'''
Stack Layout
============
.. only:: html
.. image:: images/stacklayout.gif
:align: right
.. only:: latex
.. image:: images/stacklayout.png
:align: right
.. versionadded:: 1.0.5
The :class:`StackLayout` arranges children vertically or horizontally, as many
as the layout can fit. The size of the individual children widgets do not
have to be uniform.
For example, to display widgets that get progressively larger in width::
root = StackLayout()
for i in range(25):
btn = Button(text=str(i), width=40 + i * 5, size_hint=(None, 0.15))
root.add_widget(btn)
.. image:: images/stacklayout_sizing.png
:align: left
'''
__all__ = ('StackLayout', )
from kivy.uix.layout import Layout
from kivy.properties import NumericProperty, OptionProperty, \
ReferenceListProperty, VariableListProperty
def _compute_size(c, available_size, idx):
sh_min = c.size_hint_min[idx]
sh_max = c.size_hint_max[idx]
val = c.size_hint[idx] * available_size
if sh_min is not None:
if sh_max is not None:
return max(min(sh_max, val), sh_min)
return max(val, sh_min)
if sh_max is not None:
return min(sh_max, val)
return val
[docs]class StackLayout(Layout):
'''Stack 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 single 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 single argument form [padding].
.. versionchanged:: 1.7.0
Replaced the NumericProperty with a VariableListProperty.
:attr:`padding` is a
:class:`~kivy.properties.VariableListProperty` and defaults to
[0, 0, 0, 0].
'''
orientation = OptionProperty('lr-tb', options=(
'lr-tb', 'tb-lr', 'rl-tb', 'tb-rl', 'lr-bt', 'bt-lr', 'rl-bt',
'bt-rl'))
'''Orientation of the layout.
:attr:`orientation` is an :class:`~kivy.properties.OptionProperty` and
defaults to 'lr-tb'.
Valid orientations are 'lr-tb', 'tb-lr', 'rl-tb', 'tb-rl', 'lr-bt',
'bt-lr', 'rl-bt' and 'bt-rl'.
.. versionchanged:: 1.5.0
:attr:`orientation` now correctly handles all valid combinations of
'lr','rl','tb','bt'. Before this version only 'lr-tb' and
'tb-lr' were supported, and 'tb-lr' was misnamed and placed
widgets from bottom to top and from right to left (reversed compared
to what was expected).
.. note::
'lr' means Left to Right.
'rl' means Right to Left.
'tb' means Top to Bottom.
'bt' means Bottom to Top.
'''
minimum_width = NumericProperty(0)
'''Minimum width needed to contain all children. It is automatically set
by the layout.
.. versionadded:: 1.0.8
:attr:`minimum_width` is a :class:`kivy.properties.NumericProperty` and
defaults to 0.
'''
minimum_height = NumericProperty(0)
'''Minimum height needed to contain all children. It is automatically set
by the layout.
.. versionadded:: 1.0.8
:attr:`minimum_height` is a :class:`kivy.properties.NumericProperty` and
defaults to 0.
'''
minimum_size = ReferenceListProperty(minimum_width, minimum_height)
'''Minimum size needed to contain all children. It is automatically set
by the layout.
.. versionadded:: 1.0.8
:attr:`minimum_size` is a
:class:`~kivy.properties.ReferenceListProperty` of
(:attr:`minimum_width`, :attr:`minimum_height`) properties.
'''
def __init__(self, **kwargs):
super(StackLayout, self).__init__(**kwargs)
trigger = self._trigger_layout
fbind = self.fbind
fbind('padding', trigger)
fbind('spacing', trigger)
fbind('children', trigger)
fbind('orientation', trigger)
fbind('size', trigger)
fbind('pos', trigger)
[docs] def do_layout(self, *largs):
if not self.children:
self.minimum_size = (0., 0.)
return
# optimize layout by preventing looking at the same attribute in a loop
selfpos = self.pos
selfsize = self.size
orientation = self.orientation.split('-')
padding_left = self.padding[0]
padding_top = self.padding[1]
padding_right = self.padding[2]
padding_bottom = self.padding[3]
padding_x = padding_left + padding_right
padding_y = padding_top + padding_bottom
spacing_x, spacing_y = self.spacing
# Determine which direction and in what order to place the widgets
posattr = [0] * 2
posdelta = [0] * 2
posstart = [0] * 2
for i in (0, 1):
posattr[i] = 1 * (orientation[i] in ('tb', 'bt'))
k = posattr[i]
if orientation[i] == 'lr':
# left to right
posdelta[i] = 1
posstart[i] = selfpos[k] + padding_left
elif orientation[i] == 'bt':
# bottom to top
posdelta[i] = 1
posstart[i] = selfpos[k] + padding_bottom
elif orientation[i] == 'rl':
# right to left
posdelta[i] = -1
posstart[i] = selfpos[k] + selfsize[k] - padding_right
else:
# top to bottom
posdelta[i] = -1
posstart[i] = selfpos[k] + selfsize[k] - padding_top
innerattr, outerattr = posattr
ustart, vstart = posstart
deltau, deltav = posdelta
del posattr, posdelta, posstart
u = ustart # inner loop position variable
v = vstart # outer loop position variable
# space calculation, used for determining when a row or column is full
if orientation[0] in ('lr', 'rl'):
sv = padding_y # size in v-direction, for minimum_size property
su = padding_x # size in h-direction
spacing_u = spacing_x
spacing_v = spacing_y
padding_u = padding_x
padding_v = padding_y
else:
sv = padding_x # size in v-direction, for minimum_size property
su = padding_y # size in h-direction
spacing_u = spacing_y
spacing_v = spacing_x
padding_u = padding_y
padding_v = padding_x
# space calculation, row height or column width, for arranging widgets
lv = 0
urev = (deltau < 0)
vrev = (deltav < 0)
firstchild = self.children[0]
sizes = []
lc = []
for c in reversed(self.children):
if c.size_hint[outerattr] is not None:
c.size[outerattr] = max(
1, _compute_size(c, selfsize[outerattr] - padding_v,
outerattr))
# does the widget fit in the row/column?
ccount = len(lc)
totalsize = availsize = max(
0, selfsize[innerattr] - padding_u - spacing_u * ccount)
if not lc:
if c.size_hint[innerattr] is not None:
childsize = max(1, _compute_size(c, totalsize, innerattr))
else:
childsize = max(0, c.size[innerattr])
availsize = selfsize[innerattr] - padding_u - childsize
testsizes = [childsize]
else:
testsizes = [0] * (ccount + 1)
for i, child in enumerate(lc):
if availsize <= 0:
# no space left but we're trying to add another widget.
availsize = -1
break
if child.size_hint[innerattr] is not None:
testsizes[i] = childsize = max(
1, _compute_size(child, totalsize, innerattr))
else:
childsize = max(0, child.size[innerattr])
testsizes[i] = childsize
availsize -= childsize
if c.size_hint[innerattr] is not None:
testsizes[-1] = max(
1, _compute_size(c, totalsize, innerattr))
else:
testsizes[-1] = max(0, c.size[innerattr])
availsize -= testsizes[-1]
# Tiny value added in order to avoid issues with float precision
# causing unexpected children reordering when parent resizes.
# e.g. if size is 101 and children size_hint_x is 1./5
# 5 children would not fit in one line because 101*(1./5) > 101/5
if (availsize + 1e-10) >= 0 or not lc:
# even if there's no space, we always add one widget to a row
lc.append(c)
sizes = testsizes
lv = max(lv, c.size[outerattr])
continue
# apply the sizes
for i, child in enumerate(lc):
if child.size_hint[innerattr] is not None:
child.size[innerattr] = sizes[i]
# push the line
sv += lv + spacing_v
for c2 in lc:
if urev:
u -= c2.size[innerattr]
c2.pos[innerattr] = u
pos_outer = v
if vrev:
# v position is actually the top/right side of the widget
# when going from high to low coordinate values,
# we need to subtract the height/width from the position.
pos_outer -= c2.size[outerattr]
c2.pos[outerattr] = pos_outer
if urev:
u -= spacing_u
else:
u += c2.size[innerattr] + spacing_u
v += deltav * lv
v += deltav * spacing_v
lc = [c]
lv = c.size[outerattr]
if c.size_hint[innerattr] is not None:
sizes = [
max(1, _compute_size(c, selfsize[innerattr] - padding_u,
innerattr))]
else:
sizes = [max(0, c.size[innerattr])]
u = ustart
if lc:
# apply the sizes
for i, child in enumerate(lc):
if child.size_hint[innerattr] is not None:
child.size[innerattr] = sizes[i]
# push the last (incomplete) line
sv += lv + spacing_v
for c2 in lc:
if urev:
u -= c2.size[innerattr]
c2.pos[innerattr] = u
pos_outer = v
if vrev:
pos_outer -= c2.size[outerattr]
c2.pos[outerattr] = pos_outer
if urev:
u -= spacing_u
else:
u += c2.size[innerattr] + spacing_u
self.minimum_size[outerattr] = sv
