Simplify and clean up Win32 Cursor implementation

bundles/org.eclipse.swt/Eclipse SWT Tests/win32/org/eclipse/swt/graphics/CursorWin32Tests.java

@@ -0,0 +1,102 @@
+/*******************************************************************************
+ * Copyright (c) 2026 Contributors to the Eclipse Foundation
+ *
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package org.eclipse.swt.graphics;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import java.util.*;
+
+import org.eclipse.swt.*;
+import org.eclipse.swt.internal.*;
+import org.eclipse.swt.widgets.*;
+import org.junit.jupiter.api.*;
+import org.junit.jupiter.api.extension.*;
+
+@ExtendWith(PlatformSpecificExecutionExtension.class)
+@ExtendWith(WithMonitorSpecificScalingExtension.class)
+class CursorWin32Tests {
+
+	private Display display;
+
+	@BeforeEach
+	void setUp() {
+		display = Display.getDefault();
+	}
+
+	@Test
+	void testDisposedCursorReturnsZeroHandle() {
+		Cursor cursor = new Cursor(display, SWT.CURSOR_ARROW);
+		cursor.dispose();
+		assertEquals(0L, Cursor.win32_getHandle(cursor, 100),
+				"A disposed cursor must return a zero handle");
+	}
+
+	@Test
+	void testHandleIsCachedForSameZoomLevel() {
+		ImageData source = new ImageData(16, 16, 32,
+				new PaletteData(0xFF00, 0xFF0000, 0xFF000000));
+		source.alpha = 255;
+
+		Cursor cursor = new Cursor(display, source, 0, 0);
+		try {
+			long first  = Cursor.win32_getHandle(cursor, 100);
+			long second = Cursor.win32_getHandle(cursor, 100);
+			assertEquals(first, second,
+					"Repeated calls with the same zoom must return the cached handle");
+		} finally {
+			cursor.dispose();
+		}
+	}
+
+	@Test
+	void testImageDataCursorProducesDifferentHandlesForDifferentZoomLevels() {
+		// 32bpp image with uniform alpha — takes the ARGB path in setupCursorFromImageData
+		ImageData source = new ImageData(16, 16, 32,
+				new PaletteData(0xFF00, 0xFF0000, 0xFF000000));
+		source.alpha = 255;
+
+		Cursor cursor = new Cursor(display, source, 0, 0);
+		try {
+			long handle100 = Cursor.win32_getHandle(cursor, 100);
+			long handle200 = Cursor.win32_getHandle(cursor, 200);
+
+			assertNotEquals(0L, handle100, "Handle at 100% zoom must be non-zero");
+			assertNotEquals(0L, handle200, "Handle at 200% zoom must be non-zero");
+			assertNotEquals(handle100, handle200,
+					"Different zoom levels must produce distinct OS cursor handles (different physical sizes)");
+		} finally {
+			cursor.dispose();
+		}
+	}
+
+	@Test
+	void testDestroyHandlesExceptPreservesRetainedHandle() {
+		// 32bpp ARGB source so we get a unique, non-shared OS handle per zoom level
+		ImageData source = new ImageData(16, 16, 32,
+				new PaletteData(0xFF00, 0xFF0000, 0xFF000000));
+		source.alpha = 255;
+
+		Cursor cursor = new Cursor(display, source, 0, 0);
+		try {
+			long handle100 = Cursor.win32_getHandle(cursor, 100);
+			Cursor.win32_getHandle(cursor, 200); // populate a second zoom level
+
+			cursor.destroyHandlesExcept(Set.of(DPIUtil.getZoomForAutoscaleProperty(100)));
+
+			// The cursor itself must still be alive and the retained handle unchanged
+			assertFalse(cursor.isDisposed(), "Cursor must not be disposed after destroyHandlesExcept");
+			assertEquals(handle100, Cursor.win32_getHandle(cursor, 100),
+					"The handle for the retained zoom level must be unchanged after destroyHandlesExcept");
+		} finally {
+			cursor.dispose();
+		}
+	}
+}

bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/graphics/Cursor.java

@@ -316,25 +316,14 @@ public Cursor(Device device, ImageDataProvider imageDataProvider, int hotspotX,
  *
  * @noreference This method is not intended to be referenced by clients.
  */
-public static Long win32_getHandle (Cursor cursor, int zoom) {
+public static long win32_getHandle (Cursor cursor, int zoom) {
 	if (cursor.isDisposed()) {
 		return 0L;
 	}
-	int zoomWithPointerSizeScaleFactor = (int) (zoom * getPointerSizeScaleFactor());
-	if (cursor.zoomLevelToHandle.get(zoomWithPointerSizeScaleFactor) != null) {
-		return cursor.zoomLevelToHandle.get(zoomWithPointerSizeScaleFactor).getHandle();
-	}
-
-	CursorHandle handle = cursor.cursorHandleProvider.createHandle(cursor.device, zoomWithPointerSizeScaleFactor);
-	cursor.setHandleForZoomLevel(handle, zoomWithPointerSizeScaleFactor);
-
-	return cursor.zoomLevelToHandle.get(zoomWithPointerSizeScaleFactor).getHandle();
-}
-
-private void setHandleForZoomLevel(CursorHandle handle, Integer zoom) {
-	if (zoom != null && !zoomLevelToHandle.containsKey(zoom)) {
-		zoomLevelToHandle.put(zoom, handle);
-	}
+	int scaledZoom = (int) (zoom * getPointerSizeScaleFactor());
+	return cursor.zoomLevelToHandle
+			.computeIfAbsent(scaledZoom, z -> cursor.cursorHandleProvider.createHandle(cursor.device, z))
+			.getHandle();
 }
 
 /**
@@ -389,8 +378,7 @@ void destroy () {
 @Override
 public boolean equals (Object object) {
 	if (object == this) return true;
-	if (!(object instanceof Cursor)) return false;
-	Cursor cursor = (Cursor) object;
+	if (!(object instanceof Cursor cursor)) return false;
 	return device == cursor.device && win32_getHandle(this, DEFAULT_ZOOM) == win32_getHandle(cursor, DEFAULT_ZOOM);
 }
 
@@ -406,7 +394,7 @@ public boolean equals (Object object) {
  */
 @Override
 public int hashCode () {
-	return win32_getHandle(this, DEFAULT_ZOOM).intValue();
+	return (int) win32_getHandle(this, DEFAULT_ZOOM);
 }
 
 /**
@@ -439,7 +427,7 @@ public String toString () {
 @Override
 void destroyHandlesExcept(Set<Integer> zoomLevels) {
 	zoomLevelToHandle.entrySet().removeIf(entry -> {
-		final Integer zoom = entry.getKey();
+		Integer zoom = entry.getKey();
 		if (!zoomLevels.contains(zoom) && zoom != DPIUtil.getZoomForAutoscaleProperty(DEFAULT_ZOOM)) {
 			entry.getValue().destroy();
 			return true;
@@ -492,7 +480,7 @@ void destroy() {
 	}
 }
 
-private static interface CursorHandleProvider {
+private interface CursorHandleProvider {
 	CursorHandle createHandle(Device device, int zoom);
 }
 
@@ -513,7 +501,7 @@ public CursorHandle createHandle(Device device, int zoom) {
 		return new CustomCursorHandle(handle);
 	}
 
-	private static final long getOSCursorIdFromStyle(int style) {
+	private static long getOSCursorIdFromStyle(int style) {
 		long lpCursorName = 0;
 		switch (style) {
 		case SWT.CURSOR_HAND:
@@ -663,15 +651,15 @@ public ImageDataWithMaskCursorHandleProvider(ImageData source, ImageData mask, i
 	}
 
 	private void validateMask(ImageData source, ImageData mask) {
-		ImageData testMask = mask == null ? null : (ImageData) mask.clone();
-		if (testMask == null) {
+		ImageData effectiveMask = mask;
+		if (effectiveMask == null) {
 			if (source.getTransparencyType() != SWT.TRANSPARENCY_MASK) {
 				SWT.error(SWT.ERROR_NULL_ARGUMENT);
 			}
-			testMask = source.getTransparencyMask();
+			effectiveMask = source.getTransparencyMask();
 		}
 		/* Check the bounds. Mask must be the same size as source */
-		if (testMask.width != source.width || testMask.height != source.height) {
+		if (effectiveMask.width != source.width || effectiveMask.height != source.height) {
 			SWT.error(SWT.ERROR_INVALID_ARGUMENT);
 		}
 	}