WPE Webkit for the RaspberryPi
This project provides an easy way of running WPE Webkit for the RaspberryPi. WPEWebkit is a full featured browser that takes advantage of the GPU to provide hardware accelerated CSS, WebGL, and HTML5 video.
Showcase
- Rendering WebGL abstract shapes
-
- Playing html5 flappy bird
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- Playing HD video on YoutubeTV
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Table of contents
Getting started
- Sign up on balena
- Go through the getting started guide and create a new application
- Clone this repository to your local workspace
- Add the balena remote to your local workspace using the useful shortcut in the dashboard UI
git push balena master- See the magic happening, your device is getting updated Over-The-Air!
Configuration
A lot of the configuration of this project is about setting up config.txt.
The way you do this on balena is by setting some special fleet configuration
variables. If you don't know how to do this, you can find more info
here.
First, we need to set the GPU memory to something suitable for hardware accelerated graphics. You can set only one of the following if you know how much RAM your Pi has or you can set all of them and your Pi will autoselect based on its memory. If you don't set any of these, WPE won't work.
| Key | Value |
|---|---|
RESIN_HOST_CONFIG_gpu_mem_256 |
128 |
RESIN_HOST_CONFIG_gpu_mem_512 |
196 |
RESIN_HOST_CONFIG_gpu_mem_1024 |
396 |
Displaying on an HDMI screen
WPE will display to the primary framebuffer (HDMI output) by default. If you don't set the resolution, it will be autodetected on boot up. Depending on what you want to do, you might find the performance at FullHD resolution isn't enough. In that case you can force the HDMI to 720p by adding the following fleet configuration variables:
| Key | Value |
|---|---|
RESIN_HOST_CONFIG_hdmi_group |
1 |
RESIN_HOST_CONFIG_hdmi_mode |
4 |
Displaying on a PiTFT 2.8"
Displaying to a secondary framebuffer is accomplished by rendering on the primary and continuously copying the resulting image to the secondary. The reason for this is that the Pi can only render hardware accelerated graphics to the primary framebuffer. A side effect of this is that you can't display different content or have different resolutions between the HDMI and your PiTFT screen.
Since the rendering will happen to the primary framebuffer, we need to force the HDMI output to be 320x240, our native resolution. You can do this with the following variables. If don't set those, the Pi will render on a higher resolution and then scale down the image to fit the Pi screen.
| Key | Value |
|---|---|
RESIN_HOST_CONFIG_hdmi_force_hotplug |
1 |
RESIN_HOST_CONFIG_hdmi_group |
2 |
RESIN_HOST_CONFIG_hdmi_mode |
87 |
RESIN_HOST_CONFIG_hdmi_cvt |
320 240 60 1 0 0 0 |
Capacitive touchscreen
Warning: The PiTFT based on the ft6x06_ts kernel module is not currently
supported out of the box on balena. If your screen says "FT6206" at the back,
it's probably one of those.
| Key | Value |
|---|---|
RESIN_HOST_CONFIG_dtoverlay |
pitft28-capacitive,rotate=90,speed=62000000,fps=60 |
Resistive touchscreen
| Key | Value |
|---|---|
RESIN_HOST_CONFIG_dtoverlay |
pitft28-resistive,rotate=90,speed=62000000,fps=60 |
Controlling backlight brightness
If you have a Raspberry touchscreen, you can control the backlight brightness
by setting the environment variable RPI_BACKLIGHT to a value in the range
0-255. The default value is 255 (maximum brightness).
Sound configuration
WPE will normally try to select an appropriate audio sink to output to.
However, if you want to force a specific output to be used you can set the
WPE_GSTREAMER_AUDIO_SINK environment variable according to the following
table:
| Value | Notes |
|---|---|
autoaudiosink |
Automatically select output (default) |
omxhdmiaudiosink |
Outputs sound over HDMI |
omxanalogaudiosink |
Outputs to the 3.5mm jack |
alsasink |
Outputs using alsa (EXPERIMENTAL) |
Controlling content
Loading a URL
To configure the URL displayed by webkit, set the WPE_URL environment
variable. The default value is Youtube TV
Offline content
If you want your device to display content even without internet, you can add your content in the docker image and point WPE to them. Append a similar Dockerfile fragment to your project:
COPY public_html /var/lib/public_html
ENV WPE_URL="file:///var/lib/public_html/index.html"Changing content at runtime
balena-wpe ships with tohora so which provides a web interface for changing target URLs at runtime on port 8080
Enabling mouse
To enable the mouse cursor you have to set the following environment variable. Keep in mind that there are some known issues with mouse support when the webpage includes iframes.
| Key | Value |
|---|---|
WPE_BCMRPI_CURSOR |
1 |