'''
Compound Selection Behavior
===========================
The :class:`~kivy.uix.behaviors.compoundselection.CompoundSelectionBehavior`
`mixin <https://en.wikipedia.org/wiki/Mixin>`_ class implements the logic
behind keyboard and touch selection of selectable widgets managed by the
derived widget. For example, it can be combined with a
:class:`~kivy.uix.gridlayout.GridLayout` to add selection to the layout.
Compound selection concepts
---------------------------
At its core, it keeps a dynamic list of widgets that can be selected.
Then, as the touches and keyboard input are passed in, it selects one or
more of the widgets based on these inputs. For example, it uses the mouse
scroll and keyboard up/down buttons to scroll through the list of widgets.
Multiselection can also be achieved using the keyboard shift and ctrl keys.
Finally, in addition to the up/down type keyboard inputs, compound selection
can also accept letters from the keyboard to be used to select nodes with
associated strings that start with those letters, similar to how files
are selected by a file browser.
Selection mechanics
-------------------
When the controller needs to select a node, it calls :meth:`select_node` and
:meth:`deselect_node`. Therefore, they must be overwritten in order alter
node selection. By default, the class doesn't listen for keyboard or
touch events, so the derived widget must call
:meth:`select_with_touch`, :meth:`select_with_key_down`, and
:meth:`select_with_key_up` on events that it wants to pass on for selection
purposes.
Example
-------
To add selection to a grid layout which will contain
:class:`~kivy.uix.Button` widgets. For each button added to the layout, you
need to bind the :attr:`~kivy.uix.widget.Widget.on_touch_down` of the button
to :meth:`select_with_touch` to pass on the touch events::
from kivy.uix.behaviors.compoundselection import CompoundSelectionBehavior
from kivy.uix.button import Button
from kivy.uix.gridlayout import GridLayout
from kivy.uix.behaviors import FocusBehavior
from kivy.core.window import Window
from kivy.app import App
class SelectableGrid(FocusBehavior, CompoundSelectionBehavior, GridLayout):
def keyboard_on_key_down(self, window, keycode, text, modifiers):
"""Based on FocusBehavior that provides automatic keyboard
access, key presses will be used to select children.
"""
if super(SelectableGrid, self).keyboard_on_key_down(
window, keycode, text, modifiers):
return True
if self.select_with_key_down(window, keycode, text, modifiers):
return True
return False
def keyboard_on_key_up(self, window, keycode):
"""Based on FocusBehavior that provides automatic keyboard
access, key release will be used to select children.
"""
if super(SelectableGrid, self).keyboard_on_key_up(window, keycode):
return True
if self.select_with_key_up(window, keycode):
return True
return False
def add_widget(self, widget, *args, **kwargs):
""" Override the adding of widgets so we can bind and catch their
*on_touch_down* events. """
widget.bind(on_touch_down=self.button_touch_down,
on_touch_up=self.button_touch_up)
return super(SelectableGrid, self)\
.add_widget(widget, *args, **kwargs)
def button_touch_down(self, button, touch):
""" Use collision detection to select buttons when the touch occurs
within their area. """
if button.collide_point(*touch.pos):
self.select_with_touch(button, touch)
def button_touch_up(self, button, touch):
""" Use collision detection to de-select buttons when the touch
occurs outside their area and *touch_multiselect* is not True. """
if not (button.collide_point(*touch.pos) or
self.touch_multiselect):
self.deselect_node(button)
def select_node(self, node):
node.background_color = (1, 0, 0, 1)
return super(SelectableGrid, self).select_node(node)
def deselect_node(self, node):
node.background_color = (1, 1, 1, 1)
super(SelectableGrid, self).deselect_node(node)
def on_selected_nodes(self, grid, nodes):
print("Selected nodes = {0}".format(nodes))
class TestApp(App):
def build(self):
grid = SelectableGrid(cols=3, rows=2, touch_multiselect=True,
multiselect=True)
for i in range(0, 6):
grid.add_widget(Button(text="Button {0}".format(i)))
return grid
TestApp().run()
.. warning::
This code is still experimental, and its API is subject to change in a
future version.
'''
__all__ = ('CompoundSelectionBehavior', )
from time import time
from os import environ
from kivy.properties import NumericProperty, BooleanProperty, ListProperty
if 'KIVY_DOC' not in environ:
from kivy.config import Config
_is_desktop = Config.getboolean('kivy', 'desktop')
else:
_is_desktop = False
[docs]class CompoundSelectionBehavior(object):
'''The Selection behavior `mixin <https://en.wikipedia.org/wiki/Mixin>`_
implements the logic behind keyboard and touch
selection of selectable widgets managed by the derived widget. Please see
the :mod:`compound selection behaviors module
<kivy.uix.behaviors.compoundselection>` documentation
for more information.
.. versionadded:: 1.9.0
'''
selected_nodes = ListProperty([])
'''The list of selected nodes.
.. note::
Multiple nodes can be selected right after one another e.g. using the
keyboard. When listening to :attr:`selected_nodes`, one should be
aware of this.
:attr:`selected_nodes` is a :class:`~kivy.properties.ListProperty` and
defaults to the empty list, []. It is read-only and should not be modified.
'''
touch_multiselect = BooleanProperty(False)
'''A special touch mode which determines whether touch events, as
processed by :meth:`select_with_touch`, will add the currently touched
node to the selection, or if it will clear the selection before adding the
node. This allows the selection of multiple nodes by simply touching them.
This is different from :attr:`multiselect` because when it is True,
simply touching an unselected node will select it, even if ctrl is not
pressed. If it is False, however, ctrl must be pressed in order to
add to the selection when :attr:`multiselect` is True.
.. note::
:attr:`multiselect`, when False, will disable
:attr:`touch_multiselect`.
:attr:`touch_multiselect` is a :class:`~kivy.properties.BooleanProperty`
and defaults to False.
'''
multiselect = BooleanProperty(False)
'''Determines whether multiple nodes can be selected. If enabled, keyboard
shift and ctrl selection, optionally combined with touch, for example, will
be able to select multiple widgets in the normally expected manner.
This dominates :attr:`touch_multiselect` when False.
:attr:`multiselect` is a :class:`~kivy.properties.BooleanProperty` and
defaults to False.
'''
touch_deselect_last = BooleanProperty(not _is_desktop)
'''Determines whether the last selected node can be deselected when
:attr:`multiselect` or :attr:`touch_multiselect` is False.
.. versionadded:: 1.10.0
:attr:`touch_deselect_last` is a :class:`~kivy.properties.BooleanProperty`
and defaults to True on mobile, False on desktop platforms.
'''
keyboard_select = BooleanProperty(True)
'''Determines whether the keyboard can be used for selection. If False,
keyboard inputs will be ignored.
:attr:`keyboard_select` is a :class:`~kivy.properties.BooleanProperty`
and defaults to True.
'''
page_count = NumericProperty(10)
'''Determines by how much the selected node is moved up or down, relative
to the position of the last selected node, when pageup (or pagedown) is
pressed.
:attr:`page_count` is a :class:`~kivy.properties.NumericProperty` and
defaults to 10.
'''
up_count = NumericProperty(1)
'''Determines by how much the selected node is moved up or down, relative
to the position of the last selected node, when the up (or down) arrow on
the keyboard is pressed.
:attr:`up_count` is a :class:`~kivy.properties.NumericProperty` and
defaults to 1.
'''
right_count = NumericProperty(1)
'''Determines by how much the selected node is moved up or down, relative
to the position of the last selected node, when the right (or left) arrow
on the keyboard is pressed.
:attr:`right_count` is a :class:`~kivy.properties.NumericProperty` and
defaults to 1.
'''
scroll_count = NumericProperty(0)
'''Determines by how much the selected node is moved up or down, relative
to the position of the last selected node, when the mouse scroll wheel is
scrolled.
:attr:`right_count` is a :class:`~kivy.properties.NumericProperty` and
defaults to 0.
'''
nodes_order_reversed = BooleanProperty(True)
''' (Internal) Indicates whether the order of the nodes as displayed top-
down is reversed compared to their order in :meth:`get_selectable_nodes`
(e.g. how the children property is reversed compared to how
it's displayed).
'''
text_entry_timeout = NumericProperty(1.)
'''When typing characters in rapid succession (i.e. the time difference
since the last character is less than :attr:`text_entry_timeout`), the
keys get concatenated and the combined text is passed as the key argument
of :meth:`goto_node`.
.. versionadded:: 1.10.0
'''
_anchor = None # the last anchor node selected (e.g. shift relative node)
# the idx may be out of sync
_anchor_idx = 0 # cache indexes in case list hasn't changed
_last_selected_node = None # the absolute last node selected
_last_node_idx = 0
_ctrl_down = False # if it's pressed - for e.g. shift selection
_shift_down = False
# holds str used to find node, e.g. if word is typed. passed to goto_node
_word_filter = ''
_last_key_time = 0 # time since last press, for finding whole strs in node
_key_list = [] # keys that are already pressed, to not press continuously
_offset_counts = {} # cache of counts for faster access
def __init__(self, **kwargs):
super(CompoundSelectionBehavior, self).__init__(**kwargs)
self._key_list = []
def ensure_single_select(*l):
if (not self.multiselect) and len(self.selected_nodes) > 1:
self.clear_selection()
update_counts = self._update_counts
update_counts()
fbind = self.fbind
fbind('multiselect', ensure_single_select)
fbind('page_count', update_counts)
fbind('up_count', update_counts)
fbind('right_count', update_counts)
fbind('scroll_count', update_counts)
[docs] def select_with_touch(self, node, touch=None):
'''(internal) Processes a touch on the node. This should be called by
the derived widget when a node is touched and is to be used for
selection. Depending on the keyboard keys pressed and the
configuration, it could select or deslect this and other nodes in the
selectable nodes list, :meth:`get_selectable_nodes`.
:Parameters:
`node`
The node that received the touch. Can be None for a scroll
type touch.
`touch`
Optionally, the touch. Defaults to None.
:Returns:
bool, True if the touch was used, False otherwise.
'''
multi = self.multiselect
multiselect = multi and (self._ctrl_down or self.touch_multiselect)
range_select = multi and self._shift_down
if touch and 'button' in touch.profile and touch.button in\
('scrollup', 'scrolldown', 'scrollleft', 'scrollright'):
node_src, idx_src = self._resolve_last_node()
node, idx = self.goto_node(touch.button, node_src, idx_src)
if node == node_src:
return False
if range_select:
self._select_range(multiselect, True, node, idx)
else:
if not multiselect:
self.clear_selection()
self.select_node(node)
return True
if node is None:
return False
if (node in self.selected_nodes and (not range_select)): # selected
if multiselect:
self.deselect_node(node)
else:
selected_node_count = len(self.selected_nodes)
self.clear_selection()
if not self.touch_deselect_last or selected_node_count > 1:
self.select_node(node)
elif range_select:
# keep anchor only if not multiselect (ctrl-type selection)
self._select_range(multiselect, not multiselect, node, 0)
else: # it's not selected at this point
if not multiselect:
self.clear_selection()
self.select_node(node)
return True
[docs] def select_with_key_down(self, keyboard, scancode, codepoint, modifiers,
**kwargs):
'''Processes a key press. This is called when a key press is to be used
for selection. Depending on the keyboard keys pressed and the
configuration, it could select or deselect nodes or node ranges
from the selectable nodes list, :meth:`get_selectable_nodes`.
The parameters are such that it could be bound directly to the
on_key_down event of a keyboard. Therefore, it is safe to be called
repeatedly when the key is held down as is done by the keyboard.
:Returns:
bool, True if the keypress was used, False otherwise.
'''
if not self.keyboard_select:
return False
keys = self._key_list
multi = self.multiselect
node_src, idx_src = self._resolve_last_node()
text = scancode[1]
if text == 'shift':
self._shift_down = True
elif text in ('ctrl', 'lctrl', 'rctrl'):
self._ctrl_down = True
elif (multi and 'ctrl' in modifiers and text in ('a', 'A') and
text not in keys):
sister_nodes = self.get_selectable_nodes()
select = self.select_node
for node in sister_nodes:
select(node)
keys.append(text)
else:
s = text
if len(text) > 1:
d = {'divide': '/', 'mul': '*', 'substract': '-', 'add': '+',
'decimal': '.'}
if text.startswith('numpad'):
s = text[6:]
if len(s) > 1:
if s in d:
s = d[s]
else:
s = None
else:
s = None
if s is not None:
if s not in keys: # don't keep adding while holding down
if time() - self._last_key_time <= self.text_entry_timeout:
self._word_filter += s
else:
self._word_filter = s
keys.append(s)
self._last_key_time = time()
node, idx = self.goto_node(self._word_filter, node_src,
idx_src)
else:
self._word_filter = ''
node, idx = self.goto_node(text, node_src, idx_src)
if node == node_src:
return False
multiselect = multi and 'ctrl' in modifiers
if multi and 'shift' in modifiers:
self._select_range(multiselect, True, node, idx)
else:
if not multiselect:
self.clear_selection()
self.select_node(node)
return True
self._word_filter = ''
return False
[docs] def select_with_key_up(self, keyboard, scancode, **kwargs):
'''(internal) Processes a key release. This must be called by the
derived widget when a key that :meth:`select_with_key_down` returned
True is released.
The parameters are such that it could be bound directly to the
on_key_up event of a keyboard.
:Returns:
bool, True if the key release was used, False otherwise.
'''
if scancode[1] == 'shift':
self._shift_down = False
elif scancode[1] in ('ctrl', 'lctrl', 'rctrl'):
self._ctrl_down = False
else:
try:
self._key_list.remove(scancode[1])
return True
except ValueError:
return False
return True
def _update_counts(self, *largs):
# doesn't invert indices here
pc = self.page_count
uc = self.up_count
rc = self.right_count
sc = self.scroll_count
self._offset_counts = {'pageup': -pc, 'pagedown': pc, 'up': -uc,
'down': uc, 'right': rc, 'left': -rc, 'scrollup': sc,
'scrolldown': -sc, 'scrollright': -sc, 'scrollleft': sc}
def _resolve_last_node(self):
# for offset selection, we have a anchor, and we select everything
# between anchor and added offset relative to last node
sister_nodes = self.get_selectable_nodes()
if not len(sister_nodes):
return None, 0
last_node = self._last_selected_node
last_idx = self._last_node_idx
end = len(sister_nodes) - 1
if last_node is None:
last_node = self._anchor
last_idx = self._anchor_idx
if last_node is None:
return sister_nodes[end], end
if last_idx > end or sister_nodes[last_idx] != last_node:
try:
return last_node, self.get_index_of_node(last_node,
sister_nodes)
except ValueError:
return sister_nodes[end], end
return last_node, last_idx
def _select_range(self, multiselect, keep_anchor, node, idx):
'''Selects a range between self._anchor and node or idx.
If multiselect is True, it will be added to the selection, otherwise
it will unselect everything before selecting the range. This is only
called if self.multiselect is True.
If keep anchor is False, the anchor is moved to node. This should
always be True for keyboard selection.
'''
select = self.select_node
sister_nodes = self.get_selectable_nodes()
end = len(sister_nodes) - 1
last_node = self._anchor
last_idx = self._anchor_idx
if last_node is None:
last_idx = end
last_node = sister_nodes[end]
else:
if last_idx > end or sister_nodes[last_idx] != last_node:
try:
last_idx = self.get_index_of_node(last_node, sister_nodes)
except ValueError:
# list changed - cannot do select across them
return
if idx > end or sister_nodes[idx] != node:
try: # just in case
idx = self.get_index_of_node(node, sister_nodes)
except ValueError:
return
if last_idx > idx:
last_idx, idx = idx, last_idx
if not multiselect:
self.clear_selection()
for item in sister_nodes[last_idx:idx + 1]:
select(item)
if keep_anchor:
self._anchor = last_node
self._anchor_idx = last_idx
else:
self._anchor = node # in case idx was reversed, reset
self._anchor_idx = idx
self._last_selected_node = node
self._last_node_idx = idx
[docs] def clear_selection(self):
''' Deselects all the currently selected nodes.
'''
# keep the anchor and last selected node
deselect = self.deselect_node
nodes = self.selected_nodes
# empty beforehand so lookup in deselect will be fast
for node in nodes[:]:
deselect(node)
[docs] def get_selectable_nodes(self):
'''(internal) Returns a list of the nodes that can be selected. It can
be overwritten by the derived widget to return the correct list.
This list is used to determine which nodes to select with group
selection. E.g. the last element in the list will be selected when
home is pressed, pagedown will move (or add to, if shift is held) the
selection from the current position by negative :attr:`page_count`
nodes starting from the position of the currently selected node in
this list and so on. Still, nodes can be selected even if they are not
in this list.
.. note::
It is safe to dynamically change this list including removing,
adding, or re-arranging its elements. Nodes can be selected even
if they are not on this list. And selected nodes removed from the
list will remain selected until :meth:`deselect_node` is called.
.. warning::
Layouts display their children in the reverse order. That is, the
contents of :attr:`~kivy.uix.widget.Widget.children` is displayed
form right to left, bottom to top. Therefore, internally, the
indices of the elements returned by this function are reversed to
make it work by default for most layouts so that the final result
is consistent e.g. home, although it will select the last element
in this list visually, will select the first element when
counting from top to bottom and left to right. If this behavior is
not desired, a reversed list should be returned instead.
Defaults to returning :attr:`~kivy.uix.widget.Widget.children`.
'''
return self.children
[docs] def get_index_of_node(self, node, selectable_nodes):
'''(internal) Returns the index of the `node` within the
`selectable_nodes` returned by :meth:`get_selectable_nodes`.
'''
return selectable_nodes.index(node)
[docs] def goto_node(self, key, last_node, last_node_idx):
'''(internal) Used by the controller to get the node at the position
indicated by key. The key can be keyboard inputs, e.g. pageup,
or scroll inputs from the mouse scroll wheel, e.g. scrollup.
'last_node' is the last node selected and is used to find the resulting
node. For example, if the key is up, the returned node is one node
up from the last node.
It can be overwritten by the derived widget.
:Parameters:
`key`
str, the string used to find the desired node. It can be any
of the keyboard keys, as well as the mouse scrollup,
scrolldown, scrollright, and scrollleft strings. If letters
are typed in quick succession, the letters will be combined
before it's passed in as key and can be used to find nodes that
have an associated string that starts with those letters.
`last_node`
The last node that was selected.
`last_node_idx`
The cached index of the last node selected in the
:meth:`get_selectable_nodes` list. If the list hasn't changed
it saves having to look up the index of `last_node` in that
list.
:Returns:
tuple, the node targeted by key and its index in the
:meth:`get_selectable_nodes` list. Returning
`(last_node, last_node_idx)` indicates a node wasn't found.
'''
sister_nodes = self.get_selectable_nodes()
end = len(sister_nodes) - 1
counts = self._offset_counts
if end == -1:
return last_node, last_node_idx
if last_node_idx > end or sister_nodes[last_node_idx] != last_node:
try: # just in case
last_node_idx = self.get_index_of_node(last_node, sister_nodes)
except ValueError:
return last_node, last_node_idx
is_reversed = self.nodes_order_reversed
if key in counts:
count = -counts[key] if is_reversed else counts[key]
idx = max(min(count + last_node_idx, end), 0)
return sister_nodes[idx], idx
elif key == 'home':
if is_reversed:
return sister_nodes[end], end
return sister_nodes[0], 0
elif key == 'end':
if is_reversed:
return sister_nodes[0], 0
return sister_nodes[end], end
else:
return last_node, last_node_idx
[docs] def select_node(self, node):
''' Selects a node.
It is called by the controller when it selects a node and can be
called from the outside to select a node directly. The derived widget
should overwrite this method and change the node state to selected
when called.
:Parameters:
`node`
The node to be selected.
:Returns:
bool, True if the node was selected, False otherwise.
.. warning::
This method must be called by the derived widget using super if it
is overwritten.
'''
nodes = self.selected_nodes
if node in nodes:
return False
if (not self.multiselect) and len(nodes):
self.clear_selection()
if node not in nodes:
nodes.append(node)
self._anchor = node
self._last_selected_node = node
return True
[docs] def deselect_node(self, node):
''' Deselects a possibly selected node.
It is called by the controller when it deselects a node and can also
be called from the outside to deselect a node directly. The derived
widget should overwrite this method and change the node to its
unselected state when this is called
:Parameters:
`node`
The node to be deselected.
.. warning::
This method must be called by the derived widget using super if it
is overwritten.
'''
try:
self.selected_nodes.remove(node)
return True
except ValueError:
return False
