Windows File Preview for Java

A Java library for native file preview on Windows using JNA.

Screenshots

Features

• Simple AWT/Swing integration, based on AWT Canvas
• Hosts interactive previews if IPreviewHandler is available
• Falls back to static thumbnails via IThumbnailProvider and IShellItemImageFactory
• Supports initialization via IInitializeWithFile, IInitializeWithStream, and IInitializeWithItem
• Supports customization via IPreviewHandlersVisuals
• Launches the default registered application when a thumbnail is double-clicked (as in Windows Explorer)
• Supports dark themes and adapts to Look & Feel changes at runtime
• Shows a checkered background on mouse over (optional)
• Uses double-buffering to avoid flickering
• Uses a separate thread for each handler, for stability and performance

Requirements

• Java 8 or later
• JNA 5.x
• Windows 7, 8, 10, 11

Usage

Copy WindowsPreviewCanvas.java and .properties files to your project and add JNA as a dependency. Add your own localization, if desired.

Example

public static void main(String[] args) {
	SwingUtilities.invokeLater(() -> {
		JFrame frame = new JFrame("Windows File Preview Example");
		WindowsPreviewCanvas canvas = new WindowsPreviewCanvas();
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.add(canvas);
		frame.setSize(800, 600);
		frame.setLocationRelativeTo(null);
		frame.setVisible(true);
		canvas.showPreview(new File("C:\\Windows\\Help\\en-US\\credits.rtf"));
	});
}

Known issues and limitations

• Sometimes Windows renders transparent pixels as black
• Does not remove focus from AWT/Swing when IPreviewHandler gets focus
• Does not implement accelerator handling
• On 32-bit Java, some thumbnail providers do not work (e.g. Affinity Thumbnail Handler); a thumbnail will only be shown if Windows already has it cached