QQuickImageProvider在QML设计中的应用

Column {
    Image { source: "image://colors/yellow" }
    Image { source: "image://colors/red" }
}

#ifndef MYIMAGEPROVIDER_H
#define MYIMAGEPROVIDER_H

#include <QQuickImageProvider>
class QNetworkAccessManager;

class MyImageProvider : public QQuickImageProvider
{
public:
    MyImageProvider(ImageType type, Flags flags = 0);
    ~MyImageProvider();
    QImage requestImage(const QString & id, QSize * size, const QSize & requestedSize);

protected:
    QNetworkAccessManager *manager;
};

#endif // MYIMAGEPROVIDER_H

#include "myimageprovider.h"

#include <QNetworkAccessManager>
#include <QNetworkReply>
#include <QEventLoop>

MyImageProvider::MyImageProvider(ImageType type, Flags flags) :
    QQuickImageProvider(type,flags)
{
    manager = new QNetworkAccessManager;
}

MyImageProvider::~MyImageProvider()
{
    delete manager;
}

QImage MyImageProvider::requestImage(const QString &id, QSize *size, const QSize &requestedSize)
{
    qDebug() << "id: " << id;
    qDebug() << "reequestedSize: " << requestedSize.width() + " " + requestedSize.height();
    QUrl url("http://lorempixel.com/" + id);
    QNetworkReply* reply = manager->get(QNetworkRequest(url));
    QEventLoop eventLoop;
    QObject::connect(reply, SIGNAL(finished()), &eventLoop, SLOT(quit()));
    eventLoop.exec();
    if (reply->error() != QNetworkReply::NoError)
        return QImage();
    QImage image = QImage::fromData(reply->readAll());
    size->setWidth(image.width());
    size->setHeight(image.height());
    return image;
}

QQuickImageProvider(ImageType type, Flags flags = 0)
virtual	~QQuickImageProvider()
Flags	flags() const
ImageType	imageType() const
virtual QImage	requestImage(const QString & id, QSize * size, const QSize & requestedSize)
virtual QPixmap	requestPixmap(const QString & id, QSize * size, const QSize & requestedSize)
virtual QQuickTextureFactory *	requestTexture(const QString & id, QSize * size, const QSize & requestedSize)

 Image { source: "image://myprovider/500/500/" }

#include "myimageprovider.h"

int main(int argc, char *argv[])
{
    QGuiApplication app(argc, argv);

    QQuickView view;
    QQmlEngine *engine = view.engine();
    MyImageProvider *imageProvider = new MyImageProvider(QQmlImageProviderBase::Image);
    engine->addImageProvider("myprovider", imageProvider );
    view.setSource(QUrl(QStringLiteral("qrc:///Main.qml")));
    view.setResizeMode(QQuickView::SizeRootObjectToView);
    view.show();
    return app.exec();
}

main.qml

import QtQuick 2.0
import Ubuntu.Components 1.1

/*!
    \brief MainView with a Label and Button elements.
*/

MainView {
    // objectName for functional testing purposes (autopilot-qt5)
    objectName: "mainView"

    // Note! applicationName needs to match the "name" field of the click manifest
    applicationName: "imageprovider.liu-xiao-guo"

    /*
     This property enables the application to change orientation
     when the device is rotated. The default is false.
    */
    //automaticOrientation: true

    // Removes the old toolbar and enables new features of the new header.
    useDeprecatedToolbar: false

    width: units.gu(60)
    height: units.gu(85)

    Page {
        title: i18n.tr("imageprovider")

        Image {
            id: img
            anchors.centerIn: parent
            source: "image://myprovider/500/500/"
            anchors.fill: parent
            onStatusChanged: {
                if(status == Image.Ready)
                    indicator.running = false;
            }

            ActivityIndicator {
                id: indicator
                anchors.centerIn: parent
                running: false
            }

            MouseArea {
                anchors.fill: parent
                onClicked: {
                    indicator.running = true;
                    img.source = "image://myprovider/500/500/?seed=" + Math.random(1000)
                }
            }
        }
    }
}

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