From 42d801f123cf3791c465d3e962d0445ea59219f7 Mon Sep 17 00:00:00 2001
From: Karl Tauber <karl@jformdesigner.com>
Date: Sun, 13 Oct 2019 14:15:37 +0200
Subject: [PATCH] Linux: - allow user scaling mode on Linux even if running in
 Java 9+ - update fonts (and scaling) when user changes text size or scaling
 in Gnome settings

(#1)
---
 flatlaf-core/src/main/java/com/formdev/flatlaf/FlatLaf.java  | 5 +++++
 .../src/main/java/com/formdev/flatlaf/util/UIScale.java      | 5 ++---
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/flatlaf-core/src/main/java/com/formdev/flatlaf/FlatLaf.java b/flatlaf-core/src/main/java/com/formdev/flatlaf/FlatLaf.java
index 3e99f945..b2bb4ad2 100644
--- a/flatlaf-core/src/main/java/com/formdev/flatlaf/FlatLaf.java
+++ b/flatlaf-core/src/main/java/com/formdev/flatlaf/FlatLaf.java
@@ -124,6 +124,11 @@ public abstract class FlatLaf
 			// Windows 10 allows increasing font size independent of scaling:
 			//   Settings > Ease of Access > Display > Make text bigger (100% - 225%)
 			desktopPropertyName = "win.messagebox.font";
+		} else if( SystemInfo.IS_LINUX ) {
+			// Linux/Gnome allows extra scaling and larger text:
+			//   Settings > Devices > Displays > Scale (100% or 200%)
+			//   Settings > Universal access > Large Text (off or on, 125%)
+			desktopPropertyName = "gnome.Xft/DPI";
 		}
 		if( desktopPropertyName != null ) {
 			desktopPropertyListener = e -> {
diff --git a/flatlaf-core/src/main/java/com/formdev/flatlaf/util/UIScale.java b/flatlaf-core/src/main/java/com/formdev/flatlaf/util/UIScale.java
index d673944e..a6a36c83 100644
--- a/flatlaf-core/src/main/java/com/formdev/flatlaf/util/UIScale.java
+++ b/flatlaf-core/src/main/java/com/formdev/flatlaf/util/UIScale.java
@@ -48,8 +48,7 @@ import javax.swing.plaf.UIResource;
  *
  * 2) user scaling mode
  *
- * This mode is for Java 8 compatibility and can be removed when changing minimum
- * required Java version to 9.
+ * This mode is mainly for Java 8 compatibility, but is also used on Linux.
  * The user scale factor is computed based on the used font.
  * The JRE does not scale anything.
  * So we have to invoke {@link #scale(float)} where necessary.
@@ -166,7 +165,7 @@ public class UIScale
 	}
 
 	private static boolean isUserScalingEnabled() {
-		if( isSystemScalingEnabled() )
+		if( isSystemScalingEnabled() && !SystemInfo.IS_LINUX )
 			return false; // disable user scaling if JRE scales
 
 		// same as in IntelliJ IDEA