Embedded Qt Porting Tutorial

Why Do Qt Porting

Qt is a cross-platform C++ GUI library that supports multiple operating systems, including embedded devices. Using Qt in embedded devices can provide a better user experience, but due to the limitations of the hardware and software environment, the transplantation of Qt may be more complicated.

Embedded Qt porting method

Qt porting generally adopts the following two methods:

Compile the Qt source code, get the Qt library file, and deploy it to the embedded system.
Use the open source embedded Linux system to automatically build the framework Buildroot.

Embedded Qt porting method comparison

There are three methods for Qt porting, namely: compiling Qt source code separately and porting to BusyBox; Buildroot to build Qt; Yocto to build Qt.

Among them, different methods are suitable for different embedded devices and application scenarios. Below we will introduce the specific operation steps of each method one by one.

Compile the Qt source code separately and port it to BusyBox

This method needs to compile the source code of Qt first, and cross-compile the generated library files to the BusyBox file system. This method is cumbersome and requires manual configuration of compilation toolchains, library files and other environments. The system suitable for embedded devices is already very customized, and standard construction tools cannot meet the requirements.

Buildroot builds Qt

Buildroot is an open source embedded Linux system automatic construction framework, which can easily build a customized Linux file system. Using Buildroot to build Qt can simplify the complexity of Qt transplantation and improve efficiency. This method is suitable for the case where the Linux system running on the embedded device has been custom built using Buildroot.

Yocto Build Qt

Similar to Buildroot, Yocto is also an open source automated build framework for embedded Linux systems. Using Yocto to build Qt allows for more customized construction and management of embedded devices, but relatively more work and learning costs are required.

Embedded Qt porting compiler and root file system preparation

Before using any of the above porting methods, we need to install a general-purpose cross-compiler and prepare the basic root file system. These tools can help us cross-compile applications for embedded devices on the host.

tslib compilation for embedded Qt porting

tslib is an open source library, it is the adaptation layer between touch screen driver and application layer. In the process of transplanting Qt, we need to compile tslib and its related file libraries first, and put the generated files into the embedded Linux system.

Qt source code compilation for embedded Qt porting

After the above preparations are completed, we can start compiling the Qt source code. By running the configure script, make command, and make install command, we can generate Qt library files that can be used in embedded systems, including Qt core modules, Qt GUI modules, etc.

The above is the basic overview and process of embedded Qt transplantation. According to different embedded devices and application scenarios, we can choose different migration methods. It should be noted that when performing Qt transplantation, we need to understand the hardware and software environment of the embedded device in detail in order to ensure the normal operation of the Qt application.

Practical case: Embedded Qt porting

overview

Qt is a cross-platform C++ GUI library that supports multiple operating systems, including embedded devices. This tutorial will take the way Buildroot builds Qt as an example to explain how to port Qt applications on embedded devices.

Preparation

Before starting Qt porting, we need to prepare the following tools and environment:

cross compiler
root file system
Qt source code
tslib library source code
Buildroot tool

For the installation process of these tools and environments, you can refer to official documents or other related materials.

Migration steps

1. Compile the tslib library

First, we need to compile the tslib library source code and generate the corresponding library files. Assuming we have downloaded tslib to the /opt directory, we can compile it according to the following steps:

cd /opt/tslib/
./autogen.sh
./configure --prefix=/usr/local/tslib
make
sudo make install

2. Configure Buildroot

Next, we need to configure Buildroot in order to build a root filesystem suitable for the target hardware. Go to the root directory of Buildroot and use the make menuconfig command to open the configuration interface:

cd /path/to/buildroot/
make menuconfig

In the configuration interface, we need to select the following options:

Target options -> Target architecture: Select the CPU architecture of the target device.
Toolchain: Select the path and version of the cross compiler.
Filesystem images: Select the root file system format and save location.

After completing the configuration, save and exit.

3. Compile Buildroot

Next, we can use the make command to start compiling Buildroot. The compilation command is as follows:

make

Compilation times may be longer, depending on the target hardware and selected software packages.

4. Configure Qt

After Buildroot is compiled, we need to make some basic configurations for Qt compilation. Enter the Qt source code directory and execute the following command:

./configure -embedded arm -xplatform qws/linux-arm-gnueabi-g++ -depths 16,24,32 -qt-mouse-tslib -plugin-mouse-linuxtp -plugin-mouse-tslib -prefix /usr/local/qt

Among them, -embedded arm means to compile the embedded version of Qt; -xplatform specifies the compilation platform, here is the ARM architecture of the Linux platform; -depths specifies the color depth; -qt-mouse-tslib uses the tslib library to drive the touch screen; -plugin-mouse- linuxtp/-plugin-mouse-tslib enables the mouse plugin; -prefix specifies the installation path.

5. Compile the Qt library

After completing the configuration, we can use the make command to compile the Qt library. The compilation command is as follows:

make

Compilation time may be longer, depending on hardware configuration and selected modules.

6. Deploy the Qt application

After the Qt library is compiled, we can start deploying the Qt application. Copy the generated library file to the target device, and then use the cross compiler to compile the Qt application.

Summarize

This article takes Buildroot to build Qt as an example to explain how to transplant Qt applications on embedded devices. It should be noted that different migration methods are suitable for different hardware and software environments, and the specific operation steps may be different. Before transplanting Qt, we need to understand the hardware and software environment of the embedded device in detail in order to ensure the normal operation of the Qt application.