swaps: factor out pubkey_to_rgb_color into core lib

electrum/gui/qml/qeswaphelper.py

@@ -13,9 +13,8 @@ from electrum.logging import get_logger
 from electrum.transaction import PartialTxOutput, PartialTransaction
 from electrum.util import (NotEnoughFunds, NoDynamicFeeEstimates, profiler, get_asyncio_loop, age,
                            wait_for2)
-from electrum.submarine_swaps import NostrTransport, SwapServerTransport
+from electrum.submarine_swaps import NostrTransport, SwapServerTransport, pubkey_to_rgb_color
 from electrum.fee_policy import FeePolicy
-from electrum.crypto import sha256
 
 from electrum.gui import messages
 
@@ -70,14 +69,6 @@ class QESwapServerNPubListModel(QAbstractListModel):
         self._services = []
         self.endResetModel()
 
-    @staticmethod
-    def str_to_color(color_input: str) -> QColor:
-        input_hash = int.from_bytes(sha256(color_input), byteorder="big")
-        r = (input_hash & 0xFF0000) >> 16
-        g = (input_hash & 0x00FF00) >> 8
-        b = input_hash & 0x0000FF
-        return QColor(r, g, b)
-
     def offer_to_model(self, x: 'SwapOffer'):
         return {
             'npub': x.server_npub,
@@ -89,7 +80,7 @@ class QESwapServerNPubListModel(QAbstractListModel):
             'max_reverse_amount': x.pairs.max_reverse,
             'timestamp': age(x.timestamp),
             'pow_bits': x.pow_bits,
-            'color': self.str_to_color(x.server_pubkey),
+            'color': QColor(*pubkey_to_rgb_color(x.server_pubkey)),
         }
 
     def updateModel(self, items: Sequence['SwapOffer']):

electrum/gui/qt/swap_dialog.py

@@ -13,8 +13,7 @@ from electrum.util import NotEnoughFunds, NoDynamicFeeEstimates, UserCancelled
 from electrum.bitcoin import DummyAddress
 from electrum.transaction import PartialTxOutput, PartialTransaction
 from electrum.fee_policy import FeePolicy
-from electrum.crypto import sha256
+from electrum.submarine_swaps import NostrTransport, pubkey_to_rgb_color
-from electrum.submarine_swaps import NostrTransport
 
 from electrum.gui import messages
 from . import util
@@ -519,14 +518,7 @@ class SwapServerDialog(WindowModalDialog, QtEventListener):
 
     @staticmethod
     def _pubkey_to_q_icon(server_pubkey: str) -> QIcon:
-        def str_to_rgb(color_input: str) -> int:
+        color = QColor(*pubkey_to_rgb_color(server_pubkey))
-            input_hash = int.from_bytes(sha256(color_input), byteorder="big")
-            r = (input_hash & 0xFF0000) >> 16
-            g = (input_hash & 0x00FF00) >> 8
-            b = input_hash & 0x0000FF
-            return (r << 16) | (g << 8) | b
-
-        color = QColor(str_to_rgb(server_pubkey))
         color_pixmap = QPixmap(100, 100)
         color_pixmap.fill(color)
         return QIcon(color_pixmap)

electrum/submarine_swaps.py

@@ -186,6 +186,16 @@ class SwapData(StoredObject):
         return self._payment_pending or bool(self.funding_txid)
 
 
+def pubkey_to_rgb_color(swapserver_pubkey: str) -> Tuple[int, int, int]:
+    assert isinstance(swapserver_pubkey, str), type(swapserver_pubkey)
+    assert len(swapserver_pubkey) == 64, len(swapserver_pubkey)
+    input_hash = int.from_bytes(sha256(swapserver_pubkey), byteorder="big")
+    r = (input_hash & 0xFF0000) >> 16
+    g = (input_hash & 0x00FF00) >> 8
+    b = input_hash & 0x0000FF
+    return r, g, b
+
+
 class SwapManager(Logger):
 
     network: Optional['Network'] = None