[win32] Create Font handles on demand

Handles will no
longer be created during initialization. Also 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.
@@ -66,12 +76,14 @@ public final class Font extends Resource {
  */
 Font(Device device) {
 	super(device);
+	this.fontData = null;
 	this.zoom = DPIUtil.getNativeDeviceZoom();
 	this.fontHeight = 0;
 }
 
 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);
@@ -99,16 +111,18 @@ 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();
 }
@@ -147,7 +161,7 @@ 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();
 }
@@ -180,8 +194,7 @@ 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();
 }
@@ -190,15 +203,15 @@ 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;
 }
 
 /**
@@ -216,7 +229,7 @@ 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);
 }
 
 /**
@@ -239,7 +252,7 @@ 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;
 }
 
@@ -255,7 +268,7 @@ private LOGFONT fetchLogFontData() {
  */
 @Override
 public int hashCode () {
-	return (int)handle;
+	return (int) win32_getHandle(this);
 }
 
 void init (FontData fd) {
@@ -280,7 +293,7 @@ void init (FontData fd) {
  */
 @Override
 public boolean isDisposed() {
-	return handle == 0;
+	return isDestroyed;
 }
 
 /**
@@ -302,7 +315,7 @@ public String toString () {
  * available on all platforms, and should never be called from
  * application code.
  *
- * Creates a new handle for the requested font
+ * Creates a new handle for the requested font or return the existing one
  *
  * @param font the font to get the handle of
  *
@@ -311,7 +324,10 @@ public String toString () {
  * @noreference This method is not intended to be referenced by clients.
  */
 public static long win32_getHandle (Font font) {
-    return font.handle;
+	if(font.handle == 0 && font.fontData != null) {
+		font.init(font.fontData);
+	}
+	return font.handle;
 }
 
 /**