Add convenient method to customize titlebar colors

platform-decorations/src/main/java/com/github/weisj/darklaf/platform/decorations/DecorationsColorProvider.java

@@ -0,0 +1,67 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2022 Jannis Weis
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
+ * associated documentation files (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge, publish, distribute,
+ * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all copies or
+ * substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
+ * NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.github.weisj.darklaf.platform.decorations;
+
+import java.awt.*;
+
+import com.github.weisj.darklaf.properties.uiresource.DarkColorUIResource;
+import com.github.weisj.darklaf.util.ColorUtil;
+
+public interface DecorationsColorProvider {
+
+    default void onLafChanged() {}
+
+    default Color borderColor() {
+        return inactiveForegroundColor();
+    }
+
+    Color backgroundColor();
+
+    default Color hoverBackgroundColor() {
+        Color background = backgroundColor();
+        int brightness = (int) ColorUtil.getPerceivedBrightness(background);
+        if (brightness >= 125) {
+            // Darken
+            return new DarkColorUIResource(
+                    Math.max((int) (background.getRed() * 0.9f), 0),
+                    Math.max((int) (background.getGreen() * 0.9f), 0),
+                    Math.max((int) (background.getBlue() * 0.9f), 0));
+        } else {
+            return background.brighter();
+        }
+    }
+
+    default Color clickBackgroundColor() {
+        return hoverBackgroundColor();
+    }
+
+    Color activeForegroundColor();
+
+    Color inactiveForegroundColor();
+
+    default Color windowButtonColor() {
+        return activeForegroundColor();
+    }
+
+    default Color inactiveWindowButtonColor() {
+        return inactiveForegroundColor();
+    }
+}

platform-decorations/src/main/java/com/github/weisj/darklaf/platform/decorations/ExternalLafDecorator.java

@@ -37,6 +37,9 @@ public final class ExternalLafDecorator {
     private final PropertyChangeListener propertyChangeListener;
     private boolean installed;
 
+    private final DecorationsColorProvider fallbackColorProvider = new DefaultDecorationsColorProvider();
+    private DecorationsColorProvider colorProvider;
+
     private ExternalLafDecorator() {
         decorationsManager = new NativeDecorationsManager();
         propertyChangeListener = evt -> {
@@ -69,6 +72,13 @@ public final class ExternalLafDecorator {
         UIManager.removePropertyChangeListener(propertyChangeListener);
     }
 
+    public void setColorProvider(final DecorationsColorProvider colorProvider) {
+        this.colorProvider = colorProvider;
+        if (colorProvider == null) {
+            this.colorProvider = fallbackColorProvider;
+        }
+    }
+
     public boolean isInstalled() {
         return installed;
     }
@@ -81,33 +91,22 @@ public final class ExternalLafDecorator {
 
     private void installExtraProperties() {
         IconLoader.updateThemeStatus(new Object());
+        colorProvider.onLafChanged();
 
         Properties props = new Properties();
         UIDefaults defaults = UIManager.getDefaults();
 
-        JLabel label = new JLabel();
-        label.setOpaque(true);
-        Color foreground = new DarkColorUIResource(label.getForeground());
-        Color background = new DarkColorUIResource(label.getBackground());
-        label.setEnabled(false);
-        Color disabledForeground = new DarkColorUIResource(label.getForeground());
-
-        putOrCopy("borderSecondary", disabledForeground, props, defaults);
-
-        Color highlight = new DarkColorUIResource(
-                Math.max((int) (background.getRed() * 0.9f), 0),
-                Math.max((int) (background.getGreen() * 0.9f), 0),
-                Math.max((int) (background.getBlue() * 0.9f), 0));
-        putOrCopy("hoverHighlight", highlight, props, defaults);
-        putOrCopy("clickHighlight", highlight, props, defaults);
-
-        putOrCopy("background", background, props, defaults);
-        putOrCopy("textForeground", foreground, props, defaults);
-        putOrCopy("textForegroundInactive", foreground, props, defaults);
-        putOrCopy("textForegroundSecondary", disabledForeground, props, defaults);
-
-        putOrCopy("windowButton", foreground, props, defaults);
-        putOrCopy("windowButtonDisabled", disabledForeground, props, defaults);
+        putOrCopy("borderSecondary", colorProvider.borderColor(), props, defaults);
+        putOrCopy("hoverHighlight", colorProvider.hoverBackgroundColor(), props, defaults);
+        putOrCopy("clickHighlight", colorProvider.clickBackgroundColor(), props, defaults);
+
+        putOrCopy("background", colorProvider.backgroundColor(), props, defaults);
+        putOrCopy("textForeground", colorProvider.activeForegroundColor(), props, defaults);
+        putOrCopy("textForegroundInactive", colorProvider.inactiveForegroundColor(), props, defaults);
+        putOrCopy("textForegroundSecondary", colorProvider.inactiveForegroundColor(), props, defaults);
+
+        putOrCopy("windowButton", colorProvider.windowButtonColor(), props, defaults);
+        putOrCopy("windowButtonDisabled", colorProvider.inactiveWindowButtonColor(), props, defaults);
         putOrCopy("windowCloseHovered", new DarkColorUIResource(Color.WHITE), props, defaults);
 
         decorationsManager.loadDecorationProperties(props, defaults);
@@ -126,4 +125,36 @@ public final class ExternalLafDecorator {
         defaults.putAll(props);
         defaults.put("RootPaneUI", BasicNativeDecorationsRootPaneUI.class.getName());
     }
+
+    private static class DefaultDecorationsColorProvider implements DecorationsColorProvider {
+
+        private Color foreground;
+        private Color background;
+        private Color disabledForeground;
+
+        @Override
+        public void onLafChanged() {
+            JLabel label = new JLabel();
+            label.setOpaque(true);
+            foreground = new DarkColorUIResource(label.getForeground());
+            background = new DarkColorUIResource(label.getBackground());
+            label.setEnabled(false);
+            disabledForeground = new DarkColorUIResource(label.getForeground());
+        }
+
+        @Override
+        public Color backgroundColor() {
+            return background;
+        }
+
+        @Override
+        public Color activeForegroundColor() {
+            return foreground;
+        }
+
+        @Override
+        public Color inactiveForegroundColor() {
+            return disabledForeground;
+        }
+    }
 }