特别是在画布上改变笔触不透明度而不是颜色

Question

I have a nice tidy script that cycles through colors and it works nicely with the #xxxxxx format, but I want to change the transparency. Is there a way to do that?

I'm referring to ctx.strokeStyle()

Here's the current code:

canvas.strokeStyle = '#' + (((16777215 / s.length) * i).toString(16));

It cycles through a for loop with i incremented by 1 each cycle and it's a part of a switch. The for loop looks like this: for(var i = 0; i < s.length; i++){}

Answer 1

在绘制所需的不透明度中的每个元素之前，您可以在0到1的范围内更改ctx.globalAlpha 。

Answer 2

Use ctx.globalAlpha like Martin Tale answered or rgba([0-255], [0-255], [0-255], [0-1]) format. So you need to convert the integer to individual rgb values:

var color = ((16777215 / s.length) * i);
var r = (color >> 16) & 255;
var g = (color >> 8) & 255;
var b = color & 255;

var alpha = 0.5;

canvas.strokeStyle = "rgba("+r+","+g+","+b+","+alpha+")";