Is there a way to provide some kind of wrapper/bridge object in
Java (via JNI) to a native NSView class so that I can make Java2D
drawing calls to something like an "NSViewJComponent" from Java,
treating it like a JComponent from within Java?
Cocoa -- do drawing --> NSView --> JNI --> JavaAWT --> draw into
Java Component
You were asking about NSImage a bit back as I remember. What about
converting the java to an image that Cocoa can render into the NSView?
Mike Hall mikehall at spacestar dot net
Haha, yes! This is where I start running in circles again.
The long story is, I'm trying to implement the Mac version of the
TrayIcon API of the JDIC project : https://jdic.dev.java.net/
It's basically an API to the System Tray on windows, and on the Mac
it's an API to the Status Bar. Some of the notification actions in
Windows OS(the balloon dialog that pops up over a tray icon) map to
the Dock notification action, but most of the TrayIcon API is
appropriate to the Mac Status Bar. I have a Cocoa test app that does
everything I need, so the native part is working.
One problem I am having is that the API I have to implement only
provides access to an Icon (javax.swing.Icon). That's just an
interface, so it is a pretty opaque object; all you can really do is
get the size of the Icon, and call paintIcon on it.
If I had access to the image URL, I could of course pass that from
Java to the JNI method and create an NSImage (actually an
NSBitmapImageRep), and I can pass that to my NSStatusItem as the
image. Or if I see the image is multi-framed, I can use a Timer to
periodically update that image and thus provide support for an
animated GIF. Or I could also create a custom NSView with an
NSImageViewer, and if my image is multi-framed, it would
automatically animate it for me.
But, I do NOT have access to the image URL. From an Icon, I would
like to at least get an Image, and maybe from that a BufferedImage,
and have some hope of getting access to the image data. But, there
are at least 8 implementations of Icon, and no guarantee what you get
passed will be an ImageIcon. And even if it IS an ImageIcon, the Mac
implementation (on my machine) shows that the actual class is an
apple.awt.OSXImage, of which I have no official documentation. On
Windows, it would either be a BufferedImage or a VolitleImage. From
the BufferedImage I could do something with the ImageIO classes,
however, there is no GIF writer in the JDK, so even if I can figure
out the image is really a GIF, there's no way to write it to a stream
or a ByteBuffer in order to pass the bytes to JNI.
I have to use the old-school ImageObserver method, and continually
monitor the state of the Image, and when I see the FRAMEBITS flag, I
have to create an offscreen Graphics in Java, paint that single new
frame, then convert that to something I can pass to a JNI method(like
a PNG), that will then install it as the image on the NSStatusItem.
So this is the only thing I can think of that will work, and be safe,
only using public, documented APIs.
Some of the not-so-safe hacks I am also contemplating are :
the ImageIcon constructor takes a String description argument, that I
do not think is used much. If you created the ImageIcon via a URL or
file name, and do not specify the description field, it gets set to
the URL or filename you used to construct the object. So I could get
this value, see if the file/url exists, and pass that to JNI, and I'm
in business.
Or, I could get a BufferedImage version of the ImageIcon by noting
that OSXImage extends sun.awt.image.ToolkitImage, and that class has
a public getBufferedImage() method. I think there may be a way of
getting an IIOImage from a BufferedImage or one of it's subclasses,
and then I could at least access the metadata that tells me how many
frames the image contains. If it's just one, I can just draw it
offscreen, and write it to a PNG (I can write to many different
formats, just not GIF). If it's multiple frames, I'm in the same boat
as above; I either update the image every time my ImageObserver tells
me a new frame is available, or I can extract each frame and pass
them to JNI as an array of PNGs, and then implement my own animation
loops.
Or, finally, I could avoid this by just drawing in Swing/AWT, to a
native NSView, and let Java handle a lot of this image processing for
me. It would require however a means of drawing into an NSView from
Java.
Rob Ross, Lead Software Engineer
E! Networks
email@hidden
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