path: root/olpcgames/pangofont.py

"""Implement Pygame's font interface using Pango for international support

Depends on:

    pygtk (to get the pango context)
    pycairo (for the pango rendering context)
    python-pango (obviously)
    numpy
    (pygame)

As soon as you import this module you have loaded *all* of the above.
You can still use pygame.font until you decide to call install(), which 
will replace pygame.font with this module.

Notes:

    * no ability to load TTF files, PangoFont uses the font files registered 
        with GTK/X to render graphics, it cannot load an arbitrary TTF file.  
        Most non-Sugar Pygame games use bundled TTF files, which means 
        that you will likely need at least some changes to your font handling.
        
        Note, however, that the Pygame Font class is available to load the TTF 
        files, so if you don't want to take advantage of PangoFont for already 
        written code, but want to use it for "system font" operations, you can 
        mix the two.
        
    * metrics are missing, Pango can provide the information, but the more 
        involved metrics system means that translating to the simplified model 
        in Pygame has as of yet not been accomplished.
        
    * better support for "exotic" languages and scripts (which is why we use it)

The main problem with SDL_ttf is that it doesn't handle internationalization 
nearly as well as Pango (in fact, pretty much nothing does). However, it is 
fairly fast and it has a rich interface. You should avoid fonts where possible, 
prerender using Pango for internationalizable text, and use Pango or SDL_ttf 
for text that really needs to be rerendered each frame. (Use SDL_ttf if profiling 
demonstrates that performance is poor with Pango.)

Note:
    Font -- is the original Pygame Font class, which allows you to load 
        fonts from TTF files/filenames
    PangoFont -- is the Pango-specific rendering engine which allows 
        for the more involved cross-lingual rendering operations.
"""
import pango
import logging
import pangocairo
import pygame.rect, pygame.image
import gtk
import struct
from pygame import surface
from pygame.font import Font
from olpcgames import _cairoimage

log = logging.getLogger( 'olpcgames.pangofont' )
##log.setLevel( logging.DEBUG )

# Install myself on top of pygame.font
def install():
    """Replace Pygame's font module with this module"""
    log.info( 'installing' )
    from olpcgames import pangofont
    import pygame
    pygame.font = pangofont
    import sys
    sys.modules["pygame.font"] = pangofont

class PangoFont(object):
    """Base class for a pygame.font.Font-like object drawn by Pango
    
    Attributes of note:
    
        fd -- instances Pango FontDescription object 
        WEIGHT_* -- parameters for use with set_weight
        STYLE_* -- parameters for use with set_style
        
    """
    WEIGHT_BOLD = pango.WEIGHT_BOLD
    WEIGHT_HEAVY = pango.WEIGHT_HEAVY
    WEIGHT_LIGHT = pango.WEIGHT_LIGHT
    WEIGHT_NORMAL = pango.WEIGHT_NORMAL
    WEIGHT_SEMIBOLD = pango.WEIGHT_SEMIBOLD
    WEIGHT_ULTRABOLD = pango.WEIGHT_ULTRABOLD
    WEIGHT_ULTRALIGHT = pango.WEIGHT_ULTRALIGHT
    STYLE_NORMAL = pango.STYLE_NORMAL
    STYLE_ITALIC = pango.STYLE_ITALIC
    STYLE_OBLIQUE = pango.STYLE_OBLIQUE
    def __init__(self, family=None, size=None, bold=False, italic=False, underline=False, fd=None):
        """If you know what pango.FontDescription (fd) you want, pass it in as
        'fd'.  Otherwise, specify any number of family, size, bold, or italic,
        and we will try to match something up for you."""

        # Always set the FontDescription (FIXME - only set it if the user wants
        # to change something?)
        if fd is None:
            fd = pango.FontDescription()
            if family is not None:
                fd.set_family(family)
            if size is not None:
                log.debug( 'Pre-conversion size: %s', size )
                size = int(size*1024)
                log.debug( 'Font size: %s', size, )
                fd.set_size(size) # XXX magic number, pango's scaling
        self.fd = fd
        self.set_bold( bold )
        self.set_italic( italic )
        self.set_underline( underline )

    def render(self, text, antialias=True, color=(255,255,255), background=None ):
        """Render the font onto a new Surface and return it.
        We ignore 'antialias' and use system settings.
        
        text -- (unicode) string with the text to render
        antialias -- attempt to antialias the text or not
        color -- three or four-tuple of 0-255 values specifying rendering 
            colour for the text 
        background -- three or four-tuple of 0-255 values specifying rendering 
            colour for the background, or None for trasparent background
        
        returns a pygame image instance
        """
        log.info( 'render: %r, antialias = %s, color=%s, background=%s', text, antialias, color, background )

        layout = self._createLayout( text )
        # determine pixel size
        (logical, ink) = layout.get_pixel_extents()
        ink = pygame.rect.Rect(ink)

        # Create a new Cairo ImageSurface
        csrf,cctx = _cairoimage.newContext( ink.w, ink.h )
        cctx = pangocairo.CairoContext(cctx)

        # Mangle the colors on little-endian machines. The reason for this 
        # is that Cairo writes native-endian 32-bit ARGB values whereas
        # Pygame expects endian-independent values in whatever format. So we
        # tell our users not to expect transparency here (avoiding the A issue)
        # and we swizzle all the colors around.

        # render onto it
        if background is not None:
            background = _cairoimage.mangle_color( background )
            cctx.set_source_rgba(*background)
            cctx.paint()
        
        log.debug( 'incoming color: %s', color )
        color = _cairoimage.mangle_color( color )
        log.debug( '  translated color: %s', color )

        cctx.new_path()
        cctx.layout_path(layout)
        cctx.set_source_rgba(*color)
        cctx.fill()

        # Create and return a new Pygame Image derived from the Cairo Surface
        return _cairoimage.asImage( csrf )
    
    def set_bold( self, bold=True):
        """Set our font description's weight to "bold" or "normal"
        
        bold -- boolean, whether to set the value to "bold" weight or not 
        """
        if bold:
            self.set_weight(  self.WEIGHT_BOLD )
        else:
            self.set_weight(  self.WEIGHT_NORMAL )
    def set_weight( self, weight ):
        """Explicitly set our pango-style weight value"""
        self.fd.set_weight(  weight )
        return self.get_weight()
    def get_weight( self ):
        """Explicitly get our pango-style weight value"""
        return self.fd.get_weight()
    def get_bold( self ):
        """Return whether our font's weight is bold (or above)"""
        return self.fd.get_weight() >= pango.WEIGHT_BOLD
    
    def set_italic( self, italic=True ):
        """Set our "italic" value (style)"""
        if italic:
            self.set_style( self.STYLE_ITALIC )
        else:
            self.set_style( self.STYLE_NORMAL )
    def set_style( self, style ):
        """Set our font description's pango-style"""
        self.fd.set_style( style )
        return self.fd.get_style()
    def get_style( self ):
        """Get our font description's pango-style"""
        return self.fd.get_style()
    def get_italic( self ):
        """Return whether we are currently italicised"""
        return self.fd.get_style() == self.STYLE_ITALIC # what about oblique?
    
    def set_underline( self, underline=True ):
        """Set our current underlining properly"""
        self.underline = underline
    def get_underline( self ):
        """Retrieve our current underline setting"""
        return self.underline

    def _createLayout( self, text ):
        """Produces a Pango layout describing this text in this font"""
        # create layout
        layout = pango.Layout(gtk.gdk.pango_context_get())
        layout.set_font_description(self.fd)
        if self.underline:
            attrs = layout.get_attributes()
            if not attrs:
                attrs = pango.AttrList()
            attrs.insert(pango.AttrUnderline(pango.UNDERLINE_SINGLE, 0, 32767))
            layout.set_attributes( attrs )
        layout.set_text(text)
        return layout

    def size( self, text ):
        """Determine space required to render given text
        
        returns tuple of (width,height)
        """
        layout = self._createLayout( text )
        (logical, ink) = layout.get_pixel_extents()
        ink = pygame.rect.Rect(ink)
        return (ink.width,ink.height)
    
##    def get_linesize( self ):
##        """Determine inter-line spacing for the font"""
##        font = self.get_context().load_font( self.fd )
##        metrics = font.get_metrics()
##        return pango.PIXELS( metrics.get_ascent() )
##        def get_height( self ):
##        def get_ascent( self ):
##        def get_descent( self ):
        

class SysFont(PangoFont):
    """Construct a PangoFont from a font description (name), size in pixels,
    bold, and italic designation. Similar to SysFont from Pygame."""
    def __init__(self, name, size, bold=False, italic=False):
        fd = pango.FontDescription(name)
        fd.set_absolute_size(size*pango.SCALE)
        if bold:
            fd.set_weight(pango.WEIGHT_BOLD)
        if italic:
            fd.set_style(pango.STYLE_OBLIQUE)
        super(SysFont, self).__init__(fd=fd)

# originally defined a new class, no reason for that...
NotImplemented = NotImplementedError

def match_font(name,bold=False,italic=False):
    """Stub, does not work, use fontByDesc instead"""
    raise NotImplementedError("PangoFont doesn't support match_font directly, use SysFont or .fontByDesc")

def fontByDesc(desc="",bold=False,italic=False):
    """Constructs a FontDescription from the given string representation.
    
The format of the fontByDesc string representation is passed directly 
to the pango.FontDescription constructor and documented at:

    http://www.pygtk.org/docs/pygtk/class-pangofontdescription.html#constructor-pangofontdescription

Bold and italic are provided as a convenience.

The format of the string representation is:

  "[FAMILY-LIST] [STYLE-OPTIONS] [SIZE]"

where FAMILY-LIST is a comma separated list of families optionally terminated by a comma, STYLE_OPTIONS is a whitespace separated list of words where each WORD describes one of style, variant, weight, or stretch, and SIZE is an decimal number (size in points). For example the following are all valid string representations:

  "sans bold 12"
  "serif,monospace bold italic condensed 16"
  "normal 10"

The commonly available font families are: Normal, Sans, Serif and Monospace. The available styles are:
Normal	the font is upright.
Oblique	the font is slanted, but in a roman style.
Italic	the font is slanted in an italic style.

The available weights are:
Ultra-Light	the ultralight weight (= 200)
Light	the light weight (=300)
Normal	the default weight (= 400)
Bold	the bold weight (= 700)
Ultra-Bold	the ultra-bold weight (= 800)
Heavy	the heavy weight (= 900)

The available variants are:
Normal	
Small-Caps	

The available stretch styles are:
Ultra-Condensed	the smallest width
Extra-Condensed	
Condensed	
Semi-Condensed	
Normal	the normal width
Semi-Expanded	
Expanded	
Extra-Expanded	
Ultra-Expanded	the widest width
    """
    fd = pango.FontDescription(name)
    if bold:
        fd.set_weight(pango.WEIGHT_BOLD)
    if italic:
        fd.set_style(pango.STYLE_OBLIQUE)
    return PangoFont(fd=fd)

def get_init():
    """Return boolean indicating whether we are initialised
    
    Always returns True 
    """
    return True

def init():
    """Initialise the module (null operation)"""
    pass

def quit():
    """De-initialise the module (null operation)"""
    pass

def get_default_font():
    """Return default-font specification to be passed to e.g. fontByDesc"""
    return "sans"

def get_fonts():
    """Return the set of all fonts available (currently just 3 generic types)"""
    return ["sans","serif","monospace"]


def stdcolor(color):
    """Produce a 4-element 0.0-1.0 color value from input"""
    def fixlen(color):
        if len(color) == 3:
            return tuple(color) + (255,)
        elif len(color) == 4:
            return color
        else:
            raise TypeError("What sort of color is this: %s" % (color,))
    return [_fixColorBase(x) for x in fixlen(color)]
def _fixColorBase( v ):
    """Return a properly clamped colour in floating-point space"""
    return max((0,min((v,255.0))))/255.0