极客教程Fabric.js getAlpha()方法
getAlpha()方法 用于获取指定颜色值的alpha通道的值。
语法:
getAlpha()
参数： 此方法不接受任何参数。
返回值： 此方法返回阿尔法通道值。
示例1：
<!DOCTYPE html>
<html>
<head>
<!-- Adding the FabricJS library -->
<script src=
"https://cdnjs.cloudflare.com/ajax/libs/fabric.js/3.6.2/fabric.min.js">
</script>
</head>
<body>
<script type="text/javascript">
// Calling the getAlpha() function over
// the specified color values
console.log(new fabric.Color("hsl(0, 100%, 50%)").getAlpha());
console.log(new fabric.Color("hsla(0, 100%, 50%, 0.2)").getAlpha());
</script>
</body>
</html>
输出：
1
0.2
示例 2：
<!DOCTYPE html>
<html>
<head>
<!-- Adding the FabricJS library -->
<script src=
"https://cdnjs.cloudflare.com/ajax/libs/fabric.js/3.6.2/fabric.min.js">
</script>
</head>
<body>
<script type="text/javascript">
// Initializing some color values in different color format
var A = "hex(fff00f)";
var B = "hsl(12, 13%, 25%)";
var C = "hsla(10, 40%, 13%, 0.6)";
var D = "rgb(10, 40, 13)";
var E = "rgba(10, 40, 13, 0.9)";
// Calling the getAlpha() function over
// the above specified color values
console.log(new fabric.Color(A).getAlpha());
console.log(new fabric.Color(B).getAlpha());
console.log(new fabric.Color(C).getAlpha());
console.log(new fabric.Color(D).getAlpha());
console.log(new fabric.Color(E).getAlpha());
</script>
</body>
</html>
输出：
1
1
0.6
1
0.9