def cairo_render_at(s,loc=None,shape=None,
fontname=None,fontfile=None,size=None,
slant=cairo.FONT_SLANT_NORMAL,
weight=cairo.FONT_WEIGHT_NORMAL,
bg=(0.0,0.0,0.0),fg=(0.9,0.9,0.9)):
"""Render a string using Cairo and the Cairo text rendering interface. Fonts can either be given
as a fontfile or as a fontname. Size should be in pixels (?). You can specify a background and
foreground color as RGB floating point triples. Images are padded by pad pixels on all sides."""
assert loc is not None
assert shape is not None
assert size is not None
w,h = shape
x,y = loc
face = None
if fontfile is not None:
# "/usr/share/fonts/truetype/msttcorefonts/comic.ttf"
if fontfile in facecache:
face = facecache[fontfile]
else:
face = create_cairo_font_face_for_file(fontfile,0)
facecache[fontfile] = face
surface = cairo.ImageSurface(cairo.FORMAT_ARGB32,w,h)
cr = cairo.Context(surface)
if face is not None:
cr.set_font_face(face)
else:
if fontname is None: fontname = "Helvetica"
if type(slant)==str:
if slant[0]=="i": slant = cairo.FONT_SLANT_ITALIC
elif slant[0]=="o": slant = cairo.FONT_SLANT_OBLIQUE
elif slant[0]=="n": slant = cairo.FONT_SLANT_NORMAL
else: raise Exception("bad font slant specification (use n/i/o)")
if type(weight)==str:
if weight[0]=="b": weight = cairo.FONT_WEIGHT_BOLD
elif weight[0]=="n": weight = cairo.FONT_WEIGHT_NORMAL
else: raise Exception("bad font weight specification (use b/n)")
cr.select_font_face(fontname,slant,weight)
if size is not None:
cr.set_font_size(size)
cr.set_source_rgb(*bg)
cr.rectangle(0,0,w,h)
cr.fill()
cr.move_to(x,y)
cr.set_source_rgb(*fg)
cr.show_text(s)
data = surface.get_data()
data = bytearray(data)
a = array(data,'B')
a.shape = (h,w,4)
a = a[:,:,:3]
a = a[:,:,::-1]
return a
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