# Copyright (c) 2008, Humanized, Inc. # All rights reserved. # # Redistribution and use in source and binary forms, with or without # modification, are permitted provided that the following conditions are met: # # 1. Redistributions of source code must retain the above copyright # notice, this list of conditions and the following disclaimer. # # 2. Redistributions in binary form must reproduce the above copyright # notice, this list of conditions and the following disclaimer in the # documentation and/or other materials provided with the distribution. # # 3. Neither the name of Enso nor the names of its contributors may # be used to endorse or promote products derived from this # software without specific prior written permission. # # THIS SOFTWARE IS PROVIDED BY Humanized, Inc. ``AS IS'' AND ANY # EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED # WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE # DISCLAIMED. IN NO EVENT SHALL Humanized, Inc. BE LIABLE FOR ANY # DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES # (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; # LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND # ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS # SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. # ---------------------------------------------------------------------------- # # enso.graphics.font # # ---------------------------------------------------------------------------- """ This module provides a high-level interface for registering and accessing fonts, including their font metrics information, their glyphs, and their rendering. This module requires no initialization or shutdown. """ # ---------------------------------------------------------------------------- # Imports # ---------------------------------------------------------------------------- import cairo # ---------------------------------------------------------------------------- # Fonts # ---------------------------------------------------------------------------- class Font: """ Encapsulates a font face, which describes both a given typeface and style. """ def __init__( self, fileName, size, cairoContext ): """ Creates a Font from the given filename pointing to a TrueType font file, at the given size (in points). """ import os if not os.path.exists( fileName ): raise IOError( "file not found: %s" % fileName ) self.fileName = fileName self.size = size self.cairoContext = cairoContext cairoContext.save() self.loadInto( cairoContext ) # Make our font metrics information visible to the client. ( self.ascent, self.descent, self.height, self.maxXAdvance, self.maxYAdvance ) = cairoContext.font_extents() cairoContext.restore() def getGlyph( self, char ): """ Returns a glyph of the font corresponding to the given Unicode character. """ # TODO: Memoize this function. return FontGlyph( char, self, self.cairoContext ) def getKerningDistance( self, charLeft, charRight ): """ Returns the kerning distance (in points) between the two Unicode characters for this font face. """ # LONGTERM TODO: Get this to work. This may involve modifying # the source code of Cairo. return 0.0 def loadInto( self, cairoContext ): """ Sets the cairo context's current font to this font. """ # Note that we are using our own modified 'interpretation' of # the select_font_face() function here, as outlined in our # modified version of the Cairo FreeType 2 Font Module; see # the file 'cairo-ft-font.c' in our modified version of the # Cairo library for more information. # TODO: Note also that our modified interpretation of the # function takes an 8-bit string, so we need to do any # necessary encoding/transformation from unicode file-paths # here. cairoContext.select_font_face( self.fileName, cairo.FONT_SLANT_NORMAL, cairo.FONT_WEIGHT_NORMAL ) cairoContext.set_font_size( self.size ) # ---------------------------------------------------------------------------- # Font Glyphs # ---------------------------------------------------------------------------- class FontGlyph: """ Encapsulates a glyph of a font face. """ def __init__( self, char, font, cairoContext ): """ Creates the font glyph corresponding to the given Unicode character, using the font specified by the given Font object and the given cairo context. """ # Encode the character to UTF-8 because that's what the cairo # API uses. self.charAsUtf8 = char.encode("UTF-8") self.char = char self.font = font cairoContext.save() self.font.loadInto( cairoContext ) # Make our font glyph metrics information visible to the client. ( xBearing, yBearing, width, height, xAdvance, yAdvance ) = cairoContext.text_extents( self.charAsUtf8 ) # The xMin, xMax, yMin, yMax, and advance attributes are used # here to correspond to their values in this image: # http://freetype.sourceforge.net/freetype2/docs/glyphs/Image3.png self.xMin = xBearing self.xMax = xBearing + width self.yMin = -yBearing + height self.yMax = -yBearing self.advance = xAdvance cairoContext.restore() # ---------------------------------------------------------------------------- # The Font Registry # ---------------------------------------------------------------------------- class FontRegistry: """ This singleton represents a registry of font faces, allowing for a client to simply retrieve a Font object in a particular size and style rather without having to know the location of a specific TrueType file. """ def __init__( self ): """ Initializes the font registry. """ self._registry = {} dummySurface = cairo.ImageSurface( cairo.FORMAT_ARGB32, 1, 1 ) self.cairoContext = cairo.Context( dummySurface ) def register( self, fileName, name, italic=False ): """ Registers the given TrueType font filename as representing the given font name with the given style. """ registryKey = (name, italic) if self._registry.has_key( registryKey ): raise FontAlreadyRegisteredError( registryKey ) else: self._registry[registryKey] = fileName def get( self, name, size, italic=False ): """ Retrieves a Font object corresponding to the given font name at the given size and style. """ # TODO: Memoize this function. registryKey = (name, italic) fileName = self._registry[registryKey] return Font( fileName, size, self.cairoContext ) class FontAlreadyRegisteredError( Exception ): """ Exception raised when the client attempts to register a font when that font has already been registered. """ pass # ---------------------------------------------------------------------------- # Singleton Instance # ---------------------------------------------------------------------------- # The font registry singleton instance. theFontRegistry = FontRegistry()