change form machinery to always have space for validation error

and display help, if present, there by default

subiquity/ui/views/filesystem/partition.py

@@ -84,7 +84,7 @@ class PartitionForm(Form):
             self.size.widget.value = val
         sz = dehumanize_size(val)
         if sz > self.max_size:
-            self.size.show_extra(Color.info_minor(Text("Capped partition size at %s"%(self.size_str,), align="center")))
+            self.size.show_extra(('info_minor', "Capped partition size at %s"%(self.size_str,)))
             self.size.widget.value = self.size_str
             return self.max_size
         return sz

subiquitycore/ui/form.py

@@ -29,7 +29,6 @@ from urwid import (
 from subiquitycore.ui.buttons import cancel_btn, done_btn
 from subiquitycore.ui.container import Columns, Pile
 from subiquitycore.ui.interactive import (
-    Help,
     PasswordEditor,
     IntegerEditor,
     StringEditor,
@@ -134,28 +133,25 @@ class BoundFormField(object):
             return validator()
 
     def validate(self):
-        self.hide_extra()
+        # cleaning/validation can call show_extra to add an
+        # informative message. We record this by having show_extra to
+        # set showing_extra so we don't immediately replace this
+        # message with the widget's help in the case that validation
+        # succeeds.
+        self.showing_extra = False
         r = self._validate()
         if r is None:
             self.in_error = False
+            if not self.showing_extra:
+                self.help_text.set_text(self.help)
         else:
             self.in_error = True
-            extra = Color.info_error(Text(r, align="center"))
-            self.show_extra(extra)
+            self.show_extra(('info_error', r))
         self.form.validated()
 
-    def hide_extra(self):
-        if self.showing_extra:
-            del self.pile.contents[1]
-            self.showing_extra = False
-
-    def show_extra(self, extra):
-        t = (extra, self.pile.options('pack'))
-        if self.showing_extra:
-            self.pile.contents[1] = t
-        else:
-            self.pile.contents[1:1] = [t]
+    def show_extra(self, extra_markup):
         self.showing_extra = True
+        self.help_text.set_text(extra_markup)
 
     @property
     def value(self):
@@ -169,12 +165,16 @@ class BoundFormField(object):
     def help(self):
         if self._help is not None:
             return self._help
-        else:
+        elif self.field.help is not None:
             return self.field.help
+        else:
+            return ""
 
     @help.setter
     def help(self, val):
         self._help = val
+        if self.pile is not None:
+            self.pile[1].set_text(val)
 
     @property
     def caption(self):
@@ -193,14 +193,9 @@ class BoundFormField(object):
             input = Color.string_input(_Validator(self, self.widget))
         else:
             input = self.widget
-        if self.help is not None:
-            help = Help(self.parent_view, self.help)
-        else:
-            help = Text("")
         cols = [
                     (self._longest_caption, text),
-                    input,
-                    (3, help),
+                    input
                 ]
         cols = Columns(cols, dividechars=2)
         if self._enabled:
@@ -213,7 +208,12 @@ class BoundFormField(object):
             raise RuntimeError("do not call as_row more than once!")
         self.parent_view = view
         self._longest_caption = longest_caption
-        self.pile = Pile([self._cols()])
+        self.help_text = Text(self.help, align="center")
+        cols = [
+                    (self._longest_caption, Text("")),
+                    self.help_text,
+                ]
+        self.pile = Pile([self._cols(), Columns(cols, dividechars=2)])
         return self.pile
 
     @property

subiquitycore/ui/interactive.py

@@ -21,19 +21,12 @@ import logging
 import re
 
 from urwid import (
-    ACTIVATE,
     Edit,
     IntEdit,
-    LineBox,
-    SelectableIcon,
-    Text,
     WidgetWrap,
     )
 
-from subiquitycore.ui.buttons import close_btn
-from subiquitycore.ui.container import Pile
 from subiquitycore.ui.selector import Selector
-from subiquitycore.ui.utils import Color, Padding, button_pile
 
 log = logging.getLogger("subiquitycore.ui.input")
 
@@ -113,24 +106,3 @@ class YesNo(Selector):
     def __init__(self):
         opts = [_('Yes'), _('No')]
         super().__init__(opts)
-
-
-class _HelpDisplay(WidgetWrap):
-    def __init__(self, closer, help_text):
-        self._closer = closer
-        buttons = [close_btn(on_press=lambda btn:self._closer())]
-        super().__init__(LineBox(Pile([Text(help_text), button_pile(buttons)]), title=_("Help")))
-
-
-class Help(WidgetWrap):
-
-    def __init__(self, view, help_text):
-        self._view = view
-        self._help_text = help_text
-        self._button = Padding.fixed_3(Color.button(SelectableIcon("[?]", 1)))
-        super().__init__(self._button)
-
-    def keypress(self, size, key):
-        if self._command_map[key] != ACTIVATE:
-            return key
-        self._view.show_overlay(_HelpDisplay(self._view.remove_overlay, self._help_text))