我一直在尝试让我的简单JavaScript脚本将弹跳球移动到鼠标点击事件发生的位置。我在这里放置了脚本。它可以与任何具有id为
game
的大小不同的画布进行交互。球会弹跳,但它忽略了鼠标点击事件。你知道哪里出了问题吗?谢谢。var canvas;
var x, y;
var dx=4;
var dy=4;
var d = 20;
var width, height;
function init() {
canvasE = document.getElementById('game');
canvas= canvasE.getContext('2d');
width = canvasE.width;
height = canvasE.height;
x = d+dx+1;
y = d+dy+1;
canvasE.addEventListener("click", onClick, false);
clear();
canvas.beginPath();
canvas.fillStyle="#0000ff";
// Draws a circle of radius 20 at the coordinates 100,100 on the canvas
canvas.arc(x-1,y-1,d,0,Math.PI*2,true);
canvas.closePath();
canvas.fill();
setInterval(loop, 15);
}
function loop() {
clear();
canvas.beginPath();
canvas.fillStyle="#0000ff";
// Draws a circle of radius 20 at the coordinates 100,100 on the canvas
canvas.arc(x,y,d,0,Math.PI*2,true);
canvas.closePath();
canvas.fill();
// Boundary Logic
if( x<(d-dx)+1 || x>width-(d+dx)-1) dx=-dx;
if( y<(d-dx)+1 || y>height-(d+dy)-1) dy=-dy;
x+=dx;
y+=dy;
}
function clear() {
canvas.fillStyle="#ffffff";
canvas.fillRect(0,0,width,height);
canvas.fillStyle="#888888";
canvas.strokeRect(0,0,width,height);
}
function onClick(e) {
var clickX;
var clickY;
if (e.pageX || e.pageY) {
clickX = e.pageX;
clickY = e.pageY;
}
else {
clickX = e.clientX + document.body.scrollLeft + document.documentElement.scrollLeft;
clickY = e.clientY + document.body.scrollTop + document.documentElement.scrollTop;
}
clickX -= gCanvasElement.offsetLeft;
clickY -= gCanvasElement.offsetTop;
x = clickX;
y = clickY;
}
requestAnimationFrame()
而不是setTimeout()
。http://jsfiddle.net/sperske/4Lanc/367/ - Jason Sperske