Is it possible to use Elide with Qlabel?

Question

I’m trying to use the element QLabel and if the text execrates the width size it can look like this:

• Add 3 points to the right:

  Foo bar baz foo bar...
  

• Add 3 points from center:

  Foo bar ba...oo bar baz
  

• Add 3 points to the left:

  ...bar baz foo bar baz
  

Is it possible to do this natively, or do I have to reimplement using QFontMetrics with QResizeEvent?

Answer 1

There seems to be nothing native. But you can use the method QFontMetrics::elidedText to implement an "elided text" of a line. Here is an example (original source for example in Soen):

QString text("some long text without elipsis");
QFontMetrics metrics(label->font());
QString elidedText = metrics.elidedText(text, Qt::ElideRight, label->width());
label->setText(elidedText);

There is also a more complete example in the Qt documentation, where a new class specific to this is implemented to allow this to be done in multi-line Labels. Ah, you can also use the class QxtLabel of the Qxt extension, because it already implements what you want in the method QxtLabel::setElideMode.

Answer 2

The response of Luiz helped me, however I needed something to do automatically, I thought to use the paintEvent or something like that, but the resizeEvent worked well,

• elidedlabel. h

  #ifndef ELIDEDLABEL_H
  #define ELIDEDLABEL_H
  
  #include <QLabel>
  
  class ElidedLabel : public QLabel
  {
      Q_OBJECT
  
  public:
      explicit ElidedLabel(QWidget *parent=0, Qt::WindowFlags f=0);
      explicit ElidedLabel(const QString &text, QWidget *parent=0, Qt::WindowFlags f=0);
      void setType(const Qt::TextElideMode type);
  
  public slots:
      void setText(const QString &text);
      void elide();
  
  protected:
      void resizeEvent(QResizeEvent *event);
  
  private:
      QString original;
      Qt::TextElideMode defaultType;
      bool eliding;
  
  };
  
  #endif // ELIDEDLABEL_H
  

• elidedlabel.cpp

  #include "elidedlabel.h"
  
  #include <QResizeEvent>
  #include <QTimer>
  
  ElidedLabel::ElidedLabel(QWidget *parent, Qt::WindowFlags f) :
      QLabel(parent, f)
  {
      defaultType = Qt::ElideMiddle;
      eliding = false;
      original = "";
  }
  
  ElidedLabel::ElidedLabel(const QString &text, QWidget *parent, Qt::WindowFlags f) :
      QLabel(text, parent, f)
  {
      defaultType = Qt::ElideMiddle;
  
      //Usado para verificar se a string está ou não sendo atualizado
      eliding = false;
  
      //Guarda o texto original
      setText(text);
  }
  
  void ElidedLabel::setType(const Qt::TextElideMode type)
  {
      /*
         Altera o tipo de elide, podendo ser:
         Esquerda: "... bar baz"
         Meido: "Foo ... baz"
         Direita: "Foo bar ..."
      */
      defaultType = type;
      elide();
  }
  
  //Atualiza o texto se o Label for redimensionado
  void ElidedLabel::resizeEvent(QResizeEvent *event)
  {
      Q_UNUSED(event);
  
      //O delay é necessário para evitar conflitos
      QTimer::singleShot(50, this, SLOT(elide()));
  }
  
  //Atualiza o texto
  void ElidedLabel::setText(const QString &text)
  {
      original = text;
      QLabel::setText(text);
  
      //Executa no momento que é atualizado
      elide();
  }
  
  void ElidedLabel::elide()
  {
      if (eliding == false) {
          eliding = true;
  
          QFontMetrics metrics(font());
          QLabel::setText(metrics.elidedText(original, defaultType, width()));
  
          eliding = false;
      }
  }
  

To use just call so:

#include "elidedlabel.h";

...

ElidedLabel label1;

Or:

ElidedLabel *label1 = new ElidedLabel;