How do I get the opacity value of the first pixel on the canvas?

Question

I want to get the opacity value of the first pixel on the canvas, which is supposed to return 0.5, I don't yet understand very well how typed arrays work and how can I get the value I want

https://code.sololearn.com/WBWnh83cajEQ/?ref=app

Answer 1

To get the opacity value of the first pixel on the canvas, you need to access the alpha value of the first pixel in the canvas data array. Since the canvas data array is a typed array, you can access the alpha value of the first pixel using the formula:

data[3] / 255

in your code. This formula maps the alpha value from the range 0-255 to 0-1, giving you the opacity value as 0.5 for a half-transparent pixel.