I am drawing a line in `Canvas` and then `rotatin...

# compose

[Vivek Sharma]

I am drawing a line in Canvas and then rotating it by angle 45f , is there a way to get that end Offset till the line is rotated
How can I get/access this Offset (?,?) ?

[Arsen]

Seems like "Point in circle" https://math.stackexchange.com/a/260115
You have angle (45f), and radius (100)

[theapache64]

val x = nextOffset.x + lineLength * kotlin.math.sin(angle)
val y = nextOffset.y + lineLength * kotlin.math.cos(angle)

rather than rotating the canvas, you can use sin and cos to calculate the target x and y
Here’s a full example

Canvas(
            modifier = Modifier.fillMaxSize()
        ) {
            var nextOffset = Offset(0f, 0f)
            repeat(noOfLines) {
                val angle = (0..360).random().toFloat()
                val x = nextOffset.x + lineLength * kotlin.math.sin(angle)
                val y = nextOffset.y + lineLength * kotlin.math.cos(angle)


                val targetOffset = Offset(x, y)
                drawLine(
                    color = colors.random(),
                    strokeWidth = 5f,
                    start = nextOffset,
                    end = targetOffset
                )

                nextOffset = targetOffset
            }
        }

[Michael Paus]

Instead of fiddling around with sines and cosines yourself, you could also create a rotation matrix and apply that to the draw scope for drawing. In addition you can apply it to any coordinate to see where it will be in the rotated system. This is more efficient and less error prone.

[Vivek Sharma]

Thanks gonna try