Headless Plotting

[cranst0n]

Is it possible to generate a plot and save it to file without needing to open a window? I'm trying to generate a few thousand plot images and I'm blocked at the moment.

(0 until 2) foreach { zone =>

  val myData = // Generate data

  val canvas = ScatterPlot.plot(myData, '*', Color.BLACK)
  val plotFile = s"/tmp/channelPlots/$zone.png".toFile

  // (1)
  canvas.save(plotFile.toJava)

  // (2)
  val imageSize = 750
  val bi = new BufferedImage(imageSize, imageSize, BufferedImage.TYPE_INT_ARGB)
  val g2d = bi.createGraphics()
  canvas.print(g2d)
  g2d.dispose()

  ImageIO.write(bi, "png", plotFile.toJava)

  // (3)
  plot(myData)

}

1. Fails with: [error] Exception in thread "main" java.lang.IllegalArgumentException: Width (0) and height (0) cannot be <= 0
2. Results in a solid colored image written to file
3. Works fine but requires an opened window

Any help would be greatly appreciated!

[haifengl]

Try this

val window = plot(data)
window.canvas.save(new java.io.File("test.png"))
window.close

[cranst0n]

That also throws the same exception. I'm guessing because the window hasn't really opened 'fully' and the width/height of the plot canvas still thinks it's zero.

[haifengl]

I see. Maybe we need to add new interface for your use case.

[haifengl]

As a quick work around, you may pause a little bit before calling save, which make sure the window is properly initialized.

[haifengl]

Read your first message again. Do you mean #2 approach works? Thanks!

[cranst0n]

No it just results in a solid image of the color as if fillRect(0, 0, width, height) were called.

[haifengl]

What platform do you use?

[cranst0n]

Linux 3.19.0-32-generic #37~14.04.1-Ubuntu SMP Thu Oct 22 09:41:40 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

java version "1.8.0_77"
Java(TM) SE Runtime Environment (build 1.8.0_77-b03)
Java HotSpot(TM) 64-Bit Server VM (build 25.77-b03, mixed mode)

[haifengl]

Can you try approach 2 on windows? Swing has al it of issues on Linux and Mac. Thanks!

[cranst0n]

Would be happy to except I don't have access to a Window machine.

[haifengl]

Have you tried pausing a little bit before save?

[haifengl]

Any updates? Did you try pause a little bit.

[cranst0n]

Ah. Sorry about that. I've haven't had time to try it out. I suspect it will work when I get a chance but it's not really a viable option in my specific use case since I was generating 100's of plots. Introducing even a small delay (i.e. a few seconds per plot) would be a show stopper.

[haifengl]

The problem is that graphics projection depends on the PlotCanvas size. Because the canvas is not materialized, nothing works as expected. If you create a multithreaded program that shows the canvas, save it, and closes automatically, I guess that it may be not too bad for your use cases.

[chhh]

I think the correct solution for this is to use Graphics2D implementation
that supports printing not only to the screen but to images(files:
vector/bitmap... etc) -- just call
smile.plot.PlotCanvas#paintComponent(Graphics g) providing the capable
implementation of graphics.I believe, there must be a constructor of
PlotCanvas that doesn't call setVisible anywhere.

For example of non-standard Graphics2D implementation, see e.g. this one:
https://github.com/freehep/freehep-vectorgraphics (
http://freehep.github.io/freehep-vectorgraphics/)

Specifically check out this example of headless painting:
https://github.com/freehep/freehep-vectorgraphics/blob/master/freehep-graphics2d-headless-example/src/main/java/org/freehep/graphics2d/example/HeadlessExample.java

On Thu, Apr 7, 2016 at 3:52 PM, Haifeng Li notifications@github.com wrote:

The problem is that graphics projection depends on the PlotCanvas size.
Because the canvas is not materialized, nothing works as expected. If you
create a multithreaded program that shows the canvas, save it, and closes
automatically, I guess that it may be not too bad for your use cases.

—
You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub
#74 (comment)

[haifengl]

Would you like to take the lead on fixing it? Thanks!

[chhh]

@haifengl I'll think about it, so far I've checked out the code and tried to explore it a little bit. It seems like it should be doable.

When I imported the code into IntelliJ IDEA there were a couple of problems, the most notable of which I guess was that SLF4J wasn't set as a dependency in pom.xml files.

[haifengl]

We use sbt now. Pom files will be deleted. Please install sbt plugin and import it again.

[haifengl]

Following @chhh suggestion, I add headless support now. You need to do a git pull and build smile by yourself to use it for now.

val toy = readTable("shell/src/universal/data/classification/toy/toy-train.txt", Some((new NominalAttribute("class"), 0)))
val (x, y) = toy.unzipInt

val canvas = ScatterPlot.plot(x, '.', java.awt.Color.BLACK)

val headless = new Headless(canvas);
headless.pack();
headless.setVisible(true);

canvas.save(new java.io.File("zone.png"))

[haifengl]

It works for me. Please let me know if it works for you too. Thanks!

[haifengl]

BTW, you show run JVM with option -Djava.awt.headless=true