Fabric JS 使用鼠标：悬停在动画对象上

Question

I can animate an object and then add a mouse:over event.

 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>

However the mouse:over event continues to fire from the rectangle's original position. Once the animate finishes then the mouse:over event works again over the animated object.

Is it possible to have a mouse:over event fire while an object is moving/animating?

Answer 1

I wasn't able to figure out a built-in way. You might want to submit this as an issue. In the meantime, I think I have a usable workaround:

 // 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(), oe); // 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>

Essentially, I listen for mouse:move . On each mouse move, I get the cursor coordinates and check to see if it's inside the shape.

Right now, it's hard-coded to only work on Rect s, but perhaps you could introduce a function like isInside(object, pos) which returns a boolean , and in there you can check what type object is and decide based on that.

Answer 2

i realise this topic is very old, but i've just run into the same issue.

after a bit of fiddling, it turned out that calling setCoords() after the object has moved will update the internal state so that mouseover works again correctly.