Core/StringExt: Add IterateOnCodepoints to remove std::u32string allocations

include/Nazara/Core/StringExt.hpp

@@ -10,6 +10,7 @@
 #include <NazaraUtils/Prerequisites.hpp>
 #include <Nazara/Core/Unicode.hpp>
 #include <NazaraUtils/Algorithm.hpp>
+#include <NazaraUtils/FunctionRef.hpp>
 #include <string>
 
 namespace Nz
@@ -35,6 +36,8 @@ namespace Nz
 
 	inline bool IsNumber(std::string_view str);
 
+	NAZARA_CORE_API void IterateOnCodepoints(std::string_view str, FunctionRef<bool(const char32_t* characters, std::size_t characterCount)> callback);
+
 	NAZARA_CORE_API bool MatchPattern(std::string_view str, std::string_view pattern);
 
 	inline std::string NumberToString(long long number, UInt8 radix = 10);

include/Nazara/Utility/Font.hpp

@@ -73,7 +73,7 @@ namespace Nz
 			bool IsValid() const;
 
 			bool Precache(unsigned int characterSize, TextStyleFlags style, float outlineThickness, char32_t character) const;
-			bool Precache(unsigned int characterSize, TextStyleFlags style, float outlineThickness, const std::string& characterSet) const;
+			bool Precache(unsigned int characterSize, TextStyleFlags style, float outlineThickness, std::string_view characterSet) const;
 
 			void SetAtlas(std::shared_ptr<AbstractAtlas> atlas);
 			void SetGlyphBorder(unsigned int borderSize);

src/Nazara/Core/StringExt.cpp

@@ -259,6 +259,29 @@ namespace Nz
 		return {};
 	}
 
+	void IterateOnCodepoints(std::string_view str, FunctionRef<bool(const char32_t* characters, std::size_t characterCount)> callback)
+	{
+		std::array<char32_t, 32> buffer;
+		std::size_t charCount = 0;
+
+		utf8::unchecked::iterator<const char*> it(str.data());
+		utf8::unchecked::iterator<const char*> end(str.data() + str.size());
+		for (; it != end; ++it)
+		{
+			buffer[charCount++] = *it;
+			if (charCount == buffer.size())
+			{
+				if (!callback(&buffer[0], charCount))
+					return;
+
+				charCount = 0;
+			}
+		}
+
+		if (charCount != 0)
+			callback(&buffer[0], charCount);
+	}
+
 	bool MatchPattern(std::string_view str, std::string_view pattern)
 	{
 		if (str.empty() || pattern.empty())

src/Nazara/Utility/Font.cpp

@@ -256,20 +256,20 @@ namespace Nz
 		return PrecacheGlyph(m_glyphes[key], characterSize, style, outlineThickness, character).valid;
 	}
 
-	bool Font::Precache(unsigned int characterSize, TextStyleFlags style, float outlineThickness, const std::string& characterSet) const
+	bool Font::Precache(unsigned int characterSize, TextStyleFlags style, float outlineThickness, std::string_view characterSet) const
 	{
-		///TODO: Itération UTF-8 => UTF-32 sans allocation de buffer (Exposer utf8cpp ?)
+		NazaraAssert(!characterSet.empty(), "empty character set");
-		std::u32string set = ToUtf32String(characterSet);
-		if (set.empty())
-		{
-			NazaraError("Invalid character set");
-			return false;
-		}
 
 		UInt64 key = ComputeKey(characterSize, style, outlineThickness);
 		auto& glyphMap = m_glyphes[key];
-		for (char32_t character : set)
+
-			PrecacheGlyph(glyphMap, characterSize, style, outlineThickness, character);
+		IterateOnCodepoints(characterSet, [&](const char32_t* characters, std::size_t characterCount)
+		{
+			for (std::size_t i = 0; i < characterCount; ++i)
+				PrecacheGlyph(glyphMap, characterSize, style, outlineThickness, characters[i]);
+
+			return true;
+		});
 
 		return true;
 	}

src/Nazara/Utility/RichTextDrawer.cpp

@@ -381,14 +381,6 @@ namespace Nz
 		if (text.empty())
 			return;
 
-		///TODO: Allow iteration on Unicode characters without allocating any buffer
-		std::u32string characters = ToUtf32String(text);
-		if (characters.empty())
-		{
-			NazaraError("Invalid character set");
-			return;
-		}
-
 		char32_t previousCharacter = 0;
 
 		const Font::SizeInfo& sizeInfo = font.GetSizeInfo(characterSize);
@@ -410,9 +402,12 @@ namespace Nz
 			m_lines.back().bounds.height += heightDifference;
 		}
 
-		m_glyphs.reserve(m_glyphs.size() + characters.size() * ((outlineThickness > 0.f) ? 2 : 1));
+		IterateOnCodepoints(text, [&](const char32_t* characters, std::size_t characterCount)
-		for (char32_t character : characters)
 		{
+			for (std::size_t i = 0; i < characterCount; ++i)
+			{
+				char32_t character = characters[i];
+
 				if (previousCharacter != 0)
 					m_drawPos.x += font.GetKerning(characterSize, previousCharacter, character);
 
@@ -490,6 +485,9 @@ namespace Nz
 				m_glyphs.push_back(glyph);
 			}
 
+			return true; //< continue iteration
+		});
+
 		m_bounds.ExtendTo(m_lines.back().bounds);
 
 		m_glyphUpdated = true;

src/Nazara/Utility/SimpleTextDrawer.cpp

@@ -187,19 +187,15 @@ namespace Nz
 		if (text.empty())
 			return;
 
-		///TODO: Allow iteration on Unicode characters without allocating any buffer
-		std::u32string characters = ToUtf32String(text);
-		if (characters.empty())
-		{
-			NazaraError("Invalid character set");
-			return;
-		}
-
 		const Font::SizeInfo& sizeInfo = m_font->GetSizeInfo(m_characterSize);
 
-		m_glyphs.reserve(m_glyphs.size() + characters.size() * ((m_outlineThickness > 0.f) ? 2 : 1));
+
-		for (char32_t character : characters)
+		IterateOnCodepoints(text, [&](const char32_t* characters, std::size_t characterCount)
 		{
+			for (std::size_t i = 0; i < characterCount; ++i)
+			{
+				char32_t character = characters[i];
+				
 				if (m_previousCharacter != 0)
 					m_drawPos.x += m_font->GetKerning(m_characterSize, m_previousCharacter, character);
 
@@ -279,6 +275,9 @@ namespace Nz
 				m_glyphs.push_back(glyph);
 			}
 
+			return true; //< continue iteration
+		});
+
 		m_bounds.ExtendTo(m_lines.back().bounds);
 
 		m_colorUpdated = true;