Is there a way to show overlay whenever I want in cytoscape.js?

Question

Is there a way to toggle overlay whenever I want? For example, I want all my nodes to have red overlays. I tried overlay-color in my style, but the overlay is only shown when it's active, that is when I drag it around. I looked at this post but I still don't know how to implement it. The complete style is listed below:

{
    selector: 'node',
    css: {
    content: 'data(id)',
    'text-valign': 'bottom',
    'text-halign': 'center',
    height: '60px',
    width: '60px',
    'border-color': 'black',
    'border-opacity': '1',
    'background-image':
        'https://farm8.staticflickr.com/7272/7633179468_3e19e45a0c_b.jpg',
    'overlay-color': 'red',
    },
},

Thank you so much!

Answer 1

The post you linked contains the solution to your problem:

Don't skip properties if you're not sure what the default values are. In general, you should specify every property explicitly if it's important to your app, just as you would for css in the dom.

This comes down to simply adding the missing overlay-* properties, namely:

• overlay-opacity
• overlay-padding

The following snippet shows a dagre graph with your node styles:

var cy = window.cy = cytoscape({
  container: document.getElementById('cy'),

  boxSelectionEnabled: false,
  autounselectify: true,

  style: [{
      selector: 'node',
      css: {

        'content': 'data(id)',
        'text-valign': 'bottom',
        'text-halign': 'center',
        'height': '60px',
        'width': '60px',
        'border-color': 'black',
        'border-opacity': '1',
        'padding': '4',
        'background-image': 'https://farm8.staticflickr.com/7272/7633179468_3e19e45a0c_b.jpg',
        'overlay-color': 'red',
        'overlay-opacity': 0.35,
        'overlay-padding': '5',
      }
    },
    {
      selector: 'edge',
      css: {
        'target-arrow-shape': 'triangle'
      }
    },
  ],

  elements: {
    nodes: [{
        data: {
          id: 'n0'
        }
      },
      {
        data: {
          id: 'n1'
        }
      },
      {
        data: {
          id: 'n2'
        }
      },
      {
        data: {
          id: 'n3'
        }
      },
      {
        data: {
          id: 'n4'
        }
      },
      {
        data: {
          id: 'n5'
        }
      },
      {
        data: {
          id: 'n6'
        }
      },
      {
        data: {
          id: 'n7'
        }
      },
      {
        data: {
          id: 'n8'
        }
      },
      {
        data: {
          id: 'n9'
        }
      },
      {
        data: {
          id: 'n10'
        }
      },
      {
        data: {
          id: 'n11'
        }
      },
      {
        data: {
          id: 'n12'
        }
      },
      {
        data: {
          id: 'n13'
        }
      },
      {
        data: {
          id: 'n14'
        }
      },
      {
        data: {
          id: 'n15'
        }
      },
      {
        data: {
          id: 'n16'
        }
      }
    ],
    edges: [{
        data: {
          source: 'n0',
          target: 'n1'
        }
      },
      {
        data: {
          source: 'n1',
          target: 'n2'
        }
      },
      {
        data: {
          source: 'n1',
          target: 'n3'
        }
      },
      {
        data: {
          source: 'n2',
          target: 'n7'
        }
      },
      {
        data: {
          source: 'n2',
          target: 'n11'
        }
      },
      {
        data: {
          source: 'n2',
          target: 'n16'
        }
      },
      {
        data: {
          source: 'n3',
          target: 'n4'
        }
      },
      {
        data: {
          source: 'n3',
          target: 'n16'
        }
      },
      {
        data: {
          source: 'n4',
          target: 'n5'
        }
      },
      {
        data: {
          source: 'n4',
          target: 'n6'
        }
      },
      {
        data: {
          source: 'n6',
          target: 'n8'
        }
      },
      {
        data: {
          source: 'n8',
          target: 'n9'
        }
      },
      {
        data: {
          source: 'n8',
          target: 'n10'
        }
      },
      {
        data: {
          source: 'n11',
          target: 'n12'
        }
      },
      {
        data: {
          source: 'n12',
          target: 'n13'
        }
      },
      {
        data: {
          source: 'n13',
          target: 'n14'
        }
      },
      {
        data: {
          source: 'n13',
          target: 'n15'
        }
      },
    ]
  },

  layout: {
    name: 'dagre',
    padding: 5
  }
});
let toggle = true

cy.on('click', function() {
  //toggle between invisible/visible overlay
  let value = toggle ? 0 : 0.35;
  toggle = !toggle;
  cy.nodes().style({
    'overlay-opacity': value
  });
});

body {
  font: 14px helvetica neue, helvetica, arial, sans-serif;
}

#cy {
  height: 100%;
  width: 100%;
  left: 0;
  top: 0;
  float: left;
  position: absolute;
}

<html>

<head>
  <meta charset=utf-8 />
  <meta name="viewport" content="user-scalable=no, initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0, minimal-ui">
  <script src="https://unpkg.com/cytoscape@3.3.0/dist/cytoscape.min.js">
  </script>
  <script src="https://unpkg.com/jquery@3.3.1/dist/jquery.js"></script>
  <!-- cyposcape dagre -->
  <script src="https://unpkg.com/dagre@0.7.4/dist/dagre.js"></script>
  <script src="https://cdn.rawgit.com/cytoscape/cytoscape.js-dagre/1.5.0/cytoscape-dagre.js"></script>
</head>

<body>
  <div id="cy"></div>
</body>

</html>