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

Anton V. Tarasov anton.tarasov at oracle.com
Thu Feb 14 05:51:16 PST 2013

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).


>             ...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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