From 9f41ec39868128549362c6edcb61f2574467d299 Mon Sep 17 00:00:00 2001
From: Karl Tauber <karl@jformdesigner.com>
Date: Sat, 25 Jul 2020 09:40:57 +0200
Subject: [PATCH] ScrollPane: support disabling smooth scrolling per component
 via client property "JScrollPane.smoothScrolling"

---
 CHANGELOG.md                                     |  2 ++
 .../formdev/flatlaf/FlatClientProperties.java    |  8 ++++++++
 .../com/formdev/flatlaf/ui/FlatScrollPaneUI.java | 16 ++++++++++++----
 3 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 43a97ad5..619117b8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,8 @@ FlatLaf Change Log
   maximizing window. E.g. restoring window state at startup. (issue #129)
 - InternalFrame: Title pane height was too small when iconify, maximize and close
   buttons are hidden. (issue #132)
+- ScrollPane: Enable/disable smooth scrolling per component if client property
+  "JScrollPane.smoothScrolling" is set to a `Boolean` on `JScrollPane`.
 
 
 ## 0.38
diff --git a/flatlaf-core/src/main/java/com/formdev/flatlaf/FlatClientProperties.java b/flatlaf-core/src/main/java/com/formdev/flatlaf/FlatClientProperties.java
index 20ee7ab5..79ac1ce1 100644
--- a/flatlaf-core/src/main/java/com/formdev/flatlaf/FlatClientProperties.java
+++ b/flatlaf-core/src/main/java/com/formdev/flatlaf/FlatClientProperties.java
@@ -200,6 +200,14 @@ public interface FlatClientProperties
 	 */
 	String SCROLL_BAR_SHOW_BUTTONS = "JScrollBar.showButtons";
 
+	/**
+	 * Specifies whether the scroll pane uses smooth scrolling.
+	 * <p>
+	 * <strong>Component</strong> {{@link javax.swing.JScrollPane}<br>
+	 * <strong>Value type</strong> {@link java.lang.Boolean}
+	 */
+	String SCROLL_PANE_SMOOTH_SCROLLING = "JScrollPane.smoothScrolling";
+
 	/**
 	 * Specifies whether separators are shown between tabs.
 	 * <p>
diff --git a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatScrollPaneUI.java b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatScrollPaneUI.java
index 5c0b72aa..13c3ea8c 100644
--- a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatScrollPaneUI.java
+++ b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatScrollPaneUI.java
@@ -114,10 +114,7 @@ public class FlatScrollPaneUI
 		return new BasicScrollPaneUI.MouseWheelHandler() {
 			@Override
 			public void mouseWheelMoved( MouseWheelEvent e ) {
-				// Note: Getting UI value "ScrollPane.smoothScrolling" here to allow
-				// applications to turn smooth scrolling on or off at any time
-				// (e.g. in application options dialog).
-				if( UIManager.getBoolean( "ScrollPane.smoothScrolling" ) &&
+				if( isSmoothScrollingEnabled() &&
 					scrollpane.isWheelScrollingEnabled() &&
 					e.getScrollType() == MouseWheelEvent.WHEEL_UNIT_SCROLL &&
 					e.getPreciseWheelRotation() != 0 &&
@@ -130,6 +127,17 @@ public class FlatScrollPaneUI
 		};
 	}
 
+	protected boolean isSmoothScrollingEnabled() {
+		Object smoothScrolling = scrollpane.getClientProperty( FlatClientProperties.SCROLL_PANE_SMOOTH_SCROLLING );
+		if( smoothScrolling instanceof Boolean )
+			return (Boolean) smoothScrolling;
+
+		// Note: Getting UI value "ScrollPane.smoothScrolling" here to allow
+		// applications to turn smooth scrolling on or off at any time
+		// (e.g. in application options dialog).
+		return UIManager.getBoolean( "ScrollPane.smoothScrolling" );
+	}
+
 	private static final double EPSILON = 1e-5d;
 
 	private void mouseWheelMovedSmooth( MouseWheelEvent e ) {