Issue 1726 batched defer window pos

bundles/org.eclipse.swt/Eclipse SWT Custom Widgets/common/org/eclipse/swt/custom/SashForm.java

@@ -287,9 +287,12 @@ void onDragSash(Event event) {
 		((SashFormData)data2).weight = (((long)b2.height << 16) + area.height - 1) / area.height;
 	}
 	if (correction || (event.doit && event.detail != SWT.DRAG)) {
+		boolean isWin32 = "win32".equals(SWT.getPlatform());
+		if (isWin32) setLayoutDeferred(true);
 		c1.setBounds(b1);
 		sash.setBounds(event.x, event.y, event.width, event.height);
 		c2.setBounds(b2);
+		if (isWin32) setLayoutDeferred(false);
 	}
 }
 /**

bundles/org.eclipse.swt/Eclipse SWT PI/win32/library/os_custom.c

@@ -439,7 +439,47 @@ JNIEXPORT jlong JNICALL OS_NATIVE(DPI_1AWARENESS_1CONTEXT_1UNAWARE_1GDISCALED)
 	#else
 		rc = 0;
 	#endif
-	OS_NATIVE_EXIT(env, that, DPI_1AWARENESS_1CONTEXT_1UNAWARE_1GDISCALED_FUNC);
+
+#ifndef NO_DeferWindowPos__J_3J_3I_3I_3I_3I_3I
+JNIEXPORT jlong JNICALL OS_NATIVE(DeferWindowPos__J_3J_3I_3I_3I_3I_3I)
+	(JNIEnv *env, jclass that, jlong arg0, jlongArray arg1, jintArray arg2, jintArray arg3, jintArray arg4, jintArray arg5, jintArray arg6)
+{
+	jlong *lparg1=NULL;
+	jint *lparg2=NULL;
+	jint *lparg3=NULL;
+	jint *lparg4=NULL;
+	jint *lparg5=NULL;
+	jint *lparg6=NULL;
+	jsize len = 0;
+	jlong rc = 0;
+	int i;
+
+	OS_NATIVE_ENTER(env, that, DeferWindowPos__J_3J_3I_3I_3I_3I_3I_FUNC);
+
+	if (arg1) if ((lparg1 = (*env)->GetLongArrayElements(env, arg1, NULL)) == NULL) goto fail;
+	if (arg2) if ((lparg2 = (*env)->GetIntArrayElements(env, arg2, NULL)) == NULL) goto fail;
+	if (arg3) if ((lparg3 = (*env)->GetIntArrayElements(env, arg3, NULL)) == NULL) goto fail;
+	if (arg4) if ((lparg4 = (*env)->GetIntArrayElements(env, arg4, NULL)) == NULL) goto fail;
+	if (arg5) if ((lparg5 = (*env)->GetIntArrayElements(env, arg5, NULL)) == NULL) goto fail;
+	if (arg6) if ((lparg6 = (*env)->GetIntArrayElements(env, arg6, NULL)) == NULL) goto fail;
+
+	len = (*env)->GetArrayLength(env, arg1);
+	rc = arg0;
+
+	for (i = 0; i < len; i++) {
+		if (rc == 0) break;
+		rc = (jlong)DeferWindowPos((HDWP)rc, (HWND)lparg1[i], (HWND)0, lparg2[i], lparg3[i], lparg4[i], lparg5[i], lparg6[i]);
+	}
+
+fail:
+	if (arg6 && lparg6) (*env)->ReleaseIntArrayElements(env, arg6, lparg6, 0);
+	if (arg5 && lparg5) (*env)->ReleaseIntArrayElements(env, arg5, lparg5, 0);
+	if (arg4 && lparg4) (*env)->ReleaseIntArrayElements(env, arg4, lparg4, 0);
+	if (arg3 && lparg3) (*env)->ReleaseIntArrayElements(env, arg3, lparg3, 0);
+	if (arg2 && lparg2) (*env)->ReleaseIntArrayElements(env, arg2, lparg2, 0);
+	if (arg1 && lparg1) (*env)->ReleaseLongArrayElements(env, arg1, lparg1, 0);
+
+	OS_NATIVE_EXIT(env, that, DeferWindowPos__J_3J_3I_3I_3I_3I_3I_FUNC);
 	return rc;
 }
 #endif

bundles/org.eclipse.swt/Eclipse SWT PI/win32/org/eclipse/swt/internal/win32/OS.java

@@ -2532,6 +2532,8 @@ public static int HRESULT_FROM_WIN32(int x) {
  * @param hWndInsertAfter cast=(HWND)
  */
 public static final native long DeferWindowPos (long hWinPosInfo, long hWnd, long hWndInsertAfter, int X, int Y, int cx, int cy, int uFlags);
+/** @method flags=no_gen */
+public static final native long DeferWindowPos (long hWinPosInfo, long[] hWnd, int[] X, int[] Y, int[] cx, int[] cy, int[] uFlags);
 /**
  * @param hWnd cast=(HWND)
  * @param wParam cast=(WPARAM)

bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Composite.java

@@ -977,13 +977,35 @@ boolean resizeChildren (boolean defer, WINDOWPOS [] pwp) {
 	if (defer) {
 		hdwp = OS.BeginDeferWindowPos (pwp.length);
 		if (hdwp == 0) return false;
-	}
-	for (WINDOWPOS wp : pwp) {
-		if (wp != null) {
-			if (defer) {
-				hdwp = OS.DeferWindowPos (hdwp, wp.hwnd, 0, wp.x, wp.y, wp.cx, wp.cy, wp.flags);
-				if (hdwp == 0) return false;
-			} else {
+		int count = 0;
+		for (WINDOWPOS wp : pwp) {
+			if (wp != null) count++;
+		}
+		if (count > 0) {
+			long [] hwnds = new long [count];
+			int [] xs = new int [count];
+			int [] ys = new int [count];
+			int [] cxs = new int [count];
+			int [] cys = new int [count];
+			int [] flags = new int [count];
+			int index = 0;
+			for (WINDOWPOS wp : pwp) {
+				if (wp != null) {
+					hwnds [index] = wp.hwnd;
+					xs [index] = wp.x;
+					ys [index] = wp.y;
+					cxs [index] = wp.cx;
+					cys [index] = wp.cy;
+					flags [index] = wp.flags;
+					index++;
+				}
+			}
+			hdwp = OS.DeferWindowPos (hdwp, hwnds, xs, ys, cxs, cys, flags);
+			if (hdwp == 0) return false;
+		}
+	} else {
+		for (WINDOWPOS wp : pwp) {
+			if (wp != null) {
 				OS.SetWindowPos (wp.hwnd, 0, wp.x, wp.y, wp.cx, wp.cy, wp.flags);
 			}
 		}

tests/org.eclipse.swt.tests/JUnit Tests/org/eclipse/swt/tests/junit/Test_CompositeDeferredLayout.java

@@ -0,0 +1,85 @@
+/*******************************************************************************
+ * Copyright (c) 2024 IBM Corporation and others.
+ *
+ * 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
+ *
+ * Contributors:
+ *     IBM Corporation - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.swt.tests.junit;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.eclipse.swt.SWT;
+import org.eclipse.swt.graphics.Rectangle;
+import org.eclipse.swt.widgets.Button;
+import org.eclipse.swt.widgets.Composite;
+import org.eclipse.swt.widgets.Shell;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class Test_CompositeDeferredLayout {
+
+	public Shell shell;
+	public Composite composite;
+
+	@BeforeEach
+	public void setUp() {
+		shell = new Shell();
+		composite = new Composite(shell, SWT.NONE);
+	}
+
+	@Test
+	public void test_deferredLayout_movesChildren() {
+		int numChildren = 5;
+		Button[] buttons = new Button[numChildren];
+		for (int i = 0; i < numChildren; i++) {
+			buttons[i] = new Button(composite, SWT.PUSH);
+			buttons[i].setBounds(0, 0, 10, 10);
+		}
+
+		composite.setLayoutDeferred(true);
+
+		for (int i = 0; i < numChildren; i++) {
+			buttons[i].setBounds(10 * i, 10 * i, 20, 20);
+		}
+
+		composite.setLayoutDeferred(false);
+
+		for (int i = 0; i < numChildren; i++) {
+			Rectangle bounds = buttons[i].getBounds();
+			assertEquals(new Rectangle(10 * i, 10 * i, 20, 20), bounds, "Button " + i + " bounds incorrect after deferred layout");
+		}
+	}
+
+	@Test
+	public void test_resizeChildren_batching() {
+		// This test indirectly targets the batching optimization in Composite.resizeChildren
+		// by verifying that a large number of children are moved correctly.
+		int numChildren = 100;
+		Button[] buttons = new Button[numChildren];
+		for (int i = 0; i < numChildren; i++) {
+			buttons[i] = new Button(composite, SWT.PUSH);
+			buttons[i].setBounds(0, 0, 10, 10);
+		}
+
+		composite.setLayoutDeferred(true);
+
+		for (int i = 0; i < numChildren; i++) {
+			buttons[i].setBounds(i, i, 15, 15);
+		}
+
+		// This call triggers resizeChildren with the deferred logic
+		composite.setLayoutDeferred(false);
+
+		for (int i = 0; i < numChildren; i++) {
+			Rectangle bounds = buttons[i].getBounds();
+			assertEquals(new Rectangle(i, i, 15, 15), bounds, "Button " + i + " bounds incorrect after large batch deferred layout");
+		}
+	}
+}

tests/org.eclipse.swt.tests/JUnit Tests/org/eclipse/swt/tests/junit/Test_org_eclipse_swt_custom_SashForm.java

@@ -0,0 +1,74 @@
+/*******************************************************************************
+ * Copyright (c) 2024 IBM Corporation and others.
+ *
+ * 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
+ *
+ * Contributors:
+ *     IBM Corporation - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.swt.tests.junit;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.eclipse.swt.SWT;
+import org.eclipse.swt.custom.SashForm;
+import org.eclipse.swt.graphics.Rectangle;
+import org.eclipse.swt.widgets.Button;
+import org.eclipse.swt.widgets.Shell;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class Test_org_eclipse_swt_custom_SashForm {
+
+	public Shell shell;
+	public SashForm sashForm;
+
+	@BeforeEach
+	public void setUp() {
+		shell = new Shell();
+		sashForm = new SashForm(shell, SWT.HORIZONTAL);
+		shell.setSize(400, 400);
+	}
+
+	@Test
+	public void test_initialLayout() {
+		Button b1 = new Button(sashForm, SWT.PUSH);
+		Button b2 = new Button(sashForm, SWT.PUSH);
+		sashForm.setWeights(new int[] {50, 50});
+
+		shell.open(); // Trigger layout
+
+		Rectangle bounds1 = b1.getBounds();
+		Rectangle bounds2 = b2.getBounds();
+
+		assertTrue(bounds1.width > 0, "Button 1 width should be > 0");
+		assertTrue(bounds2.width > 0, "Button 2 width should be > 0");
+		assertEquals(bounds1.width, bounds2.width, 5, "Buttons should have approximately equal width"); // Allow small tolerance
+	}
+
+	@Test
+	public void test_layoutDeferredDuringResize() {
+		// This test verifies that we can set layout deferred on SashForm 
+		// (simulating what happens internally on Windows during drag)
+		// and that the layout updates correctly afterwards.
+		Button b1 = new Button(sashForm, SWT.PUSH);
+		Button b2 = new Button(sashForm, SWT.PUSH);
+		sashForm.setWeights(new int[] {50, 50});
+		shell.open();
+
+		Rectangle initialBounds1 = b1.getBounds();
+
+		sashForm.setLayoutDeferred(true);
+		sashForm.setSize(600, 400); // Resize the sash form
+		sashForm.setLayoutDeferred(false); // Should trigger layout update
+
+		Rectangle newBounds1 = b1.getBounds();
+		assertTrue(newBounds1.width > initialBounds1.width, "Button 1 should have grown after SashForm resize");
+	}
+}