Subject: Rhino and overloaded drawImage Date: Wed, 08 Sep 1999 15:06:31 -0400 From: Andrew Wason <aw@softcom.com> To: norris@netscape.com CC: Howard Lin <howard@softcom.com> I'm getting an EvaluatorException for this: g.drawImage(bgImg,0,0,this); The message is: org.mozilla.javascript.EvaluatorException: The choice of Java method sun.awt.windows.WGraphics.drawImage matching JavaScript argument types (sun.awt.windows.WImage,number,number,object) is ambiguous; candidate methods are: void drawImage(java.awt.image.BufferedImage,java.awt.image.BufferedImageOp,int,in t), boolean drawImage(java.awt.Image,int,int,java.awt.image.ImageObserver) See the attached output and JS file. Andrew -- Andrew Wason SoftCom, Inc. aw@softcom.com bug3.js Name: bug3.js Type: Plain Text (text/plain) bug3.txt Name: bug3.txt Type: Plain Text (text/plain) bug3.js: importPackage(Packages.javax.swing); importPackage(java.awt); importPackage(java.net); importPackage(java.lang); var bgImg = Toolkit.getDefaultToolkit().getImage(new URL("http://www.mozilla.org/rhino/rhino50.jpg")); var foo = new JComponent() { paint: function(g) { g.drawImage(bgImg,0,0,this); super.paint(g); } }; var f = new Frame(); f.add(foo, BorderLayout.CENTER); f.setSize(300,300); f.setVisible(true); bug3.txt: org.mozilla.javascript.EvaluatorException: The choice of Java method sun.awt.win at org.mozilla.javascript.DefaultErrorReporter.runtimeError(DefaultError at org.mozilla.javascript.Context.reportRuntimeError(Context.java:484) at org.mozilla.javascript.Context.reportRuntimeError(Context.java:500) at org.mozilla.javascript.NativeJavaMethod.findFunction(NativeJavaMethod at org.mozilla.javascript.NativeJavaMethod.call(NativeJavaMethod.java, C at org.mozilla.javascript.ScriptRuntime.call(ScriptRuntime.java:1256) at org.mozilla.javascript.Interpreter.interpret(Interpreter.java, Compil at org.mozilla.javascript.InterpretedFunction.call(InterpretedFunction.j at org.mozilla.javascript.NativeClosure.call(NativeClosure.java:56) at org.mozilla.javascript.ScriptRuntime.call(ScriptRuntime.java:1256) at org.mozilla.javascript.FlattenedObject.call(FlattenedObject.java:234) at org.mozilla.javascript.FlattenedObject.callMethod(FlattenedObject.jav at org.mozilla.javascript.JavaAdapter.callMethod(JavaAdapter.java:156) at adapter0.paint(<adapter>) at java.awt.Container.paint(Container.java:773) at sun.awt.windows.WComponentPeer.handleEvent(WComponentPeer.java:117) at java.awt.Component.dispatchEventImpl(Component.java:2447) at java.awt.Container.dispatchEventImpl(Container.java:1035) at java.awt.Window.dispatchEventImpl(Window.java:749) at java.awt.Component.dispatchEvent(Component.java:2307) at java.awt.EventQueue.dispatchEvent(EventQueue.java:287) at java.awt.EventDispatchThread.pumpOneEvent(EventDispatchThread.java:10 at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:92) at java.awt.EventDispatchThread.run(EventDispatchThread.java:83) Exception occurred during event dispatching: java.lang.Error: The choice of Java method sun.awt.windows.WGraphics.drawImage m at org.mozilla.javascript.JavaAdapter.callMethod(JavaAdapter.java:162) at adapter0.paint(<adapter>) at java.awt.Container.paint(Container.java:773) at sun.awt.windows.WComponentPeer.handleEvent(WComponentPeer.java:117) at java.awt.Component.dispatchEventImpl(Component.java:2447) at java.awt.Container.dispatchEventImpl(Container.java:1035) at java.awt.Window.dispatchEventImpl(Window.java:749) at java.awt.Component.dispatchEvent(Component.java:2307) at java.awt.EventQueue.dispatchEvent(EventQueue.java:287) at java.awt.EventDispatchThread.pumpOneEvent(EventDispatchThread.java:10 at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:92) at java.awt.EventDispatchThread.run(EventDispatchThread.java:83)

This is that bug I was trying to forward to you just before some nice guy yanked my network connection. The problem is that the user is trying to use 'this' to satisfy the ImageObserver parameter in the drawImage call - but the 'this' is the JS object not the Java object he wishes it were (same applies to his use of 'super' in the statement following).

*** Bug 13415 has been marked as a duplicate of this bug. ***

Now get a verify error: js: "bug3.js", line 9: error instantiating (java.lang.VerifyError: (class: adapt er0, method: super$paint signature: (Ljava/awt/Graphics;)V) Falling off the end of the code): class javax.swing.JComponent is interface or abstract Subject: JavaAdater.generateSuper() is in Date: Fri, 24 Sep 1999 11:22:29 -0700 From: beard@netscape.com (Patrick Beard) To: Norris Boyd <norris@netscape.com> Norris - As discussed yesterday, I've implemented the facility for calling "super.method()". The method name is currently called "super$method". Since Java implements some thunk methods with '$' in identifiers, this seems reasonable, because it won't conflict with programmer generated names. So, here's an example I've written to test it: /* super.js Demonstrates calling overridden methods in a JavaAdapter class. by Patrick C. Beard. */ var runnable = new java.lang.Runnable() { hashCode: function() { return this.super$hashCode(); }, equals: function(obj) { return this.super$equals(obj); }, run: function() { print('run here.'); } }; - Patrick // Patrick C. Beard // Java Runtime Enthusiast -- "Will invoke interfaces for food." // mailto:beard@netscape.com

Patrick and I fixed this. See his post in the netscape.public.mozilla.jseng newsgroup: Subject: [Rhino] Speaking of JS Components... Date: Fri, 24 Sep 1999 19:14:58 -0700 From: Patrick Beard <beard@netscape.com> Organization: Netscape Communications Newsgroups: netscape.public.mozilla.jseng We now have the ability to do pretty much first-class subclassing of Java classes from Rhino. Whereas before you could specify a set of Java interfaces to implement using a JavaScript object, now you can sub-class real-live Java classes, and call superclass methods from within methods overridden by JavaScript. Here's a trivial example: importPackage(java.util); var enum = new Enumeration() { // override Object.hashCode: hashCode: function() { return this.super$hashCode() + 1; }, // implement the java.util.Enumeration interface: hasMoreElements: function() { return this.equals(this); }, n: 0, nextElement: function { return this.n++; } } For now, you must access the overridden method using "super$method" but I hope to eventually support "super.method" to get at superclass methods. Obviously, that should be the only way, otherwise your script can do things that even Java programs aren't allowed to do. Another recent change is that the prototype chain of the JavaScript object includes the LiveConnect wrapper of the adapter object. So, inside the JavaScript object, you can access superclass methods that aren't overridden using "this.method", demonstrated in the hasMoreElements property above, which is calling java.lang.Object.equals. - Patrick -- // Patrick C. Beard // Netscape Communications Corporation