Due to precision issues that can occur with font size measurements at different zoom levels, the auto-calculated size of node- or edge labels may sometimes not exactly match the size of the rendered label text. Although yFiles FLEX already adds a safety margin to the calculated preferred label size, label strings may still be clipped at certain combinations of zoom level, font size and font family.

This article explains various approaches for preventing cropped labels.

Using ISimpleLabelStyle.clipText

clipText

ISimpleLabelStyle

Using an embedded font

Increasing the preferred size when the graph is loaded

To increase the preferred label sizes of all labels just after a graph has been loaded, an event listener can be added to the GraphMLIOHandler that is used for parsing the graph:

override protected function createReadWriteHandler():RoundtripHandler {
  ..
  roundtripHandler.inputIOHandler.addEventListener(
                      GraphEvent.GRAPH_CHANGED,onGraphLoaded);
  return roundtripHandler;
}

In the event listener function, increase the preferred label sizes:

private function onGraphLoaded( evt:GraphEvent ):void {
  var g:IGraph = evt.graph;
	
  var it:Iterator;
  var label:ILabel;
			
  it = g.nodeLabels.iterator();
  while( it.hasNext() ) {
    label = ILabel( it.next() );
    g.setPreferredSize( label, label.preferredSize.width + 5, label.preferredSize.height + 5 ); 
  }
			
  it = g.edgeLabels.iterator();
  while( it.hasNext() ) {
    label = ILabel( it.next() );
    g.setPreferredSize( label, label.preferredSize.width + 5, label.preferredSize.height + 5 ); 
  }
}

Increasing the preferred size by overriding _getPreferredSize

The default implementation of SimpleLabelStyleRenderer._getPreferredSize already increases the measured text size by a certain amount. This behavior can be modified by overriding _getPreferredSize and using custom margins.

The default implementation uses the following formula:

override protected function _getPreferredSize():ISize {
  var origSize:ISize = _getPreferredSizeCore();
  var w:Number = origSize.width;
  var fontSize:Number = Number( ISimpleLabelStyle( this.style ).textFormat.size);
  if( w > 0 && fontSize > 4 ) {
    var f:Number = 1 + 0.5 * ((fontSize / (fontSize - 1 )) - 1);
    w *= f;
    w += 2;
  }
  return ImmutableSize.create( w, origSize.height );
}