kivy: improve amount dialog

gui/kivy/main.kv

@@ -221,20 +221,11 @@
     background_active: 'atlas://gui/kivy/theming/light/textinput_active'
 
 
-#<ElectrumScreen>
-#    ScrollView:
-#        do_scroll_x: False
-#        do_scroll_y: False if root.fullscreen else (content.height > root.height - dp(16))
-#        AnchorLayout:
-#            size_hint_y: None
-#            height: root.height if root.fullscreen else max(root.height, content.height)
-#            GridLayout:
-#                id: content
-#                cols: 1
-#                spacing: '8dp'
-#                padding: '8dp'
-#                size_hint: (1, 1) if root.fullscreen else (.8, None)
-#                height: self.height if root.fullscreen else self.minimum_height
+<KButton@Button>:
+    size_hint: 1, None
+    height: '48dp'
+    on_release: self.label.amount = app.update_amount(self.label.amount, self.text)
+
 
 <TabbedPanelStrip>:
     on_parent:

gui/kivy/main_window.py

@@ -439,6 +439,17 @@ class ElectrumWindow(App):
         status_card.quote_text = quote_text.strip()
         status_card.uncomfirmed = unconfirmed.strip()
 
+
+    def update_amount(self, amount, c):
+        if c == '<':
+            return amount[:-1]
+        try:
+            s = amount + c
+            amount = s  if Decimal(s)!=0 else ''            
+        except:
+            pass
+        return amount
+
     def format_amount(self, x, is_diff=False, whitespaces=False):
         from electrum.util import format_satoshis
         return format_satoshis(x, is_diff, self.num_zeros,
@@ -712,9 +723,9 @@ class ElectrumWindow(App):
         if label.text != label.default_text:
             a, u = label.text.split()
             assert u == self.base_unit
-            popup.ids.amount_label.value = a
+            popup.ids.a.amount = a
         def cb():
-            o = popup.ids.amount_label.text
+            o = popup.ids.a.text
             label.text = o if o else label.default_text
             if callback:
                 callback()

gui/kivy/uix/ui_screens/amount.kv

@@ -1,79 +1,93 @@
-<KButton@Button>:
-    size_hint: 1, None
-    height: '38dp'
+#:import Decimal decimal.Decimal
+
 
 Popup:
     id: popup
     title: _('Amount')
 
-    BoxLayout:
-
-        orientation: 'vertical'
-        
-        halign: 'center'
+    AnchorLayout:
+        anchor_x: 'center'
 
         BoxLayout:
-            Label:
-                id: amount_label
-                text: ''
-                value: ''
-                on_value:
-                    self.text = self.value + ' ' + app.base_unit
-            Widget:
-                size_hint_x: 1
+            orientation: 'vertical'
+            size_hint: 0.8, 1
 
-        GridLayout:
-            cols: 3
-            size_hint: 0.5, 1
-            KButton:
-                text: '1'
-                on_release: amount_label.value += self.text
-            KButton:
-                text: '2'
-                on_release: amount_label.value += self.text
-            KButton:
-                text: '3'
-                on_release: amount_label.value += self.text
-            KButton:
-                text: '4'
-                on_release: amount_label.value += self.text
-            KButton:
-                text: '5'
-                on_release: amount_label.value += self.text
-            KButton:
-                text: '6'
-                on_release: amount_label.value += self.text
-            KButton:
-                text: '7'
-                on_release: amount_label.value += self.text
-            KButton:
-                text: '8'
-                on_release: amount_label.value += self.text
-            KButton:
-                text: '9'
-                on_release: amount_label.value += self.text
-            KButton:
-                text: '.'
-                on_release: amount_label.value += self.text
-            KButton:
-                text: '0'
-                on_release: amount_label.value += self.text
-            KButton:
-                text: '<'
-                on_release: amount_label.value = amount_label.value[:-1]
-
-        BoxLayout:
-            size_hint: 0.5, None
-            Button:
-                size_hint: 0.5, None
+            BoxLayout:
+                size_hint: 1, None
                 height: '48dp'
-                text: _('Max')
-                on_release: popup.dismiss()
-            Button:
-                size_hint: 0.5, None
+                id: 'spendable'
+                Label:
+                    text: _('Spendable:')
+                    size_hint_x: 1
+                Button:
+                    size_hint_x: 1
+                    height: '48dp'
+                    text: ''
+                    on_release: a.value = "max"
+
+            BoxLayout:
+                size_hint: 1, None
                 height: '48dp'
-                text: _('OK')
-                on_release: popup.dismiss()
+                Label:
+                    id: a
+                    amount: ''
+                    text: self.amount + ' ' + app.base_unit if self.amount else ''
+                Widget:
+                    size_hint_x: 1
+
+            Widget:
+                size_hint: 1, 1
 
-        Widget:
-            size_hint: 1, None
+            GridLayout:
+                size_hint: 1, None
+                height: '300dp'
+                cols: 3
+                KButton:
+                    text: '1'
+                    label: a
+                KButton:
+                    text: '2'
+                    label: a
+                KButton:
+                    text: '3'
+                    label: a
+                KButton:
+                    text: '4'
+                    label: a
+                KButton:
+                    text: '5'
+                    label: a
+                KButton:
+                    text: '6'
+                    label: a
+                KButton:
+                    text: '7'
+                    label: a
+                KButton:
+                    text: '8'
+                    label: a
+                KButton:
+                    text: '9'
+                    label: a
+                KButton:
+                    text: '.'
+                    label: a
+                KButton:
+                    text: '0'
+                    label: a
+                KButton:
+                    text: '<'
+                    label: a
+
+            BoxLayout:
+                size_hint: 1, None
+                height: '48dp'
+                Widget:
+                    size_hint: 0.7, None
+                    height: '48dp'
+                Button:
+                    size_hint: 0.3, None
+                    height: '48dp'
+                    text: _('OK')
+                    on_release: popup.dismiss()
+