vis.js is a dynamic, browser-based visualization library
You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
 
 
 

92 lines
2.5 KiB

/**
* Set up mock 2D context, for usage in unit tests.
*
* Adapted from: https://github.com/Cristy94/canvas-mock
*/
var canvasMock; // Use one canvas instance for all calls to createElement('canvas');
function replaceCanvasContext (el) {
el.getContext = function() {
return {
fillRect: function() {},
clearRect: function(){},
getImageData: function(x, y, w, h) {
return {
data: new Array(w*h*4)
};
},
putImageData: function() {},
createImageData: function(){ return []},
setTransform: function(){},
drawImage: function(){},
save: function(){},
text: function(){},
fillText: function(){},
restore: function(){},
beginPath: function(){},
moveTo: function(){},
lineTo: function(){},
closePath: function(){},
stroke: function(){},
translate: function(){},
scale: function(){},
rotate: function(){},
circle: function(){},
arc: function(){},
fill: function(){},
//
// Following added for vis.js unit tests
//
measureText: function(text) {
return {
width: 12*text.length,
height: 14
};
}
};
}
}
/**
* Overrides document.createElement(), in order to supply a custom canvas element.
*
* In the canvas element, getContext() is overridden in order to supply a simple
* mock object for the 2D context. For all other elements, the call functions unchanged.
*
* The override is only done if there is no 2D context already present.
* This allows for normal running in a browser, and for node.js the usage of 'canvas'.
*
* @param {object} window - current global window object. This can possible come from module 'jsdom',
* when running under node.js.
*/
function mockify(window) {
var d = window.document;
var f = window.document.createElement;
// Check if 2D context already present. That happens either when running in a browser,
// or this is node.js with 'canvas' installed.
var ctx = d.createElement('canvas').getContext('2d');
if (ctx !== null && ctx !== undefined) {
//console.log('2D context is present, no need to override');
return;
}
window.document.createElement = function(param) {
if (param === 'canvas') {
if (canvasMock === undefined) {
canvasMock = f.call(d, 'canvas');
replaceCanvasContext(canvasMock);
}
return canvasMock;
} else {
return f.call(d, param);
}
};
}
module.exports = mockify;