Monday Sep 27, 2010

Moved

Since I no longer work for Sun/Oracle, this blog is closed; please visit my new personal blog at http://tornorbye.blogspot.com .

Friday Sep 24, 2010

System.exit(0)


It's time for a new adventure!



I joined Sun in 1996 and I've been here ever since -- including the Oracle acquisition six months ago. It's been a wonderful time. I've met many of the world's most talented engineers, I've had the chance to work on some interesting projects and I've learned a lot! I looked at my badge that I'm about to turn in (picture on left) and it has the original photo taken when I joined -- and I look like a kid!!


However, it's time to move on. I've chosen to take a new opportunity where I'll get to have even more fun. For now, I'd like to thank all my former Sun and Oracle coworkers for the great experiences you've given me and wish you luck with the future!



I feel privileged that so many of you have read my blog from time to time, and I would be honored if you'd follow me over to my new permanent blog:

http://tornorbye.blogspot.com/.



System.exit(0);




Thursday Sep 23, 2010

Moving My Blog


I've decided to move my blog to a more permanent URL (I'm not sure how long blogs.sun.com will be around), and at the same time it would be nice to switch to a more feature-rich blogging platform. Therefore, effective immediately, the new url for my blog is:


http://tornorbye.blogspot.com/



I'm hoping most of you will update your links and follow me over there. I plan to start writing more actively again, and I have a number of new things I can talk about soon!



P.S. I've documented what I did to migrate Roller to Blogger here in case there are other blogs.sun.com users who have similar needs.

Tuesday Jun 29, 2010

Don't Use Implicit Return Types


JavaFX, like Scala, is a fully statically typed language. However, unlike Java, it allows you to omit type declarations in many places, since it can infer it. Coupled with the fact that you can use expressions as statements, and that the last expression in a function will be the return value, this lets you write really simple and clear code.


def s = "Hello";
def len = s.length();
function product(a: Number, b: Number) {
a \* b
}

The function above shows an "Implicit Return Type": The compiler figures out the return type, which in this case will be a Number, and that is the signature computed for the function.



Unfortunately, this can sometimes lead to trouble! Here's a real-world example:


public function clearSelection() {
selected = null;
}

This function clears the selection in a node. The intention of the developer was probably for this function to have a "void" return type. But that is not the return type! The last statement is an expression, an assignment, which has the type of the left hand side, which is actually a node.
So the return type here is a Node! And it could easily have leaked an implementation class too.



This may not seem like a big deal here, but what if a subclass wanted to override this function? It would try this:


override function clearSelection() {
super.clearSelection();
moreStuff();
}

And this would fail compilation, with a surprising error message:


File.fx:1: incompatible types
found : void
required: Node
override function clearSelection() {
1 error

That's right, your subclasses will now need to deal with this return type too! If it's an implementation class, they're in trouble!



There are other reasons implicit return types are bad too. Here's a function specifying a desired padding for a node:


public function padding() {
5
}

The user may have intended for this to be a Number, but since the default is "5" instead of "5.0", the implied type here is Integer, which means that subclasses will need to round their desired padding to an integer. And this is not always a good thing - see the pixel considerations article.



For all of the above reasons, our Coding Conventions Document states that you should not use implicit types, at least not for any non-private API. That includes package, protected and public functions. However, it's a simple mistake to make. We've all made it! For that reason, to help track these down, I've created a quickfix for NetBeans which identifies and fixes these problems. Here's what happens if you look at a function like the one described above:







The light bulb and underline warns you that there is a problem here. Clicking on the light bulb, or pressing Alt+Enter when the caret is on that line, shows this info:







It's telling you that you have an implicit return for a public function, and it's offering to insert the actual, current return type of the function. It's also offering to make the function Void.



Pressing return will fix the function:







There are certain return types you cannot express in JavaFX script - such as returns including generics signatures. The quickfix won't warn about those since there is nothing you can do.




You can find the module on the Plugin Center here. Hopefully it will be as useful to you as it has been to me!



P.S. We discussed this topic (implicit return types in JavaFX and Scala) for a while on the latest
Java Posse Podcast episode.

Thursday Jun 17, 2010

NetBeans 6.9 Released



NetBeans 6.9 has been released.



There are important improvements for everyone here - whether you're a Java developer, JavaFX developer, Ruby developer, PHP developer, C++ developer, ... or all of the above :-)



Since I spend most of my time writing JavaFX and Java code, by far the biggest improvement in NetBeans 6.9 for me is the JavaFX support. While there is still room for improvement, editing works pretty well now. In particular, the source code formatter works well on most source files and constructs, so I've used it to reformat some of our large and complicated source files, though to be on the safe side I've checked the diffs carefully before checking in (and turned on whitespace diffing in the version control). I occasionally have to make manual tweaks, but it's really helpful in cleaning up poorly formatted source files. And Go To Declaration now works reliably! The debugger still needs work. Apparently this needs some help from the compiler so hopefully the combination of JavaFX 1.3.1 and NetBeans 6.9.1 will address that.



One huge improvement in 6.9 is the reduction of scanning delays. In addition to performance fixes in that area, there are two life saver features:


  1. Running is no longer blocked when a scan is in progress. Even if it's scanning, running starts immediately. This used to drive me crazy!
  2. I can turn off some of the extra aggressive scanning! There is an option for this now, so I can turn off automatic timestamp checking and instead perform scanning manually if I should need it:







    (In case it's not obvious -- I'm talking about the checkbox at the bottom of the above dialog.)



    If you turn off automatic scanning, you can invoke it explicitly:







There are many other new features, and I'll get back to some of them in some other posts, but for now I'll leave you with a link:
Git Plugin compatible with NetBeans 6.9.



Thursday May 20, 2010

LCD Subpixel Rendering


While I'm on the topic of pixels -- here's another tip. This one is both Mac OSX and NetBeans (well, Swing) specific.



Subpixel rendering, an antialiasing technique, makes text look much sharper (wikipedia article).
Subpixel rendering was added to Java 6, so the NetBeans source editor looks great on Windows and Linux provided you are running Java 6. Antialiasing was never an issue on Macs, where the JDK used its own native graphics renderer which had subpixel rendering all along - until now!!



Here's NetBeans on Linux and Windows:







Let's zoom in. Notice the "strange" colors at the perimiter of the font strokes; they look strange here but oh-so-good at the proper resolution on an LCD:







Unfortunately, when Apple released Java 6 on the Mac, they switched the default graphics renderer over from their own "Quartz" renderer to the standard JDK one. That shouldn't be a problem, since Java already renders LCD text, right? Wrong! For reasons I don't know, subpixel rendering is NOT working on the Mac with the standard renderer. Therefore, by default, NetBeans text looks blurry (because it is only grayscale antialiased) on Macs.



This is easy to "fix". Just switch the rendering back to Quartz. You can do that with the following flag, added to the netbeans.conf config file:


-J-Dapple.awt.graphics.UseQuartz=true

The -J flag just tells the NetBeans launcher that the rest of the flag is a flag for the Java interpreter, and the -D flag says set the system property apple.awt.graphics.UseQuartz to true. Therefore, in your own Swing applications you can do the same thing, just drop the -J flag.



(The config file is in a place like /Applications/NetBeans/NetBeans 6.9 Beta.app/Contents/Resources/NetBeans/etc/netbeans.conf and you would add these flags to the netbeans_default_options line.)



Here is a before-versus-after screenshot; this will only make visual sense to you if you're viewing this on an LCD screen!







The subpixel rendering text is on the left.



Here's a zoomed in view, which shows the default (non-LCD renderered text):







And here's what you get when you turn on Quartz:







I presume Apple turned off Quartz by default in Java 6 for a reason. Does anyone know what it is? The JavaFX Release Notes mention some memory leaks. I've been using the flag to turn LCD text back on since I switched to Java 6 on the Mac a year ago, and it doesn't seem to have any adverse effects for normal NetBeans usage (mostly text oriented; I don't do UML editing etc).



More importantly, does anybody know why subpixel rendering from the JDK doesn't work on the Mac since it works everywhere else? Is there a way to trick it to work with rendering hints etc?



P.S. Speaking of launcher arguments - I have one other customization too. I add -J-d32. This tells the JDK that I want a 32-bit VM. I haven't measured personally what this buys me, but I saw that Charlie Nutter recommended it for NetBeans usage, and he certainly knows his way about VM tuning parameters!



Tuesday May 11, 2010

Bay Area JUG Roundup 2010



If you live in the San Francisco bay area, I hope you can come to the Bay Area Java User Group Roundup 2010 tomorrow night! It is going to be held at the Oracle conference center, and both beer and dinner will be provided. There will be an update on the java.net migration, and the Java Posse are going to record a live podcast. Note - you need to sign up in advance so visit the event details page.



Hope to see you there!


Monday May 10, 2010

Pixel Considerations


Antialiasing makes lines and shapes look smooth - though sometimes at the expense of sharpness. What if you're trying to draw a horizontal or vertical line where you don't need antialiasing? You might be under the impression that if you position your shapes at round integer positions, you will avoid antialiasing.
But it's not quite that simple - so avoid trying to be smart with layout code like this:


...
label.layoutX = (width - labelWidth) / 2 as Integer;
....

The idea here is that when you're placing something in the middle you might end up with a fractional value, say 42.5, and so you added the "as Integer" to round things to a whole number to avoid introducing antialiasing.



Well, this may have exactly the opposite effect! Take a look at the following picture, which shows two rectangles. Both rectangles have a stroke width of 1.0, and one of them is positioned at a round integer, and the other one is positioned at 0.5.







Here's a zoomed in view which makes things clearer:







Obviously, the rectangle on the left is blurry because antialiasing is attempting to show the line as being somewhere in the middle between them. The rectangle
on the right on the other hand is clear and crisp because the lines overlap EXACTLY with the pixel grid the line is rendered into.



Here's the thing though: The rectangle on the left is the one that was positioned at round integers, and the rectangle on the right is the one positioned
at round integer + 0.5 !



So should you run out and ensure that all your horizontal and vertical edges are positioned at 0.5? No. The key here is the stroke width. Take a look at the following figure, where I have position rectangles with different stroke widths (1, 2, 3) and different pixel positions (0, 0.25, 0.5).







Zoomed in:







As you can see, whether you match the pixel grid perfectly depends on the stroke width and the pixel positions. This actually makes sense. Think of your pixel grid as having x coordinates at the boundaries of each pixel. In other words, "0.0" is the left edge of the first pixel, and 1.0 is the right edge of the first pixel. The line position has to be the center of the stroke. So if you want to have a line of thickness 1, then that line will run exactly through the pixel, so we must position its center at x=0.5. When the stroke width increases to 2 however, the center will be in the middle (e.g. 1), and so we should position it at a round number. And so on.



When you're dealing with large shapes this isn't a big deal. But if you're trying to paint a grid (like the one below), a pattern, or small controls (like disclosure arrows - which is how I came to look into this), it can pay off.







By the way -- on OSX there's a nice screen zoom (hold the Option key and then do a two-fingered drag on the trackpad up or down) which makes it easy to zoom in and look at the pixels for anything on the screen. But unfortunately it doesn't show pixels as square, it does more blending, so it's much harder to tell what's going on at the individual pixel level. Get an image editor which lets you zoom in with clear pixel boundaries, or even a screen magnifying lens. Here's how the builtin screen zoom looks - as you can see it's not as clear as the pixel zooms above:







UPDATE: Marius taught me in the comments that you can turn off the OSX zoom smoothing in the Universal Access options. Sweet! I can now instantly check the pixels without going to an intermediate screenshot! Thanks!



Finally: Jonathan Giles from the JavaFX controls team has been doing a great job aggregating and summarizing interesting FX articles each week -- highly recommended if you're doing anything with JavaFX.



Thursday Apr 29, 2010

nbgit for NetBeans 6.9 beta


My brother was asking me for a version of nbgit (git support for NetBeans) that works with NetBeans 6.9 beta. I've uploaded one here. By the way, look at the Options wiki page, and especially the sections on Custom Actions, for useful configuration tips for nbgit.




Wednesday Apr 28, 2010

IDE tip: Go To Implementation


One of the best parts of using an IDE instead of an editor is "Go To Declaration". When you hold the Control key (or the Command key on Macs), identifiers under the mouse turn into hyperlinks and when you click on the hyperlink you jump to the declaration point of say the method call.
You can also just hover over the hyperlink, and a tooltip will pop up and show you the signature of the identifier - the fully qualified type name, method arguments, and so on.



But what if the thing you are pointing at is an interface? Or an abstract class? Good Java programming style dictates that you should prefer interfaces over implementation types, so your code will typically only know about the interface or abstract type, and when you jump to the declaration, you go to the boring interface method definition, rather the interesting bits in the implementation!



This is what the Go To Implementation feature is for. And I have a confession to make: I didn't start using this until recently. At the recent IDE tips roundup session, somebody asked whether NetBeans supported Go To Implementation. By instinct I went to Google and looked for a NetBeans plugin to do it, and found one. Unfortunately, it was old and only worked with older versions of NetBeans. Uh oh. Then on a whim I decided to look in the Navigate context menu in NetBeans - and lo and behold, it's right there!







And you don't need to use a context menu to access this feature. The trick is to use a second modifier key to the normal ctrl-click on the identifier! In addition to the control key (or command on Macs), also hold the Alt key (Option on Macs).



Here's how it works. First, let's say you want to go to the actionPerformed implementation. You ctrl-click the identifier:







...and that takes you into the abstract method declaration. (In this specific case, the method is in a read-only file inside a .jar file, which is why NetBeans marks the whole file in gray)







That's not what we want. Go back to the previous editor location (Ctrl-left.) This time, hold both the Control and Alt keys (or Command and Option on Macs) when you click. When you do that you get this dialog:







This dialog has focus and you can use the arrow keys to navigate and press enter -- or just click with the mouse. As soon as you pick a specific override of this method, you jump to it:







That's all there is to it. It's doubly embarrassing that I didn't remember this feature, since I should know the implementation of it very well. You see, I shamelessly lifted most of the implementation of it for the language-infrastructure work I did to support Go To Declaration in Ruby, JavaScript etc:







P.S. I've updated the wiki page with a clarification that it's built in now.



P.S.2: Until recent builds, Go To Implementation in NetBeans only worked for interfaces, not methods extending abstract classes. So use 6.9.

Thursday Apr 01, 2010

How to Write a Memory Leak Unit Test


Unit tests are great for ensuring that your functionality is correct. But how do you make sure you don't have leaks in your code, leaks that
eventually cause your application to crash when it runs out of memory? Unit tests don't typically don't run into memory problems directly because they tend to start up, run a little bit of code, and shut down -- getting a nice fresh memory environment on each test start.



One great way to help protect yourself from uptime problems is to write leak tests. These are unit tests where you first perform some operations, then do normal cleanup, and finally you assert that the objects you were using during the operation have been cleaned up completely. In other words, that there are no references left anywhere on the heap.



Testing for leaks isn't very hard; the basic trick is to create a weak reference to your to-be-cleaned object (by constructing a WeakReference wrapping your object), then you delete all your local references to the object, then you perform garbage collection, and finally you see whether the weak reference still contains your object. This works because the weak reference is handled specially by the garbage collection system.



It turns out things aren't quite as easy as that, because garbage collectors try to be smart, and simply calling System.gc() doesn't mean it's going to actually perform a complete and final garbage collection. This means that your unit test could incorrectly conclude you have a leak, since the reference is still held.



The NetBeans team has built a really good test infrastructure for this. When I wrote unit tests for NetBeans plugins, I could simply call their assertGC method to assert that the given weak reference should be garbage collected, and it would handle the rest. (Internally, they do things like actually allocating a bunch of memory chunks to really force the garbage collection to run.)



Here's an example:


// The following unit test fragment wants to ensure that a graphics object
// which shows the current selection in the authoring tool, is cleared up after
// the user clears the selection.
view.selectAll();
Node firstHandle = /\* Node showing selection highlight, lookup code here \*/;
assertNotNull(firstHandle);

// Now clear view selection -- then assert that all the handles have disappeared
view.selectNone();

WeakReference<Node> ref = new WeakReference<Node>(firstHandle);
firstHandle = null;
assertGC("Selection handle leaked", ref);




When you write these tests you also have to make sure you null out any local variable references you are holding right there in the test.
The above test will pass if and only if the target object, firstHandle, is properly garbage collected.



But wait -- that's not the best part. Let's say you've written a leak test, and it fails. Now what? What do you do -- make the process pause and attach a profiler and try to hunt it down?



This is where their unit test support really shines. When the unit test discovers that the reference is still held somewhere, it uses its own heap walking library to hunt down the offending reference, and dumps it out as part of the test assertion failure message!!!



Here's the output of a real leak test failure:


Testcase: testMemoryLeak(SelectionHandlesTest): FAILED
Selection handle leaked:
public static java.util.List javafx.scene.Scene@dc8a29-$dirtyCSSNodes->
java.util.ArrayList@4ed14172-elementData->
[Ljava.lang.Object;@3c22de9e-[41]->
javafx.scene.shape.Rectangle@612e4cd

In other words, we see that there is a static list in Scene named dirtyCSSNodes which is holding on to our target Rectangle. The syntax here is that you first see the class name for the object (where a prefix of [L means it's an array-of), then its system id, then the field name - and if it's an array, the array index.



When the unit test fails, it takes a while -- 20 seconds or so for the above test -- to actually produce the above trace. But the important part is that this is only slow when the test fails. It only has to work hard when you have a leak, and you don't want to have leaks!



I've been wanting to write leak tests for the authoring tool (which is written in JavaFX), since uptime matters a great deal in a tool which deals with potentially large objects (such as multimedia assets). And I realized that there is absolutely nothing NetBeans specific about the NetBeans leak unit test support. So I went and pulled out the relevant code into a separate library. The library basically contains two parts: a .jar file which contains the INSANE heap walking library, and a second jar which contains the assertGC() unit test assertion method and supporting infrastructure.



I have extracted this into standalone pieces (outside the NetBeans infrastructure) so you can get the bits easily - download leaktests.zip, then add the two jars in there on your test classpath and call assertGc() and assertSize() from your tests as described above. Here's the basic skeleton for all leak tests:


// (1) Create your objects
// (2) Look up the object you want to ensure gets cleaned up later:
Foo foo = // code to get foo
assertNotNull(foo);

// (3) Call your cleanup code which is supposed to free everything

// (4) Create a weak reference to your object reference, and null out
// your reference
WeakReference<Foo> ref = new WeakReference<Foo>(foo);
foo = null;
assertGC("Foo leaked", ref);




All I've done is extract NetBeans code written by others so I've kept the licenses the same as for NetBeans. All credit goes to the author of INSANE, Petr Nejedly -- and to the authors of the memory assertion stuff in NbTestCase.java. All the source code for INSANE and NbTestCase are in the NetBeans mercurial repository.



In addition to assertGC, there is also assertSize(). This method can be used to ensure that the transitive size of an object graph is below a certain threshold! This can be good for writing tests to not only ensure that you don't have leaks, but that your data structures are of the rough expected size so you don't need excessive amounts of memory. There are more details on this on the INSANE home page.



One special note on JavaFX: The above leak isn't actually a leak; it is a deliberate optimization of the scenegraph, and the reference will be cleared up after the next scene pulse completes. Therefore, for unit leak tests, in addition to actually nulling out the weak references, you also want to run through a scene pulse as well. One really hacky, implementation-dependent and unsupported way to do that is to call scene.$scenePulseListener.pulse();. You probably want to isolate that in a utility method such that you can update it in one place when it needs to change...



Finally, note that I built this on JDK6. If there is interest perhaps we could create a wrapper project for this on Kenai or java.net, where people can also create say a Maven binary for this, a JDK 5 version (there is nothing JDK6 specific so it just needs a recompile, but I don't have JDK5 on this Snow Leopard Mac), etc. Hope you find this all as useful as I have!

Tuesday Mar 30, 2010

IDE tip: AST-based Selection


AST-based selection is a feature which lets you select the surrounding "block", based not on syntactic clues (such as braces and parentheses, as is offered by practically all editors), but based on the parse tree created by the compiler (or the "AST", for abstract syntax tree).



In NetBeans, there are two complementary actions to deal with AST selection: Select Surrounding and its reverse. They have other names which I can never remember, but the keybindings are as follows:


Select surrounding block


  • Mac: Ctrl-Shift-. (period)
  • Windows/Linux/Solaris/Others: Alt-Shift-.

Reverse:

  • Mac: Ctrl-Shift-, (comma)
  • Windows/Linux/Solaris/Others: Alt-Shift-,

On my U.S. keyboard, the comma and period keys are marked with "<" and ">" for the shift key which is somewhat reminiscent of blocks.



These two actions cooperate and are stateful: they remember the original caret location such that you can "go back".
Here's how it works. You want to select something surrounding the caret, say the whole method. In that case you just
hit the surrounding action. With your fingers holding ctrl and shift you hit dot -- once, twice, bam bam bam. If you do it
quickly you might "overshoot" and go one too far and select say the whole class instead of just the method. If so just press
comma and voila, it goes back one step down the selection hierarchy you just came up.



This makes this a very quick way to select code blocks -- no more need to grab the mouse and try to hit exactly the selection
boundaries between characters.



Here's an example of where this comes in useful. I sometimes remove long expressions from method call arguments by pulling it
out as a separate variable. Here's my call, and I want to extract the whole Math.min expression.
First I move the caret anywhere within that expression:






Then I press Alt-Shift-. (or Ctrl-Shift-. on Mac):






One more time:






Let's pretend I was doing it quickly and hit it one extra time:






That's too far, so I press comma (with the modifier keys still pressed):






In practice (and with practice) this is done very quickly, faster than I can
accurately hit both ends of the expression with a mouse drag. And to finish
out the example, let me show a couple of more things related to the task.
Notice how there's a light bulb in the left hand side margin of the editor.
That tells me there are associated quick fixes. I press Alt Enter,
and the quick fix dialog is shown:






I choose "Introduce Variable" and press Return. This gives
a dialog where I can choose the variable name (and whether to replace all occurrences
when applicable). It suggests "min" since that's the function
name of the expression we're extracting.






Just press Return to apply the refactoring, and we've pulled out the argument
expression:






I just pressed return and got the default name. Then I realize that this may
not be a great name. What is that last parameter again? I can place the caret
somewhere within the last argument and press Cmd-P (or Ctrl+P
on other platforms) to get NetBeans to "Show Method Parameters".






Let's rename it to length instead. Press Ctrl-R (all platforms) to
apply rename refactoring, which (because this is a local or private variable)
will have "instant rename" applied where your edits are applied immediately
for every keystroke:






Just type the new name - notice that all the boxed expressions are edited synchronously.






Using AST-based selection to identify code blocks to extract as variables or methods
is useful, but it can be used in other ways as well. Let's say I want to add
a second validation step to this function. First I select the code block using
AST selection:





NetBeans has a keyboard command for duplicating the current line: Ctrl-Shift-Down
(and on Mac, it's Cmd-Shift-Down.) Note that when you have a selection, this
duplicates the entire selection. So all we have to do now is apply the duplicate command
and we've got a second if clause we can just tweak to whatever it is it needs to do.





AST based selection should be available in nearly all editor types in NetBeans.
In Ruby, JavaScript, Python, etc it also handles documentation
blocks well - so if you apply select surrounding in say a Ruby comment, it will first select
the current line, then the whole documentation block, then outwards in the AST hierarchy.



Hope you find this helpful. If there are Eclipse or IntelliJ readers who know corresponding
keybindings in Eclipse, feel free to leave a comment so others can find it easily.


Thursday Mar 25, 2010

IDE tips


One of the sessions we had at the Roundup was one entitled "IDE tips and tricks". We basically sat there with our laptops and did a show & tell of various "hidden" IDE features we knew about to help productivity. There were Eclipse, IntelliJ and NetBeans users there - and even some advocacy for Vim :) We discovered pretty quickly that this would not make for compelling listening, so we just turned off the recorder.



One thing I discovered (and which I saw during our languages coding dojo day as well) is that a lot of people don't use many of the productivity boosters. Therefore, I thought I'd bring some of these up here. Since I've been intending to start blogging more again, I'll make this a regular "column".



To kick things off, I'll just point to an old blog entry which is still relevant: Hippie Completion. Learn to use Ctrl-K while editing, it will be worth your while. (Eclipse has this too as of Eclipse 3.1; I believe it's bound to Alt-/).

Transparent windows on Linux


JavaFX makes it easy to create non-rectangular windows -- just set a StageStyle.TRANSPARENT on your stage.style.
We use rounded corners on our popup menus, and we also have a non-rectangular and alpha-blended splash screen.



The other day I was checking how the cursors were looking on different platforms, and imagine my horror when I discovered how our new splash screen and rounded menus looked on Linux! Here they are -- as you can see you end up with white rectangles around the supposed-to-be-blended areas:











That looks.... craptastic!



Historically, the JDK didn't support alpha blended windows on Linux. However, that was added a while ago (I'm not sure exactly which version, but I think it was JDK 6 update 14). It turns out that the FX code which initializes the native frame for the stage does not do conditional checking for this; it simply turns off transparency on Linux. Fortunately, there's a System property you can set to force it to respect the transparency flag. You would obviously only do this if you know you are running on a JDK which supports transparency. And that's easy!



In your startup code, do something like this:


if (Utils.IS_LINUX and Utils.jdkAtLeast(1, 6, 0, 14)) {
java.lang.System.setProperty("javafx.allowTransparentStage", "true");
}

There are a couple of utility methods here that are simple - just looking at some system properties to determine whether we're on Linux and whether we're on a particular version of the JDK or higher (if you run on non-Sun/Oracle JDKs you may want to check for that as well).




public def IS_LINUX = osName.contains("linux");
public def IS_MAC = osName.contains("mac");
public def IS_WINDOWS = osName.contains("windows");
public def IS_SOLARIS = osName.contains("solaris");

/\*\*
\* Is the version of the running JDK at least major.minor.micro_update?
\* In 1.6.0_18 macro=1,minor=6,micro=0,update=18
\*/
public function jdkAtLeast(macro: Integer, minor: Integer, micro: Integer, update: Integer): Boolean {
def runtimeVersion = java.lang.System.getProperty("java.runtime.version");
def pattern = java.util.regex.Pattern.compile("\^(\\\\d)\\\\.(\\\\d)\\\\.(\\\\d)_(\\\\d+)-");
def matcher = pattern.matcher(runtimeVersion);
if (matcher.find()) {
def currentMacro = Integer.valueOf(matcher.group(1));
def currentMinor = Integer.valueOf(matcher.group(2));
def currentMicro = Integer.valueOf(matcher.group(3));
def currentUpdate = Integer.valueOf(matcher.group(4));
if (currentMacro < macro or currentMinor < minor or
currentMicro < micro or currentUpdate < update) {
return false;
}
}

true
}


With that modification at startup, we get much nicer results:











P.S. Yes, there's a JIRA issue tracking this to be automatically done by the platform, RT-4797.

P.S.2. This is for desktop; I'm not sure this code is mobile-safe.

Wednesday Mar 24, 2010

300 Episodes


We had a milestone in the podcast last week: 300 episodes. That's more than one episode per week for the 4½ years we've been doing it!
We spent our 300th episode as a retrospective, looking back at highlights over the years.



We looked up some statistics, too. The most amazing one (to us) is that we are now up to 15,000 downloads per episode! Our feedback alias has over 10,000 e-mails (not counting spam). And our discussion forum has nearly 20,000 messages at this point! Wow! Thanks for listening and participating!






(Photo by Gunnar Hillert)

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Tor Norbye

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