Create handles for ImageDataProvider and ImageFilenameProvider on demand

[ShahzaibIbrahim]

Currently, when an image is instantiated using ImageDataProvider or ImageFileNameProvider, a handle is created immediately. We aim to optimize this by deferring handle creation until it is explicitly needed. To achieve this, getBounds() will return the bounds of a 100% zoomed image when called after instantiation, without requiring a handle to be created upfront. This change improves efficiency by reducing unnecessary resource allocation during image initialization.

Attaching the snippet to test the use cases after this change:

package org.eclipse.swt.snippets;

import org.eclipse.swt.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.widgets.*;

public class SnippetTestImage {

	final static String IMAGES_ROOT = "bin/org/eclipse/swt/snippets/";

	public static void main(String[] args) {
		imageFileNameProviderExample();
		imageDataProviderExample();
	}

	private static void imageDataProviderExample() {
		Image image;
		final Display display = new Display();
		ImageDataProvider imageDataProvider = zoom -> {
			String fileName;
			switch (zoom) {
			case 100:
				fileName = "eclipse16.png";
				break;
			case 150:
				fileName = "eclipse24.png";
				break;
			case 200:
			case 250:
				fileName = "eclipse32.png";
				break;
			default:
				return null;
			}
			return new ImageData(IMAGES_ROOT + fileName);
		};
		try {
			image = new Image(display, imageDataProvider);
			System.out.println("Image Bounds initially = " + image.getBounds());
			ImageData imgData = image.getImageData(250);
			System.out.println("Image Bounds on Demand (250) = " + imgData.height + " width = " + imgData.width);
			image.dispose();
		} catch (SWTException e) {
			System.out.println(e);
		}
	}

	private static void imageFileNameProviderExample() {
		Image image;
		final Display display = new Display();
		ImageFileNameProvider provider = zoom -> {
			String fileName;
			switch (zoom) {
			case 100:
				fileName = "eclipse16.png";
				break;
			case 150:
				fileName = "eclipse24.png";
				break;
			case 200:
			case 250:
				fileName = "eclipse32.png";
				break;
			default:
				return null;
			}
			return IMAGES_ROOT + fileName;
		};
		try {
			image = new Image(display, provider);
			System.out.println("Image Bounds initially = " + image.getBounds());
			ImageData imgData = image.getImageData(250);
			System.out.println("Image Bounds on Demand (250) = " + imgData.height + " width = " + imgData.width);
			image.dispose();
		} catch (SWTException e) {
			System.out.println(e);
		}
	}
}

[github-actions]

Test Results

   510 files  ±0     510 suites  ±0   8m 10s ⏱️ -11s
 4 345 tests ±0   4 331 ✅ ±0   14 💤 ±0  0 ❌ ±0 
16 613 runs  ±0  16 502 ✅ ±0  111 💤 ±0  0 ❌ ±0 

Results for commit a46c317. ± Comparison against base commit f69194a.

♻️ This comment has been updated with latest results.

[fedejeanne]

Just a NIT: width and height could be final (also in ImageGcDrawerWrapper)

[akoch-yatta]

Looks good to me now

[HeikoKlare]

Looks good to me as well. Just minor comments from my side.

[fedejeanne]

Unintentional, I assume. Undo please:

[fedejeanne]

LGTM

[fedejeanne]

The code looks fine but some tests fail because of leaked resources. I am retriggering tests. @ShahzaibIbrahim stay tuned

Retriggering tests because of leaked resources

[fedejeanne]

The leaks are still there so it's definitely not a fluke @ShahzaibIbrahim . Here's the stack trace:

java.lang.Error: SWT Resource was not properly disposed
	at org.eclipse.swt.graphics.Resource.initNonDisposeTracking(Resource.java:184)
	at org.eclipse.swt.graphics.Resource.<init>(Resource.java:121)
	at org.eclipse.swt.graphics.Image.<init>(Image.java:593)
	at 

See https://github.com/eclipse-platform/eclipse.platform.swt/actions/runs/13899543146/job/38895976230?pr=1898#step:7:3980

[ShahzaibIbrahim]

@fedejeanne resource leak is fixed.