动态更改qlabel的位置

Question

I am a newbie in QT programming and I have a question. I have a qslider and qlabel and a video playing. While video is playing, tick of qslider is moving forward as you can guess. What I want to do is to put a qlabel just under the tick of qslider and moving it with the tick as the text of qlabel is updating...

Answer 1

You can't 'move' QLavel all over the widget due to the Qt layout system : the widget exists inside a layout. So if you want to 'move' your label just only vertically of horizontally there are few ways to solve your problem.

The easiest one is to use the QLabel::setIndent function (it will 'move' text inside the QLabel ):

If a label displays text, the indent applies to the left edge if alignment() is Qt::AlignLeft, to the right edge if alignment() is Qt::AlignRight, to the top edge if alignment() is Qt::AlignTop, and to the bottom edge if alignment() is Qt::AlignBottom.

Also you can try this way (it will 'move' QLabel itself):

1. Create box layout ( QHBoxLayout or QVBoxLayout ).
2. Add a stretch (calling QBoxLayout::addStretch ).
3. Add QLabel (calling QLayout::addWidget ).
4. Add a stretch once again.
5. Then you can change the stretching factors for 'move' imitation.

The initial stretch factor's value will define the initial position of the label.

The code example to simulate QLabel moving left to right:

class MyWidget : public QWidget
{
  Q_OBJECT

public:
  MyWidget(QWidget* parent) : QWidget(parent)
  {
    layout_ = new QHBoxLayout(this);
    layout_->addStretch();
    layout_->addWidget(new QLabel("Moving text", this));
    layout_->addStretch(100);

    connect(&timer_, SIGNAL(timeout()), SLOT(moveLabel()));
    timer_.start(1000);
  }

public slots:
  void moveLabel()
  {
    layout_->setStretch(0, layout_->stretch(0) + 1);
    layout_->setStretch(1, layout_->stretch(1) - 1);

    if(layout_->stretch(0) == 100)
      timer_.stop();
  }

private:
  QBoxLayout* layout_;
  QTimer timer_;
};

And another variant for your situation is to inherit QSlider and then reimplement protected function QWidget::paintEvent in order to paint some label over the slider.

Answer 2

First you can try QLabel.setIndent(self, int), call it whenever the tick changes. If this works for you it's the easiest possibility, if not please repost.