def generate(env):
    """Add Builders and construction variables for dvipdf to an Environment."""
    global PDFAction
    if PDFAction is None:
        PDFAction = SCons.Action.Action('$DVIPDFCOM', '$DVIPDFCOMSTR')

    global DVIPDFAction
    if DVIPDFAction is None:
        DVIPDFAction = SCons.Action.Action(DviPdfFunction, strfunction = DviPdfStrFunction)

    from . import pdf
    pdf.generate(env)

    bld = env['BUILDERS']['PDF']
    bld.add_action('.dvi', DVIPDFAction)
    bld.add_emitter('.dvi', PDFEmitter)

    env['DVIPDF']      = 'dvipdf'
    env['DVIPDFFLAGS'] = SCons.Util.CLVar('')
    env['DVIPDFCOM']   = 'cd ${TARGET.dir} && $DVIPDF $DVIPDFFLAGS ${SOURCE.file} ${TARGET.file}'

    # Deprecated synonym.
    env['PDFCOM']      = ['$DVIPDFCOM']
Add Builders and construction variables for dvipdf to an Environment.