Merge pull request #316 from CanonicalLtd/mwhudson/stretchy-overlay

add an overlay that has nicer resizing behaviour

subiquity/ui/views/filesystem/filesystem.py

@@ -20,12 +20,7 @@ configuration.
 
 """
 import logging
-from urwid import (
+from urwid import Text
-    LineBox,
-    Padding as UrwidPadding,
-    Text,
-    WidgetWrap,
-    )
 
 from subiquitycore.ui.buttons import (
     back_btn,
@@ -36,6 +31,7 @@ from subiquitycore.ui.buttons import (
     reset_btn,
     )
 from subiquitycore.ui.container import Columns, ListBox, Pile
+from subiquitycore.ui.stretchy import Stretchy
 from subiquitycore.ui.utils import button_pile, Color, Padding
 from subiquitycore.view import BaseView
 
@@ -52,22 +48,24 @@ result in the loss of data on the disks selected to be formatted.
 You will not be able to return to this or a previous screen once \
 the installation has started.
 
-Are you sure you want to continue?
+Are you sure you want to continue?""")
-""")
 
-class FilesystemConfirmationView(WidgetWrap):
+class FilesystemConfirmation(Stretchy):
     def __init__(self, parent, controller):
         self.parent = parent
         self.controller = controller
-        pile = Pile([
+        widgets = [
-            UrwidPadding(Text(confirmation_text), left=2, right=2),
+            Text(confirmation_text),
+            Text(""),
             button_pile([
                 cancel_btn(_("No"), on_press=self.cancel),
                 danger_btn(_("Continue"), on_press=self.ok)]),
-            Text(""),
+            ]
-            ])
+        super().__init__(
-        lb = LineBox(pile, title=_("Confirm destructive action"))
+            _("Confirm destructive action"),
-        super().__init__(lb)
+            widgets,
+            stretchy_index=0,
+            focus_index=2)
 
     def ok(self, sender):
         self.controller.finish()
@@ -275,4 +273,4 @@ class FilesystemView(BaseView):
         self.controller.reset()
 
     def done(self, button):
-        self.show_overlay(FilesystemConfirmationView(self, self.controller), min_width=0)
+        self.show_stretchy_overlay(FilesystemConfirmation(self, self.controller))

subiquity/ui/views/keyboard.py

@@ -18,8 +18,6 @@ import logging
 from urwid import (
     connect_signal,
     LineBox,
-    Padding as UrwidPadding,
-    SolidFill,
     Text,
     WidgetWrap,
     )
@@ -31,7 +29,6 @@ from subiquitycore.ui.buttons import (
     )
 from subiquitycore.ui.container import (
     Columns,
-    ListBox,
     Pile,
     )
 from subiquitycore.ui.form import (
@@ -39,6 +36,9 @@ from subiquitycore.ui.form import (
     Form,
     )
 from subiquitycore.ui.selector import Selector, Option
+from subiquitycore.ui.stretchy import (
+    Stretchy,
+    )
 from subiquitycore.ui.utils import button_pile, Color, Padding, screen
 from subiquitycore.view import BaseView
 
@@ -302,7 +302,7 @@ toggle_options = [
     ]
 
 
-class ToggleQuestion(WidgetWrap):
+class ToggleQuestion(Stretchy):
 
     def __init__(self, parent, setting):
         self.parent = parent
@@ -315,28 +315,24 @@ class ToggleQuestion(WidgetWrap):
             except AttributeError:
                 pass
 
-        pile = Pile([
+        widgets = [
-            ListBox([
+            Text(_(toggle_text)),
-                Text(_(toggle_text)),
+            Text(""),
-                ]),
+            Padding.center_79(Columns([
-            (1, SolidFill(" ")),
-            ('pack', Padding.center_79(Columns([
                 ('pack', Text(_("Shortcut: "))),
                 Color.string_input(self.selector),
-                ]))),
+                ])),
-            (1, SolidFill(" ")),
+            Text(""),
-            ('pack', button_pile([
+            button_pile([
                 ok_btn(label=_("OK"), on_press=self.ok),
                 cancel_btn(label=_("Cancel"), on_press=self.cancel),
-                ])),
+                ]),
-            ])
+            ]
-        pile.focus_position = 4
         super().__init__(
-            LineBox(
+            _("Select layout toggle"),
-                UrwidPadding(
+            widgets,
-                    pile,
+            stretchy_index=0,
-                    left=1, right=1),
+            focus_index=4)
-                _("Select layout toggle")))
 
     def ok(self, sender):
         self.parent.remove_overlay()
@@ -411,7 +407,7 @@ class KeyboardView(BaseView):
         setting = KeyboardSetting(layout=layout, variant=variant)
         new_setting = setting.latinizable()
         if new_setting != setting:
-            self.show_overlay(ToggleQuestion(self, new_setting), height=('relative', 100))
+            self.show_stretchy_overlay(ToggleQuestion(self, new_setting))
             return
         self.really_done(setting)
 

subiquitycore/ui/stretchy.py

@@ -0,0 +1,145 @@
+# Copyright 2018 Canonical, Ltd.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 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 Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+"""Custom overlay that only takes the space it needs but can still scroll.
+
+There are a couple of dialogs in subiquity that basically have the form:
+
+ +------ dialog title --------+
+ |                            |
+ | potentially quite long     |
+ | block of text that might   |
+ | take several lines and so  |
+ | need to be scrollable      |
+ |                            |
+ |  maybe another widget      |
+ |                            |
+ |       [ OK     ]           |
+ |       [ Cancel ]           |
+ |                            |
+ +----------------------------+
+
+The way urwid works makes doing this nicely hard.  Simply putting the
+text in a ListBox "works" but because the listbox is a box widget we
+can't let it choose its height: either we'll end up having the text
+scrollable in some situations where there is enough space on the
+screen to show it all or when the screen is large there will be a
+massive ugly space between the text and the following widgets.
+
+Because you can't make a widget that behaves the way we want, this
+module gives a way of providing a list of widgets to display in a Pile
+and and nominating one of them to be made scrollable. A title, a list
+of widgets and index to be scrollable is bundled up into an object
+called a "stretchy" but is a bad name but at least easily greppable.
+"""
+
+
+import urwid
+
+from subiquitycore.ui.container import ListBox, Pile
+
+class Stretchy:
+    def __init__(self, title, widgets, stretchy_index, focus_index):
+        """
+        title: goes in the LineBox
+        widgets: list of widgets to put in the pile
+        stretchy_index: index into widgets of widget to wrap in ListBox
+        focus_index: index into widgets of initial focus
+        """
+        self.title = title
+        self.widgets = widgets
+        self.stretchy_index = stretchy_index
+        self.focus_index = focus_index
+
+    @property
+    def stretchy_w(self):
+        return self.widgets[self.stretchy_index]
+
+
+class StretchyOverlay(urwid.Widget):
+    _selectable = True
+    _sizing = frozenset([urwid.BOX])
+    def __init__(self, bottom_w, stretchy):
+        self.bottom_w = bottom_w
+        self.stretchy = stretchy
+        self.listbox = ListBox([stretchy.stretchy_w])
+        def entry(i, w):
+            if i == stretchy.stretchy_index:
+                return ('weight', 1, self.listbox)
+            else:
+                return ('pack', w)
+        # this Filler/Padding/LineBox/Filler/Padding construction
+        # seems ridiculous but it works.
+        self.top_w = urwid.Filler(
+            urwid.Padding(
+                urwid.LineBox(
+                    urwid.Filler(
+                        urwid.Padding(
+                            Pile(
+                                [entry(i, w) for (i, w) in enumerate(stretchy.widgets)],
+                                focus_item=stretchy.widgets[stretchy.focus_index]),
+                            left=2, right=2),
+                        top=1, bottom=1, height=('relative', 100)),
+                    title=stretchy.title),
+                left=3, right=3),
+            top=1, bottom=1, height=('relative', 100))
+
+    def _top_size(self, size, focus):
+        # Returns the size of the top widget and whether the scollbar will be shown.
+
+        maxcol, maxrow = size # we are a BOX widget
+        outercol = min(maxcol, 80)
+        innercol = outercol - 10 # (3 outer padding, 1 line, 2 inner padding) x 2
+        fixed_rows = 6 # lines at top and bottom and padding
+
+        for i, widget in enumerate(self.stretchy.widgets):
+            if i == self.stretchy.stretchy_index:
+                continue
+            if urwid.FLOW in widget.sizing():
+                rows = widget.rows((innercol,), focus)
+                fixed_rows += rows
+            else:
+                w_size = widget.pack((), focus)
+                fixed_rows += w_size[1]
+
+        if fixed_rows > maxrow:
+            # There's no space for the stretchy widget at all,
+            # probably something will break but well let's defer the
+            # problem for now.
+            return (outercol, size[1]), False
+
+        stretchy_ideal_rows = self.stretchy.stretchy_w.rows((innercol,), focus)
+
+        if maxrow - fixed_rows >= stretchy_ideal_rows:
+            return (outercol, stretchy_ideal_rows + fixed_rows), False
+        else:
+            return (outercol, size[1]), True
+
+    def keypress(self, size, key):
+        top_size, scrollbar_visible = self._top_size(size, True)
+        self.listbox._selectable = scrollbar_visible
+        return self.top_w.keypress(top_size, key)
+
+    def render(self, size, focus):
+        bottom_c = self.bottom_w.render(size, False)
+        if not bottom_c.cols() or not bottom_c.rows():
+            return urwid.CompositeCanvas(bottom_c)
+
+        top_size, _ = self._top_size(size, focus)
+        top_c = self.top_w.render(top_size, focus)
+        top_c = urwid.CompositeCanvas(top_c)
+        left = (size[0] - top_size[0]) // 2
+        top = (size[1] - top_size[1]) // 2
+        return urwid.CanvasOverlay(top_c, bottom_c, left, top)

subiquitycore/view.py

@@ -18,17 +18,14 @@
 Contains some default key navigations
 """
 
-from urwid import Columns, Overlay, Pile, SolidFill, Text, WidgetWrap
+from subiquitycore.ui.stretchy import StretchyOverlay
+
+from urwid import Columns, Overlay, Pile, Text, WidgetWrap
 
 
 class BaseView(WidgetWrap):
 
-    def __init__(self, w):
-        self.orig_w = None
-        super().__init__(w)
-
     def show_overlay(self, overlay_widget, **kw):
-        self.orig_w = self._w
         args = dict(
             align='center',
             width=('relative', 60),
@@ -42,26 +39,22 @@ class BaseView(WidgetWrap):
             if isinstance(kw['width'], int):
                 kw['width'] += 2*PADDING
         args.update(kw)
-        if 'height' in kw:
-            f = SolidFill(" ")
-            p = 1
-        else:
-            f = Text("")
-            p = 'pack'
         top = Pile([
-            (p, f),
+            ('pack', Text("")),
             Columns([
-                (PADDING, f),
+                (PADDING, Text("")),
                 overlay_widget,
-                (PADDING, f)
+                (PADDING, Text(""))
                 ]),
-            (p, f),
+            ('pack', Text("")),
             ])
         self._w = Overlay(top_w=top, bottom_w=self._w, **args)
 
+    def show_stretchy_overlay(self, stretchy):
+        self._w = StretchyOverlay(self._w, stretchy)
+
     def remove_overlay(self):
-        self._w = self.orig_w
+        self._w = self._w.bottom_w
-        self.orig_w = None
 
     def cancel(self):
         pass