added class FlatSystemProperties to define/document own system properties used in FlatLaf

flatlaf-core/src/main/java/com/formdev/flatlaf/FlatSystemProperties.java

@@ -0,0 +1,66 @@
+/*
+ * Copyright 2020 FormDev Software GmbH
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.formdev.flatlaf;
+
+/**
+ * Defines/documents own system properties used in FlatLaf.
+ *
+ * @author Karl Tauber
+ */
+public interface FlatSystemProperties
+{
+	/**
+	 * Specifies a custom scale factor used to scale the UI.
+	 * <p>
+	 * If Java runtime scales (Java 9 or later), this scale factor is applied on top
+	 * of the Java system scale factor. Java 8 does not scale and this scale factor
+	 * replaces the user scale factor that FlatLaf computes based on the font.
+	 * To replace the Java 9+ system scale factor, use system property "sun.java2d.uiScale",
+	 * which has the same syntax as this one.
+	 * <p>
+	 * <strong>Allowed Values</strong> e.g. {@code 1.5}, {@code 1.5x}, {@code 150%} or {@code 144dpi} (96dpi is 100%)<br>
+	 */
+	String UI_SCALE = "flatlaf.uiScale";
+
+	/**
+	 * Specifies whether Ubuntu font should be used on Ubuntu Linux.
+	 * By default, if not running in a JetBrains Runtime, the Liberation Sans font
+	 * is used because there are rendering issues (in Java) with Ubuntu fonts.
+	 * <p>
+	 * <strong>Allowed Values</strong> {@code false} and {@code true}<br>
+	 * <strong>Default</strong> {@code false}
+	 */
+	String USE_UBUNTU_FONT = "flatlaf.useUbuntuFont";
+
+	/**
+	 * Specifies whether vertical text position is corrected when UI is scaled on HiDPI screens.
+	 * <p>
+	 * <strong>Allowed Values</strong> {@code false} and {@code true}<br>
+	 * <strong>Default</strong> {@code true}
+	 */
+	String USE_TEXT_Y_CORRECTION = "flatlaf.useTextYCorrection";
+
+	/**
+	 * Checks whether a system property is set and returns {@code true} if its value
+	 * is {@code "true"} (case-insensitive), otherwise it returns {@code false}.
+	 * If the system property is not set, {@code defaultValue} is returned.
+	 */
+	static boolean getBoolean( String key, boolean defaultValue ) {
+		String value = System.getProperty( key );
+		return (value != null) ? Boolean.parseBoolean( value ) : defaultValue;
+	}
+}

flatlaf-core/src/main/java/com/formdev/flatlaf/LinuxFontPolicy.java

@@ -78,7 +78,7 @@ class LinuxFontPolicy
 		// --> use Liberation Sans font
 		if( family.startsWith( "Ubuntu" ) &&
 			!SystemInfo.IS_JETBRAINS_JVM &&
-			!Boolean.parseBoolean( System.getProperty( "flatlaf.useUbuntuFont" ) ) )
+			!FlatSystemProperties.getBoolean( FlatSystemProperties.USE_UBUNTU_FONT, false ) )
 		  family = "Liberation Sans";
 
 		// scale font size

flatlaf-core/src/main/java/com/formdev/flatlaf/util/HiDPIUtils.java

@@ -23,6 +23,7 @@ import java.awt.geom.AffineTransform;
 import java.awt.geom.Rectangle2D;
 import java.text.AttributedCharacterIterator;
 import javax.swing.JComponent;
+import com.formdev.flatlaf.FlatSystemProperties;
 
 /**
  * @author Karl Tauber
@@ -104,7 +105,7 @@ public class HiDPIUtils
 
 	private static boolean useTextYCorrection() {
 		if( useTextYCorrection == null )
-			useTextYCorrection = Boolean.valueOf( System.getProperty( "flatlaf.useTextYCorrection", "true" ) );
+			useTextYCorrection = FlatSystemProperties.getBoolean( FlatSystemProperties.USE_TEXT_Y_CORRECTION, true );
 		return useTextYCorrection;
 	}
 

flatlaf-core/src/main/java/com/formdev/flatlaf/util/UIScale.java

@@ -32,6 +32,7 @@ import javax.swing.plaf.DimensionUIResource;
 import javax.swing.plaf.FontUIResource;
 import javax.swing.plaf.InsetsUIResource;
 import javax.swing.plaf.UIResource;
+import com.formdev.flatlaf.FlatSystemProperties;
 
 /**
  * Two scaling modes are supported for HiDPI displays:
@@ -195,8 +196,7 @@ public class UIScale
 
 	private static boolean isUserScalingEnabled() {
 		// same as in IntelliJ IDEA
-		String hidpi = System.getProperty( "hidpi" );
+		return FlatSystemProperties.getBoolean( "hidpi", true );
-		return (hidpi != null) ? Boolean.parseBoolean( hidpi ) : true;
 	}
 
 	/**
@@ -204,7 +204,7 @@ public class UIScale
 	 * to the given font.
 	 */
 	public static FontUIResource applyCustomScaleFactor( FontUIResource font ) {
-		String uiScale = System.getProperty( "flatlaf.uiScale" );
+		String uiScale = System.getProperty( FlatSystemProperties.UI_SCALE );
 		float scaleFactor = parseScaleFactor( uiScale );
 		if( scaleFactor <= 0 )
 			return font;

flatlaf-testing/src/main/java/com/formdev/flatlaf/testing/FlatPaintingStringTest.java

@@ -26,6 +26,7 @@ import java.awt.Insets;
 import java.awt.geom.AffineTransform;
 import javax.swing.*;
 import javax.swing.border.EmptyBorder;
+import com.formdev.flatlaf.FlatSystemProperties;
 import com.formdev.flatlaf.ui.FlatUIUtils;
 import com.formdev.flatlaf.util.Graphics2DProxy;
 import com.formdev.flatlaf.util.HiDPIUtils;
@@ -40,7 +41,7 @@ public class FlatPaintingStringTest
 	extends JPanel
 {
 	public static void main( String[] args ) {
-		System.setProperty( "flatlaf.uiScale", "1x" );
+		System.setProperty( FlatSystemProperties.UI_SCALE, "1x" );
 		System.setProperty( "sun.java2d.uiScale", "1x" );
 
 		SwingUtilities.invokeLater( () -> {

flatlaf-testing/src/main/java/com/formdev/flatlaf/testing/FlatTestFrame.java

@@ -35,6 +35,7 @@ import com.formdev.flatlaf.FlatDarkLaf;
 import com.formdev.flatlaf.FlatIntelliJLaf;
 import com.formdev.flatlaf.FlatLaf;
 import com.formdev.flatlaf.FlatLightLaf;
+import com.formdev.flatlaf.FlatSystemProperties;
 import com.formdev.flatlaf.IntelliJTheme;
 import com.formdev.flatlaf.demo.LookAndFeelsComboBox;
 import com.formdev.flatlaf.demo.DemoPrefs;
@@ -66,10 +67,10 @@ public class FlatTestFrame
 		DemoPrefs.init( PREFS_ROOT_PATH );
 
 		// set scale factor
-		if( System.getProperty( "flatlaf.uiScale", System.getProperty( "sun.java2d.uiScale" ) ) == null ) {
+		if( System.getProperty( FlatSystemProperties.UI_SCALE, System.getProperty( "sun.java2d.uiScale" ) ) == null ) {
 			String scaleFactor = DemoPrefs.getState().get( KEY_SCALE_FACTOR, null );
 			if( scaleFactor != null )
-				System.setProperty( "flatlaf.uiScale", scaleFactor );
+				System.setProperty( FlatSystemProperties.UI_SCALE, scaleFactor );
 		}
 
 		// set look and feel
@@ -145,7 +146,7 @@ public class FlatTestFrame
 		lookAndFeelComboBox.setModel( lafModel );
 
 		updateScaleFactorComboBox();
-		String scaleFactor = System.getProperty( "flatlaf.uiScale", System.getProperty( "sun.java2d.uiScale" ) );
+		String scaleFactor = System.getProperty( FlatSystemProperties.UI_SCALE, System.getProperty( "sun.java2d.uiScale" ) );
 		if( scaleFactor != null )
 			scaleFactorComboBox.setSelectedItem( scaleFactor );
 
@@ -472,10 +473,10 @@ public class FlatTestFrame
 		scaleFactorComboBox.setPopupVisible( false );
 
 		if( scaleFactor != null ) {
-			System.setProperty( "flatlaf.uiScale", scaleFactor );
+			System.setProperty( FlatSystemProperties.UI_SCALE, scaleFactor );
 			DemoPrefs.getState().put( KEY_SCALE_FACTOR, scaleFactor );
 		} else {
-			System.clearProperty( "flatlaf.uiScale" );
+			System.clearProperty( FlatSystemProperties.UI_SCALE );
 			DemoPrefs.getState().remove( KEY_SCALE_FACTOR );
 		}
 

flatlaf-testing/src/main/java/com/formdev/flatlaf/testing/uidefaults/UIDefaultsDump.java

@@ -84,7 +84,7 @@ public class UIDefaultsDump
 	public static void main( String[] args ) {
 		Locale.setDefault( Locale.ENGLISH );
 		System.setProperty( "sun.java2d.uiScale", "1x" );
-		System.setProperty( "flatlaf.uiScale", "1x" );
+		System.setProperty( FlatSystemProperties.UI_SCALE, "1x" );
 
 		File dir = new File( "src/main/resources/com/formdev/flatlaf/testing/uidefaults" );