make qt HistoryList.on_update() faster by caching icons

gui/qt/history_list.py

@@ -235,7 +235,7 @@ class HistoryList(MyTreeWidget, AcceptFileDragDrop):
             label = tx_item['label']
             status, status_str = self.wallet.get_tx_status(tx_hash, height, conf, timestamp)
             has_invoice = self.wallet.invoices.paid.get(tx_hash)
-            icon = QIcon(":icons/" + TX_ICONS[status])
+            icon = self.icon_cache.get(":icons/" + TX_ICONS[status])
             v_str = self.parent.format_amount(value, True, whitespaces=True)
             balance_str = self.parent.format_amount(balance, whitespaces=True)
             entry = ['', tx_hash, status_str, label, v_str, balance_str]
@@ -253,7 +253,7 @@ class HistoryList(MyTreeWidget, AcceptFileDragDrop):
             item.setToolTip(0, str(conf) + " confirmation" + ("s" if conf != 1 else ""))
             item.setData(0, SortableTreeWidgetItem.DataRole, (status, conf))
             if has_invoice:
-                item.setIcon(3, QIcon(":icons/seal"))
+                item.setIcon(3, self.icon_cache.get(":icons/seal"))
             for i in range(len(entry)):
                 if i>3:
                     item.setTextAlignment(i, Qt.AlignRight | Qt.AlignVCenter)
@@ -302,7 +302,7 @@ class HistoryList(MyTreeWidget, AcceptFileDragDrop):
 
     def update_item(self, tx_hash, height, conf, timestamp):
         status, status_str = self.wallet.get_tx_status(tx_hash, height, conf, timestamp)
-        icon = QIcon(":icons/" +  TX_ICONS[status])
+        icon = self.icon_cache.get(":icons/" +  TX_ICONS[status])
         items = self.findItems(tx_hash, Qt.UserRole|Qt.MatchContains|Qt.MatchRecursive, column=1)
         if items:
             item = items[0]
@@ -347,7 +347,7 @@ class HistoryList(MyTreeWidget, AcceptFileDragDrop):
                 if child_tx:
                     menu.addAction(_("Child pays for parent"), lambda: self.parent.cpfp(tx, child_tx))
         if pr_key:
-            menu.addAction(QIcon(":icons/seal"), _("View invoice"), lambda: self.parent.show_invoice(pr_key))
+            menu.addAction(self.icon_cache.get(":icons/seal"), _("View invoice"), lambda: self.parent.show_invoice(pr_key))
         if tx_URL:
             menu.addAction(_("View on block explorer"), lambda: webbrowser.open(tx_URL))
         menu.exec_(self.viewport().mapToGlobal(position))

gui/qt/invoice_list.py

@@ -48,7 +48,7 @@ class InvoiceList(MyTreeWidget):
             exp = pr.get_expiration_date()
             date_str = format_time(exp) if exp else _('Never')
             item = QTreeWidgetItem([date_str, requestor, pr.memo, self.parent.format_amount(pr.get_amount(), whitespaces=True), pr_tooltips.get(status,'')])
-            item.setIcon(4, QIcon(pr_icons.get(status)))
+            item.setIcon(4, self.icon_cache.get(pr_icons.get(status)))
             item.setData(0, Qt.UserRole, key)
             item.setFont(1, QFont(MONOSPACE_FONT))
             item.setFont(3, QFont(MONOSPACE_FONT))

gui/qt/request_list.py

@@ -98,10 +98,10 @@ class RequestList(MyTreeWidget):
             amount_str = self.parent.format_amount(amount) if amount else ""
             item = QTreeWidgetItem([date, address, '', message, amount_str, pr_tooltips.get(status,'')])
             if signature is not None:
-                item.setIcon(2, QIcon(":icons/seal.png"))
+                item.setIcon(2, self.icon_cache.get(":icons/seal.png"))
                 item.setToolTip(2, 'signed by '+ requestor)
             if status is not PR_UNKNOWN:
-                item.setIcon(6, QIcon(pr_icons.get(status)))
+                item.setIcon(6, self.icon_cache.get(pr_icons.get(status)))
             self.addTopLevelItem(item)
 
 

gui/qt/util.py

@@ -393,6 +393,8 @@ class MyTreeWidget(QTreeWidget):
         self.addChild = self.addTopLevelItem
         self.insertChild = self.insertTopLevelItem
 
+        self.icon_cache = IconCache()
+
         # Control which columns are editable
         self.editor = None
         self.pending_update = False
@@ -779,6 +781,17 @@ class SortableTreeWidgetItem(QTreeWidgetItem):
             return self.text(column) < other.text(column)
 
 
+class IconCache:
+
+    def __init__(self):
+        self.__cache = {}
+
+    def get(self, file_name):
+        if file_name not in self.__cache:
+            self.__cache[file_name] = QIcon(file_name)
+        return self.__cache[file_name]
+
+
 if __name__ == "__main__":
     app = QApplication([])
     t = WaitingDialog(None, 'testing ...', lambda: [time.sleep(1)], lambda x: QMessageBox.information(None, 'done', "done"))