transaction: impl tx.to_qr_data(): move logic from GUI to tx class

electrum/gui/kivy/uix/dialogs/tx_dialog.py

@@ -271,16 +271,9 @@ class TxDialog(Factory.Popup):
         self.app.broadcast(self.tx)
 
     def show_qr(self):
-        from electrum.bitcoin import base_encode, bfh
         original_raw_tx = str(self.tx)
-        tx = copy.deepcopy(self.tx)  # make copy as we mutate tx
-        if isinstance(tx, PartialTransaction):
-            # this makes QR codes a lot smaller (or just possible in the first place!)
-            tx.convert_all_utxos_to_witness_utxos()
-
-        text = tx.serialize_as_bytes()
-        text = base_encode(text, base=43)
-        self.app.qr_dialog(_("Raw Transaction"), text, text_for_clipboard=original_raw_tx)
+        qr_data = self.tx.to_qr_data()
+        self.app.qr_dialog(_("Raw Transaction"), qr_data, text_for_clipboard=original_raw_tx)
 
     def remove_local_tx(self):
         txid = self.tx.txid()

electrum/gui/qt/transaction_dialog.py

@@ -288,14 +288,9 @@ class BaseTxDialog(QDialog, MessageBoxMixin):
     def show_qr(self, *, tx: Transaction = None):
         if tx is None:
             tx = self.tx
-        tx = copy.deepcopy(tx)  # make copy as we mutate tx
-        if isinstance(tx, PartialTransaction):
-            # this makes QR codes a lot smaller (or just possible in the first place!)
-            tx.convert_all_utxos_to_witness_utxos()
-        text = tx.serialize_as_bytes()
-        text = base_encode(text, base=43)
+        qr_data = tx.to_qr_data()
         try:
-            self.main_window.show_qrcode(text, 'Transaction', parent=self)
+            self.main_window.show_qrcode(qr_data, 'Transaction', parent=self)
         except qrcode.exceptions.DataOverflowError:
             self.show_error(_('Failed to display QR code.') + '\n' +
                             _('Transaction is too large in size.'))

electrum/transaction.py

@@ -38,6 +38,7 @@ from collections import defaultdict
 from enum import IntEnum
 import itertools
 import binascii
+import copy
 
 from . import ecc, bitcoin, constants, segwit_addr, bip32
 from .bip32 import BIP32Node
@@ -46,7 +47,8 @@ from .bitcoin import (TYPE_ADDRESS, TYPE_SCRIPT, hash_160,
                       hash160_to_p2sh, hash160_to_p2pkh, hash_to_segwit_addr,
                       var_int, TOTAL_COIN_SUPPLY_LIMIT_IN_BTC, COIN,
                       int_to_hex, push_script, b58_address_to_hash160,
-                      opcodes, add_number_to_script, base_decode, is_segwit_script_type)
+                      opcodes, add_number_to_script, base_decode, is_segwit_script_type,
+                      base_encode)
 from .crypto import sha256d
 from .logging import get_logger
 
@@ -832,6 +834,15 @@ class Transaction:
         else:
             return nVersion + txins + txouts + nLocktime
 
+    def to_qr_data(self) -> str:
+        """Returns tx as data to be put into a QR code. No side-effects."""
+        tx = copy.deepcopy(self)  # make copy as we mutate tx
+        if isinstance(tx, PartialTransaction):
+            # this makes QR codes a lot smaller (or just possible in the first place!)
+            tx.convert_all_utxos_to_witness_utxos()
+        tx_bytes = tx.serialize_as_bytes()
+        return base_encode(tx_bytes, base=43)
+
     def txid(self) -> Optional[str]:
         if self._cached_txid is None:
             self.deserialize()