polymorphic tray icon loading

src/main/java/org/cryptomator/integrations/tray/TrayIconLoader.java

@@ -0,0 +1,32 @@
+package org.cryptomator.integrations.tray;
+
+import org.jetbrains.annotations.ApiStatus;
+
+/**
+ * A callback used by the {@link TrayMenuController} to load tray icons in the format required by the implementation.
+ */
+@ApiStatus.Experimental
+sealed public interface TrayIconLoader permits TrayIconLoader.PngData, TrayIconLoader.FreedesktopIconName {
+
+	@FunctionalInterface
+	non-sealed interface PngData extends TrayIconLoader {
+
+		/**
+		 * Loads an icon from a byte array holding a loaded PNG file.
+		 *
+		 * @param data png data
+		 */
+		void loadPng(byte[] data);
+	}
+
+	@FunctionalInterface
+	non-sealed interface FreedesktopIconName extends TrayIconLoader {
+
+		/**
+		 * Loads an icon by looking it up {@code iconName} inside of {@code $XDG_DATA_DIRS/icons}.
+		 *
+		 * @param iconName the icon name
+		 */
+		void lookupByName(String iconName);
+	}
+}

src/main/java/org/cryptomator/integrations/tray/TrayMenuController.java

@@ -3,9 +3,9 @@
 import org.cryptomator.integrations.common.IntegrationsLoader;
 import org.jetbrains.annotations.ApiStatus;
 
-import java.net.URI;
 import java.util.List;
 import java.util.Optional;
+import java.util.function.Consumer;
 
 /**
  * Displays a tray icon and menu
@@ -22,20 +22,20 @@ static Optional<TrayMenuController> get() {
 	/**
 	 * Displays an icon on the system tray.
 	 *
-	 * @param imageUri      What image to show
+	 * @param iconLoader    A callback responsible for retrieving the icon in the required format
 	 * @param defaultAction Action to perform when interacting with the icon directly instead of its menu
 	 * @param tooltip       Text shown when hovering
 	 * @throws TrayMenuException thrown when adding the tray icon failed
 	 */
-	void showTrayIcon(URI imageUri, Runnable defaultAction, String tooltip) throws TrayMenuException;
+	void showTrayIcon(Consumer<TrayIconLoader> iconLoader, Runnable defaultAction, String tooltip) throws TrayMenuException;
 
 	/**
 	 * Updates the icon on the system tray.
 	 *
-	 * @param imageUri What image to show
+	 * @param iconLoader A callback responsible for retrieving the icon in the required format
 	 * @throws IllegalStateException thrown when called before an icon has been added
 	 */
-	void updateTrayIcon(URI imageUri);
+	void updateTrayIcon(Consumer<TrayIconLoader> iconLoader);
 
 	/**
 	 * Show the given options in the tray menu.