Centering Qlabel on screen

[gabor53]

Hi,
I have the following code:

  QMovie* movie = new QMovie(":/images/ajax-loader.gif");

  if(!movie->isValid ()) {
    qDebug() << "Movie doesn't work.";
  } else {
    QLabel* label = new QLabel(this);
    label->setGeometry (66, 66, 66, 66);
    label->setMovie (movie);
    movie->start ();
    label->show ();
  }

How can I center the QLabel on the screen?
Thank you.

[Johnson]

you can use QHBoxLayout

[JKSH]

@gabor53 said in Centering Qlabel on screen:

How can I center the QLabel on the screen?

1. Call QApplication::desktop()->screenGeometry() or QApplication::desktop()->availableGeometry() to find the screen dimensions.
2. Use this information to calculate the center position for your QLabel.
3. Call label->setGeometry() with your calculated position.

See http://doc.qt.io/qt-5/qdesktopwidget.html for more details on QDesktopWidget.

[gabor53]

@Johnson
Hi,
Now I have this:

  QLabel* label = new QLabel(this);
  QHBoxLayout* layout = new QHBoxLayout(this);
  layout->setSpacing (0);
  layout->setContentsMargins (0, 0, 0, 0);
  layout->addWidget (label);
  QMovie* movie = new QMovie(":/images/ajax-loader.gif");

  if(!movie->isValid ()) {
    qDebug() << "Movie doesn't work.";
  } else {

    label->setGeometry (66, 66, 66, 66);
    label->setMovie (movie);
    movie->start ();
    label->show ();
  }

No error message, but the image is not centered. Any suggestions what's wrong? Thank you.

[gabor53]

@JKSH
Thank you.
I tried this:

  QRect screenGeometry = QApplication::desktop ()->screenGeometry ();
  int x = (screenGeometry.width () - label->width ()) / 2;
  int y = (screenGeometry.height () - label->height ()) / 2;

  qDebug() << "Screen width: " << screenGeometry.width ();
  qDebug() << "Screen height: " << screenGeometry.height ();
  qDebug() << "x: " << x;
  qDebug() << "y: " << y;

 label->setGeometry (x, y, 66, 66);

The label is not centered. what did I do incorrectly?
Thank you.

[JKSH]

@gabor53 said in Centering Qlabel on screen:

what did I do incorrectly?

You printed several qDebug lines, which is good. What does your debug output tell you? Are x and y what you expect?

[mrjj]

Hi
Just a small note.
QLabel is left aligned pr default.
So make sure change its set to center

[JKSH]

@gabor53 said in Centering Qlabel on screen:

QLabel* label = new QLabel(this);

I just noticed that your QLabel has a parent. That means your QLabel's geometry is relative to its parent.

@mrjj said in Centering Qlabel on screen:

QLabel is left aligned pr default.
So make sure change its set to center

This post made me wonder if I understood the original question correctly.

@gabor53, are you trying to make QLabel centered on your computer screen? Or are you trying to make the QMovie centered on the QLabel?

[gabor53]

@JKSH
I am trying to cener QLabel on the screen.

[mrjj]

@gabor53
and it NOT about centering the QMovie ? so it plays in the middle?

[gabor53]

@mrjj
Yes, you are right. It is about centering the QMovie. The qDebug gives the expected values.

[mrjj]

@gabor53
Ok, then the Horizontal Alignment should be set to center as else the actual movie
will always be shown at left side, regardless of how u place the QLabel.

[JKSH]

@gabor53 said in Centering Qlabel on screen:

The qDebug gives the expected values.

Please post your qDebug output here.

[gabor53]

@JKSH
Screen width: 1280
Screen height: 768
x: 320
y: 144

[gabor53]

@mrjj
Please show me an example how to do it in this case. Thank you.

[JKSH]

@gabor53 said in Centering Qlabel on screen:

@JKSH
Screen width: 1280
Screen height: 768
x: 320
y: 144

(320, 144) is very far from the center of 1280 x 768.

Can you explain why you got x=320 and y=144?

If your QLabel is 66x66, then you want

• Global X = (1280-66)/2 = 607
• Global Y = (768-66)/2 = 351

Make sure your code calculates the correct x and y values first.

[jsulm]

@gabor53 said in Centering Qlabel on screen:

Please show me an example how to do it in this case. Thank you.

It's all in the documentation: http://doc.qt.io/qt-5/qlabel.html#alignment-prop

[Vinod Kuntoji]

@gabor53 ,

Put the label in a layout, and set the alignment.

QMovie* movie = new QMovie(":/images/ajax-loader.gif");
QVBoxLayout *layout = new QVBoxLayout;
if(!movie->isValid ()) {
    qDebug() << "Movie doesn't work.";
} else {
    QLabel* label = new QLabel(this);
    label->setMovie (movie);
    movie->start ();
    label->show ();
    layout->addWidget(label);
    layout->setAlignment(Qt::AlignCenter);
}

this->setLayout(layout);

[gabor53]

@Vinod-Kuntoji
Thank you. This puts the movie in the top left corner:

[gabor53]

@JKSH
You were right, the calculation was incorrect. The following code puts the movie in the center:

 QLabel* label = new QLabel();
  label->setGeometry (0, 0, 66, 66);
  QRect screenGeometry = QApplication::desktop ()->screenGeometry ();
  int x = (screenGeometry.width () - label->width ()) / 2;
  int y = (screenGeometry.height () - label->height ()) / 2;

  QMovie* movie = new QMovie(":/images/ajax-loader.gif");

  if(!movie->isValid ()) {
    qDebug() << "Movie doesn't work.";
  } else {
    qDebug() << "Screen width: " << screenGeometry.width ();
    qDebug() << "Screen height: " << screenGeometry.height ();
    qDebug() << "x: " << x;
    qDebug() << "y: " << y;

    label->setGeometry (x, y, 66, 66);
    label->setMovie (movie);

    movie->start ();
    label->show ();
 }

Now it look like this:

Any way to delete the window controls from the movie?
Thank you.