From b168f9a98bbe00643e15a49075ed80ac6c82fa74 Mon Sep 17 00:00:00 2001
From: Friso Smit <fw.smit01@gmail.com>
Date: Mon, 6 Feb 2023 14:17:29 +0100
Subject: [PATCH] Fix zooming for high resolution scroll wheels

BUG: 432671
---
 src/views/dolphinview.cpp | 17 ++++++++++++++---
 src/views/dolphinview.h   |  4 ++++
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/src/views/dolphinview.cpp b/src/views/dolphinview.cpp
index 250fe4cc7a..1f61bcbf2a 100644
--- a/src/views/dolphinview.cpp
+++ b/src/views/dolphinview.cpp
@@ -931,6 +931,11 @@ bool DolphinView::eventFilter(QObject *watched, QEvent *event)
             }
         }
         break;
+    case QEvent::KeyRelease:
+        if (static_cast<QKeyEvent *>(event)->key() == Qt::Key_Control) {
+            m_controlWheelAccumulatedDelta = 0;
+        }
+        break;
     case QEvent::FocusIn:
         if (watched == m_container) {
             setActive(true);
@@ -969,10 +974,16 @@ bool DolphinView::eventFilter(QObject *watched, QEvent *event)
 void DolphinView::wheelEvent(QWheelEvent *event)
 {
     if (event->modifiers().testFlag(Qt::ControlModifier)) {
-        const QPoint numDegrees = event->angleDelta() / 8;
-        const QPoint numSteps = numDegrees / 15;
+        m_controlWheelAccumulatedDelta += event->angleDelta().y();
+
+        if (m_controlWheelAccumulatedDelta <= -QWheelEvent::DefaultDeltasPerStep) {
+            slotDecreaseZoom();
+            m_controlWheelAccumulatedDelta += QWheelEvent::DefaultDeltasPerStep;
+        } else if (m_controlWheelAccumulatedDelta >= QWheelEvent::DefaultDeltasPerStep) {
+            slotIncreaseZoom();
+            m_controlWheelAccumulatedDelta -= QWheelEvent::DefaultDeltasPerStep;
+        }
 
-        setZoomLevel(zoomLevel() + numSteps.y());
         event->accept();
     } else {
         event->ignore();
diff --git a/src/views/dolphinview.h b/src/views/dolphinview.h
index cadf3e7546..fc5fd52ff9 100644
--- a/src/views/dolphinview.h
+++ b/src/views/dolphinview.h
@@ -924,6 +924,10 @@ private:
     bool m_scrollToCurrentItem; // Used for marking we need to scroll to current item or not
     QPoint m_restoredContentsPosition;
 
+    // Used for tracking the accumulated scroll amount (for zooming with high
+    // resolution scroll wheels)
+    int m_controlWheelAccumulatedDelta;
+
     QList<QUrl> m_selectedUrls; // Used for making the view to remember selections after F5
     bool m_clearSelectionBeforeSelectingNewItems;
     bool m_markFirstNewlySelectedItemAsCurrent;