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In general a touch screen that is recognized by Linux and generates EV_ABS events will work with JavaFX.

Raspberry Pi OS

Tested:

• Raspbian Jessie

• Raspbian Jessie Lite

  • Note: is missing the Pango package for running OpenJFX. Easily fixed with "apt-get install libpango-1.0-0:armhf libpangoft2-1.0-0:armhf"
• NOOBS (v1_4_1) installing:

  • Raspbian Debian Wheezy (2015-05-05)

When the raspi_config options are displayed, there is one critical item for OpenJFX. Under "Advanced Option" choose "Memory Split" and set the value to 128 or 256. This is the memory allocated for GPU use. OpenJFX can use quite a bit of memory for textures and shaders. The amount available to OpenJFX cannot be queried from the OS, and OpenJFX cannot always handle the failure gracefully. You can always run the raspi_config tool after install to change the value.

The Jessie images were tested with jdk-8u65-linux-arm32-vfp-hflt.tar.gz, which is downloadable from the Oracle JDK8 download page. Note that this version of the JDK does not come with an integrated JavaFX. JavaFX can be obtained by building OpenJFX for ARM, or by using one of the community builds.

OLDER DISTRO NOTES

The configuration used by Oracle for testing is:

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• Make sure to expand the filesystem, or you won't have enough room to install the JDK.
• If you are using the device primarily with JavaFX, you will probably not want to select "Enable Boot to Desktop". JavaFX on the Pi takes over the whole screen and does not interact with the Linux desktop.
• Under "Advanced Options" you can select "Memory Split" to allocate memory to the graphics processor. A 50/50 split will let you get most use out of JavaFX accelerated graphics.
• If you are using JavaFX over ethernet, it can be convenient to turn on the SSH server under "Advanced Options". Since JavaFX takes over input devices, it can be hard to stop an application if you don't have an SSH connection to it from another machine.

Because of the way JavaFX is run, it is sensitive to the system screen blank timer. To disable the screen blank timer, edit the file /etc/kbd/config and change the lines for BLANK_TIME and POWERDOWN_TIME to be 0 (disable), and reboot. If not disabled, many applications will appear to stop after 30 minutes or so of use.

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Newer versions of Raspian can dynamically allocate system memory for use as VRAM.JavaFX applications tend to need significant VRAM to operate properly, particularly applications that use large images, but also for fonts and gradients.

The minimum recommended memory split for JFX on the Pi is 128 MBytes, with many applications requiring 256 MBytes.

JavaFX contains a texture caching mechanism that attempts to work within a limit of VRAM. Unfortunately, there is not an standard means of determining how much VRAM is available to start, nor is there a way to estimate the efficiency of that allocation. This is similar to standard malloc() which employs bucket mechanisms for efficiency but means that a small allocation will consume the nearest minimum bucket size. This JavaFX texture caching mechanism currently defaults to 256 512 MBytes - a value that will likely exceed what is available on the Pi. Remember that the allocated VRAM will also be consumed by the framebuffer (width * height * 2 byte per pixel * 2 for swapping) as well as any other system needs. Given the limited amount of VRAM on the Pi, it is quite possible that an image intensive application might fail when the cache exceeds the available system limit.

The property setting -Dprism.maxvram=90M can be used to set the JavaFX texture cache limit, and in this example, setting it to 90 MB. This value would be a good starting value for a memory split of 256MB for VRAM.

To debug a JavaFX application failure to allocate VRAM, -Dprism.poolstats=true can be used to monitor the texture pool to better determine the upper limit.

In general, JavaFX will try to use no more than -Dprism.targetvram=xx, freeing textures when this value is exceeded. Least used textures will be discarded, and recreated on need. The default for this setting is calculated as 75% of the  maxvram setting, equal to 45M for the example of 90M. This setting may be overly aggressive for some applications, and experimentation with a larger value and  -Dprism.poolstats=true may result in more performance.Read this page for more details on VRAM and tuning.

Touch events

A touch screen attached to the Raspberry Pi generates both TouchEvents and MouseEvents. The Monocle subsystem in the latest OpenJFX sources support supports a wider range of touch screens than the 8u6 release does and also supports calibration.