Multi Zoom Support for region for win32

This commit adds the feature of scaling region based on the zoom level of the monitor it is drawn on. The mentioned functionality is attained by using a map to maintain the handle of the region scale as per zoom level. The handle can then be obtained by the method win32_getHandle by passing the zoom information from the client.
The region object stores a history of all the operations performed on it
so that it can be used to create handles for different zoom level.
Additionally, this commit removes the public handle field from Region for win32 since
it is now replaced by win32_getHandle method for the clients and
internally the class uses a hashMap zoomToHandle to get the handle for
the particular zoomlevel. The default handle is stored in zoomToHandle
mapped to the initialZoom.

contributes #62 and #127

bundles/org.eclipse.swt/Eclipse SWT Tests/win32/org/eclipse/swt/graphics/RegionWin32Tests.java

@@ -0,0 +1,52 @@
+/*******************************************************************************
+ * Copyright (c) 2024 Yatta Solutions
+ *
+ * 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:
+ *     Yatta Solutions - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.swt.graphics;
+
+import static org.junit.Assert.assertEquals;
+
+import org.eclipse.swt.internal.*;
+import org.eclipse.swt.internal.win32.*;
+import org.junit.jupiter.api.*;
+
+class RegionWin32Tests extends Win32AutoscaleTestBase {
+
+	@Test
+	public void testRegionMustBeScaledOnHandleOfScaledZoomLevel() {
+		int zoom = DPIUtil.getDeviceZoom();
+		int scalingFactor = 2;
+
+		Region region = new Region(display);
+		region.add(0, 0, 5, 10);
+		region.subtract(0,0,1,1);
+		region.translate(0, 5);
+		region.intersect(1,1,1,1);
+
+		long handle = Region.win32_getHandle(region, zoom);
+		long scaledRegionHandle = Region.win32_getHandle(region, zoom * scalingFactor);
+
+		RECT rect = new RECT();
+		OS.GetRgnBox(handle, rect);
+		Rectangle bounds = new Rectangle(rect.left, rect.top, rect.right - rect.left, rect.bottom - rect.top);
+
+		rect = new RECT();
+		OS.GetRgnBox(scaledRegionHandle, rect);
+		Rectangle scaledBounds = new Rectangle(rect.left, rect.top, rect.right - rect.left, rect.bottom - rect.top);
+
+		assertEquals("scaled region's height should be double of unscaled region", bounds.height * scalingFactor, scaledBounds.height);
+		assertEquals("scaled region's width should be double of unscaled region", bounds.width * scalingFactor, scaledBounds.width);
+		assertEquals("scaled region's x position should be double of unscaled region", bounds.x * scalingFactor, scaledBounds.x);
+		assertEquals("scaled region's y position should be double of unscaled region", bounds.y * scalingFactor, scaledBounds.y);
+	}
+
+}

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

@@ -3386,7 +3386,7 @@ public void getClipping (Region region) {
 			Gdip.Graphics_SetPixelOffsetMode(gdipGraphics, Gdip.PixelOffsetModeNone);
 			Gdip.Graphics_GetVisibleClipBounds(gdipGraphics, rect);
 			Gdip.Graphics_SetPixelOffsetMode(gdipGraphics, Gdip.PixelOffsetModeHalf);
-			OS.SetRectRgn(region.handle, rect.X, rect.Y, rect.X + rect.Width, rect.Y + rect.Height);
+			OS.SetRectRgn(Region.win32_getHandle(region, getZoom()), rect.X, rect.Y, rect.X + rect.Width, rect.Y + rect.Height);
 		} else {
 			long matrix = Gdip.Matrix_new(1, 0, 0, 1, 0, 0);
 			long identity = Gdip.Matrix_new(1, 0, 0, 1, 0, 0);
@@ -3399,26 +3399,26 @@ public void getClipping (Region region) {
 			POINT pt = new POINT ();
 			OS.GetWindowOrgEx (handle, pt);
 			OS.OffsetRgn (hRgn, pt.x, pt.y);
-			OS.CombineRgn(region.handle, hRgn, 0, OS.RGN_COPY);
+			OS.CombineRgn(Region.win32_getHandle(region, getZoom()), hRgn, 0, OS.RGN_COPY);
 			OS.DeleteObject(hRgn);
 		}
 		Gdip.Region_delete(rgn);
 		return;
 	}
 	POINT pt = new POINT ();
 	OS.GetWindowOrgEx (handle, pt);
-	int result = OS.GetClipRgn (handle, region.handle);
+	int result = OS.GetClipRgn (handle, Region.win32_getHandle(region, getZoom()));
 	if (result != 1) {
 		RECT rect = new RECT();
 		OS.GetClipBox(handle, rect);
-		OS.SetRectRgn(region.handle, rect.left, rect.top, rect.right, rect.bottom);
+		OS.SetRectRgn(Region.win32_getHandle(region, getZoom()), rect.left, rect.top, rect.right, rect.bottom);
 	} else {
-		OS.OffsetRgn (region.handle, pt.x, pt.y);
+		OS.OffsetRgn (Region.win32_getHandle(region, getZoom()), pt.x, pt.y);
 	}
 	long metaRgn = OS.CreateRectRgn (0, 0, 0, 0);
 	if (OS.GetMetaRgn (handle, metaRgn) != 0) {
 		OS.OffsetRgn (metaRgn, pt.x, pt.y);
-		OS.CombineRgn (region.handle, metaRgn, region.handle, OS.RGN_AND);
+		OS.CombineRgn (Region.win32_getHandle(region, getZoom()), metaRgn, Region.win32_getHandle(region, getZoom()), OS.RGN_AND);
 	}
 	OS.DeleteObject(metaRgn);
 	long hwnd = data.hwnd;
@@ -3435,7 +3435,7 @@ public void getClipping (Region region) {
 			}
 			OS.MapWindowPoints (0, hwnd, pt, 1);
 			OS.OffsetRgn (sysRgn, pt.x, pt.y);
-			OS.CombineRgn (region.handle, sysRgn, region.handle, OS.RGN_AND);
+			OS.CombineRgn (Region.win32_getHandle(region, getZoom()), sysRgn, Region.win32_getHandle(region, getZoom()), OS.RGN_AND);
 		}
 		OS.DeleteObject(sysRgn);
 	}
@@ -4374,7 +4374,7 @@ public void setClipping (Rectangle rect) {
 public void setClipping (Region region) {
 	if (handle == 0) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED);
 	if (region != null && region.isDisposed()) SWT.error(SWT.ERROR_INVALID_ARGUMENT);
-	setClipping(region != null ? region.handle : 0);
+	setClipping(region != null ? Region.win32_getHandle(region, getZoom()) : 0);
 }
 
 /**