缩放图片JS

/**
*
*img 为<img/>对象
*/
function drawImg(img,boxWidth, boxHeight) {
var imgWidth = img.width;
var imgHeight = img.height;
if ((boxWidth / boxHeight) >= (imgWidth / imgHeight)) {
img.width = ((boxHeight * imgWidth) / imgHeight);
img.height = (boxHeight);
} else {
img.width = (boxWidth);
img.height = ((boxWidth * imgHeight) / imgWidth);
}
}