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50
51
52#include <qqmlextensionplugin.h>
53
54#include <qqmlengine.h>
55#include <qquickimageprovider.h>
56#include <QDebug>
57#include <QImage>
58#include <QThreadPool>
59
60class AsyncImageResponseRunnable : public QObject, public QRunnable
61{
62 Q_OBJECT
63
64signals:
65 void done(QImage image);
66
67public:
68 AsyncImageResponseRunnable(const QString &id, const QSize &requestedSize)
69 : m_id(id), m_requestedSize(requestedSize) {}
70
71 void run() override
72 {
73 auto image = QImage(50, 50, QImage::Format_RGB32);
74 if (m_id == QLatin1String("slow")) {
75 qDebug() << "Slow, red, sleeping for 5 seconds";
76 QThread::sleep(5);
77 image.fill(color: Qt::red);
78 } else {
79 qDebug() << "Fast, blue, sleeping for 1 second";
80 QThread::sleep(1);
81 image.fill(color: Qt::blue);
82 }
83 if (m_requestedSize.isValid())
84 image = image.scaled(s: m_requestedSize);
85
86 emit done(image);
87 }
88
89private:
90 QString m_id;
91 QSize m_requestedSize;
92};
93
94class AsyncImageResponse : public QQuickImageResponse
95{
96 public:
97 AsyncImageResponse(const QString &id, const QSize &requestedSize, QThreadPool *pool)
98 {
99 auto runnable = new AsyncImageResponseRunnable(id, requestedSize);
100 connect(sender: runnable, signal: &AsyncImageResponseRunnable::done, receiver: this, slot: &AsyncImageResponse::handleDone);
101 pool->start(runnable);
102 }
103
104 void handleDone(QImage image) {
105 m_image = image;
106 emit finished();
107 }
108
109 QQuickTextureFactory *textureFactory() const override
110 {
111 return QQuickTextureFactory::textureFactoryForImage(image: m_image);
112 }
113
114 QImage m_image;
115};
116
117class AsyncImageProvider : public QQuickAsyncImageProvider
118{
119public:
120 QQuickImageResponse *requestImageResponse(const QString &id, const QSize &requestedSize) override
121 {
122 AsyncImageResponse *response = new AsyncImageResponse(id, requestedSize, &pool);
123 return response;
124 }
125
126private:
127 QThreadPool pool;
128};
129
130
131class ImageProviderExtensionPlugin : public QQmlEngineExtensionPlugin
132{
133 Q_OBJECT
134 Q_PLUGIN_METADATA(IID QQmlEngineExtensionInterface_iid)
135public:
136 void initializeEngine(QQmlEngine *engine, const char *uri) override
137 {
138 Q_UNUSED(uri);
139 engine->addImageProvider(id: "async", new AsyncImageProvider);
140 }
141
142};
143
144#include "imageresponseprovider.moc"
145

source code of qtdeclarative/examples/quick/imageresponseprovider/imageresponseprovider.cpp