Create Font handles on demand

Creating a new static method to retrieve font handle. 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

@@ -46,16 +46,25 @@ public final class Font extends Resource {
 	 * platforms and should never be accessed from application code.
 	 * </p>
 	 *
-	 * @noreference This field is not intended to be referenced by clients.
 	 */
-	public long handle;
+	private long handle;
 
 	/**
 	 * The zoom in % of the standard resolution used for conversion of point height to pixel height
 	 * (Warning: This field is platform dependent)
 	 */
 	int zoom;
 
+	/**
+	 * this field is used to mark destroyed images
+	 */
+	private boolean isDestroyed;
+
+	/**
+	 * this field is used to store fontData provided during initialization
+	 */
+	private FontData fontData;
+
 	/**
 	 * Font height in points. As the conversion to pixel height involves rounding the fontHeight must
 	 * be cached.
@@ -101,15 +110,15 @@ private Font(Device device, long handle, int zoom) {
 public Font(Device device, FontData fd) {
 	super(device);
 	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);
 	this.zoom = zoom;
-	init(fd);
+	this.fontData = new FontData(fd.toString());
 	this.fontHeight = fd.height;
 	init();
 }
@@ -148,7 +157,7 @@ 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();
 }
@@ -181,7 +190,7 @@ 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();
-	init(new FontData (name, height, style));
+	this.fontData = new FontData (name, height, style);
 	this.fontHeight = height;
 	init();
 }
@@ -190,14 +199,15 @@ 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();
-	init(new FontData (name, height, style));
+	this.fontData =  new FontData (name, height, style);
 	this.fontHeight = height;
 	init();
 }
 @Override
 void destroy() {
 	OS.DeleteObject(handle);
 	handle = 0;
+	isDestroyed = true;
 }
 
 /**
@@ -238,7 +248,7 @@ 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;
 }
 
@@ -279,7 +289,7 @@ void init (FontData fd) {
  */
 @Override
 public boolean isDisposed() {
-	return handle == 0;
+	return isDestroyed;
 }
 
 /**
@@ -294,6 +304,28 @@ public String toString () {
 	return "Font {" + handle + "}";
 }
 
+/**
+ * <b>IMPORTANT:</b> This method is not part of the public
+ * API for Font. It is marked public only so that it
+ * can be shared within the packages provided by SWT. It is not
+ * available on all platforms, and should never be called from
+ * application code.
+ *
+ * Creates a new handle for the requested font or return the existing one
+ *
+ * @param font the font to get the handle of
+ *
+ * @return handle of the font
+ *
+ * @noreference This method is not intended to be referenced by clients.
+ */
+public static long win32_getHandle (Font font) {
+	if(font.handle == 0) {
+		font.init(font.fontData);
+	}
+	return font.handle;
+}
+
 /**
  * Invokes platform specific functionality to allocate a new font.
  * <p>

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

@@ -48,7 +48,7 @@ public static Font getSystemFont(Device device, int zoom) {
 	}
 
 	public static long getSystemFontHandle(Device device, int zoom) {
-		return getSystemFont(device, zoom).handle;
+		return Font.win32_getHandle(getSystemFont(device, zoom));
 	}
 
 	/**
@@ -67,14 +67,14 @@ public static Font getFont(Device device, FontData fontData, int zoom) {
 	}
 
 	public static long getFontHandle(Device device, FontData fontData, int zoom) {
-		return getFont(device, fontData, zoom).handle;
+		return Font.win32_getHandle(getFont(device, fontData, zoom));
 	}
 
 	public static long getFontHandle(Font font, int zoom) {
 		if (font == null) {
 			SWT.error(SWT.ERROR_NULL_ARGUMENT);
 		}
-		return getFont(font.getDevice(), font.getFontData()[0], zoom).handle;
+		return Font.win32_getHandle(getFont(font.getDevice(), font.getFontData()[0], zoom));
 	}
 
 	/**

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

@@ -44,7 +44,7 @@ private Font getScaledFont(int zoom) {
 
 		private Font createAndCacheFont(int zoom) {
 			Font newFont = createFont(zoom);
-			customFontHandlesKeyMap.put(newFont.handle, this);
+			customFontHandlesKeyMap.put(Font.win32_getHandle(newFont), this);
 			scaledFonts.put(zoom, newFont);
 			return newFont;
 		}

bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Control.java

@@ -3441,7 +3441,7 @@ public void setFont (Font font) {
 	long hFont = 0;
 	if (newFont != null) {
 		if (newFont.isDisposed()) error(SWT.ERROR_INVALID_ARGUMENT);
-		hFont = newFont.handle;
+		hFont = Font.win32_getHandle(newFont);
 	}
 	this.font = newFont;
 	if (hFont == 0) hFont = defaultFont ();