Tips and tricks

If you want to rotate a balloon layout, you can modify the start angle of the layout. This is the angle where the first child node is placed at the root. All subtrees rotate with this start angle. The angle spacing value FAST_PROPORTIONAL is not stable with respect to the start angle: the layout can change considerably when you change the start angle. The other angle spacing values are stable: they rotate the entire layout. The start angle must be 0° - 360°.

To change the start angle:

balloonStartAngle: "90";

layout.setBalloonStartAngle(90);  

Normally, child nodes are placed all around their parent node; they occupy an angle range of 360° around the parent. It is possible to limit the angle range available for child nodes. In the following figure, the angle range for child nodes is 360° degrees on the left, 270° in the middle and 180° on the right. You can specify a different angle range for the root, for nodes that have only leaves, and for inner nodes of the tree.

To change the angle ranges:

balloonRootChildrenAngle: "270";
balloonInnerChildrenAngle: "270";
balloonLeafChildrenAngle: "270";

layout.setBalloonRootChildrenAngle(270);  
layout.setBalloonInnerChildrenAngle(270);  
layout.setBalloonLeafChildrenAngle(270);  

Multiple disconnected trees can be laid out together by the balloon layout mode. By default, they are arranged in a sequence according to the flow direction of the layout. As an alternative, you can choose the generic disconnected graph spacing. For details, see Layout of connected components (TL). Another alternative, as for radial layout mode, is to introduce an invisible root. In this case, the balloons are arranged around the invisible root.

To add an invisible root to the layout:

layoutOfConnectedComponentsEnabled: "false";
invisibleRootUsed: "true";

layout.setLayoutOfConnectedComponentsEnabled(false); 
layout.setInvisibleRootUsed(true);