Centering Qlabel on screen

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

alt text

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.

J.Hilk

Oh, I finally figured out what you try to accomplish @gabor53 !

I have a slightly different solution for you, that way you can use it as anywhere else, later in your code as well.

#ifndef BUSYANIMATION_H
#define BUSYANIMATION_H

#include <QLabel>

class BusyAnimation : public QLabel
{
    Q_OBJECT
public:
    explicit jhLogo(QWidget *parent = nullptr) : QLabel(parent){
          setWindowFlag(Qt::FramelessWindowHint, true);
          setFixedSize(QSize(66,66));
          QMovie* movie = new QMovie(":/images/ajax-loader.gif");
          setMovie(movie);
          movie->start();
    }
}

#endif

//Main.cpp

#include <QApplication>
#include "BusyAnimation.h"

int main(int argc, char *argv[])
{
    QApplication::setAttribute(Qt::AA_Use96Dpi);
    QApplication a(argc, argv);

    BusyAnimation w; 
    w.show();
   
    return a.exec();
}

[edit: fixed typo in QSize SGaist]

mrjj

Hi
just a note
Who is going to delete movie?
QMovie* movie = new QMovie

http://doc.qt.io/qt-5/qlabel.html#setMovie
states that label do not take ownership.

JKSH

@J.Hilk said in Centering Qlabel on screen:

explicit jhLogo(QWidget *parent = nullptr) : QLabel(parent){

"jhLogo" -> "BusyAnimation"

      setFixedSize(QSite(66,66));

"QSite" -> "QSize"

Or, just use the other overload: QWidget::setFixedSize(int x, int y)

@mrjj said in Centering Qlabel on screen:

http://doc.qt.io/qt-5/qlabel.html#setMovie
states that label do not take ownership.

Ooh, I didn't know that!

BusyAnimation needs to delete the QMovie it in its destructor then