMode];