By Toradex秦海

1).?简介

目前主流的?ARM?平台嵌入式?Linux BSP?的显示后端基本都已经从?X11?升级到了?Wayland， 而常用的?Wayland Compositor - Weston?对于?Linux?下常用的?Qt?图形界面开发框架的一些?Plugin (比如?Qt VirtualKeyboard)?的配合并不完善，因此本文就基于?TI AM62?处理器平台测试?Qt?提供的?Wayland Compositor - QtWayland?的部署测试。

本文所演示的平台来自于?Toradex?Verdin?AM62?嵌入式平台。

2.?准备

a).?Verdin AM62 ARM核心版配合Dahlia载板，并连接调试串口和?HDMI?显示器以及?USB?触摸/鼠标用于测试。

3).?Verdin?AM62?Yocto?Linux?编译部署以及配置

a).?由于需要增加对Qt Eglfs/KMS, QtWayland?和?Qt VirtualKeyboard?的支持，需要通过Yocto/Openembedded?框架重新编译?Yocto Linux BSP，具体的配置方法请参考这里，部署如下修改后编译Reference-Multimedia?image镜像

-------------------------------

###?local.conf，增加Qt?eglfs/kms, Qtwayland?和?Qt VirtualKeyboard?支持###

+?TOOLCHAIN_TARGET_TASK:append = " libgles3-mesa-dev"

+?IMAGE_INSTALL:append = " qtvirtualkeyboard qtwayland ttf-droid-sans ttf-droid-sans-fallback ttf-droid-sans-mono ttf-droid-serif freetype"

+?PACKAGECONFIG:append:pn-qtvirtualkeyboard = " lang-zh_CN"

+?PACKAGECONFIG:append:pn-qtbase = " gles2extra eglfs kms"

+?PACKAGECONFIG_DISTRO:pn-qtbase = "icu examples accessibility gif gbm kms libinput"

+?PACKAGECONFIG_FONTS:pn-qtbase = "fontconfig"

+?PACKAGECONFIG:remove:pn-qtwayland = "xcomposite-egl xcomposite-glx"

###?layers/meta-toradex-ti/qt5-layer/recipes-qt/qt5/qtbase_%.bbappend，注释掉以下内容?###

############################### TDX added

# from meta-arago/conf/layer.conf

-PACKAGECONFIG_GL:am62xx = "gles2extra linuxfb"

-PACKAGECONFIG_DISTRO:am62xx = "icu examples accessibility gif gbm kms libinput"

-PACKAGECONFIG_FONTS:am62xx = "fontconfig"

+#PACKAGECONFIG_GL:am62xx = "gles2extra linuxfb"

+#PACKAGECONFIG_DISTRO:am62xx = "icu examples accessibility gif gbm kms libinput"

+#PACKAGECONFIG_FONTS:am62xx = "fontconfig"

-PACKAGECONFIG:remove:am62xx = "kms"

-PACKAGECONFIG:remove:am62xx = "vulkan"

-PACKAGECONFIG:remove:am62xx = "glib xcb"

+#PACKAGECONFIG:remove:am62xx = "kms"

+#PACKAGECONFIG:remove:am62xx = "vulkan"

+#PACKAGECONFIG:remove:am62xx = "glib xcb"

# they don't apply without changes, drop them for now

-SRC_URI:remove = " \

- ???file://0002-deform-disable-opengl-button.patch \

- ???\

- ???file://0001-deform-Fix-how-controls-are-shown.patch \

- ???file://0001-qtbase-plugins-platforms-eglfs_kms-fix-compiler-erro.patch \

- ???file://0001-eglfs-Force-888-format-only-on-env-flag.patch \

-"

+#SRC_URI:remove = " \

+# ???file://0002-deform-disable-opengl-button.patch \

+# ???\

+# ???file://0001-deform-Fix-how-controls-are-shown.patch \

+# ???file://0001-qtbase-plugins-platforms-eglfs_kms-fix-compiler-erro.patch \

+# ???file://0001-eglfs-Force-888-format-only-on-env-flag.patch \

+#"

###compile?Reference-Multimedia?image###

$?MACHINE="verdin-am62"?bitbake bitbake tdx-reference-multimedia-image

###?compile SDK###

$?MACHINE="verdin-am62"?bitbake tdx-reference-multimedia-image -c populate_sdk

-------------------------------

b).?YoctoLinux?image部署

参考这里通过Toradex?Easy?installer将上面编译好的image更新部署到?？?/p>

c).?显示配置

./?HDMI默认即可正常显示，如果实际测试是连接其他接口如?LVDS?等显示设备，可以参考这里调整?Device-Tree Overlay?设置来使能相关的显示设备。

./?输入设备如?USB HID?电容式触摸或者?USB?鼠标通常无需额外设置，插上即可使用。

?

?

4). Qtwayland compositor?编译部署

a).?Qt?Qtwayland组件可以非常方便的使用C++/QML语言开发定制化的Wayland?compositor，详细说明请见这里，也提供了很多sample?project供参考

b).?本文测试所使用的Qtwayland?compositor?来自于Qt?官方的?Pure-qml sample?示例，源代码请参考这里，这是一个基于?QML?开发的并且支持?Qt VirtualKeyboard plugin?的简单?Qtwayland?compositor

c).?参考这里说明使用上面章节?3.a编译出的SDK文件配置QtcreatorIDE?工具交叉编译环境，然后下载Pure-qml?工程源代码后通过?Qtcreator IDE?进行交叉编译，生成pure-qml?可执行二进制文件上传到Verdin AM62 Linux?系统中

d).?使用编译好的pure-qml?Qtwayland compositor?替换系统默认的Weston?compositor

./?创建pure-qml.sh执行脚本文件

-------------------------------

#copy?pure-qml?binary to /usr/bin

$ cp?pure-qml?/usr/bin/

#create?pure-qml.sh script,?detailed content in below

$?vi /usr/bin/pure-qml.sh

#?add executable permission

$chmod +x?pure-qml.sh

-------------------------------

./?pure-qml.sh –?由于系统DRM?挂载显示设备在启动过程中，其对应的card?号码可能会变化，?因此脚本前面先对?“kms.conf”?文件里面的设置和系统启动后的设备card0?或者?card1?进行匹配修改，然后再启动compositor。

-------------------------------

#!/bin/sh

set -e

# modify kms.conf if seetings is not consistent with system drm card device name

if [ -d /sys/class/drm/card0-HDMI-A-1 ];then

sed -i '2 s/card1/card0/' /etc/qt5/eglfs_kms_cfg.json

fi

if [ -d /sys/class/drm/card1-HDMI-A-1 ];then

sed -i '2 s/card0/card1/' /etc/qt5/eglfs_kms_cfg.json

fi

# execute qtwayland compositor

/usr/bin/pure-qml &

-------------------------------

./?创建Qtwayland?systemd?service?文件，参考这里说明，Qt VirtualKeyboard?基于?Wayland Compositor?使用时候，需要在?Compositor?侧配置?“QT_IM_MODULE”环境变量，而不是应用侧。

-------------------------------

$ vi /lib/systemd/system/qtwayland.service

------

# This is a system unit for launching QtWayland

[Unit]

Description=Qt Wayland, a Wayland compositor, as a system service

RequiresMountsFor=/run

# Make sure we are started after logins are permitted.

Requires=systemd-user-sessions.service

After=systemd-user-sessions.service

After=plymouth-quit-wait.service

Before=graphical.target

[Service]

Environment="QT_QPA_EGLFS_KMS_CONFIG=/etc/qt5/eglfs_kms_cfg.json"

Environment="QT_QPA_EGLFS_INTEGRATION=eglfs_kms"

Environment="QT_QPA_PLATFORM=eglfs"

Environment="QT_QPA_EGLFS_KMS_ATOMIC=1"

Environment="QT_IM_MODULE=qtvirtualkeyboard"

ExecStart=/usr/bin/pure-qml.sh

User=root

Group=root

PAMName=login

StandardOutput=journal

StandardError=journal

[Install]

WantedBy=graphical.target

------

-------------------------------

e).?测试Qtwayland?compositor

-------------------------------

###disable default?Weston compositor and?Qt demo app###

$?systemctl disable?weston.service

$?systemctl disable?weston.socket

$?systemctl disable wayland-app-launch

### enable Qt wayland compositor ###

$systemctl?enable?qtwayland

$?reboot

-------------------------------

重启后，可以看到如下?Qt Compositor pure-qml?显示结果

5). QtVirtualKeyboard Example应用测试

a).?分别使用一个Qt?Widget应用和一个Qt?Quick应用进行测试

./?Qt?Widget应用?–?Line Edits Example，详细说明请参考这里，源码从这里下载，将编译好的可执行binary“lineedits”?上传到Verdin?AM62 Linux /home/root?目录

./ Qt Quick?应用?–?Qt VirtualKeyboard Basic Example，详细说明请参考这里，源码从这里下载，如上面?4.d?章节所提到的，需要如下修改?main.cpp?将环境变量取消导出，然后将编译好的可执行binary“basic”?上传到Verdin?AM62 Linux /home/root?目录

-------------------------------

...

int main(int argc, char *argv[])

{

????//qputenv("QT_IM_MODULE", QByteArray("qtvirtualkeyboard"));

QGuiApplication app(argc, argv);

QQuickView view(QString("qrc:/%2").arg(MAIN_QML));

...

}

-------------------------------

b).?创建应用启动脚本/home/root/qtwayland-app-launch.sh

-------------------------------

#!/bin/sh

# export display environment

export XDG_RUNTIME_DIR=/run/user/`id -u`

export WAYLAND_DISPLAY=/run/user/`id -u`/wayland-0

if ! test -d "$XDG_RUNTIME_DIR"; then

mkdir --parents $XDG_RUNTIME_DIR

chmod 0700 $XDG_RUNTIME_DIR

fi

# wait for qtwayland

while [ ! -e ?$XDG_RUNTIME_DIR/wayland-0 ] ; do sleep 0.1; done

sleep 1

# run basic or lineedits app

/home/root/basic -platform wayland &

#/home/root/lineedits -platform wayland &

-------------------------------

c).?创建开机自启动systemd?service文件

-------------------------------

$?vi /lib/systemd/system/qtwayland-app-launch.service

[Unit]

Description=Start a Qt wayland application

After=qtwayland.service

Requires=qtwayland.service

[Service]

Restart=on-failure

Type=forking

ExecStart=/home/root/qtwayland-app-launch.sh

RestartSec=1

[Install]

WantedBy=graphical.target

-------------------------------

d). enable service?并测试

-------------------------------

$?systemctl enable qtwayland-app-launch

$?reboot

-------------------------------

e).?重启后分别启动?basic?和?lineedits?应用效果如下，USB HID?电容触摸和鼠标都可以正常操作虚拟键盘输入

6).?总结

本文基于?Ti AM62?处理器演示了?QtWayland compositor?的部署以及?Qt VirtualKeyboard?应用的测试。