Method initialiseFreeType

MyGUIEngine/src/MyGUI_ResourceTrueTypeFont.cpp:467–770

	template<bool LAMode, bool Antialias>
	void ResourceTrueTypeFont::initialiseFreeType()
	{
		//-------------------------------------------------------------------//
		// Initialise FreeType and load the font.
		//-------------------------------------------------------------------//

		FT_Library ftLibrary;

		if (FT_Init_FreeType(&ftLibrary) != 0)
			MYGUI_EXCEPT("ResourceTrueTypeFont: Could not init the FreeType library!");

		uint8* fontBuffer = nullptr;

		FT_Face ftFace = loadFace(ftLibrary, fontBuffer);

		if (ftFace == nullptr)
		{
			MYGUI_LOG(Error, "ResourceTrueTypeFont: Could not load the font '" << getResourceName() << "'!");
			FT_Done_FreeType(ftLibrary);
			return;
		}

	#ifdef MYGUI_MSDF_FONTS
		msdfgen::FontHandle* msdfFont = nullptr;

		if (mMsdfMode)
		{
			msdfFont = msdfgen::adoptFreetypeFont(ftFace);
		}
	#endif

		//-------------------------------------------------------------------//
		// Calculate the font metrics.
		//-------------------------------------------------------------------//

		// The font's overall ascent and descent are defined in three different places in a TrueType font, and with different
		// values in each place. The most reliable source for these metrics is usually the "usWinAscent" and "usWinDescent" pair of
		// values in the OS/2 header; however, some fonts contain inaccurate data there. To be safe, we use the highest of the set
		// of values contained in the face metrics and the two sets of values contained in the OS/2 header.
		int fontAscent = ftFace->size->metrics.ascender >> 6;
		int fontDescent = -ftFace->size->metrics.descender >> 6;

		TT_OS2* os2 = (TT_OS2*)FT_Get_Sfnt_Table(ftFace, ft_sfnt_os2);

		if (os2 != nullptr)
		{
			setMax(fontAscent, os2->usWinAscent * ftFace->size->metrics.y_ppem / ftFace->units_per_EM);
			setMax(fontDescent, os2->usWinDescent * ftFace->size->metrics.y_ppem / ftFace->units_per_EM);

			setMax(fontAscent, os2->sTypoAscender * ftFace->size->metrics.y_ppem / ftFace->units_per_EM);
			setMax(fontDescent, -os2->sTypoDescender * ftFace->size->metrics.y_ppem / ftFace->units_per_EM);
		}

		// The nominal font height is calculated as the sum of its ascent and descent as specified by the font designer. Previously
		// it was defined by MyGUI in terms of the maximum ascent and descent of the glyphs currently in use, but this caused the
		// font's line spacing to change whenever glyphs were added to or removed from the font definition. Doing it this way
		// instead prevents a lot of layout problems, and it is also more typographically correct and more aesthetically pleasing.
		mDefaultHeight = fontAscent + fontDescent;