[win32] Create Font handles on demand

Handles will no longer be created during initialization but upon first
access to the handle via its accessor. Also the destroy condition is
changed since handle being 0 doesn't mean that it was destroyed anymore.

Author: ShahzaibIbrahim

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

@@ -55,6 +55,16 @@ public final class Font extends Resource {
 	 */
 	int zoom;
 
+	/**
+	 * this field is used to mark destroyed fonts
+	 */
+	private boolean isDestroyed;
+
+	/**
+	 * this field is used to store fontData provided during initialization
+	 */
+	private final FontData fontData;
+
 	/**
 	 * Font height in points. As the conversion to pixel height involves rounding the fontHeight must
 	 * be cached.
@@ -63,6 +73,7 @@ public final class Font extends Resource {
 
 private Font(Device device, long handle, int zoom) {
 	super(device);
+	this.fontData = null;
 	this.handle = handle;
 	this.zoom = zoom;
 	this.fontHeight = device.computePoints(fetchLogFontData(), handle, zoom);
@@ -90,16 +101,18 @@ private Font(Device device, long handle, int zoom) {
  */
 public Font(Device device, FontData fd) {
 	super(device);
+	if (fd == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
 	this.zoom = DPIUtil.getNativeDeviceZoom();
-	init(fd);
+	this.fontData = new FontData(fd.toString());
 	this.fontHeight = fd.height;
 	init();
 }
 
 private Font(Device device, FontData fd, int zoom) {
 	super(device);
+	if (fd == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
 	this.zoom = zoom;
-	init(fd);
+	this.fontData = new FontData(fd.toString());
 	this.fontHeight = fd.height;
 	init();
 }
@@ -138,7 +151,7 @@ public Font(Device device, FontData[] fds) {
 	}
 	this.zoom = DPIUtil.getNativeDeviceZoom();
 	FontData fd = fds[0];
-	init(fds[0]);
+	this.fontData = new FontData(fd.toString());
 	this.fontHeight = fd.height;
 	init();
 }
@@ -171,8 +184,7 @@ public Font(Device device, String name, int height, int style) {
 	super(device);
 	if (name == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
 	this.zoom = DPIUtil.getNativeDeviceZoom();
-	FontData fd = new FontData (name, height, style);
-	init(fd);
+	this.fontData = new FontData (name, height, style);
 	this.fontHeight = height;
 	init();
 }
@@ -181,15 +193,15 @@ public Font(Device device, String name, int height, int style) {
 	super(device);
 	if (name == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
 	this.zoom = DPIUtil.getNativeDeviceZoom();
-	FontData fd = new FontData (name, height, style);
-	init(fd);
+	this.fontData =  new FontData (name, height, style);
 	this.fontHeight = height;
 	init();
 }
 @Override
 void destroy() {
 	OS.DeleteObject(handle);
 	handle = 0;
+	isDestroyed = true;
 }
 
 /**
@@ -207,7 +219,7 @@ public boolean equals(Object object) {
 	if (object == this) return true;
 	if (!(object instanceof Font)) return false;
 	Font font = (Font) object;
-	return device == font.device && handle == font.handle;
+	return device == font.device && win32_getHandle(this) == win32_getHandle(font);
 }
 
 /**
@@ -230,7 +242,7 @@ public FontData[] getFontData() {
 
 private LOGFONT fetchLogFontData() {
 	LOGFONT logFont = new LOGFONT ();
-	OS.GetObject(handle, LOGFONT.sizeof, logFont);
+	OS.GetObject(win32_getHandle(this), LOGFONT.sizeof, logFont);
 	return logFont;
 }
 
@@ -246,7 +258,7 @@ private LOGFONT fetchLogFontData() {
  */
 @Override
 public int hashCode () {
-	return (int)handle;
+	return (int) win32_getHandle(this);
 }
 
 void init (FontData fd) {
@@ -271,7 +283,7 @@ void init (FontData fd) {
  */
 @Override
 public boolean isDisposed() {
-	return handle == 0;
+	return isDestroyed;
 }
 
 /**
@@ -300,6 +312,9 @@ public String toString () {
  * @noreference This method is not intended to be referenced by clients.
  */
 public static long win32_getHandle(Font font) {
+	if (font.handle == 0 && font.fontData != null) {
+		font.init(font.fontData);
+	}
 	return font.handle;
 }