fgen.py 文件源码

def cairo_render_string(s,fontname=None,fontfile=None,size=None,bg=(0.0,0.0,0.0),fg=(0.9,0.9,0.9),pad=5):
    """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."""
    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

    # make a guess at the size
    w = max(100,int(size*len(s)))
    h = max(100,int(size*1.5))
    # possibly run through twice to make sure we get the right size buffer
    for round in range(2):
        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"
            cr.select_font_face(fontname)
        if size is not None:
            cr.set_font_size(size)
        xbear,ybear,tw,th = cr.text_extents(s)[:4]
        tw += 2*pad
        th += 2*pad
        if tw<=w and th<=h: break
        w = tw
        h = th

    cr.set_source_rgb(*bg)
    cr.rectangle(0,0,w,h)
    cr.fill()
    cr.move_to(-xbear+pad,-ybear+pad)
    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[:th,:tw,:3]
    a = a[:,:,::-1]
    return a