qml: history list: don't update fiat values during drag scoll
What the developer wrote
Authored by f321x
qml: history list: don't update fiat values during drag scoll
Don't update the fiat values during scrolling through the history
with the thing on the right side (drag scrolling), this should
improve the performance of the list when doing a quick drag scroll.
What changed, and why it matters
This commit is a performance optimization for the mobile-style QML history list in the Electrum Bitcoin wallet. It stops the fiat (local currency) value labels from being recalculated while the user is drag-scrolling, and refreshes them only when the scroll finishes. There is no security-relevant change.
No security action needed. Treat as a normal UI performance fix.
Security signals we found
No strong security signals were identified.
Evidence from the diff
In HistoryItemDelegate.qml, a new readonly property listDragActive tracks ListView.view.dragScrolling. While drag-scrolling is active, the fiatLabel.updateText() function now sets the label text to empty instead of computing a fiat conversion. An onListDragActiveChanged handler calls fiatLabel.updateText() once when drag-scrolling ends so the value is refreshed. This is purely a UI rendering/performance optimization.
Changed components
electrum/gui/qml/components/controls/HistoryItemDelegate.qmlInspect captured patch +8 / −1
diff --git a/electrum/gui/qml/components/controls/HistoryItemDelegate.qml b/electrum/gui/qml/components/controls/HistoryItemDelegate.qml
index c5a96e2..6d57f1f 100644
--- a/electrum/gui/qml/components/controls/HistoryItemDelegate.qml
+++ b/electrum/gui/qml/components/controls/HistoryItemDelegate.qml
@@ -13,6 +13,13 @@ Item {
// expose delegate model for scroll indicator
property var delegateModel: model
+ readonly property bool listDragActive: ListView.view.dragScrolling
+ onListDragActiveChanged:
+ // refresh the fiat label once drags-scroll gets released
+ if (!listDragActive) {
+ fiatLabel.updateText()
+ }
+
// reuseItems is enabled on the parent ListView. If a delegate item goes out of view it is not destroyed but
// stored in a pool and re-used when a new delegate is required.
property bool pooled: false
@@ -118,7 +125,7 @@ Item {
color: constants.mutedForeground
function updateText() {
- if (delegate.pooled || !Daemon.fx.enabled) {
+ if (delegate.pooled || delegate.listDragActive || !Daemon.fx.enabled) {
text = ''
} else if (Daemon.fx.historicRates && model.timestamp) {
text = Daemon.fx.fiatValueHistoric(model.value, model.timestamp) + ' ' + Daemon.fx.fiatCurrency
Why this scored 15/100
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