Do not store an explicit QImage in the declarative pixmap cache.

This opens up for the scene graph adaptation only storing textures which
effectively halves the memory usage for textures and images.

Change-Id: I3452a15844ceeb4fc3a465865f99ee16e3e05607
Reviewed-by: Aaron Kennedy <aaron.kennedy@nokia.com>

4 files changed, 65 insertions, 73 deletions

diff --git a/src/qml/qml/qqmlimageprovider.cpp b/src/qml/qml/qqmlimageprovider.cpp
index 863093033a..756b943fc0 100644
--- a/src/qml/qml/qqmlimageprovider.cpp
+++ b/src/qml/qml/qqmlimageprovider.cpp
@@ -70,6 +70,23 @@ QQuickTextureFactory::~QQuickTextureFactory()
 }
 
 
+/*!
+    \fn QImage QQuickTextureFactory::image() const
+
+    Returns an image version of this texture.
+
+    The lifespan of the returned image is unknown, so the implementation should
+    return a self contained QImage, not make use of the QImage(uchar *, ...)
+    constructor.
+
+    This function is not commonly used and is expected to be slow.
+ */
+
+QImage QQuickTextureFactory::image() const
+{
+    return QImage();
+}
+
 
 /*!
     \fn QSGTexture *QQuickTextureFactory::createTexture() const
diff --git a/src/qml/qml/qqmlimageprovider.h b/src/qml/qml/qqmlimageprovider.h
index fe06925123..da4d8c8248 100644
--- a/src/qml/qml/qqmlimageprovider.h
+++ b/src/qml/qml/qqmlimageprovider.h
@@ -64,6 +64,7 @@ public:
     virtual QSGTexture *createTexture(QQuickCanvas *canvas) const = 0;
     virtual QSize textureSize() const = 0;
     virtual int textureByteCount() const = 0;
+    virtual QImage image() const;
 };
 
 class Q_QML_EXPORT QQmlImageProvider
diff --git a/src/quick/util/qquickpixmapcache.cpp b/src/quick/util/qquickpixmapcache.cpp
index aae5306aa7..6ebdf57c22 100644
--- a/src/quick/util/qquickpixmapcache.cpp
+++ b/src/quick/util/qquickpixmapcache.cpp
@@ -83,6 +83,16 @@ QSGTexture *QQuickDefaultTextureFactory::createTexture(QQuickCanvas *) const
     return t;
 }
 
+static QQuickTextureFactory *textureFactoryForImage(const QImage &image)
+{
+    if (image.isNull())
+        return 0;
+    QQuickTextureFactory *texture = QSGContext::createTextureFactoryFromImage(image);
+    if (texture)
+        return texture;
+    return new QQuickDefaultTextureFactory(image);
+}
+
 class QQuickPixmapReader;
 class QQuickPixmapData;
 class QQuickPixmapReply : public QObject
@@ -104,16 +114,14 @@ public:
 
     class Event : public QEvent {
     public:
-        Event(ReadError, const QString &, const QSize &, QQuickTextureFactory *factory, const QImage &image);
+        Event(ReadError, const QString &, const QSize &, QQuickTextureFactory *factory);
 
         ReadError error;
         QString errorString;
         QSize implicitSize;
-        QImage image;
         QQuickTextureFactory *textureFactory;
     };
-    void postReply(ReadError, const QString &, const QSize &, const QImage &image);
-    void postReply(ReadError, const QString &, const QSize &, QQuickTextureFactory *factory, const QImage &image);
+    void postReply(ReadError, const QString &, const QSize &, QQuickTextureFactory *factory);
 
 
 Q_SIGNALS:
@@ -208,27 +216,21 @@ public:
         declarativePixmaps.insert(pixmap);
     }
 
-    QQuickPixmapData(QQuickPixmap *pixmap, const QUrl &u, const QImage &p, const QSize &s, const QSize &r)
+    QQuickPixmapData(QQuickPixmap *pixmap, const QUrl &u, QQuickTextureFactory *texture, const QSize &s, const QSize &r)
     : refCount(1), inCache(false), privatePixmap(false), pixmapStatus(QQuickPixmap::Ready),
-      url(u), image(p), implicitSize(s), requestSize(r), textureFactory(new QQuickDefaultTextureFactory(p)), reply(0), prevUnreferenced(0),
+      url(u), implicitSize(s), requestSize(r), textureFactory(texture), reply(0), prevUnreferenced(0),
       prevUnreferencedPtr(0), nextUnreferenced(0)
     {
         declarativePixmaps.insert(pixmap);
     }
 
-    QQuickPixmapData(QQuickPixmap *pixmap, const QUrl &u, QQuickTextureFactory *factory, const QImage &p, const QSize &s, const QSize &r)
-    : refCount(1), inCache(false), privatePixmap(false), pixmapStatus(QQuickPixmap::Ready),
-      url(u), image(p), implicitSize(s), requestSize(r), textureFactory(factory), reply(0), prevUnreferenced(0),
-      prevUnreferencedPtr(0), nextUnreferenced(0)
-    {
-        declarativePixmaps.insert(pixmap);
-    }
-
-    QQuickPixmapData(QQuickPixmap *pixmap, const QImage &p)
+    QQuickPixmapData(QQuickPixmap *pixmap, QQuickTextureFactory *texture)
     : refCount(1), inCache(false), privatePixmap(true), pixmapStatus(QQuickPixmap::Ready),
-      image(p), implicitSize(p.size()), requestSize(p.size()), textureFactory(new QQuickDefaultTextureFactory(p)), reply(0), prevUnreferenced(0),
+      textureFactory(texture), reply(0), prevUnreferenced(0),
       prevUnreferencedPtr(0), nextUnreferenced(0)
     {
+        if (texture)
+            requestSize = implicitSize = texture->textureSize();
         declarativePixmaps.insert(pixmap);
     }
 
@@ -256,7 +258,6 @@ public:
     QQuickPixmap::Status pixmapStatus;
     QUrl url;
     QString errorString;
-    QImage image;
     QSize implicitSize;
     QSize requestSize;
 
@@ -284,22 +285,14 @@ int QQuickPixmapReader::threadNetworkRequestDone = -1;
 
 
 void QQuickPixmapReply::postReply(ReadError error, const QString &errorString,
-                                        const QSize &implicitSize, const QImage &image)
+                                        const QSize &implicitSize, QQuickTextureFactory *factory)
 {
     loading = false;
-    QCoreApplication::postEvent(this, new Event(error, errorString, implicitSize, new QQuickDefaultTextureFactory(image), image));
+    QCoreApplication::postEvent(this, new Event(error, errorString, implicitSize, factory));
 }
 
-void QQuickPixmapReply::postReply(ReadError error, const QString &errorString,
-                                        const QSize &implicitSize, QQuickTextureFactory *factory,
-                                        const QImage &image)
-{
-    loading = false;
-    QCoreApplication::postEvent(this, new Event(error, errorString, implicitSize, factory, image));
-}
-
-QQuickPixmapReply::Event::Event(ReadError e, const QString &s, const QSize &iSize, QQuickTextureFactory *factory, const QImage &i)
-    : QEvent(QEvent::User), error(e), errorString(s), implicitSize(iSize), image(i), textureFactory(factory)
+QQuickPixmapReply::Event::Event(ReadError e, const QString &s, const QSize &iSize, QQuickTextureFactory *factory)
+    : QEvent(QEvent::User), error(e), errorString(s), implicitSize(iSize), textureFactory(factory)
 {
 }
 
@@ -431,13 +424,8 @@ void QQuickPixmapReader::networkRequestDone(QNetworkReply *reply)
        }
         // send completion event to the QQuickPixmapReply
         mutex.lock();
-        if (!cancelled.contains(job)) {
-            QQuickTextureFactory *factory = QSGContext::createTextureFactoryFromImage(image);
-            if (factory)
-                job->postReply(error, errorString, readSize, factory, image);
-            else
-                job->postReply(error, errorString, readSize, image);
-        }
+        if (!cancelled.contains(job))
+            job->postReply(error, errorString, readSize, textureFactoryForImage(image));
         mutex.unlock();
     }
     reply->deleteLater();
@@ -524,7 +512,7 @@ void QQuickPixmapReader::processJob(QQuickPixmapReply *runningJob, const QUrl &u
             QImage image;
             mutex.lock();
             if (!cancelled.contains(runningJob))
-                runningJob->postReply(errorCode, errorStr, readSize, image);
+                runningJob->postReply(errorCode, errorStr, readSize, textureFactoryForImage(image));
             mutex.unlock();
         } else if (imageType == QQmlImageProvider::Image) {
             QImage image = ep->getImageFromProvider(url, &readSize, requestSize);
@@ -535,14 +523,8 @@ void QQuickPixmapReader::processJob(QQuickPixmapReply *runningJob, const QUrl &u
                 errorStr = QQuickPixmap::tr("Failed to get image from provider: %1").arg(url.toString());
             }
             mutex.lock();
-            if (!cancelled.contains(runningJob)) {
-                QQuickTextureFactory *factory = QSGContext::createTextureFactoryFromImage(image);
-                if (factory)
-                    runningJob->postReply(errorCode, errorStr, readSize, factory, image);
-                else
-                    runningJob->postReply(errorCode, errorStr, readSize, image);
-            }
-
+            if (!cancelled.contains(runningJob))
+                runningJob->postReply(errorCode, errorStr, readSize, textureFactoryForImage(image));
             mutex.unlock();
         } else {
             QQuickTextureFactory *t = ep->getTextureFromProvider(url, &readSize, requestSize);
@@ -554,7 +536,7 @@ void QQuickPixmapReader::processJob(QQuickPixmapReply *runningJob, const QUrl &u
             }
             mutex.lock();
             if (!cancelled.contains(runningJob))
-                runningJob->postReply(errorCode, errorStr, readSize, t, QImage());
+                runningJob->postReply(errorCode, errorStr, readSize, t);
             mutex.unlock();
 
         }
@@ -576,13 +558,8 @@ void QQuickPixmapReader::processJob(QQuickPixmapReply *runningJob, const QUrl &u
                 errorCode = QQuickPixmapReply::Loading;
             }
             mutex.lock();
-            if (!cancelled.contains(runningJob)) {
-                QQuickTextureFactory *factory = QSGContext::createTextureFactoryFromImage(image);
-                if (factory)
-                    runningJob->postReply(errorCode, errorStr, readSize, factory, image);
-                else
-                    runningJob->postReply(errorCode, errorStr, readSize, image);
-            }
+            if (!cancelled.contains(runningJob))
+                runningJob->postReply(errorCode, errorStr, readSize, textureFactoryForImage(image));
             mutex.unlock();
         } else {
             // Network resource
@@ -863,10 +840,7 @@ bool QQuickPixmapReply::event(QEvent *event)
             data->pixmapStatus = (de->error == NoError) ? QQuickPixmap::Ready : QQuickPixmap::Error;
 
             if (data->pixmapStatus == QQuickPixmap::Ready) {
-                if (de->textureFactory) {
-                    data->textureFactory = de->textureFactory;
-                }
-                data->image = de->image;
+                data->textureFactory = de->textureFactory;
                 data->implicitSize = de->implicitSize;
             } else {
                 data->errorString = de->errorString;
@@ -888,7 +862,7 @@ int QQuickPixmapData::cost() const
 {
     if (textureFactory)
         return textureFactory->textureByteCount();
-    return image.byteCount();
+    return 0;
 }
 
 void QQuickPixmapData::addref()
@@ -957,7 +931,7 @@ static QQuickPixmapData* createPixmapDataSync(QQuickPixmap *declarativePixmap, Q
                 QQuickTextureFactory *texture = ep->getTextureFromProvider(url, &readSize, requestSize);
                 if (texture) {
                     *ok = true;
-                    return new QQuickPixmapData(declarativePixmap, url, texture, QImage(), readSize, requestSize);
+                    return new QQuickPixmapData(declarativePixmap, url, texture, readSize, requestSize);
                 }
             }
 
@@ -966,7 +940,7 @@ static QQuickPixmapData* createPixmapDataSync(QQuickPixmap *declarativePixmap, Q
                 QImage image = ep->getImageFromProvider(url, &readSize, requestSize);
                 if (!image.isNull()) {
                     *ok = true;
-                    return new QQuickPixmapData(declarativePixmap, url, image, readSize, requestSize);
+                    return new QQuickPixmapData(declarativePixmap, url, textureFactoryForImage(image), readSize, requestSize);
                 }
             }
             case QQmlImageProvider::Pixmap:
@@ -974,7 +948,7 @@ static QQuickPixmapData* createPixmapDataSync(QQuickPixmap *declarativePixmap, Q
                 QPixmap pixmap = ep->getPixmapFromProvider(url, &readSize, requestSize);
                 if (!pixmap.isNull()) {
                     *ok = true;
-                    return new QQuickPixmapData(declarativePixmap, url, pixmap.toImage(), readSize, requestSize);
+                    return new QQuickPixmapData(declarativePixmap, url, textureFactoryForImage(pixmap.toImage()), readSize, requestSize);
                 }
             }
         }
@@ -997,7 +971,7 @@ static QQuickPixmapData* createPixmapDataSync(QQuickPixmap *declarativePixmap, Q
 
         if (readImage(url, &f, &image, &errorString, &readSize, requestSize)) {
             *ok = true;
-            return new QQuickPixmapData(declarativePixmap, url, image, readSize, requestSize);
+            return new QQuickPixmapData(declarativePixmap, url, textureFactoryForImage(image), readSize, requestSize);
         }
         errorString = QQuickPixmap::tr("Invalid image data: %1").arg(url.toString());
 
@@ -1109,10 +1083,10 @@ QQuickTextureFactory *QQuickPixmap::textureFactory() const
     return 0;
 }
 
-const QImage &QQuickPixmap::image() const
+QImage QQuickPixmap::image() const
 {
-    if (d) 
-        return d->image;
+    if (d && d->textureFactory)
+        return d->textureFactory->image();
     else
         return nullPixmap()->image;
 }
@@ -1122,29 +1096,29 @@ void QQuickPixmap::setImage(const QImage &p)
     clear();
 
     if (!p.isNull())
-        d = new QQuickPixmapData(this, p);
+        d = new QQuickPixmapData(this, textureFactoryForImage(p));
 }
 
 int QQuickPixmap::width() const
 {
-    if (d) 
-        return d->textureFactory ? d->textureFactory->textureSize().width() : d->image.width();
+    if (d && d->textureFactory)
+        return d->textureFactory->textureSize().width();
     else
         return 0;
 }
 
 int QQuickPixmap::height() const
 {
-    if (d) 
-        return d->textureFactory ? d->textureFactory->textureSize().height() : d->image.height();
+    if (d && d->textureFactory)
+        return d->textureFactory->textureSize().height();
     else
         return 0;
 }
 
 QRect QQuickPixmap::rect() const
 {
-    if (d)
-        return d->textureFactory ? QRect(QPoint(), d->textureFactory->textureSize()) : d->image.rect();
+    if (d && d->textureFactory)
+        return QRect(QPoint(), d->textureFactory->textureSize());
     else
         return QRect();
 }
diff --git a/src/quick/util/qquickpixmapcache_p.h b/src/quick/util/qquickpixmapcache_p.h
index 0b4c2fb473..b339e6f1a0 100644
--- a/src/quick/util/qquickpixmapcache_p.h
+++ b/src/quick/util/qquickpixmapcache_p.h
@@ -104,7 +104,7 @@ public:
     const QUrl &url() const;
     const QSize &implicitSize() const;
     const QSize &requestSize() const;
-    const QImage &image() const;
+    QImage image() const;
     void setImage(const QImage &);
 
     QQuickTextureFactory *textureFactory() const;