当我将鼠标悬停在PNG的透明部分上时,它仍然就像我在实际图像上方盘旋一样.有没有办法可以防止这种情况发生？因此,当我将鼠标悬停在图像的可见部分而不是透明部分时,它只会采取行动？
我试图裁掉透明度,但我找不到怎样的方法.
解决方法
可以通过将png转换为canvas元素来完成
这可以通过将png加载到HTML-5 canvas元素中,然后在画布中查询所单击像素的alpha值来实现.
工作演示：http://jsfiddle.net/x9ScK/3/
HTML如下……
<!-- create a canvas element to hold the PNG image --> <canvas id="canvas1" width="500" height="500"></canvas>
像这样的Javascript ……
// select the canvas element with jQuery,and set up
// a click handler for the whole canvas
$('#canvas1').on('click',function(e) {
// utility function for finding the position of the clicked pixel
function findPos(obj) {
var curleft = 0,curtop = 0;
if (obj.offsetParent) {
do {
curleft += obj.offsetLeft;
curtop += obj.offsetTop;
} while (obj = obj.offsetParent);
return { x: curleft,y: curtop };
}
return undefined;
}
// get the position of clicked pixel
var pos = findPos(this);
var x = e.pageX - pos.x;
var y = e.pageY - pos.y;
// get reference to canvas element clicked on
var canvas = this.getContext('2d');
// return array of [RED,GREEN,BLUE,ALPHA] as 0-255 of clicked pixel
var pixel = canvas.getImageData(x,y,1,1).data;
// if the alpha is not 0,we clicked a non-transparent pixel
// could be easily adjusted to detect other features of the clicked pixel
if(pixel[3] != 0){
// do something when clicking on image...
alert("Clicked the dice!");
}
});
// get reference to canvas DOM element
var canvas = $('#canvas1')[0];
// get reference to canvas context
var context = canvas.getContext('2d');
// create an empty image
var img = new Image();
// after loading...
img.onload = function() {
// draw the image onto the canvas
context.drawImage(img,0);
}
// set the image source (can be any url - I used data URI to keep demo self contained)
img.src = "data:image/png;base64,iVBORw0KGgoAAAANS ... more image data ...TkSuQmCC"; // PNG with transparency