You will need:
Touch screens known to work with JavaFX are:
In general a touch screen that is recognized by Linux and generates EV_ABS events will work with JavaFX.
The configuration used by Oracle for testing is:
Note that you need the hard-float Raspbian image. If you use the soft-float Debian "wheezy" image you will not be able to run JDK 8 (or any other software compiled for ARM hard float).
Raspbian setup instructions are at http://elinux.org/RPi_Easy_SD_Card_Setup.
When you first power up the board with Raspbian you will get the raspi-config tool. There are a few things to note here:
If you are connecting to your Pi over the network, you can save some time by setting a host name, and enabling ssh access for it in |
If the Raspberry Pi isn't detecting the screen size correctly, you might need to tweak video mode settings and maybe tell the Pi to ignore the capabilities reported by the display. For example, some of the Chalkboard Electronics screens require installing an EDID file and/or changing the boot configuration.
If you run into problems with input events being dropped, you should try reducing the USB bus speed. You need recent firmware to do this, so first you should update firmware:
sudo apt-get update sudo apt-get install raspberrypi-bootloader --reinstall |
Then open /boot/cmdline.txt in an editor and add on the same line as the other options dwc_otg.speed=1. Run sudo sync and reboot. This drops USB speeds from 480Mbits/s to 12Mbits/s, which is known to resolve issues with a variety of USB devices on the Raspberry Pi.
Raspbian has Java SE 7 preinstalled on the image. This version does not contain JavaFX. To obtain JavaFX download either:
This downloaded bundle should be unpacked on the Pi. For example,
sudo tar zxvf jdk-8-linux-arm-vfp-hflt.tar.gz -C /opt |
To check that the JDK is installed correctly, run:
/opt/jdk1.8.0/bin/java -version |
This should show that you are running JDK 8. If the VM won't even start, you might be running a hard-float VM on a soft-float system.
To avoid confusion, change your PATH variable so that the newer version is earlier in the path.
You can use the samples bundle from https://jdk8.java.net/download.html on the Raspberry Pi. Not all the samples will work on the Pi; here are some that will:
You can run these applications without any additional parameters. For example,
/opt/jdk1.8.0/bin/java -cp Stopwatch.jar stopwatch.MainScreen |
Note that the default configuration of JavaFX on the Raspberry Pi does not use X11. Instead JavaFX works directly with the display framebuffer and input devices. So you should not have the X11 desktop running when starting JavaFX.
JDK 8 EA builds for the Raspberry Pi include full support for hardware accelerated graphics, with everything from the base, graphics, controls and FXML modules. Media and Web modules are not included.
JavaFX on the Raspberry Pi takes over the whole screen and captures all Linux input devices. While this will generally be the behavior you want in a deployed application, it is less convenient for development because you can't stop an application using control-C unless the JavaFX application has a KeyEvent handler that listens for control-C and calls Platform.exit(). There's nothing unusual about this - many Linux full-screen console applications have the same behavior - but it is often useful to have a quick way to end an an application during development without changing the application code.
There are two ways to run applications with the ability to be terminated by control-C:
JAVA_DEBUG=1 before starting Java then JavaFX will exit when you press control-C. For exampleJAVAFX_DEBUG=1 /opt/jdk1.8.0/bin/java -cp Stopwatch.jar stopwatch.MainScreen |
The |
The older versions Raspberry Pi Raspian preallocate a fixed amount of the system memory for use by the video engine (VRAM). The utility raspi_config can be used to alter how much memory is allocated to VRAM.
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 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.
A touch screen attached to the Raspberry Pi generates both TouchEvents and MouseEvents. The Monocle subsystem in the latest OpenJFX sources supports a wider range of touch screens than the 8u6 release does and also supports calibration.