I am using QT 4.6
Nokia N8 (Symbian)
I am having a bit of a memory issue using the SlidingStackedWidget to hold nine list view widgets, that each display approx 20 items.
To try and conserve memory I am loading only the images for the currently displayed widget.
I am controlling the loading/unloading by capturing the widget event for show and hide, and using this to repolulate my model for the list view.
I am also using the PixmapCache as a mechanism to cache images that I have loaded, I have set my cache size to 2048k
My code for loading the pixmap, and populating / clearing the list model is listed below.
When I run this on the Nokia N8, and transition between widgets, I very quickly run out of memory, when loading images.
From my observations (I have included the code I use to trace memory usage) there is a mismatch between the amount of data allocated between
the populateModel and clearModel methods. When I transition to a new screen the memory allways increases, and when I clear the model, it never seems to remove enough memory.
1. I am concerned that I am misusing the PixmapCache, the help states,
"QPixmaps are automatically added to the QPixmapCache when loaded from a file; the key used is internal and can not be acquired."
Should I be bothering to cache Pixmaps as I load them, as it would appear the system is already doing this for me?
2. Does the models appendRow method take ownership of the item data?
do I need to clear the model row by row, prior to calling clear?
3. can anyone point out where I am leaking memory?
thanks in advance
Guus Davidson
#ifdef Q_OS_SYMBIAN
TInt mem, size, limit;
User::Heap().AllocSize(mem);
size = User::Heap().Size();
limit = User::Heap().MaxLength();
qDebug
() <<
QString("Heap Mem : %1").
arg(mem
);
qDebug
() <<
QString("Heap Size : %1").
arg(size
);
qDebug
() <<
QString("Heap Limit : %1").
arg(limit
);
#endif
#ifdef Q_OS_SYMBIAN
TInt mem, size, limit;
User::Heap().AllocSize(mem);
size = User::Heap().Size();
limit = User::Heap().MaxLength();
qDebug() << QString("Heap Mem : %1").arg(mem);
qDebug() << QString("Heap Size : %1").arg(size);
qDebug() << QString("Heap Limit : %1").arg(limit);
#endif
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QPixmap FileImageCache
::getPixmap(const QString
& key
) {
{
pm.load(diskCacheDirectory + "//" +key);
return pm;
}
QPixmap FileImageCache::getPixmap(const QString& key)
{
QPixmap pm;
if (!QPixmapCache::find(key, &pm))
{
pm.load(diskCacheDirectory + "//" +key);
bool result = QPixmapCache::insert(key, pm);
return pm;
}
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void DisplayWidget::populateModel()
{
if(iModelCleared == true)
{
BaseDisplayWidget::populateModel();
int defaultIconCount = 0;
if(model != 0 && iAppStoreChannel != 0)
{
QList<AppstoreItem*> items = iAppStoreChannel->getItems();
int count = items.count();
AppstoreItem* currentItem = 0;
for(int i = 0; i < count ; i++)
{
bool defaultIconUsed = true;
currentItem = items.at(i);
QString url
= currentItem
->getIconUrl
();
if(url.length() > 0)
{
QString key
= iImageCache
->getKeyForImageLocation
(url
);
if(iImageCache->containsKey(key) == true)
{
QPixmap pixmap
= iImageCache
->getPixmap
(key
);
if(!pixmap.isNull())
{
defaultIconUsed = false;
icon_image.addPixmap(pixmap);
}
else
{
defaultIconCount ++;
}
}
}
isdefaultIcon.append(defaultIconUsed);
item->setData(currentItem ->getHeadline(),ChannelListViewDelegate::headerTextRole);
item->setData(currentItem ->getDescription(),ChannelListViewDelegate::subHeaderTextrole);
if(icon_image.isNull())
{
item->setData(*icon_default,ChannelListViewDelegate::IconRole);
}
else
{
item->setData(icon_image,ChannelListViewDelegate::IconRole);
}
model->appendRow(item);
}
}
}
}
void DisplayWidget::populateModel()
{
if(iModelCleared == true)
{
BaseDisplayWidget::populateModel();
QStandardItemModel* model = dynamic_cast<QStandardItemModel*>(iListView->model());
int defaultIconCount = 0;
if(model != 0 && iAppStoreChannel != 0)
{
QList<AppstoreItem*> items = iAppStoreChannel->getItems();
int count = items.count();
AppstoreItem* currentItem = 0;
for(int i = 0; i < count ; i++)
{
bool defaultIconUsed = true;
currentItem = items.at(i);
QString url = currentItem->getIconUrl();
QIcon icon_image;
if(url.length() > 0)
{
QString key = iImageCache->getKeyForImageLocation(url);
if(iImageCache->containsKey(key) == true)
{
QPixmap pixmap= iImageCache->getPixmap(key);
if(!pixmap.isNull())
{
defaultIconUsed = false;
icon_image.addPixmap(pixmap);
}
else
{
defaultIconCount ++;
}
}
}
isdefaultIcon.append(defaultIconUsed);
QStandardItem* item = new QStandardItem();
item->setData(currentItem ->getHeadline(),ChannelListViewDelegate::headerTextRole);
item->setData(currentItem ->getDescription(),ChannelListViewDelegate::subHeaderTextrole);
if(icon_image.isNull())
{
item->setData(*icon_default,ChannelListViewDelegate::IconRole);
}
else
{
item->setData(icon_image,ChannelListViewDelegate::IconRole);
}
model->appendRow(item);
}
}
}
}
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void DisplayWidget::clearModel()
{
if(iModelCleared == false)
{
if(ptr != 0)
{
ptr->clear();
iModelCleared = true;
delete ptr;
}
}
}
void DisplayWidget::clearModel()
{
if(iModelCleared == false)
{
QStandardItemModel* ptr = dynamic_cast<QStandardItemModel*>(iListView->model());
if(ptr != 0)
{
ptr->clear();
iModelCleared = true;
delete ptr;
}
}
}
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When I use Listview with icons its causing memory leak
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