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#Copyright (c) 2011-2013, Walter Bender
# This procedure is invoked when the user-definable block on the
# "extras" palette is selected.
# Usage: Import this code into a Python (user-definable) block; when
# it is run, a u-turn block will be added to the Turtle Palette. You
# can use the u-turn block as you would any other block.
def myblock(tw, args):
''' Add a uturn block to the 'turtle' palette '''
# def_prim takes 3 arguments: the primitive name, the number of
# arguments -- 0 in this case -- and the function to call -- in this
# case, we define the _prim_uturn function to set heading += 180.
def _prim_uturn(tw):
value = tw.turtles.get_active_turtle().get_heading() + 180
tw.turtles.get_active_turtle().set_heading(value)
# We also update the label on the heading block to indicate
# the current heading value
if tw.lc.update_values:
tw.lc.update_label_value('heading', value)
from TurtleArt.tapalette import make_palette, palette_name_to_index
from TurtleArt.taprimitive import Primitive, ConstantArg
from gettext import gettext as _
# Choose a palette for the new block.
palette = make_palette('turtle')
# Create a new block prototype.
palette.add_block('uturn',
style='basic-style-extended-vertical',
label=_('uturn'),
prim_name='uturn',
help_string=_('turns the turtle 180 degrees'))
# Add its primitive to the LogoCode dictionary.
tw.lc.def_prim('uturn', 0, Primitive(_prim_uturn, arg_descs=[ConstantArg(tw)]))
# Regenerate the palette, which will now include the new block.
tw.show_toolbar_palette(palette_name_to_index('turtle'),
regenerate=True)
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