feat: add runtime UI font size multiplier (#1224)

fxgl-core/src/main/kotlin/com/almasb/fxgl/core/UISettings.kt

@@ -0,0 +1,34 @@
+/*
+ * FXGL - JavaFX Game Library. The MIT License (MIT).
+ * Copyright (c) AlmasB (almaslvl@gmail.com).
+ * See LICENSE for details.
+ */
+
+package com.almasb.fxgl.core
+
+import javafx.beans.property.DoubleProperty
+import javafx.beans.property.SimpleDoubleProperty
+
+/**
+ * Cross-cutting runtime UI configuration accessible from any FXGL module.
+ *
+ * Lives in fxgl-core rather than on the FXGL facade because subsystems in
+ * fxgl-scene (and potentially other downstream modules) need to consume
+ * these properties at render time, and module direction prohibits an
+ * upward reference to the fxgl facade from fxgl-scene.
+ *
+ * The FXGL facade exposes thin @JvmStatic accessors that delegate here,
+ * so the public API stays unchanged.
+ *
+ * See issue #1224.
+ */
+object UISettings {
+
+    /**
+     * Global UI font size multiplier. All dialog and notification text is
+     * scaled by this factor at render time. Default is 1.0 (no scaling).
+     * Can be modified at runtime; bound listeners will update rendered
+     * fonts on change.
+     */
+    val uiFontSizeMultiplier: DoubleProperty = SimpleDoubleProperty(1.0)
+}

fxgl-scene/src/main/kotlin/com/almasb/fxgl/notification/view/XboxNotificationView.kt

@@ -8,6 +8,7 @@ package com.almasb.fxgl.notification.view
 
 import com.almasb.fxgl.animation.Animation
 import com.almasb.fxgl.animation.AnimationBuilder
+import com.almasb.fxgl.core.UISettings
 import com.almasb.fxgl.notification.Notification
 import javafx.geometry.Point2D
 import javafx.scene.Group
@@ -39,14 +40,20 @@ class XboxNotificationView : NotificationView() {
      * These two will be replacing one another.
      */
     private val text1 = Text().also {
-        it.fill = textColor
-        it.font = Font.font(18.0)
-    }
+            it.fill = textColor
+            it.font = Font.font(18.0 * UISettings.uiFontSizeMultiplier.value)
+            UISettings.uiFontSizeMultiplier.addListener { _, _, newValue ->
+                it.font = Font.font(18.0 * newValue.toDouble())
+            }
+        }
 
     private val text2 = Text().also {
-        it.fill = textColor
-        it.font = Font.font(18.0)
-    }
+            it.fill = textColor
+            it.font = Font.font(18.0 * UISettings.uiFontSizeMultiplier.value)
+            UISettings.uiFontSizeMultiplier.addListener { _, _, newValue ->
+                it.font = Font.font(18.0 * newValue.toDouble())
+            }
+        }
 
     init {
         bg.arcWidth = 55.0

fxgl-scene/src/main/kotlin/com/almasb/fxgl/ui/FXGLDialogFactoryServiceProvider.kt

@@ -6,7 +6,7 @@
 
 package com.almasb.fxgl.ui
 
-import com.almasb.fxgl.core.Inject
+import com.almasb.fxgl.core.UISettings
 import com.almasb.fxgl.core.util.EmptyRunnable
 import com.almasb.fxgl.localization.LocalizationService
 import com.almasb.fxgl.logging.Logger
@@ -36,8 +36,35 @@ import java.util.function.Predicate
  */
 class FXGLDialogFactoryServiceProvider : DialogFactoryService() {
 
-    @Inject("fontSizeScaleUI")
-    private var fontSizeScaleUI = 1.0
+    /**
+     * Returns the current scaled font size based on the global multiplier.
+     * See issue #1224.
+     */
+    private fun scaledSize(baseSize: Double): Double =
+            baseSize * UISettings.uiFontSizeMultiplier.value
+
+    /**
+     * Creates a Text node whose font size scales with the global UI font size
+     * multiplier (issue #1224). The font is updated live when the multiplier changes.
+     */
+    private fun scaledText(message: String, baseSize: Double): Text {
+        val text = uiFactory.newText(message, scaledSize(baseSize))
+        UISettings.uiFontSizeMultiplier.addListener { _, _, _ ->
+            text.font = uiFactory.newFont(scaledSize(baseSize))
+        }
+        return text
+    }
+
+    /**
+     * Applies a scaled font to an existing node that uses setFont (Button, TextField).
+     * Re-applies on multiplier changes (issue #1224).
+     */
+    private fun applyScaledFont(setFont: (javafx.scene.text.Font) -> Unit, baseSize: Double) {
+        setFont(uiFactory.newFont(scaledSize(baseSize)))
+        UISettings.uiFontSizeMultiplier.addListener { _, _, _ ->
+            setFont(uiFactory.newFont(scaledSize(baseSize)))
+        }
+    }
 
     private lateinit var uiFactory: UIFactoryService
 
@@ -302,9 +329,9 @@ class FXGLDialogFactoryServiceProvider : DialogFactoryService() {
     }
 
     private fun createMessage(message: String): Text {
-        return uiFactory.newText(message, fontSizeScaleUI * 18.0)
-    }
-
+            return scaledText(message, 18.0)
+        }
+        
     private fun localizedStringProperty(key: String): StringBinding {
         return local.localizedStringProperty(key)
     }

fxgl/src/main/kotlin/com/almasb/fxgl/dsl/FXGL.kt

@@ -16,6 +16,7 @@ import com.almasb.fxgl.app.services.SystemBundleService
 import com.almasb.fxgl.audio.AudioPlayer
 import com.almasb.fxgl.audio.Music
 import com.almasb.fxgl.core.EngineService
+import com.almasb.fxgl.core.UISettings
 import com.almasb.fxgl.core.collection.PropertyChangeListener
 import com.almasb.fxgl.core.concurrent.Async
 import com.almasb.fxgl.core.concurrent.Executor
@@ -54,6 +55,8 @@ import com.almasb.fxgl.ui.DialogService
 import com.almasb.fxgl.ui.UIFactoryService
 import javafx.animation.Interpolator
 import javafx.application.Application
+import javafx.beans.property.DoubleProperty
+import javafx.beans.property.SimpleDoubleProperty
 import javafx.beans.binding.StringExpression
 import javafx.beans.property.*
 import javafx.concurrent.Task
@@ -242,6 +245,28 @@ class FXGL private constructor() { companion object {
 
     @JvmStatic fun getTaskService() = engine.getService(IOTaskExecutorService::class.java)
 
+
+    /**
+     * Global UI font size multiplier. All dialog and notification text is
+     * scaled by this factor at render time. Default is 1.0 (no scaling). Can
+     * be modified at runtime; bound listeners will update the rendered fonts
+     * on change.
+     *
+     * Backed by UISettings.uiFontSizeMultiplier in fxgl-core so downstream
+     * modules (e.g. fxgl-scene) can consume the property without an upward
+     * module dependency.
+     *
+     * See issue #1224.
+     */
+    @JvmStatic fun uiFontSizeMultiplierProperty(): DoubleProperty = UISettings.uiFontSizeMultiplier
+
+    @JvmStatic fun getUIFontSizeMultiplier(): Double = UISettings.uiFontSizeMultiplier.value
+
+    @JvmStatic fun setUIFontSizeMultiplier(value: Double) {
+        require(value > 0) { "UI font size multiplier must be > 0, got: $value" }
+        UISettings.uiFontSizeMultiplier.value = value
+    }
+
     /**
      * @return time per frame (in this frame)
      */