允许鼠标事件通过 Fabrixjs Canvas 实例？

Question

我已经使用了几年Fabricjs了，如果这是一个基本问题，请原谅我我Canvas在一些按钮元素上添加了一个窗口大小的元素，我还希望用户能够单击这些元素。是否有Fabricjs允许鼠标事件传递到底层元素的属性？我一直在查看文档，但没有找到任何东西

Answer 1

我最终使用“指针事件：无”作为内联样式应用于 2 个画布元素（第一个类名为“lower-canvas”，第二个类名为“upper-canvas”）和包装 div .Canvas(...) 从我提供的画布元素创建的构造函数。

这让鼠标事件传递到下面的元素。

// Setting up the vanilla canvas to pass to FabricJS

const canvasEl = document.createElement("canvas");

...

canvasEl.style.pointerEvents = "none"; // This gets copied onto the 2 canvas elements that FabricJS will create below

document.body.appendChild(canvasEl);

// Start of FabricJS part 

const canvas = new fabric.Canvas(canvasEl); // Creates the div and 2 canvas elements and replaces what was passed in with them (in the DOM)

canvas.wrapperEl.style.pointerEvents = "none"; //"wrapperEl" refers to the div. I found it by looking through https://github.com/fabricjs/fabric.js/blob/master/dist/fabric.js to see where the upperCanvasEl & lowerCanvasEl were attached

Answer 2

你可以使用document.elementsFromPoint. 点击左上角：

let doc, html, bod, M, I, mobile, S, Q, aC, rC; // for use on other loads

addEventListener('load', ()=>{

doc = document; html = doc.documentElement; bod = doc.body; nav = navigator; M = tag=>doc.createElement(tag); I = id=>doc.getElementById(id);

mobile = nav.userAgent.match(/Mobi/i) ? true : false;

S = (selector, within)=>{

  var w = within || doc;

  return w.querySelector(selector);

}

Q = (selector, within)=>{

  var w = within || doc;

  return w.querySelectorAll(selector);

}

aC = function(){

  const a = [].slice.call(arguments);

  a.shift().classList.add(...a);

  return aC;

}

rC = function(){

  const a = [].slice.call(arguments);

  a.shift().classList.remove(...a);

  return rC;

}

// can do below on another page except end load

const canvas = I('canvas'), ctx = canvas.getContext('2d'), test = I('test');

ctx.fillStyle = '#070'; ctx.fillRect(0, 0, canvas.width, canvas.height);

test.onclick = ()=>{

  console.log('test worked');

}

canvas.onclick = function(e){

  const all = doc.elementsFromPoint(e.clientX, e.clientY);

  for(let q of all){

    switch(q){

      case test:

        test.click();

        break;

    }

  }

}

canvas.onmousemove = function(e){

  const all = doc.elementsFromPoint(e.clientX, e.clientY);

  for(let q of all){

    switch(q){

      case test:

        aC(this, 'pointer');

        break;

      case this:

        rC(this, 'pointer');

        break;

    }

  }

}

}); // end load

*{

  box-sizing:border-box;

}

html,body{

 padding:0; margin:0;

}

html,body,#outer,#canvas{

  width:100%; height:100%;

}

#outer{

  position:relative;

}

#outer>*{

  position:absolute;

}

.pointer{

  cursor:pointer;

}

<div id='outer'>

  <input id='test' type='button' value='test' />

  <canvas id='canvas'></canvas>

</div>

我希望您也可以看到如何测试其他情况。