javascript - Fabric JS 使用鼠标 :over on an animating object

Question

我可以为一个对象设置动画，然后添加一个 mouse:over 事件。

var canvas = new fabric.Canvas('c');
var x1 = 5;
var y1 = 5;
var x2 = 100;
var y2 = 100;

var rect = new fabric.Rect({
    width: 10,
    height: 10,
    left: x1,
    top: y1,
    stroke: '#000',
    strokeWidth: 2,
    fill: '#faa',
    selectable: false
});
canvas.add(rect);

rect.animate({
    'left': x2,
    'top': y2
}, {
    duration: 10000,
    onChange: canvas.renderAll.bind(canvas),
    onComplete: function() {
    }
});

canvas.on('mouse:over', function (e) {
    console.log('mouseover');
});

<canvas id="c"></canvas>
<script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/1.6.3/fabric.min.js"></script>

但是 mouse:over 事件继续从矩形的原始位置触发。动画完成后，mouse:over 事件会再次作用于动画对象。

是否可以在对象移动/设置动画时触发 mouse:over 事件？

Answer 1

我想不出一个内置的方法。您可能希望将此作为问题提交。与此同时，我认为我有一个可用的解决方法:

// Setup

var canvas = new fabric.Canvas('c');
var x1 = 5;
var y1 = 5;
var x2 = 100;
var y2 = 100;
var rectWidth = 10;
var rectHeight = 10;

var rect = new fabric.Rect({
    width: rectWidth,
    height: rectHeight,
    left: x1,
    top: y1,
    stroke: '#000',
    strokeWidth: 2,
    fill: '#faa',
    selectable: false
});
canvas.add(rect);

rect.animate({
    'left': x2,
    'top': y2
}, {
    duration: 10000,
    onChange: canvas.renderAll.bind(canvas),
    onComplete: function() {
    }
});

// http://stackoverflow.com/questions/17130395/real-mouse-position-in-canvas
function  getMousePos(canvas, evt) {
  var rect = canvas.getBoundingClientRect(), // abs. size of element
      scaleX = canvas.width / rect.width,    // relationship bitmap vs. element for X
      scaleY = canvas.height / rect.height;  // relationship bitmap vs. element for Y

  return {
    x: (evt.clientX - rect.left) * scaleX,   // scale mouse coordinates after they have
    y: (evt.clientY - rect.top) * scaleY     // been adjusted to be relative to element
  }
}

// The important stuff

canvas.on('mouse:move', function (o) {
  var pos = getMousePos(canvas.getElement(), o.e);
  // Do math to figure out if the mouse move was inside the the object. For a Rect:
  if (
    pos.x >= rect.left &&
    pos.x <= rect.left + rectWidth &&
    pos.y >= rect.top &&
    pos.y <= rect.top + rectHeight
  ) {
    console.log('mouseover');
  }
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/1.6.3/fabric.min.js"></script>
<canvas id="c"></canvas>

本质上，我会监听 mouse:move。每次鼠标移动时，我都会获取光标坐标并检查它是否在形状内。

现在，它被硬编码为只能在 Rect 上工作，但也许你可以引入一个像 isInside(object, pos) 这样的函数，它返回一个 boolean，您可以在其中检查 object 的类型并据此做出决定。