Display camera preview using Qt Mobility

ID		Creation date	28th Mar 2010
Platform	S60 5th Edition	Tested on devices	Nokia N97 Mini
Category	Qt for Symbian	Subcategory	Qt Mobility API

Keywords (APIs, classes, methods, functions): QCamera, QVideoWidget

Tip: Read this article before moving forward: Setting up environment for Qt Mobility API

Overview

Display Camera Preview on Widget using Qt Mobility APIs

Project configuration file (.Pro file)

• Add the Qt Mobility project configuration option in the .Pro file as shown below

CONFIG += mobility
MOBILITY += multimedia

Header File

#include <qcamera.h>
#include <qvideowidget.h>
 
public slots:
    void error(QCamera::Error);
private:
    void InitCamera();
 
private:
    QStackedWidget* m_stackedWidget;
    QCamera* m_camera;
    QVideoWidget* m_videoWidget;

Source File

    QGridLayout* layout = new QGridLayout;
    layout->setSpacing(0);
    layout->setMargin(0);
 
    m_videoWidget = new QVideoWidget();
 
    QPalette black(Qt::black);
    m_stackedWidget = new QStackedWidget();
    m_stackedWidget->setPalette(black);
 
    m_stackedWidget->addWidget(m_videoWidget);
 
    m_stackedWidget->setCurrentIndex(0);
    layout->addWidget(m_stackedWidget);
 
    setLayout(layout);
 
    InitCamera();

void CameraApp::InitCamera() {
    QByteArray cameraDevice = QCamera::availableDevices()[0];
    m_camera = new QCamera(cameraDevice);
 
    connect(m_camera, SIGNAL(error(QCamera::Error)), this, SLOT(error(QCamera::Error)));
 
    m_camera->setFocusMode(QCamera::AutoFocus);
 
    m_videoWidget->setMediaObject(m_camera);
    m_videoWidget->setAspectRatioMode(QVideoWidget::KeepAspectRatio);
 
    if (m_camera->state() == QCamera::ActiveState) {
        m_camera->stop();
        }
    m_camera->start();
    }

void CameraApp::error(QCamera::Error e) {
       switch (e) {
        case QCamera::CameraError: {
            QMessageBox::warning(this, "Camera error", "General camera error");
            break;
            }
        case QCamera::NotReadyToCaptureError: {
            QMessageBox::warning(this, "Camera error", "Camera not ready to capture image");
            break;
            }
        case QCamera::InvalidRequestError: {
            QMessageBox::warning(this, "Camera error", "Invalid request");
            break;
            }
        case QCamera::ServiceMissingError: {
            QMessageBox::warning(this, "Camera error", "Service missing");
            break;
            }
        case QCamera::NotSupportedFeatureError: {
            QMessageBox::warning(this, "Camera error", "Not supported feature");
            break;
            }
        default:
            break;
        };
    }

Classes

• QCamera
• QVideoWidget

Reference links

• Qt - cross-platform application and UI framework
• Qt Mobility API
• New Qt APIs Beta - Mobility Project
• SDK help

--skumar_rao 03:02, 28 March 2010 (UTC)