Make declarative pixmap cache easier to use

The QDeclarativePixmapCache was both slow, and very trickey to use correctly.
Many QML elements did not correctly cancel outstanding requests, which leads
to pixmaps leaking indefinately.  Other elements, such as Text, were
subject to race conditions that meant they may never actually load all their
images.

QDeclarativePixmap is a single class than encapsulates the action of
fetching a pixmap, as well as the pixmap itself and the responsibility of
canceling outstanding requests.  Rather than relying on Qt's pixmap cache
that doesn't cache all the information QML needs, QDeclarativePixmap
implements its own cache, that correctly degrades over time (unlike
QPixmapCache that can stop expiring items in some conditions).

Reviewed-by: Warwick Allison
(cherry picked from commit 09f07b98dfdaec2e48749768b967a48e588d3f7f)

1 files changed, 10 insertions, 23 deletions

diff --git a/src/imports/particles/qdeclarativeparticles.cpp b/src/imports/particles/qdeclarativeparticles.cpp
index 630c068..a7c445d 100644
--- a/src/imports/particles/qdeclarativeparticles.cpp
+++ b/src/imports/particles/qdeclarativeparticles.cpp
@@ -437,7 +437,7 @@ public:
         , lifeSpanDev(1000), fadeInDur(200), fadeOutDur(300)
         , angle(0), angleDev(0), velocity(0), velocityDev(0), emissionCarry(0.)
         , addParticleTime(0), addParticleCount(0), lastAdvTime(0)
-        , motion(0), pendingPixmapCache(false), clock(this)
+        , motion(0), clock(this)
     {
     }
 
@@ -456,7 +456,7 @@ public:
     void updateOpacity(QDeclarativeParticle &p, int age);
 
     QUrl url;
-    QPixmap image;
+    QDeclarativePixmap image;
     int count;
     int emissionRate;
     qreal emissionVariance;
@@ -475,7 +475,6 @@ public:
     QDeclarativeParticleMotion *motion;
     QDeclarativeParticlesPainter *paintItem;
 
-    bool pendingPixmapCache;
 
     QList<QPair<int, int> > bursts;//countLeft, emissionRate pairs
     QList<QDeclarativeParticle> particles;
@@ -709,9 +708,6 @@ QDeclarativeParticles::QDeclarativeParticles(QDeclarativeItem *parent)
 
 QDeclarativeParticles::~QDeclarativeParticles()
 {
-    Q_D(QDeclarativeParticles);
-    if (d->pendingPixmapCache)
-        QDeclarativePixmapCache::cancel(d->url, this);
 }
 
 /*!
@@ -732,10 +728,8 @@ QUrl QDeclarativeParticles::source() const
 void QDeclarativeParticles::imageLoaded()
 {
     Q_D(QDeclarativeParticles);
-    d->pendingPixmapCache = false;
-    QString errorString;
-    if (QDeclarativePixmapCache::get(d->url, &d->image, &errorString)==QDeclarativePixmapReply::Error)
-        qmlInfo(this) << errorString;
+    if (d->image.isError())
+        qmlInfo(this) << d->image.error();
     d->paintItem->updateSize();
     d->paintItem->update();
 }
@@ -747,27 +741,20 @@ void QDeclarativeParticles::setSource(const QUrl &name)
     if ((d->url.isEmpty() == name.isEmpty()) && name == d->url)
         return;
 
-    if (d->pendingPixmapCache) {
-        QDeclarativePixmapCache::cancel(d->url, this);
-        d->pendingPixmapCache = false;
-    }
     if (name.isEmpty()) {
         d->url = name;
-        d->image = QPixmap();
+        d->image.clear(this);
         d->paintItem->updateSize();
         d->paintItem->update();
     } else {
         d->url = name;
         Q_ASSERT(!name.isRelative());
-        QString errorString;
-        QDeclarativePixmapReply::Status status = QDeclarativePixmapCache::get(d->url, &d->image, &errorString);
-        if (status != QDeclarativePixmapReply::Ready && status != QDeclarativePixmapReply::Error) {
-            QDeclarativePixmapReply *reply = QDeclarativePixmapCache::request(qmlEngine(this), d->url);
-            connect(reply, SIGNAL(finished()), this, SLOT(imageLoaded()));
-            d->pendingPixmapCache = true;
+        d->image.load(qmlEngine(this), d->url);
+        if (d->image.isLoading()) {
+            d->image.connectFinished(this, SLOT(imageLoaded()));
         } else {
-            if (status == QDeclarativePixmapReply::Error)
-                qmlInfo(this) << errorString;
+            if (d->image.isError()) 
+                qmlInfo(this) << d->image.error();
             //### unify with imageLoaded
             d->paintItem->updateSize();
             d->paintItem->update();