允许鼠标事件通过 Fabrixjs Canvas 实例？

Question

我已经有几年没有使用Fabricjs了，如果这是一个基本问题，请原谅我

我在一些按钮元素上添加了一个窗口大小的Canvas 元素，我还希望用户能够点击这些元素。

Fabricjs 中是否有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“pointer-events: none”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”）和包装器 div从我提供的 canvas 元素创建的 fabric.Canvas(...) 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

您可以使用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>

我希望你也可以看看你将如何测试其他情况。