In addition to the Viso Online announcement today, Microsoft is also releasing Visio JavaScript APIs that extend the capabilities of Visio Online for developers. Using these APIs, IT professionals can now build rich mashup solutions to meet their organization’s specific needs.
The APIs enable programmatic access to the embedded Visio Online diagrams in a SharePoint Online page. Developers can use them to interact with Visio diagram elements—like pages and shapes—expose diagram data, write custom handlers for mouse events, create visual mark-ups on the diagram canvas and more. As a mashup example, developers can create a custom overlay, such as a list of steps required to complete before moving forward in a process, that appears when users select or hover over a diagram shape.
Embed Visio Online diagrams into SharePoint Online using JavaScript APIs.
Please visit the Office Dev Center and read the related blog for detailed instructions and more information on how to use JavaScript APIs with Visio Online.