wallet.get_max_amount method, used by qt and kivy

gui/kivy/main_window.py

@@ -440,6 +440,11 @@ class ElectrumWindow(App):
         status_card.uncomfirmed = unconfirmed.strip()
 
 
+    def get_max_amount(self):
+        inputs = self.wallet.get_spendable_coins(None)
+        amount, fee = self.wallet.get_max_amount(self.electrum_config, inputs, None)
+        return self.format_amount(amount)
+
     def update_amount(self, amount, c):
         if c == '<':
             return amount[:-1]

gui/kivy/uix/ui_screens/amount.kv

@@ -22,8 +22,9 @@ Popup:
                 Button:
                     size_hint_x: 1
                     height: '48dp'
-                    text: ''
-                    on_release: a.value = "max"
+                    amount: app.get_max_amount()
+                    text: self.amount + ' ' + app.base_unit
+                    on_release: a.amount = self.amount
 
             BoxLayout:
                 size_hint: 1, None

gui/qt/main_window.py

@@ -965,22 +965,15 @@ class ElectrumWindow(QMainWindow, PrintError):
         grid.addLayout(buttons, 6, 1, 1, 2)
 
         def on_shortcut():
-            sendable = self.get_sendable_balance()
             inputs = self.get_coins()
-            for i in inputs:
-                self.wallet.add_input_info(i)
-            addr = self.payto_e.payto_address if self.payto_e.payto_address else self.dummy_address
-            output = ('address', addr, sendable)
-            dummy_tx = Transaction.from_io(inputs, [output])
+            amount, fee = self.wallet.get_max_amount(self.config, inputs, self.fee_e.get_amount())
             if self.fee_e.get_amount() is None:
-                fee_per_kb = self.wallet.fee_per_kb(self.config)
-                self.fee_e.setAmount(self.wallet.estimated_fee(dummy_tx, fee_per_kb))
-            self.amount_e.setAmount(max(0, sendable - self.fee_e.get_amount()))
+                self.fee_e.setAmount(fee)
+            self.amount_e.setAmount(max(0, amount))
             # emit signal for fiat_amount update
             self.amount_e.textEdited.emit("")
 
         self.amount_e.shortcut.connect(on_shortcut)
-
         self.payto_e.textChanged.connect(self.update_fee)
         self.amount_e.textEdited.connect(self.update_fee)
         self.fee_e.textEdited.connect(self.update_fee)
@@ -1539,10 +1532,6 @@ class ElectrumWindow(QMainWindow, PrintError):
         menu.exec_(self.address_list.viewport().mapToGlobal(position))
 
 
-    def get_sendable_balance(self):
-        return sum(map(lambda x:x['value'], self.get_coins()))
-
-
     def get_coins(self):
         if self.pay_from:
             return self.pay_from

lib/wallet.py

@@ -633,6 +633,19 @@ class Abstract_Wallet(PrintError):
                     coins = coins[1:] + [ coins[0] ]
         return [value for height, value in coins]
 
+    def get_max_amount(self, config, inputs, fee):
+        sendable = sum(map(lambda x:x['value'], inputs))
+        for i in inputs:
+            self.add_input_info(i)
+        addr = self.addresses(False)[0]
+        output = ('address', addr, sendable)
+        dummy_tx = Transaction.from_io(inputs, [output])
+        if fee is None:
+            fee_per_kb = self.fee_per_kb(config)
+            fee = self.estimated_fee(dummy_tx, fee_per_kb)
+        amount = max(0, sendable - fee)
+        return amount, fee
+
     def get_account_name(self, k):
         return self.labels.get(k, self.accounts[k].get_name(k))