Qt +Opencv 在ARM-A9上视频拍照

OpenCV包含了大量的机器视觉处理算法，Qt是一个跨平台的C++图形用户界面库，一般通过OpenCV完成图像处理算法，用Qt实现人机交互接口。本文主要实现 Qt+Opencv在ARM-A9 4412上实现图像采集拍照的功能。

Opencv移植到ARM上参考上篇博客 Ubuntu14.04 Opencv2.4.9交叉编译

Qt4.7.1库采用讯为公司提供的，Qtcreator之前使用Qtcreator5.3.2，编译过程中出现各种奇葩的错误，也不知道为什么，后来使用Qtcreator2.6.1就基本没出现那

些奇怪的问题了。本人目前对Qt还不是很熟，出现这样问题留给以后解决…

摄像头采用某宝上普通的USB摄像头。

打开Qtcreator，新建一个Qt Gui工程，首先修改.pro文件，包含Opencv的头文件和库文件路径。

QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = DIalogCam
TEMPLATE = app

UI_DIR=./UI

SOURCES += main.cpp\
dialog.cpp

HEADERS  += dialog.h

FORMS    += dialog.ui

#INCLUDEPATH += /opt/qt-4.7.1/include
#INCLUDEPATH += /opt/qt-4.7.1/include/QtGui

#INCLUDEPATH += /usr/local/include
#INCLUDEPATH += /usr/local/include/opencv
#INCLUDEPATH += /usr/local/include/opencv2

#LIBS += /usr/local/lib/libopencv_highgui.so
#LIBS += /usr/local/lib/libopencv_legacy.so
#LIBS += /usr/local/lib/libopencv_imgproc.so
#LIBS += /usr/local/lib/libopencv_flann.so
#LIBS += /usr/local/lib/libopencv_ml.so
#LIBS += /usr/local/lib/libopencv_core.so
#LIBS += /usr/local/lib/libopencv_photo.so
#LIBS += /usr/local/lib/libopencv_contrib.so
#LIBS += /usr/local/lib/libopencv_video.so
#LIBS += /usr/local/lib/libopencv_objdetect.so
#LIBS += /usr/local/lib/libopencv_nonfree.so
#LIBS += /usr/local/lib/libopencv_calib3d.so
#LIBS += /usr/local/lib/libopencv_features2d.so

INCLUDEPATH += /usr/local/arm/opencv-install/include/
INCLUDEPATH += /usr/local/arm/opencv-install/include/opencv
INCLUDEPATH += /usr/local/arm/opencv-install/include/opencv2

LIBS += /usr/local/arm/opencv-install/lib/libopencv_highgui.so
LIBS += /usr/local/arm/opencv-install/lib/libopencv_legacy.so
LIBS += /usr/local/arm/opencv-install/lib/libopencv_imgproc.so
LIBS += /usr/local/arm/opencv-install/lib/libopencv_flann.so
LIBS += /usr/local/arm/opencv-install/lib/libopencv_ml.so
LIBS += /usr/local/arm/opencv-install/lib/libopencv_core.so
LIBS += /usr/local/arm/opencv-install/lib/libopencv_photo.so
LIBS += /usr/local/arm/opencv-install/lib/libopencv_contrib.so
LIBS += /usr/local/arm/opencv-install/lib/libopencv_video.so
LIBS += /usr/local/arm/opencv-install/lib/libopencv_objdetect.so
LIBS += /usr/local/arm/opencv-install/lib/libopencv_nonfree.so
LIBS += /usr/local/arm/opencv-install/lib/libopencv_calib3d.so
LIBS += /usr/local/arm/opencv-install/lib/libopencv_features2d.so

上面Opencv路径是安装在ubuntu上x86架构opencv，下面是交叉编译的ARM架构opencv，在ubuntu上或者ARM上运行分别包含对应的路径。一般先在PC上调试，再在板子上运行。

在dialog.ui加上一个lable和四个button

dialog.cpp部分

#include "dialog.h"
#include "ui_dialog.h"
#include "switch.h"
#include "QtGui"

Dialog::Dialog(QWidget *parent) :
QDialog(parent),
ui(new Ui::Dialog)
{
ui->setupUi(this);

cam     = NULL;
timer   = new QTimer(this);
imag    = new QImage();

/*信号和槽*/
connect(timer, SIGNAL(timeout()), this, SLOT(readFarme()));  // 时间到，读取当前摄像头信息
connect(ui->openCam, SIGNAL(clicked()), this, SLOT(openCamara()));
connect(ui->closeCam, SIGNAL(clicked()), this, SLOT(closeCamara()));
connect(ui->savePic, SIGNAL(clicked()), this, SLOT(takingPictures()));
connect(ui->openPic, SIGNAL(clicked()), this, SLOT(OpenPictures()));
}

void Dialog::openCamara()
{
cam = cvCreateCameraCapture(204);//204
timer->start(33);              // 开始计时，超时则发出timeout()信号
}

void Dialog::readFarme()
{
frame = cvQueryFrame(cam);

QImage image = QImage((const uchar*)frame->imageData, frame->width, frame->height,
QImage::Format_RGB888).rgbSwapped();
ui->label->setPixmap(QPixmap::fromImage(image));
//    ui->label->resize(image.width(),image.height());
}

void Dialog::closeCamara()
{
timer->stop();         // 停止读取数据。

cvReleaseCapture(&cam);//释放内存；

ui->label->setPixmap(NULL);
}

void Dialog::takingPictures()
{
cvSaveImage("saveImage.jpg",frame);
}

void Dialog::OpenPictures()
{
timer->stop();         // 停止读取数据。
cvReleaseCapture(&cam);//释放内存；
ui->label->setPixmap(NULL);

QString filename;
filename=QFileDialog::getOpenFileName(this,
tr("Choose Picture"),
"",
tr("Images (*.png *.bmp *.jpg *.tif *.GIF )"));
if(filename.isEmpty())
{
return ;
}
else
{
if(! ( imag->load(filename) ) ) //加载图像
{
return ;
}
ui->label->setPixmap(QPixmap::fromImage(*imag));
}
}

Dialog::~Dialog()
{
delete ui;
delete timer;
delete imag;
delete frame;
}

我的4412板子USB摄像头设备节点是/dev/video4，其中 cam =cvCreateCameraCapture(204) 部分，这个函数意思打开video4，网上讨论括号里参数可以是0 -1 202 ，需要根据自己实际情况修改，我在ubuntu运行 0 -1都可以。

dialog.h部分

#ifndef DIALOG_H
#define DIALOG_H

#include <QDialog>
#include <QImage>
#include <QTimer>     // 设置采集数据的间隔时间

#include "highgui.h"  //包含opencv库头文件
#include "cv.h"

namespace Ui {
class Dialog;
}

class Dialog : public QDialog
{
Q_OBJECT

public:
explicit Dialog(QWidget *parent = 0);
~Dialog();

private slots:
void openCamara();      // 打开摄像头
void readFarme();       // 读取当前帧信息
void closeCamara();     // 关闭摄像头
void takingPictures();  // 拍照
void OpenPictures();

private:
Ui::Dialog *ui;
QTimer    *timer;
QImage    *imag;
CvCapture *cam;// 视频获取结构， 用来作为视频获取函数的一个参数
IplImage  *frame;//申请IplImage类型指针，就是申请内存空间来存放每一帧图像
};

#endif // DIALOG_H

使用qtcreator在release目录下生成可执行文件，通过file命令查看是x86-64架构，不能在ARM上运行。

root@ubuntu:/home/itop/Qtwork/DIalogCam/DIalogCam-build-Desktop-Release# file DIalogCam

DIalogCam: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.24, BuildID[sha1]=21ccf5af51609796c148650ece5a45903c4b99ac, not stripped

在工程目录下运行qt-4.7.1的qmake，生成makefile文件，最后再make生成ARM可运行文件

root@ubuntu:/home/itop/Qtwork/DIalogCam# /opt/qt-4.7.1/bin/qmake

root@ubuntu:/home/itop/Qtwork/DIalogCam# make

root@ubuntu:/home/itop/Qtwork/DIalogCam# file DIalogCam

DIalogCam: ELF 32-bit LSB executable, ARM, EABI5 version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.14, not stripped

哈哈，至此就可以把生成可运行文件拷贝到板子上run了...

./DIalogCam -qws &

看下实际效果图