Reading image from QSqlTableModel

raven-worx

@gabor53
what is output of the following code in the console:

qDebug() << QImageReader::supportedImageFormats();

Also on what system are you running your application?

gabor53

Hi @raven-worx ,

The output is

("bmp", "cur", "dds", "gif", "icns", "ico", "jpeg", "jpg", "pbm", "pgm", "png", "ppm", "svg", "svgz", "tga", "tif", "tiff", "wbmp", "webp", "xbm", "xpm").
I run Qt 5.8 on Windows 10.

raven-worx

@gabor53
ok that at least ensures you can read jpg images.
Now the only possibility is that the data you retrieve from the database isn't valid imagedata.

QByteArray ba = fixModel->record (1).value ("Pic").toByteArray ();
qDebug() << ba.size() << ba;

gabor53

@raven-worx
I added it to the

void FixViewDelegate::setModelData(QWidget* editor, QSqlTableModel* fixModel, const QModelIndex& index) const {

function but it doesnt display anything. I know program execution goes from fixdb.cpp to FixViewDelegate, but it does nothing with setModelData. As this delegate supposed to handle displaying the image without clicking on the table I think something is missing. How can I render the image using this delegate each time the tableView is displayed?
The delegate so far looks like this:

#include "fixviewdelegate.h"

FixViewDelegate::FixViewDelegate(QObject* parent) : QStyledItemDelegate(parent) {
  qDebug() << "Entered fixViewDelegate (1).";
}

void FixViewDelegate::paint(QPainter* painter, const QStyleOptionViewItem& option, const QModelIndex& index) const {

  Q_UNUSED(painter);
  Q_UNUSED(option);
  Q_UNUSED(index);
}

QSize FixViewDelegate::sizeHint(const QStyleOptionViewItem& option, const QModelIndex& index) const {

  Q_UNUSED(option);
  Q_UNUSED(index);

}

void FixViewDelegate::setEditorData(QWidget* editor, const QModelIndex& index) const {

  Q_UNUSED(editor);
  Q_UNUSED(index);

}

void FixViewDelegate::setModelData(QWidget* editor, QSqlTableModel* fixModel, const QModelIndex& index) const {

  Q_UNUSED(index);
  Q_UNUSED(editor);


  qDebug() << "Entered fixViewDelegate (2).";
  QByteArray ba = fixModel->record (1).value ("Pic").toByteArray ();
  qDebug() << ba.size() << ba;

//  qDebug() << "Fixmodel pic: " << fixPic;
//  qDebug() << "Fixmodel pic size: " << fixPic.size ();

}

Thank you for your help.

raven-worx

@gabor53
2 reasons your csetModelData() isn't called:

the correct signatur for setModelData() would be: void setModelData(QWidget * editor, QAbstractItemModel * model, const QModelIndex & index) const
setModelData() is used as the name implies to set data in the model. Means when the editor has finished editing and wants to save

the correct method to reimplement is the delegates paint() and sizeHint() methods. In there you check if the column is your image column and do the work appropriately, else just call the base class implementation.

gabor53

@raven-worx
Thank you. I'm working on it.

gabor53

@raven-worx
I believe in the paint() method I need to use

void QPainter::drawPixmap(const QRectF &target, const QPixmap &pixmap, const QRectF &source)

How can I get the pixmap out of the model?

artwaw

@gabor53 of course. Model's data() method returns QVariant, you can get QByteArray this way.

gabor53

This post is deleted!

gabor53

@artwaw
The delegate's paint looks like this:

void FixViewDelegate::paint(QPainter* painter, const QStyleOptionViewItem& option, const QModelIndex& index) const {

I can get the index of the item from QModelIndex& index, but as there is no model, how can I get the QByteArray from the db (or model)?
Thank you.

gabor53

@artwaw
As I have no access to the model, is it OK to use a query to get the bytearray from the model?

SGaist

Index is your point of access to the model. See QModelIndex::data.

gabor53

@SGaist
I tried the following:

QVariant fixImg;

  fixImg = index.data (Qt::DisplayRole);

  QPixmap pixMap2;
  pixMap2 = fixImg.value<QPixmap>();

  qDebug() << "pixMap2 size: " << pixMap2.size ();
  qDebug() << "pixMap2 width: " << pixMap2.width ();

No error message, but the size is 0. Did I miss a step?
Thank you.

SGaist

Do you store a QPixmap in your model for that role ?

gabor53

It's a QByteArray.

gabor53

@SGaist
I ran

 QVariant fixImg(index.data (Qt::EditRole));

  qDebug() << "QVariant type: " << fixImg.type ();

and the result was
QVariant type: QVariant::QString

jsulm

@gabor53 said in Reading image from QSqlTableModel:

It's a QByteArray.

QByteArray of what? What and how are you storing in the DB? What is the data type of the corresponding column?

gabor53

@jsulm
QByteArray of the original image. The data type of that column is BLOB.

raven-worx

@gabor53
i asked in a post before:

QByteArray ba = fixModel->record (1).value ("Pic").toByteArray ();
qDebug() << ba.size() << ba;

in your delegates paint() method (if really a QByteArray is returned) do the following:

if( index.column() == NUMBER_OF_PIXMAP_COLUMN )
{
      QByteArray ba = index.data( ROLE_USED_IN_MODEL ).toByteArray();
     QPixmap pix;
        pix.loadFromData ( ba );
     painter->save();
         painter->translate( option.rect.topLeft() );
         painter->drawPixmap( pix );
     painter->restore();
}

I you should probably post your model code to avoid further guessing.

VRonin

I don't like index.column() == NUMBER_OF_PIXMAP_COLUMN as it ties the delegate to a single model so I consider it bad design, view->setItemDelegateForColumn() should be used instead.
index.data( ROLE_USED_IN_MODEL ) it's a QSqlTableModel so just delete ROLE_USED_IN_MODEL and use the default
It's a QStyledItemDelegate so let's use style

void FixViewDelegate::paint(QPainter* painter, const QStyleOptionViewItem& option, const QModelIndex& index) const {
QPixmap loadedImage;
loadedImage.loadFromData(index.data().toByteArray());
const QWidget *widget = option.widget;
QStyle *style = widget ? widget->style() : QApplication::style();
style->drawItemPixmap(painter,option.rect,Qt::AlignCenter,loadedImage);
}