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Source code for kivy.uix.gridlayout

'''
Grid Layout
===========

.. only:: html

    .. image:: images/gridlayout.gif
        :align: right

.. only:: latex

    .. image:: images/gridlayout.png
        :align: right

.. versionadded:: 1.0.4

The :class:`GridLayout` arranges children in a matrix. It takes the available
space and divides it into columns and rows, then adds widgets to the resulting
"cells".

.. versionchanged:: 1.0.7
    The implementation has changed to use the widget size_hint for calculating
    column/row sizes. `uniform_width` and `uniform_height` have been removed
    and other properties have added to give you more control.

Background
----------

Unlike many other toolkits, you cannot explicitly place a widget in a specific
column/row. Each child is automatically assigned a position determined by the
layout configuration and the child's index in the children list.

A GridLayout must always have at least one input constraint:
:attr:`GridLayout.cols` or :attr:`GridLayout.rows`. If you do not specify cols
or rows, the Layout will throw an exception.

Column Width and Row Height
---------------------------

The column width/row height are determined in 3 steps:

    - The initial size is given by the :attr:`col_default_width` and
      :attr:`row_default_height` properties. To customize the size of a single
      column or row, use :attr:`cols_minimum` or :attr:`rows_minimum`.
    - The `size_hint_x`/`size_hint_y` of the children are taken into account.
      If no widgets have a size hint, the maximum size is used for all
      children.
    - You can force the default size by setting the :attr:`col_force_default`
      or :attr:`row_force_default` property. This will force the layout to
      ignore the `width` and `size_hint` properties of children and use the
      default size.

Using a GridLayout
------------------

In the example below, all widgets will have an equal size. By default, the
`size_hint` is (1, 1), so a Widget will take the full size of the parent::

    layout = GridLayout(cols=2)
    layout.add_widget(Button(text='Hello 1'))
    layout.add_widget(Button(text='World 1'))
    layout.add_widget(Button(text='Hello 2'))
    layout.add_widget(Button(text='World 2'))

.. image:: images/gridlayout_1.jpg

Now, let's fix the size of Hello buttons to 100px instead of using
size_hint_x=1::

    layout = GridLayout(cols=2)
    layout.add_widget(Button(text='Hello 1', size_hint_x=None, width=100))
    layout.add_widget(Button(text='World 1'))
    layout.add_widget(Button(text='Hello 2', size_hint_x=None, width=100))
    layout.add_widget(Button(text='World 2'))

.. image:: images/gridlayout_2.jpg

Next, let's fix the row height to a specific size::

    layout = GridLayout(cols=2, row_force_default=True, row_default_height=40)
    layout.add_widget(Button(text='Hello 1', size_hint_x=None, width=100))
    layout.add_widget(Button(text='World 1'))
    layout.add_widget(Button(text='Hello 2', size_hint_x=None, width=100))
    layout.add_widget(Button(text='World 2'))

.. image:: images/gridlayout_3.jpg

'''

__all__ = ('GridLayout', 'GridLayoutException')

from kivy.logger import Logger
from kivy.uix.layout import Layout
from kivy.properties import NumericProperty, BooleanProperty, DictProperty, \
    BoundedNumericProperty, ReferenceListProperty, VariableListProperty, \
    ObjectProperty, StringProperty
from math import ceil


def nmax(*args):
    # merge into one list
    args = [x for x in args if x is not None]
    return max(args)


def nmin(*args):
    # merge into one list
    args = [x for x in args if x is not None]
    return min(args)


[docs]class GridLayoutException(Exception): '''Exception for errors if the grid layout manipulation fails. ''' pass
[docs]class GridLayout(Layout): '''Grid layout class. See module documentation for more information. ''' spacing = VariableListProperty([0, 0], length=2) '''Spacing between children: [spacing_horizontal, spacing_vertical]. spacing also accepts a one argument form [spacing]. :attr:`spacing` is a :class:`~kivy.properties.VariableListProperty` and defaults to [0, 0]. ''' padding = VariableListProperty([0, 0, 0, 0]) '''Padding between the layout box and it's children: [padding_left, padding_top, padding_right, padding_bottom]. padding also accepts a two argument form [padding_horizontal, padding_vertical] and a one argument form [padding]. .. versionchanged:: 1.7.0 Replaced NumericProperty with VariableListProperty. :attr:`padding` is a :class:`~kivy.properties.VariableListProperty` and defaults to [0, 0, 0, 0]. ''' cols = BoundedNumericProperty(None, min=0, allownone=True) '''Number of columns in the grid. .. versionchanged:: 1.0.8 Changed from a NumericProperty to BoundedNumericProperty. You can no longer set this to a negative value. :attr:`cols` is a :class:`~kivy.properties.NumericProperty` and defaults to 0. ''' rows = BoundedNumericProperty(None, min=0, allownone=True) '''Number of rows in the grid. .. versionchanged:: 1.0.8 Changed from a NumericProperty to a BoundedNumericProperty. You can no longer set this to a negative value. :attr:`rows` is a :class:`~kivy.properties.NumericProperty` and defaults to 0. ''' col_default_width = NumericProperty(0) '''Default minimum size to use for a column. .. versionadded:: 1.0.7 :attr:`col_default_width` is a :class:`~kivy.properties.NumericProperty` and defaults to 0. ''' row_default_height = NumericProperty(0) '''Default minimum size to use for row. .. versionadded:: 1.0.7 :attr:`row_default_height` is a :class:`~kivy.properties.NumericProperty` and defaults to 0. ''' col_force_default = BooleanProperty(False) '''If True, ignore the width and size_hint_x of the child and use the default column width. .. versionadded:: 1.0.7 :attr:`col_force_default` is a :class:`~kivy.properties.BooleanProperty` and defaults to False. ''' row_force_default = BooleanProperty(False) '''If True, ignore the height and size_hint_y of the child and use the default row height. .. versionadded:: 1.0.7 :attr:`row_force_default` is a :class:`~kivy.properties.BooleanProperty` and defaults to False. ''' cols_minimum = DictProperty({}) '''Dict of minimum width for each column. The dictionary keys are the column numbers, e.g. 0, 1, 2... .. versionadded:: 1.0.7 :attr:`cols_minimum` is a :class:`~kivy.properties.DictProperty` and defaults to {}. ''' rows_minimum = DictProperty({}) '''Dict of minimum height for each row. The dictionary keys are the row numbers, e.g. 0, 1, 2... .. versionadded:: 1.0.7 :attr:`rows_minimum` is a :class:`~kivy.properties.DictProperty` and defaults to {}. ''' minimum_width = NumericProperty(0) '''Automatically computed minimum width needed to contain all children. .. versionadded:: 1.0.8 :attr:`minimum_width` is a :class:`~kivy.properties.NumericProperty` and defaults to 0. It is read only. ''' minimum_height = NumericProperty(0) '''Automatically computed minimum height needed to contain all children. .. versionadded:: 1.0.8 :attr:`minimum_height` is a :class:`~kivy.properties.NumericProperty` and defaults to 0. It is read only. ''' minimum_size = ReferenceListProperty(minimum_width, minimum_height) '''Automatically computed minimum size needed to contain all children. .. versionadded:: 1.0.8 :attr:`minimum_size` is a :class:`~kivy.properties.ReferenceListProperty` of (:attr:`minimum_width`, :attr:`minimum_height`) properties. It is read only. ''' def __init__(self, **kwargs): self._cols = self._rows = None super(GridLayout, self).__init__(**kwargs) fbind = self.fbind update = self._trigger_layout fbind('col_default_width', update) fbind('row_default_height', update) fbind('col_force_default', update) fbind('row_force_default', update) fbind('cols', update) fbind('rows', update) fbind('parent', update) fbind('spacing', update) fbind('padding', update) fbind('children', update) fbind('size', update) fbind('pos', update) def get_max_widgets(self): if self.cols and self.rows: return self.rows * self.cols else: return None def on_children(self, instance, value): # if that makes impossible to construct things with deffered method, # migrate this test in do_layout, and/or issue a warning. smax = self.get_max_widgets() if smax and len(value) > smax: raise GridLayoutException( 'Too many children in GridLayout. Increase rows/cols!') def _init_rows_cols_sizes(self, count): # the goal here is to calculate the minimum size of every cols/rows # and determine if they have stretch or not current_cols = self.cols current_rows = self.rows # if no cols or rows are set, we can't calculate minimum size. # the grid must be contrained at least on one side if not current_cols and not current_rows: Logger.warning('%r have no cols or rows set, ' 'layout is not triggered.' % self) return if current_cols is None: current_cols = int(ceil(count / float(current_rows))) elif current_rows is None: current_rows = int(ceil(count / float(current_cols))) current_cols = max(1, current_cols) current_rows = max(1, current_rows) self._has_hint_bound_x = False self._has_hint_bound_y = False self._cols_min_size_none = 0. # min size from all the None hint self._rows_min_size_none = 0. # min size from all the None hint self._cols = cols = [self.col_default_width] * current_cols self._cols_sh = [None] * current_cols self._cols_sh_min = [None] * current_cols self._cols_sh_max = [None] * current_cols self._rows = rows = [self.row_default_height] * current_rows self._rows_sh = [None] * current_rows self._rows_sh_min = [None] * current_rows self._rows_sh_max = [None] * current_rows # update minimum size from the dicts items = (i for i in self.cols_minimum.items() if i[0] < len(cols)) for index, value in items: cols[index] = max(value, cols[index]) items = (i for i in self.rows_minimum.items() if i[0] < len(rows)) for index, value in items: rows[index] = max(value, rows[index]) return True def _fill_rows_cols_sizes(self): cols, rows = self._cols, self._rows cols_sh, rows_sh = self._cols_sh, self._rows_sh cols_sh_min, rows_sh_min = self._cols_sh_min, self._rows_sh_min cols_sh_max, rows_sh_max = self._cols_sh_max, self._rows_sh_max # calculate minimum size for each columns and rows n_cols = len(cols) has_bound_y = has_bound_x = False for i, child in enumerate(reversed(self.children)): (shw, shh), (w, h) = child.size_hint, child.size shw_min, shh_min = child.size_hint_min shw_max, shh_max = child.size_hint_max row, col = divmod(i, n_cols) # compute minimum size / maximum stretch needed if shw is None: cols[col] = nmax(cols[col], w) else: cols_sh[col] = nmax(cols_sh[col], shw) if shw_min is not None: has_bound_x = True cols_sh_min[col] = nmax(cols_sh_min[col], shw_min) if shw_max is not None: has_bound_x = True cols_sh_max[col] = nmin(cols_sh_max[col], shw_max) if shh is None: rows[row] = nmax(rows[row], h) else: rows_sh[row] = nmax(rows_sh[row], shh) if shh_min is not None: has_bound_y = True rows_sh_min[col] = nmax(rows_sh_min[col], shh_min) if shh_max is not None: has_bound_y = True rows_sh_max[col] = nmin(rows_sh_max[col], shh_max) self._has_hint_bound_x = has_bound_x self._has_hint_bound_y = has_bound_y def _update_minimum_size(self): # calculate minimum width/height needed, starting from padding + # spacing l, t, r, b = self.padding spacing_x, spacing_y = self.spacing cols, rows = self._cols, self._rows width = l + r + spacing_x * (len(cols) - 1) self._cols_min_size_none = sum(cols) + width # we need to subtract for the sh_max/min the already guaranteed size # due to having a None in the col. So sh_min gets smaller by that size # since it's already covered. Similarly for sh_max, because if we # already exceeded the max, the subtracted max will be zero, so # it won't get larger if self._has_hint_bound_x: cols_sh_min = self._cols_sh_min cols_sh_max = self._cols_sh_max for i, (c, sh_min, sh_max) in enumerate( zip(cols, cols_sh_min, cols_sh_max)): if sh_min is not None: width += max(c, sh_min) cols_sh_min[i] = max(0., sh_min - c) else: width += c if sh_max is not None: cols_sh_max[i] = max(0., sh_max - c) else: width = self._cols_min_size_none height = t + b + spacing_y * (len(rows) - 1) self._rows_min_size_none = sum(rows) + height if self._has_hint_bound_y: rows_sh_min = self._rows_sh_min rows_sh_max = self._rows_sh_max for i, (r, sh_min, sh_max) in enumerate( zip(rows, rows_sh_min, rows_sh_max)): if sh_min is not None: height += max(r, sh_min) rows_sh_min[i] = max(0., sh_min - r) else: height += r if sh_max is not None: rows_sh_max[i] = max(0., sh_max - r) else: height = self._rows_min_size_none # finally, set the minimum size self.minimum_size = (width, height) def _finalize_rows_cols_sizes(self): selfw = self.width selfh = self.height # resolve size for each column if self.col_force_default: cols = [self.col_default_width] * len(self._cols) for index, value in self.cols_minimum.items(): cols[index] = value self._cols = cols else: cols = self._cols cols_sh = self._cols_sh cols_sh_min = self._cols_sh_min cols_weight = float(sum((x for x in cols_sh if x is not None))) stretch_w = max(0., selfw - self._cols_min_size_none) if stretch_w > 1e-9: if self._has_hint_bound_x: # fix the hints to be within bounds self.layout_hint_with_bounds( cols_weight, stretch_w, sum((c for c in cols_sh_min if c is not None)), cols_sh_min, self._cols_sh_max, cols_sh) for index, col_stretch in enumerate(cols_sh): # if the col don't have stretch information, nothing to do if not col_stretch: continue # add to the min width whatever remains from size_hint cols[index] += stretch_w * col_stretch / cols_weight # same algo for rows if self.row_force_default: rows = [self.row_default_height] * len(self._rows) for index, value in self.rows_minimum.items(): rows[index] = value self._rows = rows else: rows = self._rows rows_sh = self._rows_sh rows_sh_min = self._rows_sh_min rows_weight = float(sum((x for x in rows_sh if x is not None))) stretch_h = max(0., selfh - self._rows_min_size_none) if stretch_h > 1e-9: if self._has_hint_bound_y: # fix the hints to be within bounds self.layout_hint_with_bounds( rows_weight, stretch_h, sum((r for r in rows_sh_min if r is not None)), rows_sh_min, self._rows_sh_max, rows_sh) for index, row_stretch in enumerate(rows_sh): # if the row don't have stretch information, nothing to do if not row_stretch: continue # add to the min height whatever remains from size_hint rows[index] += stretch_h * row_stretch / rows_weight def _iterate_layout(self, count): selfx = self.x padding_left = self.padding[0] padding_top = self.padding[1] spacing_x, spacing_y = self.spacing i = count - 1 y = self.top - padding_top cols = self._cols for row_height in self._rows: x = selfx + padding_left for col_width in cols: if i < 0: break yield i, x, y - row_height, col_width, row_height i = i - 1 x = x + col_width + spacing_x y -= row_height + spacing_y def do_layout(self, *largs): children = self.children if not children or not self._init_rows_cols_sizes(len(children)): l, t, r, b = self.padding self.minimum_size = l + r, t + b return self._fill_rows_cols_sizes() self._update_minimum_size() self._finalize_rows_cols_sizes() for i, x, y, w, h in self._iterate_layout(len(children)): c = children[i] c.pos = x, y shw, shh = c.size_hint shw_min, shh_min = c.size_hint_min shw_max, shh_max = c.size_hint_max if shw_min is not None: if shw_max is not None: w = max(min(w, shw_max), shw_min) else: w = max(w, shw_min) else: if shw_max is not None: w = min(w, shw_max) if shh_min is not None: if shh_max is not None: h = max(min(h, shh_max), shh_min) else: h = max(h, shh_min) else: if shh_max is not None: h = min(h, shh_max) if shw is None: if shh is not None: c.height = h else: if shh is None: c.width = w else: c.size = (w, h)