context_menu.py

from kivy.uix.gridlayout import GridLayout
from kivy.uix.relativelayout import RelativeLayout
from kivy.core.window import Window
from kivy.uix.behaviors import ButtonBehavior
from kivy.lang import Builder
from kivy.clock import Clock
from functools import partial

import kivy.properties as kp
import os


HIGHLIGHT_COLOR = [0.2, 0.71, 0.9, 1]


class AbstractMenu(object):
    cancel_handler_widget = kp.ObjectProperty(None)
    bounding_box_widget = kp.ObjectProperty(None)

    def __init__(self, *args, **kwargs):
        self.clock_event = None

    def add_item(self, widget):
        self.add_widget(widget)

    def add_text_item(self, text, on_release=None):
        item = ContextMenuTextItem(text=text)
        if on_release:
            item.bind(on_release=on_release)
        self.add_item(item)

    def get_height(self):
        height = 0
        for widget in self.children:
            height += widget.height
        return height

    def hide_submenus(self):
        for widget in self.menu_item_widgets:
            widget.hovered = False
            widget.hide_submenu()

    def self_or_submenu_collide_with_point(self, x, y):
        raise NotImplementedError()

    def on_cancel_handler_widget(self, obj, widget):
        self.cancel_handler_widget.bind(on_touch_down=self.hide_app_menus)

    def hide_app_menus(self, obj, pos):
        raise NotImplementedError()

    @property
    def menu_item_widgets(self):
        """
        Return all children that are subclasses of ContextMenuItem
        """
        return [w for w in self.children if issubclass(w.__class__, AbstractMenuItem)]

    def _setup_hover_timer(self):
        if self.clock_event is None:
            self.clock_event = Clock.schedule_interval(partial(self._check_mouse_hover), 0.05)

    def _check_mouse_hover(self, obj):
        self.self_or_submenu_collide_with_point(*Window.mouse_pos)

    def _cancel_hover_timer(self):
        if self.clock_event:
            self.clock_event.cancel()
            self.clock_event = None


class ContextMenu(GridLayout, AbstractMenu):
    visible = kp.BooleanProperty(False)
    spacer = kp.ObjectProperty(None)
    hl_color = kp.ListProperty(HIGHLIGHT_COLOR)


    def __init__(self, *args, **kwargs):
        super(ContextMenu, self).__init__(*args, **kwargs)
        self.orig_parent = None
        # self._on_visible(False)

    def hide(self):
        self.visible = False

    def show(self, x=None, y=None):
        self.visible = True
        self._add_to_parent()
        self.hide_submenus()

        root_parent = self.bounding_box_widget if self.bounding_box_widget is not None else self.get_context_menu_root_parent()
        if root_parent is None:
            return

        point_relative_to_root = root_parent.to_local(*self.to_window(x, y))

        # Choose the best position to open the menu
        if x is not None and y is not None:
            if point_relative_to_root[0] + self.width < root_parent.width:
                pos_x = x
            else:
                pos_x = x - self.width
                if issubclass(self.parent.__class__, AbstractMenuItem):
                    pos_x -= self.parent.width

            if point_relative_to_root[1] - self.height < 0:
                pos_y = y
                if issubclass(self.parent.__class__, AbstractMenuItem):
                    pos_y -= self.parent.height + self.spacer.height
            else:
                pos_y = y - self.height

            self.pos = pos_x, pos_y

    def self_or_submenu_collide_with_point(self, x, y):
        queue = self.menu_item_widgets
        collide_widget = None

        # Iterate all siblings and all children
        while len(queue) > 0:
            widget = queue.pop(0)
            submenu = widget.get_submenu()
            if submenu is not None and widget.hovered:
                queue += submenu.menu_item_widgets

            widget_pos = widget.to_window(0, 0)
            if widget.collide_point(x - widget_pos[0], y - widget_pos[1]) and not widget.disabled:
                widget.hovered = True

                collide_widget = widget
                for sib in widget.siblings:
                    sib.hovered = False
            elif submenu and submenu.visible:
                widget.hovered = True
            else:
                widget.hovered = False

        return collide_widget

    def _on_visible(self, new_visibility):
        if new_visibility:
            self.size = self.get_max_width(), self.get_height()
            self._add_to_parent()
            # @todo: Do we need to remove self from self.parent.__context_menus? Probably not.

        elif self.parent and not new_visibility:
            self.orig_parent = self.parent

            '''
            We create a set that holds references to all context menus in the parent widget.
            It's necessary to keep at least one reference to this context menu. Otherwise when
            removed from parent it might get de-allocated by GC.
            '''
            if not hasattr(self.parent, '_ContextMenu__context_menus'):
                self.parent.__context_menus = set()
            self.parent.__context_menus.add(self)

            self.parent.remove_widget(self)
            self.hide_submenus()
            self._cancel_hover_timer()

    def _add_to_parent(self):
        if not self.parent:
            self.orig_parent.add_widget(self)
            self.orig_parent = None

            # Create the timer on the outer most menu object
            if self._get_root_context_menu() == self:
                self._setup_hover_timer()

    def get_max_width(self):
        max_width = 0
        for widget in self.menu_item_widgets:
            width = widget.content_width if widget.content_width is not None else widget.width
            if width is not None and width > max_width:
                max_width = width

        return max_width

    def get_context_menu_root_parent(self):
        """
        Return the bounding box widget for positioning sub menus. By default it's root context menu's parent.
        """
        if self.bounding_box_widget is not None:
            return self.bounding_box_widget
        root_context_menu = self._get_root_context_menu()
        return root_context_menu.bounding_box_widget if root_context_menu.bounding_box_widget else root_context_menu.parent

    def _get_root_context_menu(self):
        """
        Return the outer most context menu object
        """
        root = self
        while issubclass(root.parent.__class__, ContextMenuItem) \
                or issubclass(root.parent.__class__, ContextMenu):
            root = root.parent
        return root

    def hide_app_menus(self, obj, pos):
        return self.self_or_submenu_collide_with_point(pos.x, pos.y) is None and self.hide()


class AbstractMenuItem(object):
    submenu = kp.ObjectProperty(None)

    def get_submenu(self):
        return self.submenu if self.submenu != "" else None

    def show_submenu(self, x=None, y=None):
        if self.get_submenu():
            self.get_submenu().show(*self._root_parent.to_local(x, y))

    def hide_submenu(self):
        submenu = self.get_submenu()
        if submenu:
            submenu.visible = False
            submenu.hide_submenus()

    def _check_submenu(self):
        if self.parent is not None and len(self.children) > 0:
            submenus = [w for w in self.children if issubclass(w.__class__, ContextMenu)]
            if len(submenus) > 1:
                raise Exception('Menu item (ContextMenuItem) can have maximum one submenu (ContextMenu)')
            elif len(submenus) == 1:
                self.submenu = submenus[0]

    @property
    def siblings(self):
        return [w for w in self.parent.children if issubclass(w.__class__, AbstractMenuItem) and w != self]

    @property
    def content_width(self):
        return None

    @property
    def _root_parent(self):
        return self.parent.get_context_menu_root_parent()


class ContextMenuItem(RelativeLayout, AbstractMenuItem):
    submenu_arrow = kp.ObjectProperty(None)

    def _check_submenu(self):
        super(ContextMenuItem, self)._check_submenu()
        if self.get_submenu() is None:
            self.submenu_arrow.opacity = 0
        else:
            self.submenu_arrow.opacity = 1


class AbstractMenuItemHoverable(object):
    hovered = kp.BooleanProperty(False)

    def _on_hovered(self, new_hovered):
        if new_hovered:
            spacer_height = self.parent.spacer.height if self.parent.spacer else 0
            self.show_submenu(self.width, self.height + spacer_height)
        else:
            self.hide_submenu()


class ContextMenuText(ContextMenuItem):
    label = kp.ObjectProperty(None)
    submenu_postfix = kp.StringProperty(' ...')
    text = kp.StringProperty('')
    font_size = kp.NumericProperty(14)
    color = kp.ListProperty([1,1,1,1])

    def __init__(self, *args, **kwargs):
        super(ContextMenuText, self).__init__(*args, **kwargs)

    @property
    def content_width(self):
        # keep little space for eventual arrow for submenus
        return self.label.texture_size[0] + 10


class ContextMenuDivider(ContextMenuText):
    pass


class ContextMenuTextItem(ButtonBehavior, ContextMenuText, AbstractMenuItemHoverable):
    pass


_path = os.path.dirname(os.path.realpath(__file__))
Builder.load_file(os.path.join(_path, 'context_menu.kv'))