极客教程Fabric.js setAlpha()方法
setAlpha() 方法 用于设置指定颜色的 alpha 通道值。
语法:
setAlpha(alpha)
参数: 该方法接受一个如上所述的参数，并在下面进行描述：
- alpha: 该参数保存指定的alpha通道值。
返回值: 该方法返回指定的RGBA格式的颜色值以及给定的alpha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 setAlpha() function over
// the specified color values
console.log(new fabric.Color("hsl(0, 100%, 50%)").setAlpha(0.4));
</script>
</body>
</html>
输出：
{"_source":[255,0,0,0.4]}
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 setAlpha() function over
// the above specified color values
console.log(new fabric.Color(A).setAlpha(0));
console.log(new fabric.Color(B).setAlpha(0.4));
console.log(new fabric.Color(C).setAlpha(0.2));
console.log(new fabric.Color(D).setAlpha(0.7));
console.log(new fabric.Color(E).setAlpha(0.9));
</script>
</body>
</html>
输出：
{"_source":[0,0,0,0]}
{"_source":[72,59,55,0.4]}
{"_source":[46,24,20,0.2]}
{"_source":[10,40,13,0.7]}
{"_source":[10,40,13,0.9]}