plink – A Python/Tk link editor

Technical documentation of the Python objects that underly PLink. Of interest only to Marc, Nathan, or similar folks.

class plink.LinkEditor(*args, **kwargs)

A complete graphical link drawing tool based on the one embedded in Jeff Weeks’ original SnapPea program.

active_crossing_data()

Return the tuple of edges crossed by the in and out arrows of the active vertex.

attach_cursor(reason='')

clear()

clicked_on_arrow(vertex)

crossed_arrows(arrow, ignore_list=[])

Return a tuple containing the arrows of the diagram which are crossed by the given arrow, in order along the given arrow.

cursor_on_arrow(point)

destroy_arrow(arrow)

detach_cursor(reason='')

done(event=None)

double_click(event)

Event handler for mouse double-clicks.

end_dragging_state()

focus_in(event)

focus_out(event)

generic_arrow(arrow)

generic_vertex(vertex)

goto_drawing_state(x1, y1)

goto_start_state()

make_alternating()

Changes crossings to make the projection alternating. Requires that all components be closed.

mouse_moved(event)

Handler for mouse motion events.

move_active(x, y)

move_is_ok()

notice_focus()

reflect()

set_start_cursor(x, y)

shift_click(event)

Event handler for mouse shift-clicks.

single_click(event)

Event handler for mouse clicks.

update_crossings(this_arrow)

Redraw any arrows which were changed by moving this_arrow.

verify_drag()

This module exports the class Arrow which represents a (directed) line segment in a PL link diagram.

class plink.arrow.Arrow(start, end, canvas=None, style='normal', color='black', other_params=None)

An arrow in a PL link diagram.

draw(crossings=[], recurse=True, skip_frozen=True)

epsilon = 8

erase()

Prepare the arrow for the garbage collector.

expose(crossings=[])

find_segments(crossings, include_overcrossings=False)

Return a list of segments that make up this arrow, each segment being a list of 4 coordinates [x0,y0,x1,y1]. The first segment starts at the start vertex, and the last one ends at the end vertex. Otherwise, endpoints are near crossings where this arrow goes under, leaving a gap between the endpoint and the crossing point. If the include_overcrossings flag is True, then the segments are also split at overcrossings, with no gap.

freeze()

property frozen

property hidden

hide()

make_faint()

reverse(crossings=[])

set_color(color)

set_end(vertex, crossings=[])

set_start(vertex, crossings=[])

too_close(vertex, tolerance=None)

vectorize()

This module exports the Crossing class, which represents a crossing in a link diagram, and the ECrossing class which represents an edge of the diagram passing through a crossing.

class plink.crossings.Crossing(over, under, is_virtual=False, label=None)

A pair of crossing arrows in a PL link diagram.

DT_hit(count, ecrossing)

Count the crossing, using DT conventions. Return True on the first hit if the count is odd and the crossing is shared by two components of the diagram. As a side effect, set the flipped attribute on the first hit.

clear_marks()

height(arrow)

locate()

mark_component(component)

reverse()

sign()

strand(arrow)

class plink.crossings.ECrossing(crossing, arrow)

A pair: (Crossing, Arrow), where the Arrow is involved in the Crossing. The ECrossings correspond 1-1 with edges of the link diagram.

goes_over()

pair()