Template:FriendlyCoreRK3399QtDev

1 Develop Qt Application

The Qt 5.10.0 FriendlyELEC ported for RK3399 supports the following plug-ins:KMS, EGLFS and XCB. All these three plug-ins support OpenGL ES and GPU hardware acceleration but in different ways:

• KMS - it calls Linux kernel's DRM interface to display
  
• EGLFS - it calls OpenGL ES interface to display
  
• XCB - it runs on X11 server and is integrated in X11 windows system
  

Three plug-ins support different Qt features and here is a table:

Plug-in	OpenGL ES	QtWebEngine	QtMultimedia	Video Playing with Hardware Decoding	Different Display
KMS	Yes	No	Yes	No	Yes
EGLFS	Yes	No	Yes	No	No
XCB	Yes	Yes	Yes	Yes	Yes

We recommend to use KMS or XCB.

FriendlyCore has four scripts for setting Qt environmental variables for users and here is a table:

Script	Comment
/usr/bin/setqt5env-kms	set kms' environmental variables
/usr/bin/setqt5env-eglfs	set eglfs' environmental variables
/usr/bin/setqt5env-xcb	set xcb's environmental variables
/usr/bin/setqt5env-nogui	set environmental variables for a system without a Qt GUI

For instance, if you want to use KMS to display you can run the following commands:

. setqt5env-kms
./apps

(Note:there is a space between '.' and 's')

1.1 Setup Qt Development Envronment

FriendlyELEC developed two methods for RK3399 to cross-compile a Qt program:

• 1:Use Docker. For more details you can refer to github :http://github.com/friendlyarm/friendlyelec-ubuntu18-docker
• 2:Setup a local cross-compiler. You need to run a Ubuntu 18.04 64-bit OS and you can refer to :How to Build and Install Qt Application for FriendlyELEC Boards/zh

1.2 Qt Demo

FriendlyCore has several Qt demo programs:

• Qt QML: CinematicExperience

CinematicExperience is a utility for selecting a video file and it is developed with Qt QML.
This demo uses Qt QML's various features and runs very smoothly on RK3399. This performance is achieved by hardware and software optimization.
You can start it in a commandline utility by running the following commands:

cd /opt/Qt5_CinematicExperience
./run.sh

Here is what it looks like:

• QQt WebEngine: web browser

Qt WebEngine uses Chromium and supports HTML5.
You can start it by running the following commands:

cd /opt/qt5-brower
./run.sh

Here is what it looks like:

Note:Qt WebEngine depends on the Xcb plug-in.

• Qt Different Display

This demo shows that when a board is connected to an HDMI monitor and an eDP LCD these two devices display differently. You can start it by running the following commands:

cd /opt/qt5-multi-screen-demo
./run.sh

Here is what it looks like:

• Qt Multimedia: qt5-player with hard decoding

The qt5-player works with Rockchip's gstreamer plug-in and supports 4K video playing. Since Rockchip's plug-in only supports output images to an X11 window the qt5-player needs to use XCB for display.
You can start the demo by running the following commands:

cd /opt/qt5-player
./run.sh

Here is what it looks like. You can set it to display in full-screen and adjust the voice's volume:

• Qt WebGL demo: nmapper

Qt WebGL allows you to remotely access a Qt program running on your board.
Before you run the demo you need to connect your board to the internet and run the following commands:

cd /opt/qt5-nmapper
./run-with-webgl.sh

You can open a browser on another device, type the IP address of your board on the browser's address bar, enter and you will be able to see a Qt GUI. Here is what it looks like:

• Qt VNC demo: Smart home applicance GUI

Qt VNC allows you to run a program as a VNC Server on your board and you can access the program from a VNC client on another device. This program can be developed with either QtWidgets or QML.
You can start it by running the following commands:

cd /opt/qt5-smarthome
./run-with-vnc.sh

Start a VNC viewer on a smart phone or mobile device and type your board's IP address and port number 5900. For instance if your board's IP address is 192.168.1.100 you can type "192.168.1.100:5900", enter and you will see the following GUI:

1.3 Dual Camera in Qt

This sample shows how to enable two USB cameras. Before run this sample make sure two USB cameras and an LCD have been connected to your board. Most UVC cameras should work but we still suggest you try the cameras we list here:

Index	Model
1	Logitech C270
2	Logitech C270i
3	Logitech C922 Pro

Run the following commands:

cd /opt/dual-camera
./run.sh

Here is what you should observe: