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cytoscape-canvas

Preview

Description

An extension to create a canvas over or under a Cytoscape graph. Useful for customizing nodes/edges, drawing backgrounds, etc.

Demo

Demo

Dependencies

  • Cytoscape.js >=3.0.0

Example

var cytoscape = require('cytoscape');
var cyCanvas = require('cytoscape-canvas');

cyCanvas(cytoscape); // Register extension

var cy = cytoscape({/* ... */});

var layer = cy.cyCanvas();
var canvas = layer.getCanvas();
var ctx = canvas.getContext('2d');

cy.on("render cyCanvas.resize", function(evt) {
	layer.resetTransform(ctx);
	layer.clear(ctx);

	// Draw fixed elements
	ctx.fillRect(0, 0, 100, 100); // Top left corner

	layer.setTransform(ctx);

	// Draw model elements
	cy.nodes().forEach(function(node) {
		var pos = node.position();
		ctx.fillRect(pos.x, pos.y, 100, 100); // At node position
	});
});

Usage instructions

Download the library:

  • via npm: npm install cytoscape-canvas,
  • via bower: bower install cytoscape-canvas , or
  • via direct download in the repository (probably from a tag).

require() the library as appropriate for your project:

CommonJS:

var cytoscape = require('cytoscape');
var cyCanvas = require('cytoscape-canvas');

cyCanvas(cytoscape); // Register extension

AMD:

require(['cytoscape', 'cytoscape-canvas'], function(cytoscape, cyCanvas) {
  cyCanvas(cytoscape); // Register extension
});

Plain HTML/JS has the extension registered for you automatically, because no require() is needed.

Initialisation

var cy = cytoscape({/* ... */});

var layer = cy.cyCanvas({
  zIndex: 1,
  pixelRatio: "auto",
});

API

layer.getCanvas()

  • return: Canvas The generated canvas

layer.setTransform(ctx)

Set the context transform to match Cystoscape's zoom & pan. Further drawing will be on model position.

  • param: CanvasRenderingContext2D ctx

layer.resetTransform(ctx)

Reset the context transform. Further drawing will be on rendered position.

  • param: CanvasRenderingContext2D ctx

layer.clear(ctx)

Clear the entire canvas.

  • param: CanvasRenderingContext2D ctx

Events

cyCanvas.resize: When the extension's canvas is resized

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A Cytoscape extension to enable drawing over and under a graph

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