Can "_draw_component" methods be removed?

[rahulporuri]

enable/enable/component.py

Lines 344 to 350 in a1a6059

	def _draw_component(self, gc, view_bounds=None, mode="normal"):
	""" Renders the component.
	Subclasses must implement this method to actually render themselves.
	Note: This method is used only by the "old" drawing calls.
	"""
	pass

enable/enable/container.py

Lines 601 to 616 in a1a6059

	def _draw_component(self, gc, view_bounds=None, mode="normal"):
	""" Draws the component.
	This method is preserved for backwards compatibility. Overrides
	the implementation in Component.
	"""
	with gc:
	gc.set_antialias(False)
	self._draw_container(gc, mode)
	self._draw_background(gc, view_bounds, mode)
	self._draw_underlay(gc, view_bounds, mode)
	self._draw_children(
	gc, view_bounds, mode
	) # This was children_draw_mode
	self._draw_overlays(gc, view_bounds, mode)

These seem to have been introduced in the commit - d8fc3d1. This commit seems to have changed the DEFAULT_DRAWING_ORDER to what we are mostly familiar with - "background", "mainlayer", "border", "overlay". _draw_component seems to have been introduced as a backwards compatibility measure.

As you can see from here -

enable/enable/component.py

Lines 787 to 799 in a1a6059

	for layer in self.draw_order:
	if layer != "overlay":
	self._dispatch_draw(layer, bb, view_bounds, mode)
	self._backbuffer = bb
	self.draw_valid = True
	# Blit the backbuffer and then draw the overlay on top
	gc.draw_image(self._backbuffer, (x, y, width, height))
	self._dispatch_draw("overlay", gc, view_bounds, mode)
	else:
	for layer in self.draw_order:
	self._dispatch_draw(layer, gc, view_bounds, mode)

- the _dispatch_draw methods looks for methods like e.g. _draw_mainlayer where layer is mainlayer. And there are no layer which is container so we should be able to remove the _draw_container methods.

enable/enable/component.py

Lines 815 to 817 in a1a6059

	handler = getattr(self, "_draw_" + layer, None)
	if handler:
	handler(gc, view_bounds, mode)

[rahulporuri]

Note that there are a lot more occurances of _draw_component in chaco so we need a separate issues in chaco to track the necessary changes.

[rahulporuri]

Note that there are a lot more occurances of _draw_component in chaco so we need a separate issues in chaco to track the necessary changes.

There are only two uses of _draw_component in chaco which rely on the empty method on the enable Component - StatusLayer and SVGRangeSelectionOverlay. Note that SVGRangeSelectionOverlay inherits from StatusLayer.

Ref https://github.com/enthought/chaco/blob/f5cd0aba7bb296c452e0bad39770f5e9e43adb09/chaco/layers/status_layer.py#L117 and https://github.com/enthought/chaco/blob/f5cd0aba7bb296c452e0bad39770f5e9e43adb09/chaco/layers/svg_range_selection_overlay.py#L87