当用户将鼠标悬停在画布上时,我试图添加图像并对它们进行动画处理,一旦它们将鼠标从画布上移开,我想停止出现新图像。
为此,我尝试在新图像上设置一个间隔,以每100毫秒触发一次,然后,如果用户将鼠标从画布上移开,则此功能应停止触发。
canvas.addEventListener("mouseover", setInterval(newImage, 100), false);
canvas.addEventListener("mouseout", clearInterval(newImage), false);
下面的JS代码
//gets canvas element
var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
function newImage() {
//random position on the canvas
var randomPosition = parseInt(Math.random() * window.innerWidth);
var images = [
'http://www.convoy.me/image/landing/Scratcher.png',
'http://www.convoy.me/image/landing/push_harder_0006.png'
];
var y = window.innerHeight;
//selects a random image
var randomImage = parseInt(Math.random() * images.length);
//IIFE draw
(function draw() {
var imageObj = new Image();
imageObj.onload = function() {
ctx.clearRect(randomPosition - imageObj.width, y, imageObj.width, imageObj.height);
y -= 10;
ctx.drawImage(imageObj, randomPosition - imageObj.width, y, imageObj.width, imageObj.height);
if (y > -imageObj.height) {
requestAnimationFrame(draw)
}
};
imageObj.src = images[randomImage];
})();
}
canvas.addEventListener("mouseover", setInterval(newImage, 100), false);
canvas.addEventListener("mouseout", clearInterval(newImage), false);
<canvas id="canvas"></canvas>
最佳答案
我认为问题在于间隔永远不会清除。您需要将间隔分配给变量,然后按变量名称清除间隔:
var newImageInterval;
canvas.addEventListener("mouseover", function(){
newImageInterval = setInterval(newImage, 100);
}, false);
canvas.addEventListener("mouseout", function(){
clearInterval(newImageInterval);
}, false);
关于javascript - 当用户将鼠标悬停在 Canvas 上时创建动画,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/39794186/