<AWT Dev> [8] Review request for CR 8006406: lightweight embedding in other Java UI toolkits

Anton V. Tarasov anton.tarasov at oracle.com
Mon Feb 18 06:10:09 PST 2013

Hi Anthony,

On 18.02.2013 16:50, Anthony Petrov wrote:
> Hi Anton et al.,
> I see a way to simplify the current fix which requires a bit different changes to the specification.
> As far as I know there's no RFEs filed that request to provide public API for grab/ungrab 
> functionality. Also, it isn't clear whether this API could be useful for GUI applications.

Current grab API was created as a draft, with an intention to make it public later. However you're 
right, there's no RFE which could prove this fact (but we did have in our todo list :)).

> As such I don't find it ultimately needed to extend the WindowPeer interface with 
> grabFocus/ungrabFocus() methods, nor add these methods as public interface to the LightweightFrame 
> class at this time.
> Instead, I propose to introduce a sun.awt.FocusGrabbable interface with two methods: grabFocus() 
> and ungrabFocus(). This interface needs to be implemented by the JLightweightFrame class only, 
> where we can provide reasonable implementation by redirecting the calls to FX. In 
> SunToolkit.grab()/ungrab() we should check for instanceof FocusGrabbable, and call the methods 
> appropriately. Otherwise, if the window doesn't implement this interface, we proceed as usual.
> This would eliminate changes to the WindowPeer, remove the unneeded 
> LightweightFrame.grab/ungrabFocus() methods, and generally simplify the fix (e.g. we won't need 
> any changes in XWindowPeer, etc.)
> Opinions?

At least, your suggestion bring us back to the discussion about the direction of the call chain. 
What should a user expect from the JLF.grabFocus() method? I think the same as from the 
SunToolkit.grab(JLF), right?
However, your version of JLF.grabFocus() looks more like a callback - JLF.notifyGrabbed. It won't do 
real grab, but will tell the frame that someone has grabbed focus on it. Evolving this approach, I'd 
say that,
from AWT perspective, it would be more natural to have a listener - GrabListener, and 
GrabEvent/UngrabEvent appropriately. In which case, we would need to add a GrabEvent class, a pair 
for the existing UngrabEvent.
This seems consistent to me (with AWT standarts). But at the same time, IMHO, this doesn't worth the 
candle. And so, I still think the original approach better serves the needs.

By the way, current SunToolkit.ungrab() implementation does ungrab silently, without posting 
UngrabEvent. This is not enough for FX SwingNode. And thus, we anyway need SunToolkit.ungrab(boolean) or
SunToolkit.ungrabAndPost() or something of the like. LightweightFrame.ungrabFocus(boolean) looks 
better to me.

I don't think having it in WindowPeer is a big price. Moreover, the implementation is already in the 
peers. I just added the methods to the peer interfaces.

And also, com.sun.javafx.tk.TKStage has grabFocus() and ungrabFocus() methods (the latter does send 
the event with no option). Why not in AWT? At worst, it can stay in sun.awt.LightweightFrame forever.


> -- 
> best regards,
> Anthony
> On 02/15/13 13:56, Anton V. Tarasov wrote:
>> Hi Jim,
>> I agree with the rest of your comments, fixed it.
>> Here's the latest:
>> http://cr.openjdk.java.net/~ant/8006406/webrev.8
>> http://cr.openjdk.java.net/~ant/8006406/javadoc.8
>> Thanks!
>> Anton.
>> On 2/15/13 3:56 AM, Jim Graham wrote:
>>> Great Anton,
>>> Some spelling fixes.
>>> occures -> occurs
>>> {@code {i, j}} -> {@code (i, j)}
>>> (I usually use parens to encapculate coordinates, but maybe there are
>>> conventions in other places that use braces?)
>>> It might be good to put parens around the (0 <= i/j < width) formulas?
>>> But that would depend on how it looks in a browser and I didn't
>>> compile and javadoc the code to see that - if it looks fine without
>>> the parens then that's good.
>>> But, the description(s) look(s) good and accurate. Thanks!
>>> ...jim
>>> On 2/14/13 5:51 AM, Anton V. Tarasov wrote:
>>>> Hi Jim,
>>>> On 2/14/13 6:26 AM, Jim Graham wrote:
>>>>> I've been busy with FX things, but I just got a chance to look at some
>>>>> of the new interfaces.
>>>> Ok, thanks =)
>>>>> Here are some (hopefully) minor comments:
>>>>> LightweightContent:
>>>>> You never really define "image origin". The imageBufferReset() takes
>>>>> an x,y, but it doesn't state what those are referring to. Is that the
>>>>> x,y on the screen/scene where the image should be rendered to? Are
>>>>> they the values to use to figure out what the starting offset in the
>>>>> data array for the data for the image should be? One thing that would
>>>>> help would be to include a formula in the method comments that
>>>>> indicates how the data for pixels is retrieved from the buffer so
>>>>> there is no confusion, something like:
>>>>> -----
>>>>> The {w} and {h} should match the width and height of the component
>>>>> returned from {getComponent()} with the pixel at the origin of the
>>>>> component, {(0, 0)} in the coordinate space of the component,
>>>>> appearing at {data[y * linestride + x]}. All indices {data[(y + j) *
>>>>> linestride + (x + i)]} where {0 <= i < w} and {0 <= j < h} will
>>>>> represent valid pixel data for the component.
>>>>> -----
>>>>> Did I interpret that correctly?
>>>> Yes, the formula is correct. I've put it into the doc:
>>>> /**
>>>> * {@code JLightweightFrame} calls this method to notify the client
>>>> application that a new data buffer
>>>> * has been set as a content pixel buffer. Typically this occures
>>>> when a buffer of a larger size is
>>>> * created in response to a content resize event. The method
>>>> reports a reference to the pixel data buffer,
>>>> * the content image bounds within the buffer and the line stride
>>>> of the buffer. These values have the
>>>> * following correlation.
>>>> * <p>
>>>> * The {@code width} and {@code height} matches the size of the
>>>> content (the component returned from the
>>>> * {@link #getComponent} method). The {@code x} and {@code y} is
>>>> the origin of the content, {@code {0, 0}}
>>>> * in the coordinate space of the content, appearing at {@code
>>>> data[y * linestride + x]} in the buffer.
>>>> * All indices {@code data[(y + j) * linestride + (x + i)]} where
>>>> {@code 0 <= i < width} and {@code 0 <= j < height}
>>>> * will represent valid pixel data, {@code {i, j}} in the
>>>> coordinate space of the content.
>>>> *
>>>> * @param data the content pixel data buffer of INT_ARGB_PRE type
>>>> * @param x the x coordinate of the image
>>>> * @param y the y coordinate of the image
>>>> * @param width the width of the image
>>>> * @param height the height of the image
>>>> * @param linestride the line stride of the pixel buffer
>>>> */
>>>> public void imageBufferReset(int[] data, int x, int y, int width,
>>>> int height, int linestride);
>>>> Is that enough clear now?
>>>>> Then when you refer to xywh in imageReshaped I'm guessing it is just
>>>>> supplying 4 new parameters to replace the identical parameters that
>>>>> were in the Reset() method?
>>>> That's right. There're three distinct events: buffer recreation (always
>>>> or usually connected with new image bounds), image reshape (may not be
>>>> connected to the first event)
>>>> and image update (may not be connected to the first and second events).
>>>> So, I thought all the three events should be reflected separately.
>>>>> Then in imageUpdated(), are the xywh relative to the coordinate system
>>>>> of the Component? Or are they in the same space as the original xywh
>>>>> were supplied to imageBufferReset? When you say they are "relative to
>>>>> the origin" I think you mean the former. The thing that makes it
>>>>> difficult to describe that is that you have the parameters to Reset
>>>>> and Reshape both named x,y and the parameters to Updated are also
>>>>> named x,y and one set of x,y parameters is relative to the other set
>>>>> and you end up having to say "The x and y are relative to the x and
>>>>> y". One of the sets of parameters should be renamed to make it easier
>>>>> to discuss how they relate. Some sort of "All indices in the range
>>>>> ..." statement would help to show how all of the numbers relate to
>>>>> each other.
>>>> OK, I put it into the formula:
>>>> /**
>>>> * {@code JLightweightFrame} calls this method to notify the client
>>>> application that a part of
>>>> * the content image, or the whole image has been updated. The
>>>> method reports bounds of the
>>>> * rectangular dirty region. The {@code dirtyX} and {@code dirtyY}
>>>> is the origin of the dirty
>>>> * rectangle, which is relative to the origin of the content,
>>>> appearing at
>>>> * {@code data[(y + dirtyY] * linestride + (x + dirtyX)] in the
>>>> pixel buffer
>>>> * (see {@link #imageBufferReset}). All indices {@code data[(y +
>>>> dirtyY + j] * linestride +
>>>> * (x + dirtyX + i)]} where {@code 0 <= i < dirtyWidth} and {@code
>>>> 0 <= j < dirtyHeight}
>>>> * will represent valid pixel data, {@code {i, j}} in the
>>>> coordinate space of the dirty rectangle.
>>>> *
>>>> * @param dirtyX the x coordinate of the dirty rectangle, relative
>>>> to the image origin
>>>> * @param dirtyY the y coordinate of the dirty rectangle, relative
>>>> to the image origin
>>>> * @param dirtyWidth the width of the dirty rectangle
>>>> * @param dirtyHeight the height of the dirty rectangle
>>>> *
>>>> * @see #imageBufferReset
>>>> * @see #imageReshaped
>>>> */
>>>> public void imageUpdated(int dirtyX, int dirtyY, int dirtyWidth,
>>>> int dirtyHeight);
>>>>> In SwingNode:
>>>>> Why is getContent() not just "return content;"?
>>>> Actually, I had some more complicated construction there (wrapped
>>>> content ref), in which I needed the local copy, then I reduced it, but
>>>> missed the fact that it's even simpler now.
>>>> Thanks for noticing, I'll fix it.
>>>>> Have you discussed the threading issues with anyone in FX? There is a
>>>>> big discussion right now on the appropriate threads for various
>>>>> activities...
>>>> Not yet. I think we can start this discussion in the context of the
>>>> review of the fx part (which actually does the threading stuff).
>>>> Thanks,
>>>> Anton.
>>>>> ...jim
>>>>> On 2/13/13 4:57 AM, Anton V. Tarasov wrote:
>>>>>> Hi Sergey,
>>>>>> new webrev: http://cr.openjdk.java.net/~ant/8006406/webrev.7
>>>>>> On 2/12/13 4:57 PM, Sergey Bylokhov wrote:
>>>>>>> Hi, Anton.
>>>>>>> Notes about implementation:
>>>>>>> 1 Seems some code was changed for debug simplifications or changes
>>>>>>> from previous implementations. It would be good to revert them back.
>>>>>>> (Ex /LWComponentPeer.bounds).
>>>>>> Fixed all such occurrences (replaced with public "get" methods where
>>>>>> available). Also, added "protected initializeBase(..)" method for
>>>>>> field
>>>>>> only initialization.
>>>>>>> 2 Probably it would be good to move grab/ungrab implementation from
>>>>>>> LWToolkit/WToolkit to SunToolkit? It looks unclear why we need so
>>>>>>> many
>>>>>>> grab/ungrab/grabFocus/ungrabFocus methods with the same
>>>>>>> implementation
>>>>>>> in the different places.
>>>>>> We don't really need so much grabs and I will clean it when (and
>>>>>> if) we
>>>>>> publish the grab API. Please, see my replies to Anthony on this
>>>>>> subject.
>>>>>>> 3 I suggest make all methods in LightweightFrame final if possible.
>>>>>> Ok, I made toplevel related methods final. I'm not sure we should make
>>>>>> final all the rest... (and by the way, the extender JLF class is
>>>>>> final).
>>>>>>> 4 JLightweightFrame.rootPane could be final
>>>>>> Did.
>>>>>>> 5 JLightweightFrame.getGraphics() probably graphics should be
>>>>>>> initialized by correct window fonts/background/foreground? Also when
>>>>>>> you create backbuffer probably it should be filled by background
>>>>>>> color? Note that if transparent images are supported you should be
>>>>>>> aware about composite.
>>>>>> Ok, I did:
>>>>>> 1) set transparent background for JLightweightFrame
>>>>>> 2) set font/background/foreground for the Graphics.
>>>>>> Now I think I shouldn't specially care about the composite (am I
>>>>>> right?).
>>>>>>> 6 JLightweightFrame.initInterior you shouldn't dispose graphics.
>>>>>> Yes, it seems this adheres to the javadoc:
>>>>>> * Graphics objects which are provided as arguments to the
>>>>>> * <code>paint</code> and <code>update</code> methods
>>>>>> * of components are automatically released by the system when
>>>>>> * those methods return. For efficiency, programmers should
>>>>>> * call <code>dispose</code> when finished using
>>>>>> * a <code>Graphics</code> object only if it was created
>>>>>> * directly from a component or another <code>Graphics</code>
>>>>>> object.
>>>>>> Fixed it.
>>>>>>> 7 JLightweightFrame.reshape width * height could be changed to
>>>>>>> width |
>>>>>>> height ?
>>>>>> No =) It rather could be changed to w & h, but in order not to
>>>>>> confuse a
>>>>>> reader, I've changed it to w == 0 || h == 0.
>>>>>>> 8 JLightweightFrame.reshape you did not flush old backbuffer.
>>>>>> Did.
>>>>>> Also, I had to override LWWindowPeer.updateCursorImmediately() in
>>>>>> LWLFP
>>>>>> to workaround the deadlock I faced on Mac.
>>>>>> The deadlock has the following nature:
>>>>>> - EDT: holding the paintLock (a shared lock b/w JLF and SwingNode),
>>>>>> and
>>>>>> the cursor manager dives to native code and tries to invoke a
>>>>>> method on
>>>>>> Main (FX App) thread.
>>>>>> - FX Renderer: is about to render a SwingNode content, waiting on the
>>>>>> paintLock.
>>>>>> - FX App: (as far as I can guess) waiting for the Renderer to finish.
>>>>>> I can start looking for the solution in parallel with the review,
>>>>>> and if
>>>>>> not yet found, I'd push the first patch with cursor updates disabled.
>>>>>> Thanks!
>>>>>> Anton.
>>>>>>> 08.02.2013 21:27, Anton V. Tarasov wrote:
>>>>>>>> Hi All,
>>>>>>>> Please, review the changes for the CR:
>>>>>>>> http://bugs.sun.com/view_bug.do?bug_id=8006406
>>>>>>>> webrev: http://cr.openjdk.java.net/~ant/8006406/webrev.6
>>>>>>>> It introduces sun.swing.JLightweightFrame class, aimed at
>>>>>>>> lightweight
>>>>>>>> embedding of Swing components into java-based toolkits.
>>>>>>>> The primary target is JavaFX toolkit, however the class is not
>>>>>>>> limited to this usage and the API it provides is quite generic.
>>>>>>>> Below I'm giving a link to the jfx side implementation. This
>>>>>>>> implementation should not be reviewed in this thread (it is in a
>>>>>>>> pre-review phase),
>>>>>>>> it should just clarify how the introduced API is supposed to be
>>>>>>>> used.
>>>>>>>> Namely, SwingNode.SwingNodeContent which implements
>>>>>>>> sun.swing.LightweightContent and forwards requests from
>>>>>>>> sun.swing.JLightweightFrame to NGExternalNode which does the
>>>>>>>> rendering.
>>>>>>>> webrev: http://cr.openjdk.java.net/~ant/RT-27887/webrev.1
>>>>>>>> Some comments on the awt/swing part:
>>>>>>>> - Only Win and Mac implementation is currently available, X11 will
>>>>>>>> come lately.
>>>>>>>> - Win implementation uses a heavyweight window behind the
>>>>>>>> lightweight
>>>>>>>> frame, while it is not actually needed for lightweight embedding.
>>>>>>>> This is due to the architecture of the Win AWT peers which are
>>>>>>>> strongly tight to the native code, and it's not a trivial task to
>>>>>>>> separate them.
>>>>>>>> On Mac the lightweight frame peer is truly lightweight, meaning
>>>>>>>> that it doesn't create an NSWindow object behind it. The Mac port LW
>>>>>>>> abstraction
>>>>>>>> allows to override and substitute CPlatform* classes with their
>>>>>>>> lightweight stubs.
>>>>>>>> - LightweightFrame, among others, introduces two new methods -
>>>>>>>> grabFocus() and ungrabFocus(boolean). Ideally, these methods should
>>>>>>>> go to
>>>>>>>> the super Window class where the grab API becomes public (which is
>>>>>>>> a long-term project...). Current host of the grab API is SunToolkit,
>>>>>>>> which
>>>>>>>> now forwards the calls to LightweightFrame. This is necessary to
>>>>>>>> intercommunicate with the client when grab/ungrab happens on both
>>>>>>>> sides.
>>>>>>>> - Unresolved issues exist, like modal dialogs, d&d etc. They are to
>>>>>>>> be addressed further.
>>>>>>>> Thanks,
>>>>>>>> Anton.

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