http://www.cnblogs.com/yuliyang/p/3525107.html
项目pro文件：
#-------------------------------------------------
#
# Project created by QtCreator 2014-01-18T14:39:58
#
#------------------------------------------------- QT += core gui greaterThan(QT_MAJOR_VERSION, 4): QT += widgets TARGET = opencv_vedio
TEMPLATE = app
INCLUDEPATH +=D:\program\opencv\build\include\
INCLUDEPATH +D:\program\opencv\build\include\opencv\
INCLUDEPATH +=D:\program\opencv\build\include\opencv2\ CONFIG(debug,debug|release) {
LIBS += -LD:\program\opencv\build\x86\vc10\lib \
-lopencv_core244d \
-lopencv_highgui244d \
-lopencv_imgproc244d \
-lopencv_features2d244d \
-lopencv_calib3d244d
} else {
LIBS += -LD:\program\opencv\build\x86\vc10\lib \
-lopencv_core244 \
-lopencv_highgui244 \
-lopencv_imgproc244 \
-lopencv_features2d244 \
-lopencv_calib3d244
} SOURCES += main.cpp\
dialog.cpp HEADERS += dialog.h FORMS += dialog.ui
dialog.h：
#ifndef DIALOG_H
#define DIALOG_H #include <QDialog>
#include <opencv/cv.h>
#include <opencv/highgui.h>
#include <QTimer>
#include <QPixmap>
namespace Ui {
class Dialog;
} class Dialog : public QDialog
{
Q_OBJECT public:
explicit Dialog(QWidget *parent = 0);
~Dialog(); private:
Ui::Dialog *ui;
CvCapture *capture; //highgui 里提供的一个专门处理摄像头图像的结构体
IplImage *frame; //摄像头每次抓取的图像为一帧，使用该指针指向一帧图像的内存空间
QTimer *timer; //定时器用于定时取帧，上面说的隔一段时间就去取就是用这个实现。
private slots:
void getFrame(); //实现定时从摄像头取图并显示在label上的功能。 }; #endif // DIALOG_H
dialog.cpp：
#include "dialog.h"
#include "ui_dialog.h"
#include <QDebug>
Dialog::Dialog(QWidget *parent) :
QDialog(parent),
ui(new Ui::Dialog)
{
ui->setupUi(this);
timer = new QTimer(this);
capture = cvCaptureFromCAM(0); //cvCaptureFromCAM其实是一个宏，就是cvCreateCameraCapture的别名，0代表第一个摄像头。-1代表默认摄像头。
if(capture==NULL){
qDebug()<<"error!";
}
timer->start(50); //1000为1秒，50毫秒去取一帧
connect(timer,SIGNAL(timeout()),this,SLOT(getFrame())); //超时就去取
} Dialog::~Dialog()
{
timer->stop(); //停止取帧
cvReleaseCapture(&capture); //释放资源是个好习惯
delete ui;
}
void Dialog::getFrame(){
frame = cvQueryFrame(capture); //从摄像头取帧
QImage image = QImage((const uchar*)frame->imageData, frame->width, frame->height, QImage::Format_RGB888).rgbSwapped(); //简单地转换一下为Image对象，rgbSwapped是为了显示效果色彩好一些。
ui->label->setPixmap(QPixmap::fromImage(image));
}
效果：