Reduce flickering in embedded controls

Ignore calls to Control::setRedraw(false) if the control contains any
embedded application as a child.

This change does not completely get rid of the flickering but it reduces
it drastically.

Contributes to
#1122

Co-authored-by: Federico Jeanne <[email protected]>
Co-authored-by: Heiko Klare <[email protected]>

Author: 3 people

bundles/org.eclipse.swt/Eclipse SWT Browser/common/org/eclipse/swt/browser/Browser.java

@@ -729,6 +729,14 @@ public int getStyle () {
 	return super.getStyle () | (userStyle & SWT.BORDER);
 }
 
+/**
+ * @since 3.129
+ */
+@Override
+protected boolean win32_embeds() {
+	// The Edge browser embeds webView2
+	return (getStyle() & SWT.EDGE) != 0;
+}
 /**
  * Returns a string with HTML that represents the content of the current page.
  *

bundles/org.eclipse.swt/Eclipse SWT OLE Win32/win32/org/eclipse/swt/ole/win32/OleClientSite.java

@@ -916,6 +916,15 @@ private boolean isOffice2007(boolean program) {
 	if (programID.equals("PowerPoint.Show.12")) return true; //$NON-NLS-1$
 	return false;
 }
+
+/**
+ * @since 3.129
+ */
+@Override
+protected boolean win32_embeds() {
+	// OLE objects are always embedded by windows
+	return true;
+}
 private int OnClose() {
 	return COM.S_OK;
 }

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

@@ -14,6 +14,8 @@
 package org.eclipse.swt.widgets;
 
 
+import java.util.stream.*;
+
 import org.eclipse.swt.*;
 import org.eclipse.swt.graphics.*;
 import org.eclipse.swt.internal.*;
@@ -1183,6 +1185,16 @@ void setResizeChildren (boolean resize) {
 	}
 }
 
+/**
+ * @return <code>true</code> if this component or any of its children embeds a win32 component
+ * @since 3.129
+ */
+@Override
+protected boolean win32_embeds() {
+	return super.win32_embeds() ||
+			Stream.of(getChildren()).anyMatch(Control::win32_embeds);
+}
+
 @Override
 boolean setTabGroupFocus () {
 	if (isTabItem ()) return setTabItemFocus ();

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

@@ -3631,6 +3631,21 @@ boolean setRadioSelection (boolean value) {
  */
 public void setRedraw (boolean redraw) {
 	checkWidget ();
+
+	/*
+	 * Some embedded applications like webview2 (Edge), Excel, etc have a renderer
+	 * that will draw the whole application white when setting redraw to false and
+	 * will repaint it completely when setting it to true. This causes flickering,
+	 * which is why turning redraw off is not allowed in case this control has an
+	 * embedded application as a child.
+	 *
+	 * https://github.com/eclipse-platform/eclipse.platform.swt/issues/1122
+	 */
+	boolean isShown = isVisible() && !isDisposed();
+	if (!redraw && isShown && win32_embeds()) {
+		return;
+	}
+
 	/*
 	 * Feature in Windows.  When WM_SETREDRAW is used to turn
 	 * off drawing in a widget, it clears the WS_VISIBLE bits
@@ -3667,6 +3682,15 @@ public void setRedraw (boolean redraw) {
 	}
 }
 
+/**
+ * @return <code>true</code> if this component embeds a win32 component.
+ * @since 3.129
+ */
+protected boolean win32_embeds() {
+	// Default implementation. It should be rewritten by sub-classes that embed windows components.
+	return false;
+}
+
 /**
  * Sets the shape of the control to the region specified
  * by the argument.  When the argument is null, the