Design improvement for scaling win32 widgets #62

This commit improves thes design implementation for widgets in win32 by
moving away from DPIZoomChangeRegistry to an event-driven design using
ZoomChanged event and inheritance.

contributes to
#62 and
#128

Author: amartya4256

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

@@ -173,6 +173,7 @@ public CCombo (Composite parent, int style) {
 	}
 
 	initAccessible();
+	addListener(SWT.ZoomChanged, this::handleDPIChange);
 }
 static int checkStyle (int style) {
 	int mask = SWT.BORDER | SWT.READ_ONLY | SWT.FLAT | SWT.LEFT_TO_RIGHT | SWT.RIGHT_TO_LEFT | SWT.LEAD | SWT.CENTER | SWT.TRAIL;
@@ -2026,19 +2027,24 @@ public boolean traverse(int event){
 	return super.traverse(event);
 }
 
+private void handleDPIChange(Event event) {
+	updateAndRefreshChildren(childWidget -> {
+		childWidget.notifyListeners(SWT.ZoomChanged, event);
+	});
+}
+
 /**
  * The method accepts a combo and a callback which takes
  * all the child of the CCombo as the argument and executes it.
  * All children are refreshed after the execution of the callback.
  *
- * @noreference This method is not intended to be referenced by clients.
  * @param combo the Combo to get the children widget from
  * @param childUpdater the callback which works with the child widgets
  */
-public static void updateAndRefreshChildren(CCombo combo, Consumer<Widget> childUpdater) {
-	childUpdater.accept(combo.text);
-	childUpdater.accept(combo.list);
-	childUpdater.accept(combo.arrow);
-	childUpdater.accept(combo.popup);
+private void updateAndRefreshChildren(Consumer<Widget> childUpdater) {
+	childUpdater.accept(text);
+	childUpdater.accept(list);
+	childUpdater.accept(arrow);
+	childUpdater.accept(popup);
 }
 }

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

@@ -19,7 +19,6 @@
 
 
 import java.util.*;
-import java.util.function.*;
 import java.util.stream.*;
 
 import org.eclipse.swt.*;
@@ -759,6 +758,7 @@ public StyledText(Composite parent, int style) {
 	initializeAccessible();
 	setData("DEFAULT_DROP_TARGET_EFFECT", new StyledTextDropTargetEffect(this));
 	if (IS_MAC) setData(STYLEDTEXT_KEY);
+	addListener(SWT.ZoomChanged, this::handleDPIChange);
 }
 /**
  * Adds an extended modify listener. An ExtendedModify event is sent by the
@@ -10901,29 +10901,20 @@ void updateSelection(int startOffset, int replacedLength, int newLength) {
 	setCaretLocations();
 }
 
-/**
- * The method accepts a StyledText and a callback which takes
- * all the carets of the StyledText as the argument and executes it.
- * The caret is refreshed after the execution of the callback.
- *
- * @param styledText the StyledText to get the carets from
- * @param caretUpdater the callback which works with the carets
- *
- * @noreference This method is not intended to be referenced by clients.
- */
-public static void updateAndRefreshCarets(StyledText styledText, Consumer<Caret> caretUpdater) {
-	styledText.updateCaretVisibility();
-	styledText.setCaretLocations();
+private void handleDPIChange(Event event) {
+	updateCaretVisibility();
+	setCaretLocations();
 	Set<Caret> caretSet = new LinkedHashSet<>();
-	caretSet.add(styledText.defaultCaret);
-	caretSet.add(styledText.getCaret());
-	if (styledText.carets != null) {
-		for (Caret caret : styledText.carets) {
+	caretSet.add(defaultCaret);
+	caretSet.add(getCaret());
+	if (carets != null) {
+		for (Caret caret : carets) {
 			caretSet.add(caret);
 		}
 	}
-	caretSet.stream().filter(Objects::nonNull).forEach(caretUpdater);
-
+	caretSet.stream().filter(Objects::nonNull).forEach(caretToRefresh -> {
+		caretToRefresh.notifyListeners(SWT.ZoomChanged, event);
+	});
 }
 
 }

bundles/org.eclipse.swt/Eclipse SWT Tests/win32/org/eclipse/swt/internal/DPITestUtil.java

@@ -13,6 +13,7 @@
  *******************************************************************************/
 package org.eclipse.swt.internal;
 
+import org.eclipse.swt.*;
 import org.eclipse.swt.widgets.*;
 
 public final class DPITestUtil {
@@ -22,8 +23,12 @@ private DPITestUtil() {
 
 	public static void changeDPIZoom (Shell shell, int nativeZoom) {
 		DPIUtil.setDeviceZoom(nativeZoom);
-		float scalingFactor = 1f * DPIUtil.getZoomForAutoscaleProperty(nativeZoom) / DPIUtil.getZoomForAutoscaleProperty(shell.nativeZoom);
-		DPIZoomChangeRegistry.applyChange(shell, nativeZoom, scalingFactor);
+		Event event = new Event();
+		event.type = SWT.ZoomChanged;
+		event.widget = shell;
+		event.detail = nativeZoom;
+		event.doit = true;
+		shell.notifyListeners(SWT.ZoomChanged, event);
 	}
 
 }

bundles/org.eclipse.swt/Eclipse SWT/common/org/eclipse/swt/widgets/Item.java

@@ -75,6 +75,7 @@ public abstract class Item extends Widget {
 public Item (Widget parent, int style) {
 	super (parent, style);
 	text = "";
+	this.addListener(SWT.ZoomChanged, this::handleDPIChange);
 }
 
 /**
@@ -224,4 +225,13 @@ boolean updateTextDirection(int textDirection) {
 	return textDirection == AUTO_TEXT_DIRECTION;
 }
 
+
+private void handleDPIChange(Event event) {
+	// Refresh the image
+	Image image = getImage();
+	if (image != null) {
+		setImage(image);
+	}
+}
+
 }

bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/internal/CommonWidgetsDPIChangeHandlers.java

@@ -65,8 +65,6 @@ public class Button extends Control {
 		WNDCLASS lpWndClass = new WNDCLASS ();
 		OS.GetClassInfo (0, ButtonClass, lpWndClass);
 		ButtonProc = lpWndClass.lpfnWndProc;
-
-		DPIZoomChangeRegistry.registerHandler(Button::handleDPIChange, Button.class);
 	}
 
 /**
@@ -1561,16 +1559,15 @@ LRESULT wmDrawChild (long wParam, long lParam) {
 	return null;
 }
 
-private static void handleDPIChange(Widget widget, int newZoom, float scalingFactor) {
-	if (!(widget instanceof Button button)) {
-		return;
-	}
+@Override
+void handleDPIChange(Event event, float scalingFactor) {
+	super.handleDPIChange(event, scalingFactor);
 	//Refresh the CheckSize
-	button.refreshCheckSize(newZoom);
+	refreshCheckSize(event.detail);
 	// Refresh the image
-	if (button.image != null) {
-		button._setImage(button.image);
-		button.updateImageList();
+	if (image != null) {
+		_setImage(image);
+		updateImageList();
 	}
 }
 }

bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/internal/DPIZoomChangeHandler.java

@@ -51,10 +51,6 @@ public class Caret extends Widget {
 	Font font;
 	LOGFONT oldFont;
 
-static {
-	DPIZoomChangeRegistry.registerHandler(Caret::handleDPIChange, Caret.class);
-}
-
 /**
  * Constructs a new instance of this class given its parent
  * and a style value describing its behavior and appearance.
@@ -658,20 +654,18 @@ public void setVisible (boolean visible) {
 	}
 }
 
-private static void handleDPIChange(Widget widget, int newZoom, float scalingFactor) {
-	if (!(widget instanceof Caret caret)) {
-		return;
-	}
-
-	Image image = caret.getImage();
+@Override
+void handleDPIChange(Event event, float scalingFactor) {
+	super.handleDPIChange(event, scalingFactor);
+	Image image = getImage();
 	if (image != null) {
-		caret.setImage(image);
+		setImage(image);
 	}
 
-	if (caret.font != null) {
-		caret.setFont(caret.font);
+	if (font != null) {
+		setFont(font);
 	}
-	if (caret.isVisible && caret.hasFocus ()) caret.resize();
+	if (isVisible && hasFocus ()) resize();
 }
 }