Quick search

Table Of Contents

Source code for kivy.uix.behaviors.compoundselection

'''
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):
            """ 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)

        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, gird, 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.config import Config
from kivy.properties import NumericProperty, BooleanProperty, ListProperty


if 'KIVY_DOC' not in environ:
    _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 sucession (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 indexs 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