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import type {Position} from './@types'
export type TransformMatrix = [
number,
number,
number,
number,
number,
number,
number,
number,
number,
]
// These are affine transforms. See explanation of every cell here:
// https://en.wikipedia.org/wiki/Transformation_matrix#/media/File:2D_affine_transformation_matrix.svg
export function createTransform(): TransformMatrix {
'worklet'
return [1, 0, 0, 0, 1, 0, 0, 0, 1]
}
export function applyRounding(t: TransformMatrix) {
'worklet'
t[2] = Math.round(t[2])
t[5] = Math.round(t[5])
// For example: 0.985, 0.99, 0.995, then 1:
t[0] = Math.round(t[0] * 200) / 200
t[4] = Math.round(t[0] * 200) / 200
}
// We're using a limited subset (always scaling and translating while keeping aspect ratio) so
// we can assume the transform doesn't encode have skew, rotation, or non-uniform stretching.
// All write operations are applied in-place to avoid unnecessary allocations.
export function readTransform(t: TransformMatrix): [number, number, number] {
'worklet'
const scale = t[0]
const translateX = t[2]
const translateY = t[5]
return [translateX, translateY, scale]
}
export function prependTranslate(t: TransformMatrix, x: number, y: number) {
'worklet'
t[2] += t[0] * x + t[1] * y
t[5] += t[3] * x + t[4] * y
}
export function prependScale(t: TransformMatrix, value: number) {
'worklet'
t[0] *= value
t[1] *= value
t[3] *= value
t[4] *= value
}
export function prependTransform(ta: TransformMatrix, tb: TransformMatrix) {
'worklet'
// In-place matrix multiplication.
const a00 = ta[0],
a01 = ta[1],
a02 = ta[2]
const a10 = ta[3],
a11 = ta[4],
a12 = ta[5]
const a20 = ta[6],
a21 = ta[7],
a22 = ta[8]
ta[0] = a00 * tb[0] + a01 * tb[3] + a02 * tb[6]
ta[1] = a00 * tb[1] + a01 * tb[4] + a02 * tb[7]
ta[2] = a00 * tb[2] + a01 * tb[5] + a02 * tb[8]
ta[3] = a10 * tb[0] + a11 * tb[3] + a12 * tb[6]
ta[4] = a10 * tb[1] + a11 * tb[4] + a12 * tb[7]
ta[5] = a10 * tb[2] + a11 * tb[5] + a12 * tb[8]
ta[6] = a20 * tb[0] + a21 * tb[3] + a22 * tb[6]
ta[7] = a20 * tb[1] + a21 * tb[4] + a22 * tb[7]
ta[8] = a20 * tb[2] + a21 * tb[5] + a22 * tb[8]
}
export function prependPan(t: TransformMatrix, translation: Position) {
'worklet'
prependTranslate(t, translation.x, translation.y)
}
export function prependPinch(
t: TransformMatrix,
scale: number,
origin: Position,
translation: Position,
) {
'worklet'
prependTranslate(t, translation.x, translation.y)
prependTranslate(t, origin.x, origin.y)
prependScale(t, scale)
prependTranslate(t, -origin.x, -origin.y)
}
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