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