Format the transaction window fee rate with 1 decimal place (#4286)

* Fix format_satoshi to properly handle non-integer values

Handling the integer and fraction parts together via string formatting
simplifies the initial composition because the default behavior manages
the - sign, and the incorporation of the fractional part.

* Limit fee rate output to one decimal place

Via a new precision arg

* Introduce format_fee_satoshis and use it for all fee display

gui/kivy/main_window.py

@@ -671,7 +671,7 @@ class ElectrumWindow(App):
         return format_satoshis_plain(amount, self.decimal_point())
 
     def format_amount(self, x, is_diff=False, whitespaces=False):
-        return format_satoshis(x, is_diff, 0, self.decimal_point(), whitespaces)
+        return format_satoshis(x, 0, self.decimal_point(), is_diff=is_diff, whitespaces=whitespaces)
 
     def format_amount_and_units(self, x):
         return format_satoshis_plain(x, self.decimal_point()) + ' ' + self.base_unit

gui/qt/main_window.py

@@ -44,8 +44,8 @@ from electrum.bitcoin import COIN, is_address, TYPE_ADDRESS
 from electrum import constants
 from electrum.plugins import run_hook
 from electrum.i18n import _
-from electrum.util import (format_time, format_satoshis, PrintError,
+from electrum.util import (format_time, format_satoshis, format_fee_satoshis,
-                           format_satoshis_plain, NotEnoughFunds,
+                           format_satoshis_plain, NotEnoughFunds, PrintError,
                            UserCancelled, NoDynamicFeeEstimates, profiler,
                            export_meta, import_meta, bh2u, bfh, InvalidPassword)
 from electrum import Transaction
@@ -639,7 +639,7 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, PrintError):
             self.require_fee_update = False
 
     def format_amount(self, x, is_diff=False, whitespaces=False):
-        return format_satoshis(x, is_diff, self.num_zeros, self.decimal_point, whitespaces)
+        return format_satoshis(x, self.num_zeros, self.decimal_point, is_diff=is_diff, whitespaces=whitespaces)
 
     def format_amount_and_units(self, amount):
         text = self.format_amount(amount) + ' '+ self.base_unit()
@@ -649,7 +649,7 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, PrintError):
         return text
 
     def format_fee_rate(self, fee_rate):
-        return format_satoshis(fee_rate/1000, False, self.num_zeros, 0, False)  + ' sat/byte'
+        return format_fee_satoshis(fee_rate/1000, self.num_zeros) + ' sat/byte'
 
     def get_decimal_point(self):
         return self.decimal_point
@@ -3192,5 +3192,3 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, PrintError):
             self.need_update.set()
             self.msg_box(QPixmap(":icons/offline_tx.png"), None, _('Success'), _("Transaction added to wallet history"))
             return True
-
-

lib/simple_config.py

@@ -7,7 +7,7 @@ import stat
 from copy import deepcopy
 
 from .util import (user_dir, print_error, PrintError,
-                   NoDynamicFeeEstimates, format_satoshis)
+                   NoDynamicFeeEstimates, format_fee_satoshis)
 from .i18n import _
 
 FEE_ETA_TARGETS = [25, 10, 5, 2]
@@ -367,7 +367,11 @@ class SimpleConfig(PrintError):
         text is what we target: static fee / num blocks to confirm in / mempool depth
         tooltip is the corresponding estimate (e.g. num blocks for a static fee)
         """
-        rate_str = (format_satoshis(fee_rate/1000, False, 0, 0, False)  + ' sat/byte') if fee_rate is not None else 'unknown'
+        if fee_rate is None:
+            rate_str = 'unknown'
+        else:
+            rate_str = format_fee_satoshis(fee_rate/1000) + ' sat/byte'
+
         if dyn:
             if mempool:
                 depth = self.depth_target(pos)

lib/tests/test_util.py

@@ -8,6 +8,43 @@ class TestUtil(unittest.TestCase):
         expected = "0.00001234"
         self.assertEqual(expected, result)
 
+    def test_format_satoshis_negative(self):
+        result = format_satoshis(-1234)
+        expected = "-0.00001234"
+        self.assertEqual(expected, result)
+
+    def test_format_fee(self):
+        result = format_satoshis(1700/1000, 0, 0)
+        expected = "1.7"
+        self.assertEqual(expected, result)
+
+    def test_format_fee_precision(self):
+        result = format_satoshis(1666/1000, 0, 0, precision=6)
+        expected = "1.666"
+        self.assertEqual(expected, result)
+
+        result = format_satoshis(1666/1000, 0, 0, precision=1)
+        expected = "1.7"
+        self.assertEqual(expected, result)
+
+    def test_format_satoshis_whitespaces(self):
+        result = format_satoshis(12340, whitespaces=True)
+        expected = "     0.0001234 "
+        self.assertEqual(expected, result)
+
+        result = format_satoshis(1234, whitespaces=True)
+        expected = "     0.00001234"
+        self.assertEqual(expected, result)
+
+    def test_format_satoshis_whitespaces_negative(self):
+        result = format_satoshis(-12340, whitespaces=True)
+        expected = "    -0.0001234 "
+        self.assertEqual(expected, result)
+
+        result = format_satoshis(-1234, whitespaces=True)
+        expected = "    -0.00001234"
+        self.assertEqual(expected, result)
+
     def test_format_satoshis_diff_positive(self):
         result = format_satoshis(1234, is_diff=True)
         expected = "+0.00001234"
@@ -67,4 +104,3 @@ class TestUtil(unittest.TestCase):
 
     def test_parse_URI_parameter_polution(self):
         self.assertRaises(Exception, parse_URI, 'bitcoin:15mKKb2eos1hWa6tisdPwwDC1a5J1y9nma?amount=0.0003&label=test&amount=30.0')
-

lib/util.py

@@ -412,20 +412,18 @@ def format_satoshis_plain(x, decimal_point = 8):
     return "{:.8f}".format(Decimal(x) / scale_factor).rstrip('0').rstrip('.')
 
 
-def format_satoshis(x, is_diff=False, num_zeros = 0, decimal_point = 8, whitespaces=False):
+def format_satoshis(x, num_zeros=0, decimal_point=8, precision=None, is_diff=False, whitespaces=False):
     from locale import localeconv
     if x is None:
         return 'unknown'
-    x = int(x)  # Some callers pass Decimal
+    if precision is None:
-    scale_factor = pow (10, decimal_point)
+        precision = decimal_point
-    integer_part = "{:d}".format(int(abs(x) / scale_factor))
+    decimal_format = ".0" + str(precision) if precision > 0 else ""
-    if x < 0:
+    if is_diff:
-        integer_part = '-' + integer_part
+        decimal_format = '+' + decimal_format
-    elif is_diff:
+    result = ("{:" + decimal_format + "f}").format(x / pow (10, decimal_point)).rstrip('0')
-        integer_part = '+' + integer_part
+    integer_part, fract_part = result.split(".")
     dp = localeconv()['decimal_point']
-    fract_part = ("{:0" + str(decimal_point) + "}").format(abs(x) % scale_factor)
-    fract_part = fract_part.rstrip('0')
     if len(fract_part) < num_zeros:
         fract_part += "0" * (num_zeros - len(fract_part))
     result = integer_part + dp + fract_part
@@ -434,6 +432,9 @@ def format_satoshis(x, is_diff=False, num_zeros = 0, decimal_point = 8, whitespa
         result = " " * (15 - len(result)) + result
     return result
 
+def format_fee_satoshis(fee, num_zeros=0):
+    return format_satoshis(fee, num_zeros, 0, precision=1)
+
 def timestamp_to_datetime(timestamp):
     if timestamp is None:
         return None

lib/wallet.py

@@ -45,8 +45,8 @@ import sys
 
 from .i18n import _
 from .util import (NotEnoughFunds, PrintError, UserCancelled, profiler,
-                   format_satoshis, NoDynamicFeeEstimates, TimeoutException,
+                   format_satoshis, format_fee_satoshis, NoDynamicFeeEstimates,
-                   WalletFileException, BitcoinException)
+                   TimeoutException, WalletFileException, BitcoinException)
 
 from .bitcoin import *
 from .version import *
@@ -1169,7 +1169,7 @@ class Abstract_Wallet(PrintError):
             if fee is not None:
                 size = tx.estimated_size()
                 fee_per_byte = fee / size
-                extra.append('%.1f sat/b'%(fee_per_byte))
+                extra.append(format_fee_satoshis(fee_per_byte) + ' sat/b')
             if fee is not None and height in (TX_HEIGHT_UNCONF_PARENT, TX_HEIGHT_UNCONFIRMED) \
                and self.network and self.network.config.has_fee_mempool():
                 exp_n = self.network.config.fee_to_depth(fee_per_byte)
@@ -2362,4 +2362,3 @@ class Wallet(object):
         if wallet_type in wallet_constructors:
             return wallet_constructors[wallet_type]
         raise RuntimeError("Unknown wallet type: " + str(wallet_type))
-