How to show on QML (Qt) from SQLite BLOB data as image? - qt

Question

My code is like below.
Name - as TEXT field,
Photo - as BLOB data
class SqlQueryModel: public QSqlQueryModel
{
Q_OBJECT
QHash<int,QByteArray> *hash;
public:
explicit SqlQueryModel(QObject * parent) : QSqlQueryModel(parent)
{
hash = new QHash<int,QByteArray>;
hash->insert(Qt::UserRole, QByteArray("Name"));
hash->insert(Qt::UserRole + 1, QByteArray("Photo"));
}
inline RoleNameHash roleNames() const { return *hash; }
};
Selecting data
view = new QQuickView();
QSqlQueryModel *someSqlModel = new SqlQueryModel(this);
someSqlModel->setQuery("SELECT Name, Photo FROM some_table");
QQmlContext *context = view->rootContext();
context->setContextProperty("someSqlModel", someSqlModel);
view->setSource(QUrl("qrc:///MainView.qml"));
view->show();
Binding in QML
ListView {
id: someListView
model: SqlContactModel {}
delegate: ItemDelegate {
text: Name
Image {
id: Photo
source: ???
}
}
}
How to show on QML (Qt) from SQLite BLOB data as image?

Answer 1

You have three options:
let the model hand out some ID and use that with a QQuickImageProvider
let the model hand out a QImage and write a custom item that can display that
let the model hand out the image data as a data URI
For (2) the simplest solution is a QQuickPaintedItem derived class, something like this
class QImageItem : public QQuickPaintedItem
{
Q_OBJECT
Q_PROPERTY(QImage image READ image WRITE setImage NOTIFY imageChanged)
public:
explicit QImageItem(QQuickItem *parent = Q_NULLPTR) : QQuickPaintedItem(parent) {}
QImage image() const { return m_image; }
void setImage(const QImage &image);
void paint(QPainter *painter) Q_DECL_OVERRIDE;
private:
QImage m_image;
};
void QImageItem::setImage(const QImage &image)
{
m_image = image;
emit imageChanged();
update();
setImplicitWidth(m_image.width());
setImplicitHeight(m_image.height());
}
void QImageItem::paint(QPainter *painter)
{
if (m_image.isNull()) return;
painter.drawImage(m_image.scaled(width(), height()));
}
Register as usual with qmlRegisterType<QImageItem>("SomeModuleName", 1, 0, "SomeTypeName") and in QML import SomeModuleName 1.0 and use SomeTypeName in instead of Image, with the QImage returned by the model bound to the item's image property