前言：本文将介绍Qt5源码方式的交叉编译及安装

下载源码包：qt-everywhere-src-5.12.8.tar.xz

官网下载网址：Index of /

依次选择：

【official_releases】 =>【qt】 =>【5.12】 =>【5.12.8】 =>【single】 =>【qt-everywhere-src-5.12.8.tar.xz】

先解压QT库压缩包出来，并进入解压出来的库目录。

接下来请按以下步骤进行：

1. 配置

1.1 配置工具链

         配置编译工具链：

$ vi qtbase/mkspecs/linux-arm-gnueabi-g++/qmake.conf

​

1.2 配置编译选项

请回到库的根目录下操作。

有以下2种情况：

1.2.1 不支持触摸屏tslib

配置如下：

$ ./configure -prefix /data/arm-linux/libs/qt-5.6.0-arm -opensource -confirm-license -release -make libs -xplatform  linux-arm-gnueabi-g++ -pch -sql-sqlite -qt-libjpeg -qt-libpng -qt-zlib -no-opengl -no-sse2 -no-openssl -no-cups -no-glib -no-iconv -no-separate-debug-info -nomake tests -nomake examples -nomake tools -no-pkg-config

配置完成输出如下：
Qt is now configured for building. Just run 'make'.
Once everything is built, you must run 'make install'.
Qt will be installed into /data/arm-linux/libs/qt-5.6.0-arm

Prior to reconfiguration, make sure you remove any leftovers from
the previous build.

 1.2.2 支持触摸屏tslib

若要支持触摸屏，请先移植触摸屏tslib，请参考以下博文：

触摸屏tslib库交叉编译并移植ARM校准测试_曾哥电子设计的博客-CSDN博客。

首先添加-tslib项，如tslib安装在/data/arm-linux/libs/tslib-1.12-arm目录下，还需通过-I和-L指定include和lib路径，配置如下：

$ ./configure -prefix /data/arm-linux/libs/qt-5.6.0-arm -opensource -confirm-license -release -make libs -xplatform  linux-arm-gnueabi-g++ -pch -sql-sqlite -qt-libjpeg -qt-libpng -tslib -qt-zlib -no-opengl -no-sse2 -no-openssl -no-cups -no-glib -no-iconv -no-separate-debug-info -nomake tests -nomake examples -nomake tools -no-pkg-config -I /data/arm-linux/libs/tslib-1.12-arm/include -L /data/arm-linux/libs/tslib-1.12-arm/lib

 2. 编译及安装

 2.1 编译

执行编译命令：

$ make

Make过程可能发生以下错误：

错误1：

In file included from qtiffhandler.cpp:40:0:
tiffio.h:33:18: fatal error: tiff.h: No such file or directory
compilation terminated.
Makefile:1357: recipe for target '.obj/qtiffhandler.o' failed

解决1：

找不到tiff.h头文件，在库源码可搜索到此文件，将其复制到qtiffhandler.cpp同目录下：

$ cp ./qtimageformats/src/3rdparty/libtiff/libtiff/tiff.h ./qtimageformats/src/plugins/imageformats/tiff/

错误2：

In file included from main.cpp:37:0:
socketcanbackend.h:83:5: error: ‘canfd_frame’ does not name a type
     canfd_frame m_frame;
     ^
Makefile:944: recipe for target '.obj/main.o' failed
make[5]: *** [.obj/main.o] Error 1
make[5]: Leaving directory '/data/open_source/qt-everywhere-src-5.12.8/qtserialbus/src/plugins/canbus/socketcan'
Makefile:75: recipe for target 'sub-socketcan-make_first' failed
make[4]: *** [sub-socketcan-make_first] Error 2

解决2：

$ vi qtserialbus/src/plugins/canbus/socketcan/socketcanbackend.cpp

In file included from main.cpp:37:0:
socketcanbackend.h:63:18: error: ‘CANFD_MAX_DLEN’ was not declared in this scope
     __u8    data[CANFD_MAX_DLEN] __attribute__((aligned(8)));
                  ^
Makefile:944: recipe for target '.obj/main.o' failed
make[5]: *** [.obj/main.o] Error 1

同样，该CANFD_MAX_DLEN移到从.cpp移到.h。

修改后：socketcanbackend.cpp

socketcanbackend.h

注：若.cpp和.h中没有这几行代码，则手动输入到.h中即可。

此外，还可能还提示类似未定义，则手动给它定义，如下：  

typedef unsigned char __u8;
typedef unsigned int __u32;
typedef __u32 canid_t;

 2.2 安装

$ make install

Install过程发生以下错误：

make[5]: Entering directory '/data/open_source/qt-everywhere-opensource-src-5.6.0/qtimageformats/src/plugins/imageformats/tiff'
arm-linux-g++ -c -pipe -O2 -std=c++0x -fvisibility=hidden -fvisibility-inlines-hidden -fno-exceptions -Wall -W -D_REENTRANT -fPIC -DQT_NO_MTDEV -DQT_NO_LIBUDEV -DQT_NO_LIBINPUT -DQT_NO_EXCEPTIONS -D_LARGEFILE64_SOURCE -D_LARGEFILE_SOURCE -DQT_NO_DEBUG -DQT_PLUGIN -DQT_GUI_LIB -DQT_CORE_LIB -I. -I/data/arm-linux/libs/tslib-1.12-arm/include -I/data/open_source/qt-everywhere-opensource-src-5.6.0/qtbase/include -I/data/open_source/qt-everywhere-opensource-src-5.6.0/qtbase/include/QtGui -I/data/open_source/qt-everywhere-opensource-src-5.6.0/qtbase/include/QtCore -I.moc -I/data/open_source/qt-everywhere-opensource-src-5.6.0/qtbase/mkspecs/linux-arm-gnueabi-g++ -o .obj/qtiffhandler.o qtiffhandler.cpp
qtiffhandler.cpp:40:20: fatal error: tiffio.h: No such file or directory
compilation terminated.
Makefile:1357: recipe for target '.obj/qtiffhandler.o' failed
make[5]: *** [.obj/qtiffhandler.o] Error 1
make[5]: Leaving directory '/data/open_source/qt-everywhere-opensource-src-5.6.0/qtimageformats/src/plugins/imageformats/tiff'
Makefile:134: recipe for target 'sub-tiff-install_subtargets' failed
make[4]: *** [sub-tiff-install_subtargets] Error 2
make[4]: Leaving directory '/data/open_source/qt-everywhere-opensource-src-5.6.0/qtimageformats/src/plugins/imageformats'
Makefile:54: recipe for target 'sub-imageformats-install_subtargets' failed
make[3]: *** [sub-imageformats-install_subtargets] Error 2
make[3]: Leaving directory '/data/open_source/qt-everywhere-opensource-src-5.6.0/qtimageformats/src/plugins'
Makefile:55: recipe for target 'sub-plugins-install_subtargets' failed
make[2]: *** [sub-plugins-install_subtargets] Error 2
make[2]: Leaving directory '/data/open_source/qt-everywhere-opensource-src-5.6.0/qtimageformats/src'
Makefile:55: recipe for target 'sub-src-install_subtargets' failed
make[1]: *** [sub-src-install_subtargets] Error 2
make[1]: Leaving directory '/data/open_source/qt-everywhere-opensource-src-5.6.0/qtimageformats'
Makefile:159: recipe for target 'module-qtimageformats-install_subtargets' failed
make: *** [module-qtimageformats-install_subtargets] Error 2

未解待解

注：虽然报错了，但在安装目录下也安装了库，可当作安装成功，暂跳过此步，实验证明库可以正常使用，可能未安装完全而已。继续下面的操作，回来再解。

 3. 测试

 3.1 测试程序

编写测试程序如下：

$ vi qt_ts.cpp

#include <QApplication>
#include <QWidget>
#include <QLabel>
#include <QSlider>
#include <QHBoxLayout>
 
int main(int argc, char **argv)
{
	QApplication app(argc, argv);
	QWidget *window  = new QWidget;
	window->setWindowTitle("I am a slider");
 
	QLabel *label = new QLabel;		// QLabel控件，用于显示数字
	QSlider *slider = new QSlider(Qt::Horizontal);		// 滑动条
	slider->setRange(0, 100);
 
	QObject::connect(slider, SIGNAL(valueChanged(int)), label, SLOT(setNum(int)));
	slider->setValue(50);
 
	QHBoxLayout *layout = new QHBoxLayout;	//level 
	layout->addWidget(label);
	layout->addWidget(slider);
	window->setLayout(layout);
 
	window->resize(400, 240);
 
	window->show();
 
	return app.exec();
}

可先在PC端测试：（若ubuntu未安装qt则跳过此步）

$ qmake –project

$ vi qt_ts.pro

在qt_ts.pro中加入一行：QT += widgets

$ qmake

$ make

PC端验证成功！ 

 3.2 交叉编译

qmake用交叉编译出来的库的bin目录下的，如/data/arm-linux/libs/qt-5.6.0-arm/bin/qmake

相同的步骤：

最后编译出来的可执行文件为qt_ts，通过file命令可知其是ARM格式的。 

 3.3 移植到开发板

交叉编译出来的QT库有以下目录：

bin  doc  include  lib  mkspecs  plugins

将交叉编译出来的库移植到开发板的/lib目录下，或其他目录（需设置环境变量LD_LIBRARY_PATH）。

如将整个库qt-5.6.0-arm（或lib和plugins）移到开发板的/lib/下，并命名为qt-5.6.0。

Qt库在开发板下的路径：/lib/qt-5.6.0

编译程序时要链接的为.so动态库文件，在lib目录下，因此配置环境变量：

$ export LD_LIBRARY_PATH=$LD_LIBRARY_PATH: /lib/qt-5.6.0/lib

将测试程序qt_ts也放于开发板上。

移植好库及设置好环境变量后，运行程序：

[root@GEC210 mnt]#./qt_ts 
This application failed to start because it could not find or load the Qt platform plugin "xcb"
in "".

Reinstalling the application may fix this problem.
Aborted

这是因为运行环境还没有配置好，详见下节。

 3.4 配置运行环境

在/etc/profile中添加以下环境变量：

不带触摸屏tslib的：

# qt-lib environment variables

export QT_ROOT=/lib/qt-5.6.0

export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$QT_ROOT/lib/

export QT_QPA_PLATFORM_PLUGIN_PATH=$QT_ROOT/plugins

export QT_QPA_PLATFORM=linuxfb:tty=/dev/fb0

export QT_QPA_FONTDIR=/usr/share/fonts/SourceHanSans

# qt-lib environment variables
export QT_ROOT=/lib/qt-5.6.0
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$QT_ROOT/lib/
export QT_QPA_PLATFORM_PLUGIN_PATH=$QT_ROOT/plugins
export QT_QPA_PLATFORM=linuxfb:tty=/dev/fb0
export QT_QPA_FONTDIR=/usr/share/fonts/SourceHanSans
export QT_QPA_GENERIC_PLUGINS=tslib
export LD_PRELOAD=$TS_ROOT/lib/libts.so

QFontDatabase: Cannot find font directory /lib/qt-5.12.8/lib/fonts.
Note that Qt no longer ships fonts. Deploy some (from https://dejavu-fonts.github.io/ for example) or switch to fontconfig.
QFontDatabase: Cannot find font directory /lib/qt-5.12.8/lib/fonts.
Note that Qt no longer ships fonts. Deploy some (from https://dejavu-fonts.github.io/ for example) or switch to fontconfig.
QFontDatabase: Cannot find font directory /lib/qt-5.12.8/lib/fonts.
Note that Qt no longer ships fonts. Deploy some (from https://dejavu-fonts.github.io/ for example) or switch to fontconfig.

若QT插件出现问题，如：

This application failed to start because it could not find or load the Qt platform plugin "linuxfb"
in "/lib/qt-5.6.0/plugins".

Available platform plugins are: linuxfb, minimal, offscreen.

Reinstalling the application may fix this problem.

可通过以下变量来调试追踪：

$ export QT_DEBUG_PLUGINS=1

QFactoryLoader::QFactoryLoader() checking directory path "/face_sys/platforms" ...
loaded library "/lib/qt-5.6.0/plugins/platforms/libqlinuxfb.so"
QLibraryPrivate::loadPlugin failed on "/lib/qt-5.6.0/plugins/platforms/libqlinuxfb.so" : "Cannot load library /lib/qt-5.6.0/plugins/platforms/libqlinuxfb.so: (libts.so.0: cannot open shared object file: No such file or directory)"
This application failed to start because it could not find or load the Qt platform plugin "linuxfb"
in "/lib/qt-5.6.0/plugins".

Available platform plugins are: linuxfb, minimal, offscreen.

Reinstalling the application may fix this problem.

由上可知：缺少libts.so.0库，补上即可。