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# <![CDATA[
"""Demo item for DiaCanvas2.
"""
# vim:sw=4:et
# generators can be used to iterate shapes and child objects
from __future__ import generators
import gobject
import diacanvas
import diacanvas.shape as shape
class DemoItem(diacanvas.CanvasElement, diacanvas.CanvasAbstractGroup):
def __init__(self):
self.__gobject_init__()
# create our line shapes (a red and a green line)
self.top_line = shape.Path()
self.top_line.set_color(diacanvas.color(255, 0, 0))
self.top_line.set_line_width(2)
self.bottom_line = shape.Path()
self.bottom_line.set_color(diacanvas.color(0, 255, 0))
self.bottom_line.set_line_width(2)
# create a text object (CanvasText is a composite object)
self.text = diacanvas.CanvasText()
# make the text a child of this canvas item
self.add_construction(self.text)
def on_update(self, affine):
# create a line on the top
# (line() takes one argument: a list of points)
self.top_line.line([(0, 0), (self.width, 0)])
# create a line on the bottom
self.bottom_line.line([(0, self.height), (self.width, self.height)])
# give the text the same width and height as out object
self.text.set(width=self.width, height=self.height)
# update the text
self.update_child(self.text, affine)
# update the parent
diacanvas.CanvasElement.on_update(self, affine)
# expand the boundries of this canvas item so the lines (with
# width 2.0) are inside the boundries of this canvas item.
self.expand_bounds(1.0)
def on_shape_iter(self):
# an iterator
yield self.top_line
yield self.bottom_line
# alternative:
#return iter([self.top_line, self.bottom_line])
def on_event(self, event):
# make sure key events are send to our text object
if event.type == diacanvas.EVENT_KEY_PRESS:
self.text.focus()
return self.text.on_event(event)
else:
return diacanvas.CanvasElement.on_event(self, event)
# Groupable
def on_groupable_add(self, item):
"""Add a new item. This is not allowed in this case.
"""
return 0
def on_groupable_remove(self, item):
"""Do not allow the text to be removed.
"""
return 1
def on_groupable_iter(self):
"""Return an iterator that can be used to traverse the children.
"""
yield self.text
# alternative:
# return iter([self.text])
def on_groupable_length(self):
"""Return the number of child objects, we have just the text object.
"""
return 1
def on_groupable_pos(self, item):
"""Return the position of the item wrt other child objects.
(we have only one child).
"""
if item == self.text:
return 0
else:
return -1
gobject.type_register(DemoItem)
# add CanvasItem callbacks
diacanvas.set_callbacks(DemoItem)
# make the item groupable
diacanvas.set_groupable(DemoItem)
# end-of-file ]]>
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