Make DPI_CHANGED event handling async

amartya4256 · akoch-yatta · commit 94489c20f1fd · 2025-09-26T14:17:07.000+02:00
With this commit, all the widgets scale themselves asynchronously
independent of the order saving the wait time over their children to
scale.
diff --git a/bundles/org.eclipse.swt/Eclipse SWT Tests/win32/org/eclipse/swt/internal/DPITestUtil.java b/bundles/org.eclipse.swt/Eclipse SWT Tests/win32/org/eclipse/swt/internal/DPITestUtil.java
@@ -13,6 +13,9 @@
  *******************************************************************************/
 package org.eclipse.swt.internal;
 
+import java.time.*;
+import java.util.concurrent.atomic.*;
+
 import org.eclipse.swt.*;
 import org.eclipse.swt.widgets.*;
 
@@ -21,14 +24,34 @@ public final class DPITestUtil {
 	private DPITestUtil() {
 	}
 
+	private static final int TIMEOUT_MILLIS = 10000;
+
 	public static void changeDPIZoom (Shell shell, int nativeZoom) {
 		DPIUtil.setDeviceZoom(nativeZoom);
 		Event event = new Event();
 		event.type = SWT.ZoomChanged;
 		event.widget = shell;
 		event.detail = nativeZoom;
 		event.doit = true;
+		AtomicInteger scalingCounter = new AtomicInteger(0);
+		event.data = scalingCounter;
 		shell.notifyListeners(SWT.ZoomChanged, event);
+		waitForDPIChange(shell, TIMEOUT_MILLIS, scalingCounter);
+	}
+
+	public static void waitForPassCondition(Shell shell, int timeout, AtomicInteger scalingCounter) {
+		final Instant timeOut = Instant.now().plusMillis(timeout);
+		final Display display = shell == null ? Display.getDefault() : shell.getDisplay();
+
+		while (Instant.now().isBefore(timeOut) && scalingCounter.get() != 0) {
+			if (!display.isDisposed()) {
+				display.readAndDispatch();
+			}
+		}
+	}
+
+	public static void waitForDPIChange(Shell shell, int timeout, AtomicInteger scalingCounter) {
+		waitForPassCondition(shell, timeout, scalingCounter);
 	}
 
 }
diff --git a/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Composite.java b/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Composite.java
@@ -1977,7 +1977,7 @@ public String toString() {
 void handleDPIChange(Event event, float scalingFactor) {
 	super.handleDPIChange(event, scalingFactor);
 	for (Control child : getChildren()) {
-		child.notifyListeners(SWT.ZoomChanged, event);
+		child.sendZoomChangedEvent(event, getShell());
 	}
 }
 }
diff --git a/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Control.java b/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Control.java
@@ -16,6 +16,7 @@
 
 
 import java.util.*;
+import java.util.concurrent.atomic.*;
 import java.util.stream.*;
 
 import org.eclipse.swt.*;
@@ -4757,7 +4758,7 @@ public boolean setParent (Composite parent) {
 	if (parent.nativeZoom != nativeZoom) {
 		int newZoom = parent.nativeZoom;
 		Event zoomChangedEvent = createZoomChangedEvent(newZoom);
-		notifyListeners(SWT.ZoomChanged, zoomChangedEvent);
+		sendZoomChangedEvent(zoomChangedEvent, getShell());
 	}
 	int flags = OS.SWP_NOSIZE | OS.SWP_NOMOVE | OS.SWP_NOACTIVATE;
 	OS.SetWindowPos (topHandle, OS.HWND_BOTTOM, 0, 0, 0, 0, flags);
@@ -4953,7 +4954,7 @@ LRESULT WM_DESTROY (long wParam, long lParam) {
 void handleMonitorSpecificDpiChange(int newNativeZoom, Rectangle newBoundsInPixels) {
 	DPIUtil.setDeviceZoom (newNativeZoom);
 	Event zoomChangedEvent = createZoomChangedEvent(newNativeZoom);
-	notifyListeners(SWT.ZoomChanged, zoomChangedEvent);
+	sendZoomChangedEvent(zoomChangedEvent, getShell());
 	this.setBoundsInPixels(newBoundsInPixels.x, newBoundsInPixels.y, newBoundsInPixels.width, newBoundsInPixels.height);
 }
 
@@ -4963,6 +4964,7 @@ private Event createZoomChangedEvent(int zoom) {
 	event.widget = this;
 	event.detail = zoom;
 	event.doit = true;
+	event.data = new AtomicInteger(0);
 	return event;
 }
 
diff --git a/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Decorations.java b/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Decorations.java
@@ -1720,13 +1720,13 @@ void handleDPIChange(Event event, float scalingFactor) {
 
 	Menu menuBar = getMenuBar();
 	if (menuBar != null) {
-		menuBar.notifyListeners(SWT.ZoomChanged, event);
+		menuBar.sendZoomChangedEvent(event, getShell());
 	}
 
 	if (menus != null) {
 		for (Menu menu : menus) {
 			if (menu != null) {
-				menu.notifyListeners(SWT.ZoomChanged, event);
+				menu.sendZoomChangedEvent(event, getShell());
 			}
 		}
 	}
diff --git a/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/ExpandBar.java b/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/ExpandBar.java
@@ -871,7 +871,7 @@ LRESULT wmScroll (ScrollBar bar, boolean update, long hwnd, int msg, long wParam
 void handleDPIChange(Event event, float scalingFactor) {
 	super.handleDPIChange(event, scalingFactor);
 	for (ExpandItem item : getItems()) {
-		item.notifyListeners(SWT.ZoomChanged, event);
+		item.sendZoomChangedEvent(event, getShell());
 	}
 	layoutItems(0, true);
 	redraw();
diff --git a/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Menu.java b/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Menu.java
@@ -1366,7 +1366,7 @@ LRESULT wmTimer (long wParam, long lParam) {
 void handleDPIChange(Event event, float scalingFactor) {
 	super.handleDPIChange(event, scalingFactor);
 	for (MenuItem item : getItems()) {
-		item.notifyListeners(SWT.ZoomChanged, event);
+		item.sendZoomChangedEvent(event, getShell());
 	}
 }
 }
diff --git a/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/MenuItem.java b/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/MenuItem.java
@@ -1463,7 +1463,7 @@ void handleDPIChange(Event event, float scalingFactor) {
 	// Refresh the sub menu
 	Menu subMenu = getMenu();
 	if (subMenu != null) {
-		subMenu.notifyListeners(SWT.ZoomChanged, event);
+		subMenu.sendZoomChangedEvent(event, subMenu.getShell());
 	}
 }
 }
diff --git a/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/TabFolder.java b/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/TabFolder.java
@@ -1136,7 +1136,7 @@ void handleDPIChange(Event event, float scalingFactor) {
 		imageList = null;
 	}
 	for (int i = 0; i < getItemCount(); i++) {
-		items[i].notifyListeners(SWT.ZoomChanged, event);
+		items[i].sendZoomChangedEvent(event, getShell());
 	}
 	layout(true, true);
 }
diff --git a/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Table.java b/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Table.java
@@ -7363,10 +7363,10 @@ void handleDPIChange(Event event, float scalingFactor) {
 	setItemHeight(-1);
 
 	for (TableItem item : getItems()) {
-		item.notifyListeners(SWT.ZoomChanged, event);
+		item.sendZoomChangedEvent(event, getShell());
 	}
 	for (TableColumn tableColumn : getColumns()) {
-		tableColumn.notifyListeners(SWT.ZoomChanged, event);
+		tableColumn.sendZoomChangedEvent(event, getShell());
 	}
 
 	if (getColumns().length == 0 && scrollWidth != 0) {
diff --git a/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/ToolBar.java b/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/ToolBar.java
@@ -1770,7 +1770,7 @@ record ToolItemData(ToolItem toolItem, TBBUTTON button) {
 			// at the end
 			seperatorWidth[i] = item.getWidth();
 		}
-		item.notifyListeners(SWT.ZoomChanged, event);
+		item.sendZoomChangedEvent(event, getShell());
 		buttondata.push(new ToolItemData(item, lpButton));
 		OS.SendMessage(handle, OS.TB_DELETEBUTTON, i, 0);
 	}
diff --git a/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Tree.java b/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Tree.java
@@ -8318,10 +8318,10 @@ void handleDPIChange(Event event, float scalingFactor) {
 	setItemHeight(-1);
 
 	for (TreeColumn treeColumn : getColumns()) {
-		treeColumn.notifyListeners(SWT.ZoomChanged, event);
+		treeColumn.sendZoomChangedEvent(event, getShell());
 	}
 	for (TreeItem item : getItems()) {
-		item.notifyListeners(SWT.ZoomChanged, event);
+		item.sendZoomChangedEvent(event, getShell());
 	}
 
 	calculateAndApplyIndentSize();
diff --git a/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/TreeItem.java b/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/TreeItem.java
@@ -1825,7 +1825,7 @@ void handleDPIChange(Event event, float scalingFactor) {
 		}
 	}
 	for (TreeItem item : getItems()) {
-		item.notifyListeners(SWT.ZoomChanged, event);
+		item.sendZoomChangedEvent(event, getParent().getShell());
 	}
 }
 }
diff --git a/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Widget.java b/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Widget.java
@@ -15,6 +15,7 @@
 package org.eclipse.swt.widgets;
 
 import java.util.*;
+import java.util.concurrent.atomic.*;
 import java.util.stream.*;
 
 import org.eclipse.swt.*;
@@ -2730,6 +2731,25 @@ void handleDPIChange(Event event, float scalingFactor) {
 	this.setData(DATA_NATIVE_ZOOM, newZoom);
 }
 
+void sendZoomChangedEvent(Event event, Shell shell) {
+	AtomicInteger handleDPIChangedScheduledTasksCount = (AtomicInteger) event.data;
+	handleDPIChangedScheduledTasksCount.incrementAndGet();
+	getDisplay().asyncExec(() -> {
+		try {
+			if(!this.isDisposed()) {
+				notifyListeners(SWT.ZoomChanged, event);
+			}
+		} finally {
+			if (shell.isDisposed()) {
+				return;
+			}
+			if (handleDPIChangedScheduledTasksCount.decrementAndGet() <= 0) {
+				shell.WM_SIZE(0, 0);
+			}
+		}
+	});
+}
+
 int getSystemMetrics(int nIndex) {
 	return OS.GetSystemMetricsForDpi(nIndex, DPIUtil.mapZoomToDPI(nativeZoom));
 }

Original file line number	Diff line number	Diff line change
`@@ -1977,7 +1977,7 @@ public String toString() {`
`1977`	`1977`	`void handleDPIChange(Event event, float scalingFactor) {`
`1978`	`1978`	`super.handleDPIChange(event, scalingFactor);`
`1979`	`1979`	`for (Control child : getChildren()) {`
`1980`		`- child.notifyListeners(SWT.ZoomChanged, event);`
	`1980`	`+ child.sendZoomChangedEvent(event, getShell());`
`1981`	`1981`	`}`
`1982`	`1982`	`}`
`1983`	`1983`	`}`
Original file line number	Diff line number	Diff line change
`@@ -1720,13 +1720,13 @@ void handleDPIChange(Event event, float scalingFactor) {`
`1720`	`1720`
`1721`	`1721`	`Menu menuBar = getMenuBar();`
`1722`	`1722`	`if (menuBar != null) {`
`1723`		`- menuBar.notifyListeners(SWT.ZoomChanged, event);`
	`1723`	`+ menuBar.sendZoomChangedEvent(event, getShell());`
`1724`	`1724`	`}`
`1725`	`1725`
`1726`	`1726`	`if (menus != null) {`
`1727`	`1727`	`for (Menu menu : menus) {`
`1728`	`1728`	`if (menu != null) {`
`1729`		`- menu.notifyListeners(SWT.ZoomChanged, event);`
	`1729`	`+ menu.sendZoomChangedEvent(event, getShell());`
`1730`	`1730`	`}`
`1731`	`1731`	`}`
`1732`	`1732`	`}`
Original file line number	Diff line number	Diff line change
`@@ -871,7 +871,7 @@ LRESULT wmScroll (ScrollBar bar, boolean update, long hwnd, int msg, long wParam`
`871`	`871`	`void handleDPIChange(Event event, float scalingFactor) {`
`872`	`872`	`super.handleDPIChange(event, scalingFactor);`
`873`	`873`	`for (ExpandItem item : getItems()) {`
`874`		`- item.notifyListeners(SWT.ZoomChanged, event);`
	`874`	`+ item.sendZoomChangedEvent(event, getShell());`
`875`	`875`	`}`
`876`	`876`	`layoutItems(0, true);`
`877`	`877`	`redraw();`
Original file line number	Diff line number	Diff line change
`@@ -1366,7 +1366,7 @@ LRESULT wmTimer (long wParam, long lParam) {`
`1366`	`1366`	`void handleDPIChange(Event event, float scalingFactor) {`
`1367`	`1367`	`super.handleDPIChange(event, scalingFactor);`
`1368`	`1368`	`for (MenuItem item : getItems()) {`
`1369`		`- item.notifyListeners(SWT.ZoomChanged, event);`
	`1369`	`+ item.sendZoomChangedEvent(event, getShell());`
`1370`	`1370`	`}`
`1371`	`1371`	`}`
`1372`	`1372`	`}`
Original file line number	Diff line number	Diff line change
`@@ -1463,7 +1463,7 @@ void handleDPIChange(Event event, float scalingFactor) {`
`1463`	`1463`	`// Refresh the sub menu`
`1464`	`1464`	`Menu subMenu = getMenu();`
`1465`	`1465`	`if (subMenu != null) {`
`1466`		`- subMenu.notifyListeners(SWT.ZoomChanged, event);`
	`1466`	`+ subMenu.sendZoomChangedEvent(event, subMenu.getShell());`
`1467`	`1467`	`}`
`1468`	`1468`	`}`
`1469`	`1469`	`}`
Original file line number	Diff line number	Diff line change
`@@ -1136,7 +1136,7 @@ void handleDPIChange(Event event, float scalingFactor) {`
`1136`	`1136`	`imageList = null;`
`1137`	`1137`	`}`
`1138`	`1138`	`for (int i = 0; i < getItemCount(); i++) {`
`1139`		`- items[i].notifyListeners(SWT.ZoomChanged, event);`
	`1139`	`+ items[i].sendZoomChangedEvent(event, getShell());`
`1140`	`1140`	`}`
`1141`	`1141`	`layout(true, true);`
`1142`	`1142`	`}`
Original file line number	Diff line number	Diff line change
`@@ -7363,10 +7363,10 @@ void handleDPIChange(Event event, float scalingFactor) {`
`7363`	`7363`	`setItemHeight(-1);`
`7364`	`7364`
`7365`	`7365`	`for (TableItem item : getItems()) {`
`7366`		`- item.notifyListeners(SWT.ZoomChanged, event);`
	`7366`	`+ item.sendZoomChangedEvent(event, getShell());`
`7367`	`7367`	`}`
`7368`	`7368`	`for (TableColumn tableColumn : getColumns()) {`
`7369`		`- tableColumn.notifyListeners(SWT.ZoomChanged, event);`
	`7369`	`+ tableColumn.sendZoomChangedEvent(event, getShell());`
`7370`	`7370`	`}`
`7371`	`7371`
`7372`	`7372`	`if (getColumns().length == 0 && scrollWidth != 0) {`
Original file line number	Diff line number	Diff line change
`@@ -1770,7 +1770,7 @@ record ToolItemData(ToolItem toolItem, TBBUTTON button) {`
`1770`	`1770`	`// at the end`
`1771`	`1771`	`seperatorWidth[i] = item.getWidth();`
`1772`	`1772`	`}`
`1773`		`- item.notifyListeners(SWT.ZoomChanged, event);`
	`1773`	`+ item.sendZoomChangedEvent(event, getShell());`
`1774`	`1774`	`buttondata.push(new ToolItemData(item, lpButton));`
`1775`	`1775`	`OS.SendMessage(handle, OS.TB_DELETEBUTTON, i, 0);`
`1776`	`1776`	`}`