Layout diagram using Open API

Visual Paradigm bundled with auto-layout engine which help user to perform auto layout to their diagrams. The auto-layout can triggered via user interface as well as via Open API. In this article we will teach you how to layout your diagram via Open API.

Obtain current opening diagram

In this sample we will change the layout of the active opening diagram. To do this first we have to retrieve the reference of the active diagram.

// Obtain DiagramManager from ApplicationManager 
DiagramManager diagramManager = ApplicationManager.instance().getDiagramManager(); 
IDiagramUIModel diagram = diagramManager.getActiveDiagram();

Create layout options

Next we can create different layout options for layout our diagram. In the sample we use Orthogonal Layout, Hierarchical Layout and Directed Tree Layout to layout our diagram. Different properties can apply to different layout options to control how the diagram being layout.

// Initialize different LayoutOptions
LayoutOption$Orthogonal orthogonalLayoutOption = diagramManager.createOrthogonalLayoutOption();
orthogonalLayoutOption.setLayoutGridSize(100);

LayoutOption$Hierarchical hierarchicalLayoutOption = diagramManager.createHierarchicalLayoutOption();
hierarchicalLayoutOption.setMinimumConnectorDistance(10);
hierarchicalLayoutOption.setMinimumLayerDistance(20);
hierarchicalLayoutOption.setMinimumShapeDistance(30);

LayoutOption$DirectedTree directedTreeLayoutOption = diagramManager.createDirectedTreeLayoutOption();
directedTreeLayoutOption.setMinimumLaterDistance(50);
directedTreeLayoutOption.setMinimumShapeDistance(50);
directedTreeLayoutOption.setOrientation(LayoutOption$Orientation.TopToBottom);

Apply layout to diagram

Once the layout options are ready we can then apply layout to diagram. We generate a random number to control which layout will apply to diagram. The layout can be trigger using DiagramManager.openAndLayoutDiagram(IDiagramUIModel, LayoutOptions).

// Generate random number to perform different layout 
int min = 0;
int max = 2;
int range = max - min + 1;

int rand = (int) (Math.random() * range) + min;
System.out.println("rand: " + rand);
switch (rand) {
  //passing different option to perform layout
  case 0: diagramManager.openAndLayoutDiagram(diagram, orthogonalLayoutOption);
      break;
  
  case 1: diagramManager.openAndLayoutDiagram(diagram, hierarchicalLayoutOption);
      break;

  case 2: diagramManager.openAndLayoutDiagram(diagram, directedTreeLayoutOption);
      break;
}

Sample plugin

The sample plugin attached demonstrate how to change the layout of the active diagram. After you deploy the plugin into Visual Paradigm you can click the plugin button in application toolbar to change the diagram layout.

Perform random layout with the plugin

Download sample plugin

You can click this link to download the sample plugin.