function fitSize(argImage, maxWidth, maxHeight)
{
	var varImage = new Image();
	varImage.src = argImage.src;

	if(varImage.width>0 && varImage.height>0)
	{
		if (varImage.width/varImage.height >= maxWidth/maxHeight)
		{
			// 以宽度约束缩小
			if (varImage.width != maxWidth)
			{
				var numScale = varImage.width/maxWidth;
				varImage.width = maxWidth;
				varImage.height = Math.round(varImage.height/numScale);
			}
		}
		else
		{
			// 以高度约束缩小
			if (varImage.height != maxHeight)
			{
				var numScale = varImage.height/maxHeight;
				varImage.width = Math.round(varImage.width/numScale);
				varImage.height = maxHeight;
			}
		}
	
		argImage.width = varImage.width;
		argImage.height = varImage.height;
	}
}
function placeSize(argImage, maxWidth, maxHeight)
{
	var varImage = new Image();
	varImage.src = argImage.src;

	if(varImage.width>0 && varImage.height>0)
	{
		if (varImage.width/varImage.height >= maxWidth/maxHeight)
		{
			// 以宽度约束缩小
			if (varImage.width > maxWidth)
			{
				var numScale = varImage.width/maxWidth;
				varImage.width = maxWidth;
				varImage.height = Math.round(varImage.height/numScale);
			}
		}
		else
		{
			// 以高度约束缩小
			if (varImage.height > maxHeight)
			{
				var numScale = varImage.height/maxHeight;
				varImage.width = Math.round(varImage.width/numScale);
				varImage.height = maxHeight;
			}
		}
	
		argImage.width = varImage.width;
		argImage.height = varImage.height;
	}
}