Reading image from QSqlTableModel

SGaist

Hi,

How did you store the image data in your database ?

gabor53

Hi @SGaist ,
I store them as a QByteArray:

QPixmap pix2(fileNameChosen);
  int w = 0;
  int h = 0;
  w = ui->Image_Display_Label->width ();
  h = ui->Image_Display_Label->height ();
  ui->Image_Display_Label->setPixmap (pix2.scaled(w, h, Qt::KeepAspectRatio));

  QFile fileReview(fileNameChosen);

  if(fileReview.open (QIODevice::ReadOnly)) {
    fileByteArray = fileReview.readAll ();

jsulm

@gabor53 What @SGaist probably means is: what data type do you use for the pixmap column in the table in the database?

gabor53

Hi @jsulm ,
It's BLOB.

Vinod Kuntoji

@gabor53 ,

What is the size of the bytearray?

gabor53

@Vinod-Kuntoji
100 x 100

Vinod Kuntoji

@gabor53 ,
The blob you are using, is it a raw bytearray or png, jpeg byterray?

gabor53

@Vinod-Kuntoji
It is jpeg bytearray.

Vinod Kuntoji

@gabor53 ,

Then you should specify "JPG" in loadFromData function.

QPixmap fixPic;
fixPic.loadFromData (fixModel->record (1).value ("Pic").toByteArray (),"JPG");

gabor53

@Vinod-Kuntoji
Thank you. I've noticed an other issue: the program execution enters fixviewdelegate.cpp but never reads the actual function:

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

  Q_UNUSED(index);
  Q_UNUSED(editor);

  qDebug() << "Entered fixViewDelegate (2).";

  QPixmap fixPic;
  fixPic.loadFromData (fixModel->record (1).value ("Pic").toByteArray (), "JPG");
  qDebug() << "Fixmodel pic: " << fixPic;
  qDebug() << "Fixmodel pic size: " << fixPic.size ();

}

What can I do to fix this problem?

Vinod Kuntoji

@gabor53 said in Reading image from QSqlTableModel:

execution

What is that function?

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

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