如何在鼠标悬停时调整画布元素的大小

Question

我想在鼠标悬停事件上调整画布元素的大小并缓慢增大其大小（如弧线）。我该怎么做？

Answer 1

鼠标悬停在画布本身上？只需添加一个事件侦听器并按照您想要的方式重绘场景：

// Every time the mouse comes over the canvas the radius increases.
// you could even add a timer so that every time the mouse stays over
// the canvas the radius continues to increase constantly
can.addEventListener('mouseover', function(e) {
    radius += 10;
    ctx.clearRect(0,0,can.width, can.height);
    ctx.beginPath();
    ctx.arc(150, 150, radius, 0, Math.PI*.8, false);
    ctx.stroke();
}, false);

http://jsfiddle.net/dAQdL/

将鼠标悬停在画布上绘制的“对象”上？您必须向画布添加对象持久性和检测。