[win32] Dynamic handle creation for transform

This commit refactors Transform in the win32 implementation to better
support multiple handles for different zoom settings of a Transform when
monitor-specific scaling is enabled. The previous implementation
only applied adaptions to the initial handle of the transform  and relied
on the transform not to be changed afterwards. This doesn't cover all
scenarios and can lead to unexpected behavior when re-using Transform
objects over different zoom settings.

Author: akoch-yatta

bundles/org.eclipse.swt/Eclipse SWT Tests/win32/org/eclipse/swt/graphics/TransformWin32Tests.java

@@ -40,15 +40,21 @@ public void testShouldHaveDifferentHandlesAtDifferentZoomLevels() {
 	@Test
 	public void testScaledTrasformMustHaveScaledValues() {
 		Display display = Display.getDefault();
-		int zoom = DPIUtil.getDeviceZoom();
 		Transform transform = new Transform(display, 0, 0, 0, 0, 4, 2);
 		float[] elements = new float[6];
 		transform.getElements(elements);
-		long scaledHandle = transform.getHandle(zoom * 2);
-		float[] scaledElements = new float[6];
-		Gdip.Matrix_GetElements(scaledHandle, scaledElements);
-		assertEquals(elements[4] * 2, scaledElements[4], 0);
-		assertEquals(elements[5] * 2, scaledElements[5], 0);
+
+		long handle200 = transform.getHandle(200);
+		float[] scaledElements200 = new float[6];
+		Gdip.Matrix_GetElements(handle200, scaledElements200);
+		assertEquals(elements[4] * 2, scaledElements200[4], 0);
+		assertEquals(elements[5] * 2, scaledElements200[5], 0);
+
+		long handle300 = transform.getHandle(300);
+		float[] scaledElements300 = new float[6];
+		Gdip.Matrix_GetElements(handle300, scaledElements300);
+		assertEquals(elements[4] * 3, scaledElements300[4], 0);
+		assertEquals(elements[5] * 3, scaledElements300[5], 0);
 	}
 
 }