How to use

redraws

method

in

org.eclipse.jface.text.TextViewer

@Override
public Point getSelectedRange() {
  if (!redraws() && fViewerState != null)
    return fViewerState.getSelection();
  if (fTextWidget != null) {
    Point p= fTextWidget.getSelectionRange();
    p= widgetSelection2ModelSelection(p);
    if (p != null)
      return p;
  }
  return new Point(-1, -1);
}

@Override
public Point getSelectedRange() {
  if (!redraws() && fViewerState != null)
    return fViewerState.getSelection();
  if (fTextWidget != null) {
    Point p= fTextWidget.getSelectionRange();
    p= widgetSelection2ModelSelection(p);
    if (p != null)
      return p;
  }
  return new Point(-1, -1);
}

/**
 * Checks whether the view port changed and if so informs all registered
 * listeners about the change.
 *
 * @param origin describes under which circumstances this method has been called.
 *
 * @see IViewportListener
 */
protected void updateViewportListeners(int origin) {
  if (redraws()) {
    int topPixel= fTextWidget.getTopPixel();
    if (topPixel >= 0 && topPixel != fLastTopPixel) {
      if (fViewportListeners != null) {
        for (int i= 0; i < fViewportListeners.size(); i++) {
          IViewportListener l= fViewportListeners.get(i);
          l.viewportChanged(topPixel);
        }
      }
      fLastTopPixel= topPixel;
    }
  }
}

/**
 * Checks whether the view port changed and if so informs all registered
 * listeners about the change.
 *
 * @param origin describes under which circumstances this method has been called.
 *
 * @see IViewportListener
 */
protected void updateViewportListeners(int origin) {
  if (redraws()) {
    int topPixel= fTextWidget.getTopPixel();
    if (topPixel >= 0 && topPixel != fLastTopPixel) {
      if (fViewportListeners != null) {
        for (int i= 0; i < fViewportListeners.size(); i++) {
          IViewportListener l= fViewportListeners.get(i);
          l.viewportChanged(topPixel);
        }
      }
      fLastTopPixel= topPixel;
    }
  }
}

/**
 * Informs all registered text listeners about the change specified by the
 * widget command. This method does not use a robust iterator.
 *
 * @param cmd the widget command translated into a text event sent to all text listeners
 */
protected void updateTextListeners(WidgetCommand cmd) {
  List<ITextListener> textListeners= fTextListeners;
  if (textListeners != null) {
    textListeners= new ArrayList<>(textListeners);
    DocumentEvent event= cmd.event;
    if (event instanceof SlaveDocumentEvent)
      event= ((SlaveDocumentEvent) event).getMasterEvent();
    TextEvent e= new TextEvent(cmd.start, cmd.length, cmd.text, cmd.preservedText, event, redraws());
    for (int i= 0; i < textListeners.size(); i++) {
      ITextListener l= textListeners.get(i);
      l.textChanged(e);
    }
  }
}

/**
 * Informs all registered text listeners about the change specified by the
 * widget command. This method does not use a robust iterator.
 *
 * @param cmd the widget command translated into a text event sent to all text listeners
 */
protected void updateTextListeners(WidgetCommand cmd) {
  List<ITextListener> textListeners= fTextListeners;
  if (textListeners != null) {
    textListeners= new ArrayList<>(textListeners);
    DocumentEvent event= cmd.event;
    if (event instanceof SlaveDocumentEvent)
      event= ((SlaveDocumentEvent) event).getMasterEvent();
    TextEvent e= new TextEvent(cmd.start, cmd.length, cmd.text, cmd.preservedText, event, redraws());
    for (int i= 0; i < textListeners.size(); i++) {
      ITextListener l= textListeners.get(i);
      l.textChanged(e);
    }
  }
}

@Override
public void changeTextPresentation(TextPresentation presentation, boolean controlRedraw) {
  if (presentation == null || !redraws())
    return;
  if (fTextWidget == null)
    return;
  /*
   * Call registered text presentation listeners
   * and let them apply their presentation.
   */
  if (fTextPresentationListeners != null) {
    ArrayList<ITextPresentationListener> listeners= new ArrayList<>(fTextPresentationListeners);
    for (int i= 0, size= listeners.size(); i < size; i++) {
      ITextPresentationListener listener= listeners.get(i);
      listener.applyTextPresentation(presentation);
    }
  }
  if (presentation.isEmpty())
    return;
  if (controlRedraw)
    fTextWidget.setRedraw(false);
  if (fReplaceTextPresentation)
    applyTextPresentation(presentation);
  else
    addPresentation(presentation);
  if (controlRedraw)
    fTextWidget.setRedraw(true);
}

@Override
public void changeTextPresentation(TextPresentation presentation, boolean controlRedraw) {
  if (presentation == null || !redraws())
    return;
  if (fTextWidget == null)
    return;
  /*
   * Call registered text presentation listeners
   * and let them apply their presentation.
   */
  if (fTextPresentationListeners != null) {
    ArrayList<ITextPresentationListener> listeners= new ArrayList<>(fTextPresentationListeners);
    for (int i= 0, size= listeners.size(); i < size; i++) {
      ITextPresentationListener listener= listeners.get(i);
      listener.applyTextPresentation(presentation);
    }
  }
  if (presentation.isEmpty())
    return;
  if (controlRedraw)
    fTextWidget.setRedraw(false);
  if (fReplaceTextPresentation)
    applyTextPresentation(presentation);
  else
    addPresentation(presentation);
  if (controlRedraw)
    fTextWidget.setRedraw(true);
}

/**
 * Sends out a text selection changed event to all registered listeners.
 *
 * @param offset the offset of the newly selected range in the visible document
 * @param length the length of the newly selected range in the visible document
 * @since 3.0
 */
protected void fireSelectionChanged(int offset, int length) {
  if (redraws()) {
    if (length < 0) {
      length= -length;
      offset= offset + length;
    }
    IRegion r= widgetRange2ModelRange(new Region(offset, length));
    if ((r != null && !r.equals(fLastSentSelectionChange)) || r == null)  {
      fLastSentSelectionChange= r;
      ISelection selection= r != null ? new TextSelection(getDocument(), r.getOffset(), r.getLength()) : TextSelection.emptySelection();
      SelectionChangedEvent event= new SelectionChangedEvent(this, selection);
      fireSelectionChanged(event);
    }
  }
}

/**
 * Sends out a text selection changed event to all registered listeners.
 *
 * @param offset the offset of the newly selected range in the visible document
 * @param length the length of the newly selected range in the visible document
 * @since 3.0
 */
protected void fireSelectionChanged(int offset, int length) {
  if (redraws()) {
    if (length < 0) {
      length= -length;
      offset= offset + length;
    }
    IRegion r= widgetRange2ModelRange(new Region(offset, length));
    if ((r != null && !r.equals(fLastSentSelectionChange)) || r == null)  {
      fLastSentSelectionChange= r;
      ISelection selection= r != null ? new TextSelection(getDocument(), r.getOffset(), r.getLength()) : TextSelection.emptySelection();
      SelectionChangedEvent event= new SelectionChangedEvent(this, selection);
      fireSelectionChanged(event);
    }
  }
}

/**
 * Sends out a mark selection changed event to all registered listeners.
 *
 * @param offset the offset of the mark selection in the visible document, the offset is <code>-1</code> if the mark was cleared
 * @param length the length of the mark selection, may be negative if the caret is before the mark.
 * @since 2.0
 */
protected void markChanged(int offset, int length) {
  if (redraws()) {
    if (offset != -1) {
      IRegion r= widgetRange2ModelRange(new Region(offset, length));
      offset= r.getOffset();
      length= r.getLength();
    }
    ISelection selection= new MarkSelection(getDocument(), offset, length);
    SelectionChangedEvent event= new SelectionChangedEvent(this, selection);
    fireSelectionChanged(event);
  }
}

@Override
public void setSelectedRange(int selectionOffset, int selectionLength) {
  if (!redraws()) {
    if (fViewerState != null)
      fViewerState.updateSelection(selectionOffset, selectionLength);
    return;
  }
  if (fTextWidget == null)
    return;
  IRegion widgetSelection= modelRange2ClosestWidgetRange(new Region(selectionOffset, selectionLength));
  if (widgetSelection != null) {
    int[] selectionRange= new int[] { widgetSelection.getOffset(), widgetSelection.getLength() };
    validateSelectionRange(selectionRange);
    if (selectionRange[0] >= 0) {
      fTextWidget.setSelectionRange(selectionRange[0], selectionRange[1]);
      selectionChanged(selectionRange[0], selectionRange[1]);
    }
  }
}

@Override
public void setSelectedRange(int selectionOffset, int selectionLength) {
  if (!redraws()) {
    if (fViewerState != null)
      fViewerState.updateSelection(selectionOffset, selectionLength);
    return;
  }
  if (fTextWidget == null)
    return;
  IRegion widgetSelection= modelRange2ClosestWidgetRange(new Region(selectionOffset, selectionLength));
  if (widgetSelection != null) {
    int[] selectionRange= new int[] { widgetSelection.getOffset(), widgetSelection.getLength() };
    validateSelectionRange(selectionRange);
    if (selectionRange[0] >= 0) {
      fTextWidget.setSelectionRange(selectionRange[0], selectionRange[1]);
      selectionChanged(selectionRange[0], selectionRange[1]);
    }
  }
}

/**
 * Sends out a text selection changed event to all registered post selection changed listeners.
 *
 * @param offset the offset of the newly selected range in the visible document
 * @param length the length of the newly selected range in the visible document
 * @since 3.0
 */
protected void firePostSelectionChanged(int offset, int length) {
  if (redraws()) {
    IRegion r= widgetRange2ModelRange(new Region(offset, length));
    ISelection selection= r != null ? new TextSelection(getDocument(), r.getOffset(), r.getLength()) : TextSelection.emptySelection();
    SelectionChangedEvent event= new SelectionChangedEvent(this, selection);
    firePostSelectionChanged(event);
  }
}

/**
 * Sends out a mark selection changed event to all registered listeners.
 *
 * @param offset the offset of the mark selection in the visible document, the offset is <code>-1</code> if the mark was cleared
 * @param length the length of the mark selection, may be negative if the caret is before the mark.
 * @since 2.0
 */
protected void markChanged(int offset, int length) {
  if (redraws()) {
    if (offset != -1) {
      IRegion r= widgetRange2ModelRange(new Region(offset, length));
      offset= r.getOffset();
      length= r.getLength();
    }
    ISelection selection= new MarkSelection(getDocument(), offset, length);
    SelectionChangedEvent event= new SelectionChangedEvent(this, selection);
    fireSelectionChanged(event);
  }
}

/**
 * Sends out a text selection changed event to all registered post selection changed listeners.
 *
 * @param offset the offset of the newly selected range in the visible document
 * @param length the length of the newly selected range in the visible document
 * @since 3.0
 */
protected void firePostSelectionChanged(int offset, int length) {
  if (redraws()) {
    IRegion r= widgetRange2ModelRange(new Region(offset, length));
    ISelection selection= r != null ? new TextSelection(getDocument(), r.getOffset(), r.getLength()) : TextSelection.emptySelection();
    SelectionChangedEvent event= new SelectionChangedEvent(this, selection);
    firePostSelectionChanged(event);
  }
}

@Override
public void revealRange(int start, int length) {
  if (fTextWidget == null || !redraws())
    return;
  IRegion modelRange= new Region(start, length);
  IRegion widgetRange= modelRange2ClosestWidgetRange(modelRange);
  if (widgetRange != null) {
    int[] range= new int[] { widgetRange.getOffset(), widgetRange.getLength() };
    validateSelectionRange(range);
    if (range[0] >= 0)
      internalRevealRangeWithWorkaround(range[0], range[0] + range[1]);
  } else {
    IRegion coverage= getModelCoverage();
    int cursor= (coverage == null || start < coverage.getOffset()) ? 0 : getVisibleDocument().getLength();
    internalRevealRangeWithWorkaround(cursor, cursor);
  }
}

@Override
public void revealRange(int start, int length) {
  if (fTextWidget == null || !redraws())
    return;
  IRegion modelRange= new Region(start, length);
  IRegion widgetRange= modelRange2ClosestWidgetRange(modelRange);
  if (widgetRange != null) {
    int[] range= new int[] { widgetRange.getOffset(), widgetRange.getLength() };
    validateSelectionRange(range);
    if (range[0] >= 0)
      internalRevealRangeWithWorkaround(range[0], range[0] + range[1]);
  } else {
    IRegion coverage= getModelCoverage();
    int cursor= (coverage == null || start < coverage.getOffset()) ? 0 : getVisibleDocument().getLength();
    internalRevealRangeWithWorkaround(cursor, cursor);
  }
}

@Override
public boolean canDoOperation(int operation) {
  if (fTextWidget == null || !redraws())
    return false;

@Override
public boolean canDoOperation(int operation) {
  if (fTextWidget == null || !redraws())
    return false;