画面内检测鼠标的点击位置(Detect mouse click location within ca

我在试图定义，我点击空白区域的功能一个真正的问题。到目前为止，我已经成功地定义，我点击的对象上 - 其中有10 - 但现在我需要的时候我不点击任何对象的一个单独的功能。总体思路，可以发现http://deciballs.co.uk/experience.html 。的对象是环。我的代码如下...任何想法？

var shapeObj = function (context, canvas, settingsBox, radius) {
    this.ctx = context;
    this.canvas = canvas;
    this.sBox = settingsBox;

    this.frequencies = new Array(220, 440, 1024, 2048);
    this.cols = new Array(255, 225, 200, 175, 150);
    this.strokes = new Array(1, 1.5, 2);
    this.waves = new Array('sine', 'sawtooth', 'triangle', 'square');

    this.properties = {
        dur: Math.random()*0.5,
        freq: this.frequencies[Math.floor(Math.random() * this.frequencies.length)],
        radius: radius,
        stroke: this.strokes[Math.floor(Math.random() * this.strokes.length)],
        speed: Math.random()*6-3,
        vol: Math.random()*10,
        col1: this.cols[Math.floor(Math.random() * this.cols.length)],
        col2: this.cols[Math.floor(Math.random() * this.cols.length)],
        col3: this.cols[Math.floor(Math.random() * this.cols.length)],
        alpha: 0,
        wave: this.waves[Math.floor(Math.random() * this.waves.length)],
        delay: 0 
    }

    this.x = Math.random()*this.ctx.canvas.width;
    this.y = Math.random()*this.ctx.canvas.height; 
    this.vx = 0.5;
    this.vy = 1;

    this.draw = function () {
        this.ctx.beginPath();
        this.ctx.arc(this.x, this.y, this.properties.radius, 0, Math.PI*2, false);
        this.ctx.closePath();
        this.ctx.stroke();
        this.ctx.fill();
    }

    this.clickTest = function (e) {
        var canvasOffset = this.canvas.offset();
        var canvasX = Math.floor(e.pageX-canvasOffset.left);
        var canvasY = Math.floor(e.pageY-canvasOffset.top);     
            var dX = this.x-canvasX;
            var dY = this.y-canvasY;
            var distance = Math.sqrt((dX*dX)+(dY*dY));
            if (distance < this.properties.radius) {
                this.manageClick();
            } else {
                this.properties.alpha = 0;
            }
    };

    this.manageClick = function () {
        this.sBox.populate(this.properties, this);
        var divs = document.getElementsByTagName('section');
        for(var i = 0, e = divs[0], n = divs.length; i < n; e = divs[++i]){
            e.className='class2';
        }
        this.properties.alpha = 0.5;
    }
}

日臻完善的鼠标点击是有点难，我会分享我创建了迄今最防弹鼠标代码。它适用于所有的浏览器将填充，边距，边框的所有方式，和加载项（如StumbleUpon公司最上面一栏）。

// Creates an object with x and y defined,
// set to the mouse position relative to the state's canvas
// If you wanna be super-correct this can be tricky,
// we have to worry about padding and borders
// takes an event and a reference to the canvas
function getMouse(e, canvas) {
  var element = canvas, offsetX = 0, offsetY = 0, mx, my;

  // Compute the total offset. It's possible to cache this if you want
  if (element.offsetParent !== undefined) {
    do {
      offsetX += element.offsetLeft;
      offsetY += element.offsetTop;
    } while ((element = element.offsetParent));
  }

  // Add padding and border style widths to offset
  // Also add the <html> offsets in case there's a position:fixed bar (like the stumbleupon bar)
  // This part is not strictly necessary, it depends on your styling
  offsetX += stylePaddingLeft + styleBorderLeft + htmlLeft;
  offsetY += stylePaddingTop + styleBorderTop + htmlTop;

  mx = e.pageX - offsetX;
  my = e.pageY - offsetY;

  // We return a simple javascript object with x and y defined
  return {x: mx, y: my};
}

你会发现，我用在函数未定义一些（可选）变量。他们是：

  stylePaddingLeft = parseInt(document.defaultView.getComputedStyle(canvas, null)['paddingLeft'], 10)      || 0;
  stylePaddingTop  = parseInt(document.defaultView.getComputedStyle(canvas, null)['paddingTop'], 10)       || 0;
  styleBorderLeft  = parseInt(document.defaultView.getComputedStyle(canvas, null)['borderLeftWidth'], 10)  || 0;
  styleBorderTop   = parseInt(document.defaultView.getComputedStyle(canvas, null)['borderTopWidth'], 10)   || 0;
  // Some pages have fixed-position bars (like the stumbleupon bar) at the top or left of the page
  // They will mess up mouse coordinates and this fixes that
  var html = document.body.parentNode;
  htmlTop = html.offsetTop;
  htmlLeft = html.offsetLeft;

我建议只计算那些一次，这就是为什么他们不在getMouse功能。

你真的应该有一个单一功能的帽子处理的鼠标点击，来电getMouse一次，然后就尽管对象的列表，检查，对每一个与x和y。伪代码：

function onMouseDown(e) {
  var mouse = getMouse(e, canvas)
  var l = myObjects.length;
  var found = false;

  // Maybe "deselect" them all right here

  for (var i = 0; i < l; i++) {
    if (distance sqrt to myObjects[i]) {
      found = true;
      myObjects[i].ManageClickOrWhateverYouWantHere()
    }
    break;
  }

  // And now we can know if we clicked on empty space or not!
  if (!found) {
    // No objects found at the click, so nothing has been clicked on
    // do some relevant things here because of that
    // I presume from your question this may be part of what you want
  }

}