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# @Base: Miro - an RSS based video player application
# Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011
# Participatory Culture Foundation
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
#
# In addition, as a special exception, the copyright holders give
# permission to link the code of portions of this program with the OpenSSL
# library.
#
# You must obey the GNU General Public License in all respects for all of
# the code used other than OpenSSL. If you modify file(s) with this
# exception, you may extend this exception to your version of the file(s),
# but you are not obligated to do so. If you do not wish to do so, delete
# this exception statement from your version. If you delete this exception
# statement from all source files in the program, then also delete it here.
"""tableselection.py -- High-level selection management. Subclasses defined in
the platform tableview modules provide the platform-specific methods used here.
"""
from contextlib import contextmanager
from mvc.errors import WidgetActionError, WidgetUsageError
class SelectionOwnerMixin(object):
"""Encapsulates the selection functionality of a TableView, for
consistent behavior across platforms.
Emits:
:signal selection-changed: the selection has been changed
:signal selection-invalid: the item selected can no longer be selected
:signal deselected: all items have been deselected
"""
def __init__(self):
self._ignore_selection_changed = 0
self._allow_multiple_select = None
self.create_signal('selection-changed')
self.create_signal('selection-invalid')
self.create_signal('deselected')
@property
def allow_multiple_select(self):
"""Return whether the widget allows multiple selection."""
if self._allow_multiple_select is None:
self._allow_multiple_select = self._get_allow_multiple_select()
return self._allow_multiple_select
@allow_multiple_select.setter
def allow_multiple_select(self, allow):
"""Set whether to allow multiple selection; this method is expected
always to work.
"""
if self._allow_multiple_select != allow:
self._set_allow_multiple_select(allow)
self._allow_multiple_select = allow
@property
def num_rows_selected(self):
"""Override on platforms with a way to count rows without having to
retrieve them.
"""
if self.allow_multiple_select:
return len(self._get_selected_iters())
else:
return int(self._get_selected_iter() is not None)
def select(self, iter_, signal=False):
"""Try to select an iter.
:raises WidgetActionError: iter does not exist or is not selectable
"""
self.select_iters((iter_,), signal)
def select_iters(self, iters, signal=False):
"""Try to select multiple iters (signaling at most once).
:raises WidgetActionError: iter does not exist or is not selectable
"""
with self._ignoring_changes(not signal):
for iter_ in iters:
self._select(iter_)
if not all(self._is_selected(iter_) for iter_ in iters):
raise WidgetActionError("the specified iter cannot be selected")
def is_selected(self, iter_):
"""Test if an iter is selected"""
return self._is_selected(iter_)
def unselect(self, iter_):
"""Unselect an Iter. Fails silently if the Iter is not selected.
"""
self._validate_iter(iter_)
with self._ignoring_changes():
self._unselect(iter_)
def unselect_iters(self, iters):
"""Unselect iters. Fails silently if the iters are not selected."""
with self._ignoring_changes():
for iter_ in iters:
self.unselect(iter_)
def unselect_all(self, signal=True):
"""Unselect all. emits only the 'deselected' signal."""
with self._ignoring_changes():
self._unselect_all()
if signal:
self.emit('deselected')
def on_selection_changed(self, _widget_or_notification):
"""When we receive a selection-changed signal, we forward it if we're
not in a 'with _ignoring_changes' block. Selection-changed
handlers are run in an ignoring block, and anything that changes the
selection to reflect the current state.
"""
# don't bother sending out a second selection-changed signal if
# the handler changes the selection (#15767)
if not self._ignore_selection_changed:
with self._ignoring_changes():
self.emit('selection-changed')
def get_selection_as_strings(self):
"""Returns the current selection as a list of strings.
"""
return [self._iter_to_string(iter_) for iter_ in self.get_selection()]
def set_selection_as_strings(self, selected):
"""Given a list of selection strings, selects each Iter represented by
the strings.
Raises WidgetActionError upon failure.
"""
# iter may not be destringable (yet) - bounds error
# destringed iter not selectable if parent isn't open (yet)
self.set_selection(self._iter_from_string(sel) for sel in selected)
def get_cursor(self):
"""Get the location of the keyboard cursor for the tableview.
Returns a string that represents the row that the keyboard cursor is
on.
"""
def set_cursor(self, location):
"""Set the location of the keyboard cursor for the tableview.
:param location: return value from a call to get_cursor()
Raises WidgetActionError upon failure.
"""
def get_selection(self):
"""Returns a list of GTK Iters. Works regardless of whether multiple
selection is enabled.
"""
return self._get_selected_iters()
def get_selected(self):
"""Return the single selected item.
:raises WidgetUsageError: multiple selection is enabled
"""
if self.allow_multiple_select:
raise WidgetUsageError("table allows multiple selection")
return self._get_selected_iter()
def _validate_iter(self, iter_):
"""Check whether an iter is valid.
:raises WidgetDomainError: the iter is not valid
:raises WidgetActionError: there is no model right now
"""
@contextmanager
def _ignoring_changes(self, ignoring=True):
"""Use this with with to prevent sending signals when we're changing
our own selection; that way, when we get a signal, we know it's
something important.
"""
if ignoring:
self._ignore_selection_changed += 1
try:
yield
finally:
if ignoring:
self._ignore_selection_changed -= 1
@contextmanager
def preserving_selection(self):
"""Prevent selection changes in a block from having any effect or
sticking - no signals will be sent, and the selection will be restored
to its original value when the block exits.
"""
iters = self._get_selected_iters()
with self._ignoring_changes():
try:
yield
finally:
self.set_selection(iters)
def set_selection(self, iters, signal=False):
"""Set the selection to the given iters, replacing any previous
selection and signaling at most once.
"""
self.unselect_all(signal=False)
for iter_ in iters:
self.select(iter_, signal=False)
if signal: self.emit('selection-changed')
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