tldraw/state/state.ts

import { createSelectorHook, createState } from "@state-designer/react"
import { clamp, screenToWorld } from "utils/utils"
import * as vec from "utils/vec"
import { Data } from "types"
import { defaultDocument } from "./data"
import * as Sessions from "./sessions"

const initialData: Data = {
  camera: {
    point: [0, 0],
    zoom: 1,
  },
  brush: undefined,
  pointedId: null,
  selectedIds: [],
  currentPageId: "page0",
  document: defaultDocument,
}

const state = createState({
  data: initialData,
  on: {
    ZOOMED_CAMERA: {
      do: "zoomCamera",
    },
    PANNED_CAMERA: {
      do: "panCamera",
    },
  },
  initial: "selecting",
  states: {
    selecting: {
      on: {
        POINTED_CANVAS: { to: "brushSelecting" },
      },
    },
    brushSelecting: {
      onEnter: "startBrushSession",
      on: {
        MOVED_POINTER: "updateBrushSession",
        PANNED_CAMERA: "updateBrushSession",
        STOPPED_POINTING: { do: "completeSession", to: "selecting" },
        CANCELLED: { do: "cancelSession", to: "selecting" },
      },
    },
  },
  actions: {
    cancelSession(data) {
      session.cancel(data)
      session = undefined
    },
    completeSession(data) {
      session.complete(data)
      session = undefined
    },
    startBrushSession(data, payload: { point: number[] }) {
      session = new Sessions.BrushSession(
        data,
        screenToWorld(payload.point, data)
      )
    },
    updateBrushSession(data, payload: { point: number[] }) {
      session.update(data, screenToWorld(payload.point, data))
    },
    zoomCamera(data, payload: { delta: number; point: number[] }) {
      const { camera } = data
      const p0 = screenToWorld(payload.point, data)
      camera.zoom = clamp(
        camera.zoom - (payload.delta / 100) * camera.zoom,
        0.5,
        3
      )
      const p1 = screenToWorld(payload.point, data)
      camera.point = vec.add(camera.point, vec.sub(p1, p0))
    },
    panCamera(data, payload: { delta: number[]; point: number[] }) {
      const { camera } = data
      data.camera.point = vec.sub(
        camera.point,
        vec.div(payload.delta, camera.zoom)
      )
    },
  },
})

let session: Sessions.BaseSession

export default state

export const useSelector = createSelectorHook(state)