nltk.draw.util.ScrollWatcherWidget

class documentation

class ScrollWatcherWidget(CanvasWidget): (source)

Constructor: ScrollWatcherWidget(canvas, *children, **attribs)

A special canvas widget that adjusts its Canvas's scrollregion to always include the bounding boxes of all of its children. The scroll-watcher widget will only increase the size of the Canvas's scrollregion; it will never decrease it.

Method	`__init__`	Create a new scroll-watcher widget.
Method	`add_child`	Add a new canvas widget to the scroll-watcher. The scroll-watcher will ensure that the new canvas widget is always contained in its canvas's scrollregion.
Method	`remove_child`	Remove a canvas widget from the scroll-watcher. The scroll-watcher will no longer ensure that the new canvas widget is always contained in its canvas's scrollregion.
Method	`_adjust_scrollregion`	Adjust the scrollregion of this scroll-watcher's `Canvas` to include the bounding boxes of all of its children.
Method	`_tags`	No summary
Method	`_update`	Update this canvas widget in response to a change in one of its children.

Inherited from CanvasWidget:

Method	`__getitem__`	No summary
Method	`__repr__`	No summary
Method	`__setitem__`	Set the value of the attribute `attr` to `value`. See the class documentation for a list of attributes supported by this canvas widget.
Method	`bbox`	No summary
Method	`bind_click`	Register a new callback that will be called whenever this `CanvasWidget` is clicked on.
Method	`bind_drag`	Register a new callback that will be called after this `CanvasWidget` is dragged. This implicitly makes this `CanvasWidget` draggable.
Method	`canvas`	No summary
Method	`child_widgets`	No summary
Method	`destroy`	Remove this `CanvasWidget` from its `Canvas`. After a `CanvasWidget` has been destroyed, it should not be accessed.
Method	`height`	No summary
Method	`hidden`	No summary
Method	`hide`	Temporarily hide this canvas widget.
Method	`manage`	Arrange this canvas widget and all of its descendants.
Method	`move`	Move this canvas widget by a given distance. In particular, shift the canvas widget right by `dx` pixels, and down by `dy` pixels. Both `dx` and `dy` may be negative, resulting in leftward or upward movement.
Method	`moveto`	Move this canvas widget to the given location. In particular, shift the canvas widget such that the corner or side of the bounding box specified by `anchor` is at location (`x`, `y`).
Method	`parent`	No summary
Method	`show`	Show a hidden canvas widget.
Method	`tags`	No summary
Method	`unbind_click`	Remove a callback that was registered with `bind_click`.
Method	`unbind_drag`	Remove a callback that was registered with `bind_drag`.
Method	`update`	Update the graphical display of this canvas widget, and all of its ancestors, in response to a change in one of this canvas widget's children.
Method	`width`	No summary
Method	`__click`	If this `CanvasWidget` has a drag callback, then call it; otherwise, find the closest ancestor with a click callback, and call it. If no ancestors have a click callback, do nothing.
Method	`__drag`	If this `CanvasWidget` has a drag callback, then call it; otherwise, find the closest ancestor with a drag callback, and call it. If no ancestors have a drag callback, do nothing.
Method	`__motion_cb`	move this object to the new location
Method	`__press_cb`	record the button press event in `self.__press`
Method	`__release_cb`	unregister motion & button release callbacks.
Method	`__start_drag`	register a motion callback
Method	`_add_child_widget`	Register a hierarchical child widget. The child will be considered part of this canvas widget for purposes of user interaction. `_add_child_widget` has two direct effects:
Method	`_manage`	Arrange the child widgets of this canvas widget. This method is called when the canvas widget is initially created. It is also called if the user calls the `manage` method on this canvas widget or any of its ancestors.
Method	`_remove_child_widget`	Remove a hierarchical child widget. This child will no longer be considered part of this canvas widget for purposes of user interaction. `_add_child_widget` has two direct effects:
Instance Variable	`__callbacks`	Registered callbacks. Currently, four keys are used: `1`, `2`, `3`, and `'drag'`. The values are callback functions. Each callback function takes a single argument, which is the `CanvasWidget` that triggered the callback.
Instance Variable	`__canvas`	This `CanvasWidget`'s canvas.
Instance Variable	`__children`	This `CanvasWidget`'s hierarchical child widgets.
Instance Variable	`__drag_x`	Where it's been moved to (to find dx)
Instance Variable	`__drag_y`	Where it's been moved to (to find dy)
Instance Variable	`__draggable`	Is this canvas widget draggable?
Instance Variable	`__hidden`	Undocumented
Instance Variable	`__parent`	This `CanvasWidget`'s hierarchical parent widget.
Instance Variable	`__press`	The ButtonPress event that we're currently handling.
Instance Variable	`__updating`	Is this canvas widget currently performing an update? If it is, then it will ignore any new update requests from child widgets.

def __init__(self, canvas, *children, **attribs): (source) ¶

overrides nltk.draw.util.CanvasWidget.__init__

Create a new scroll-watcher widget.

Parameters
canvas:Tkinter.Canvas	This canvas widget's canvas.
*children:list(CanvasWidget)	The canvas widgets watched by the scroll-watcher. The scroll-watcher will ensure that these canvas widgets are always contained in their canvas's scrollregion.
**attribs	The new canvas widget's attributes.

def add_child(self, canvaswidget): (source) ¶

Add a new canvas widget to the scroll-watcher. The scroll-watcher will ensure that the new canvas widget is always contained in its canvas's scrollregion.

Parameters
canvaswidget:CanvasWidget	The new canvas widget.
Returns
None	Undocumented

def remove_child(self, canvaswidget): (source) ¶

Remove a canvas widget from the scroll-watcher. The scroll-watcher will no longer ensure that the new canvas widget is always contained in its canvas's scrollregion.

Parameters
canvaswidget:CanvasWidget	The canvas widget to remove.
Returns
None	Undocumented

def _adjust_scrollregion(self): (source) ¶

Adjust the scrollregion of this scroll-watcher's Canvas to include the bounding boxes of all of its children.

def _tags(self): (source) ¶

overrides nltk.draw.util.CanvasWidget._tags

Returns
list of int	a list of canvas tags for all graphical elements managed by this canvas widget, not including graphical elements managed by its child widgets.

def _update(self, child): (source) ¶

overrides nltk.draw.util.CanvasWidget._update

Update this canvas widget in response to a change in one of its children.

Parameters
child:CanvasWidget	The child that changed.
Returns
None	Undocumented