enso_core: enso/graphics/font.py comparison

comparison enso/graphics/font.py @ 29:47bcdb1de2e8

Added implementation for enso.graphics.font.

author	Atul Varma <varmaa@toolness.com>
date	Sat, 23 Feb 2008 10:33:54 -0600
parents	203d6a15652c
children	605d8cb2728c

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-:cff69f571315
+:47bcdb1de2e8
+# 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()

Mercurial > enso_core

comparison enso/graphics/font.py @ 29:47bcdb1de2e8