Dynamically set imageSource in ImageView Blackberry 10

Please help me.,i m stuck with this for more than a week.I am emitting a signal with image from my cpp file.I need to replace the default image that i placed in the imageView at QMl using this emitted image. Here is my full code.

PostHttp.hpp

/* Copyright (c) 2012 Research In Motion Limited.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

 #ifndef POSTHTTP_HPP
 #define POSTHTTP_HPP
 #include "qvariant.h"
 #include <bb/ImageData>
 #include <bb/cascades/GroupDataModel>
 #include <QtCore/QObject>
 #include <bb/data/JsonDataAccess>
 #include <bb/cascades/QListDataModel>
 #include <bb/cascades/Image>
 #include <bb/cascades/ImageView>
 #include <bb/cascades/CustomControl>
 namespace bb {
namespace cascades {
    class Container;
}
 }
  using namespace bb::cascades;

 class QNetworkAccessManager;

class PostHttp: public QObject {
Q_OBJECT
public:
PostHttp(QObject* parent = 0);
 bb::cascades::Image m_image;
 ImageView* imageView;
 Container* mRootContainer;
 bool createFolder(QString path);
 bool openAndSaveFile(QString filePathWithName, QNetworkReply* reply);
public Q_SLOTS:
void loginWebService(const QString &body, const QString &pass,
        bool istoken);
void newsFeedWebService(const qint16 num);
void logoutWebService();
void imageFetcher();
void get(const QUrl &url);
void post(const QVariantMap &body, const QUrl &url);


Q_SIGNALS:
void complete(const QVariantList &info);
void newsfeedComplete(const QVariantList &info);
void imageLoaded(const QVariant &image);

private Q_SLOTS:
void onGetReply();
void onNewsFeedReply();
void onImageReply();

Q_INVOKABLE void generatePage();
 Q_INVOKABLE void loadImages();
private:
bb::cascades::QListDataModel<QObject*>* m_model;
QImage setImage(const QImage &image);
bb::cascades::DataModel* model() const;
QNetworkAccessManager* m_networkAccessManager;
bb::data::JsonDataAccess* dataAccess;

public:
QString token;

};

#endif

PostHttp.cpp

#include "PostHttp.hpp"
#include <QDebug>
#include <QNetworkAccessManager>
#include <QNetworkReply>
#include <QNetworkRequest>
#include <QSslConfiguration>
#include <QUrl>
#include <bb/data/JsonDataAccess>
#include <QDateTime>
#include <bb/cascades/AbstractPane>
#include <bb/cascades/Application>
#include <bb/cascades/QmlDocument>
#include <bb/cascades/Page>
#include <bb/cascades/StandardListItem>
#include <QFile>
#include <bb/ImageData>
#include <QNetworkReply>
#include <QNetworkDiskCache>
#include <QDesktopServices>
#include <bb/cascades/Image>
#include <bb/cascades/Container>
#include <bb/cascades/ImageView>
#include <bb/cascades/ScalingMethod>
#include <bb/cascades/DockLayout>
#include <bb/cascades/controls/activityindicator.h>
#include <bb/cascades/controls/scrollview.h>
#include <bb/cascades/controls/page.h>
#include <bb/cascades/NavigationPaneProperties>
#include <bb/cascades/Color>
using namespace bb::data;
using namespace bb::cascades;
using namespace bb::utility;
QString globalTokenValue;
int globalUserId;
bool flag = true;
bool flag1 = true;
QVariantList data;

PostHttp::PostHttp(QObject* parent) :
    QObject(parent), m_networkAccessManager(
            new QNetworkAccessManager(this)), m_model(
            new QListDataModel<QObject*>()) {

}

//! [0]

/**
 * PostHttp::post
 *
 * Make a network request to httpbin.org/post with POST data and get
 * the response
 */
//! [1]
void PostHttp::post(const QVariantMap &body, const QUrl &url) {
JsonDataAccess jda;
QByteArray jsonData;
jda.saveToBuffer(*(&body), &jsonData);

QByteArray postDataSize = QByteArray::number(jsonData.size());
QNetworkRequest request(*(&url));

request.setHeader(QNetworkRequest::ContentTypeHeader, "application/json");
request.setHeader(QNetworkRequest::ContentLengthHeader,
        QString(postDataSize).toUtf8());
//QNetworkReply* reply = m_networkAccessManager->post(request, body.toAscii());
qDebug() << "json" << jsonData;
QNetworkReply* reply = m_networkAccessManager->post(request, jsonData);
qDebug() << "strdgfyusujnm kjh " << (&url)->toString();
if ((&url)->toString()
        ==    "http:///GetNewsFeed") {
    connect(reply, SIGNAL(finished()), this, SLOT(onNewsFeedReply()));
} else {
    connect(reply, SIGNAL(finished()), this, SLOT(onGetReply()));
}
}

void PostHttp::loginWebService(const QString &body, const QString &pass,
    bool istoken) {

qint64 date = QDateTime::currentMSecsSinceEpoch();
QString time = QString::number(date);
QVariantMap data;
QVariantMap loginData;
QVariantMap devicedata;
devicedata.insert("OS", "BlackBerry OS 6.0.0.706");
devicedata.insert("deviceId", "232BC441");
devicedata.insert("deviceModel", "9800");
devicedata.insert("screenSize", "480x360");
loginData.insert("device", devicedata);
loginData.insert("email", *(&body));
loginData.insert("password", *(&pass));
loginData.insert("requestDate", "/Date(" + time + "+200)/");
data.insert("apiKey", "4f74721be9b51f24f065b044");
data.insert("data", loginData);
data.insert("requestDate", "/Date(" + time + "+200)/");
if (istoken) {

} else {
    data.insert("token", "");
}
const QUrl url(
         "http:///LoginRequest");
post(data, url);
}

void PostHttp::newsFeedWebService(const qint16 num) {

qint64 date = QDateTime::currentMSecsSinceEpoch();
QString time = QString::number(date);
QVariantMap data;
QVariantMap newsfeedData;
newsfeedData.insert("postId", 0);
newsfeedData.insert("requestType", 2);
newsfeedData.insert("requestedCount", num);
newsfeedData.insert("userId", globalUserId);
data.insert("apiKey", "4f74721be9b51f24f065b044");
data.insert("data", newsfeedData);
data.insert("requestDate", "/Date(" + time + "+200)/");
data.insert("token", globalTokenValue);
const QUrl url(
        "http:///GetNewsFeed");
if (flag == true) {
    post(data, url);
}

}

void PostHttp::logoutWebService() {
qint64 date = QDateTime::currentMSecsSinceEpoch();
QString time = QString::number(date);
QVariantMap data;
QVariantMap logoutData;
logoutData.insert("logoutRequestType", 1);
logoutData.insert("userId", globalUserId);
data.insert("apiKey", "4f74721be9b51f24f065b044");
data.insert("data", logoutData);
data.insert("requestDate", "/Date(" + time + "+200)/");
data.insert("token", globalTokenValue);
const QUrl url(
        "http:///LogoutUser");
post(data, url);
}

void PostHttp::imageFetcher() {
const QUrl url(
        "http://upload.wikimedia.org/wikipedia/commons/e/e7/Nuvola_filesystems_services.png");
if (flag1 == true) {
    get(url);
}
}

void PostHttp::get(const QUrl &url) {
QNetworkRequest request(*(&url));
QNetworkReply* reply = m_networkAccessManager->get(request);
connect(reply, SIGNAL(finished()), this, SLOT(onImageReply()));
}
/**
 * PostHttp::onGetReply()
 *
 * SLOT
 * Read and return the http response from our http post request
 */
void PostHttp::onGetReply() {
QNetworkReply* reply = qobject_cast<QNetworkReply*>(sender());
QString response;
if (reply) {
    if (reply->error() == QNetworkReply::NoError) {
        const int available = reply->bytesAvailable();
        if (available > 0) {
            const QByteArray buffer(reply->readAll());
            response = QString::fromUtf8(buffer);
            JsonDataAccess dataAccess;
            QVariantMap results =
                       dataAccess.loadFromBuffer(response).toMap();
            QString token = (results["Token"]).value<QString>();
            int userId = (results["userId"]).value<int>();
            if (globalTokenValue == "") {
                globalTokenValue = token;
                globalUserId = userId;
            } else
                flag = false;
            QString success = (results["Success"]).value<QString>();

        }
    } else {
        response =
                tr("Error: %1 status: %2").arg(reply- >errorString(),
                        reply->attribute(
                                   QNetworkRequest::HttpStatusCodeAttribute).toString());
        qDebug() << response;
    }

    reply->deleteLater();
}

if (response.trimmed().isEmpty()) {
    response = tr("Unable to retrieve post response");
}
qDebug() << "response" << response;

}

void PostHttp::onNewsFeedReply() {

QNetworkReply* reply = qobject_cast<QNetworkReply*>(sender());
QString response;
if (reply) {
    if (reply->error() == QNetworkReply::NoError) {
        flag = false;
        const int available = reply->bytesAvailable();
        if (available > 0) {
            const QByteArray buffer(reply->readAll());
            response = QString::fromUtf8(buffer);
            JsonDataAccess dataAccess;
            QVariantMap results =
                      dataAccess.loadFromBuffer(response).toMap();
            data = results.value("Data").toList();
            qDebug() << "first element is" << data.first().toString();
            emit newsfeedComplete(data);

        }
    }
}

}
 void PostHttp::onImageReply() {
QNetworkReply* reply = qobject_cast<QNetworkReply*>(sender());
QString response;
QImage img;
QString filePathWithName = "data/img/";
QString imageName;

if (reply) {
    if (reply->error() == QNetworkReply::NoError) {
        flag1 = false;
        const int available = reply->bytesAvailable();
        if (available > 0) {
            const QByteArray buffer(reply->readAll());
            response = QString::fromUtf8(buffer);
            img.loadFromData(buffer);
            img = img.scaled(40, 40, Qt::KeepAspectRatioByExpanding);
            const QImage swappedImage = img.rgbSwapped();
            const bb::ImageData imageData = bb::ImageData::fromPixels(
                    swappedImage.bits(), bb::PixelFormat::RGBX,
                    swappedImage.width(),  swappedImage.height(),
                    swappedImage.bytesPerLine());
            QByteArray byteArray = bb::utility::ImageConverter::encode(
                    "image/png", imageData, 75);
            qDebug() << "bytearray is" << byteArray;
//              QVariant image(byteArray);
            QVariant realImage(byteArray);

            qDebug() << "imag of image is" << realImage;
            emit imageLoaded(realImage);
        }
    }
}
}
//! [1]

And finally my QML file is

NewsFeed.qml

import bb.cascades 1.0
import Network.PostHttp 1.0
import bb.cascades 1.0
import "controls"
import my.library 1.0

Page {
actions: [
    ActionItem {
        title: "Logout"
        onTriggered: {
            netpost.logoutWebService();
            Application.quit();
        }
        ActionBar.placement: ActionBarPlacement.OnBar
    }
]
id:mainpage
onCreationCompleted: {
    Qt.mainImageview = imageviewid;
}
Container {

    layout: DockLayout {
    }

    // The background image
    ImageView {
        horizontalAlignment: HorizontalAlignment.Fill
        verticalAlignment: VerticalAlignment.Fill
        imageSource: "asset:///images/background.png"
    }
    //! [0]

    Container {
        id : innercontainer

        ActivityIndicator {
            id: progressIndicator

            horizontalAlignment: HorizontalAlignment.Fill
            verticalAlignment: VerticalAlignment.Fill
            onStarted: {

            }
            onCreationCompleted: {
                progressIndicator.running = true;

            }

        }

        ListView {
            id: listView
            objectName: "listView"

            dataModel: ArrayDataModel {
                id: myListModel

            }

            // Override default GroupDataModel::itemType() behaviour, which is to return item type "header"
            listItemComponents: ListItemComponent {
                id: listcomponent
                // StandardListItem is a convivience component for lists with default cascades look and feel
                StandardListItem {
                    title: ListItemData.postText
                    description: ListItemData.postDate
                    status: ListItemData.filePath
                    imageSource: "asset:///images/4.png"
                }

            }
            layoutProperties: StackLayoutProperties {
                spaceQuota: 1.0
            }
            horizontalAlignment: HorizontalAlignment.Fill
            verticalAlignment: VerticalAlignment.Fill

        }


        Container {
            id: root
            layout: StackLayout {
            }
            Label {
                text: ListItemData.postText
                horizontalAlignment: HorizontalAlignment.Left
                verticalAlignment: VerticalAlignment.Bottom
            }
            Label {
                text: ListItemData.postDate
                //                    textStyle.fontSize: 5
                horizontalAlignment: HorizontalAlignment.Right
                verticalAlignment: VerticalAlignment.Bottom
            }

            attachedObjects: [
                QTimer {
                    id: timer
                    property int f: 0
                    interval: 5000
                    onTimeout: {
                        progressIndicator.running = false;
                        netpost.imageFetcher();
                        netpost.newsFeedWebService("10");
                    }

                },
                PostHttp {

                    id: netpost
                    onComplete: {
                        progressIndicator.running = false;
                        progressIndicator.visible = false;
                        console.log("dsfdsafs"+netpost.model)
                        timer.stop();
                    }

                    onImageLoaded:{
                        console.log("value is image from cpp jhgsdh " + image)
                        imageviewid.setImageSource(image)
                    }
                    onNewsfeedComplete: {
                        console.log("response from newsfeed is "+info)
                        myListModel.append(info)

                    }
                }

            ]
        }

        onCreationCompleted: {
            // this slot is called when declarative scene is created
            // write post creation initialization here
            console.log("Page - onCreationCompleted()")

            // enable layout to adapt to the device rotation
            // don't forget to enable screen rotation in bar-bescriptor.xml (Application->Orientation->Auto-orient)
            OrientationSupport.supportedDisplayOrientation = SupportedDisplayOrientation.All;

            // populate list view model with the sample data
            timer.start();
            //                myListModel.load("app/native/assets/mydata.json")

        }
        ImageView {
            id: imageviewid
            imageSource: "asset:///images/4.png"
            enabled: true
            loadEffect: ImageViewLoadEffect.FadeZoom

        } 
    }
}
}

Please help me with this.

So you've defined your slot with QVariant parameter however trying to emit it with QByteArray type which is returned by ImageConverter::encode() call.

Try to change that part of your code to this and give it a go:

QByteArray byteArray = bb::utility::ImageConverter::encode(QUrl(QDir::currentPath() + "/shared/camera/img.png"), imageData, 75);
QVariant image(byteArray);
emit imageLoaded(image);

Also, double check that everywhere where you declare/define this pair of signal/slot you're specified exactly the same parameter notation (ie const QVariant& in case of imageLoaded() signal and so on)

Try this sample code and implement by re-altering in your project

1.QML FILE

import bb.cascades 1.0

Page {
    content: Container {
        ListView {
            dataModel: _app.model

            function itemType (data, indexPath) {
                return data["type"];
            }
            listItemComponents: [

            ]
        }
    }
}

2.HPP FILE

#ifndef APP_HPP
#define APP_HPP

#include <QtCore/QObject>
#include <QtNetwork/QNetworkAccessManager>

#include <bb/cascades/QListDataModel>

class App: public QObject
{
    Q_OBJECT

    Q_PROPERTY(bb::cascades::DataModel *model READ model NOTIFY modelChanged)

public:
    App();
    bb::cascades::DataModel * model() const;

Q_SIGNALS:

    void modelChanged();

private Q_SLOTS:

    void handleNetworkData(QNetworkReply *reply);

private:

    mutable bb::cascades::QMapListDataModel *dataModel;


    QNetworkAccessManager networkManager;

};

#endif // APP_HPP

3.CPP FILE

#include <bb/cascades/Page>
#include <bb/cascades/QmlDocument>
#include <bb/data/JsonDataAccess>

#include "App.hpp"

using namespace bb::cascades;
using namespace bb::data;

App::App() :
{

    // Load up the QML for our view
    QmlDocument *qml = QmlDocument::create("view.qml");

    // Provide a reference to this class
    qml->setContextProperty("_app", this);

    // Create the root node of this view
    Page *view = qml->createRootNode<Page>();

    dataModel = new QMapListDataModel();

    // Hook this signal so we can respond to network replies
    connect(&networkManager, SIGNAL(finished(QNetworkReply *)), this,
            SLOT(handleNetworkData(QNetworkReply *)));

    // Do the request
    QUrl url = "http://jsonservice.com/news/headlines/";
    networkManager.get(QNetworkRequest(url));

}

DataModel * App::model() const
{
    return dataModel;
}

void App::handleNetworkData(QNetworkReply *reply)
{

    if (!reply->error()) {

        const QByteArray response(reply->readAll());

        JsonDataAccess jda;
        QVariantMap results = jda.loadFromBuffer(response).toMap();

        // Get the relevant parts we want from the JSON
        QVariantList posts = results["data"].toMap()["children"].toList();

        Q_FOREACH(QVariant post, posts) {


            dataModel->append(post);

        }

    }

    // Cleanup
    reply->deleteLater();

}

来源：https://stackoverflow.com/questions/17715533/dynamically-set-imagesource-in-imageview-blackberry-10

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