paint-ui/store/canvas-store.ts

import { create } from 'zustand';
import { persist } from 'zustand/middleware';
import type { CanvasState, CanvasSelection, Point } from '@/types';

interface CanvasStore extends CanvasState {
  /** Selection state */
  selection: CanvasSelection;

  /** Set canvas dimensions */
  setDimensions: (width: number, height: number) => void;
  /** Set zoom level */
  setZoom: (zoom: number) => void;
  /** Zoom in (1.2x) */
  zoomIn: () => void;
  /** Zoom out (0.8x) */
  zoomOut: () => void;
  /** Fit canvas to viewport */
  zoomToFit: (viewportWidth: number, viewportHeight: number) => void;
  /** Zoom to actual size (100%) */
  zoomToActual: () => void;
  /** Set pan offset */
  setPanOffset: (x: number, y: number) => void;
  /** Pan by delta */
  pan: (dx: number, dy: number) => void;
  /** Reset pan to center */
  resetPan: () => void;
  /** Toggle grid visibility */
  toggleGrid: () => void;
  /** Set grid size */
  setGridSize: (size: number) => void;
  /** Toggle rulers */
  toggleRulers: () => void;
  /** Toggle snap to grid */
  toggleSnapToGrid: () => void;
  /** Set background color */
  setBackgroundColor: (color: string) => void;
  /** Set selection */
  setSelection: (selection: Partial<CanvasSelection>) => void;
  /** Clear selection */
  clearSelection: () => void;
  /** Convert screen coordinates to canvas coordinates */
  screenToCanvas: (screenX: number, screenY: number, containerWidth?: number, containerHeight?: number) => Point;
  /** Convert canvas coordinates to screen coordinates */
  canvasToScreen: (canvasX: number, canvasY: number) => Point;
}

const DEFAULT_CANVAS_WIDTH = 800;
const DEFAULT_CANVAS_HEIGHT = 600;
const MIN_ZOOM = 0.1;
const MAX_ZOOM = 10;
const ZOOM_STEP = 1.2;

export const useCanvasStore = create<CanvasStore>()(
  persist(
    (set, get) => ({
      width: DEFAULT_CANVAS_WIDTH,
      height: DEFAULT_CANVAS_HEIGHT,
      zoom: 1,
      offsetX: 0,
      offsetY: 0,
      backgroundColor: 'transparent',
      showGrid: false,
      gridSize: 20,
      showRulers: true,
      snapToGrid: false,
      selection: {
        active: false,
        x: 0,
        y: 0,
        width: 0,
        height: 0,
      },

  setDimensions: (width, height) => {
    set({ width, height });
  },

  setZoom: (zoom) => {
    const clampedZoom = Math.max(MIN_ZOOM, Math.min(MAX_ZOOM, zoom));
    set({ zoom: clampedZoom });
  },

  zoomIn: () => {
    const { zoom } = get();
    get().setZoom(zoom * ZOOM_STEP);
  },

  zoomOut: () => {
    const { zoom } = get();
    get().setZoom(zoom / ZOOM_STEP);
  },

  zoomToFit: (viewportWidth, viewportHeight) => {
    const { width, height } = get();
    const padding = 40;
    const scaleX = (viewportWidth - padding * 2) / width;
    const scaleY = (viewportHeight - padding * 2) / height;
    const zoom = Math.min(scaleX, scaleY, 1);
    set({ zoom, offsetX: 0, offsetY: 0 });
  },

  zoomToActual: () => {
    set({ zoom: 1 });
  },

  setPanOffset: (x, y) => {
    set({ offsetX: x, offsetY: y });
  },

  pan: (dx, dy) => {
    set((state) => ({
      offsetX: state.offsetX + dx,
      offsetY: state.offsetY + dy,
    }));
  },

  resetPan: () => {
    set({ offsetX: 0, offsetY: 0 });
  },

  toggleGrid: () => {
    set((state) => ({ showGrid: !state.showGrid }));
  },

  setGridSize: (size) => {
    set({ gridSize: Math.max(1, size) });
  },

  toggleRulers: () => {
    set((state) => ({ showRulers: !state.showRulers }));
  },

  toggleSnapToGrid: () => {
    set((state) => ({ snapToGrid: !state.snapToGrid }));
  },

  setBackgroundColor: (color) => {
    set({ backgroundColor: color });
  },

  setSelection: (selection) => {
    set((state) => ({
      selection: { ...state.selection, ...selection },
    }));
  },

  clearSelection: () => {
    set({
      selection: {
        active: false,
        x: 0,
        y: 0,
        width: 0,
        height: 0,
      },
    });
  },

  screenToCanvas: (screenX, screenY, containerWidth = 0, containerHeight = 0) => {
    const { zoom, offsetX, offsetY, width, height } = get();
    // The canvas is rendered with this transformation:
    // 1. translate(offsetX + containerWidth/2, offsetY + containerHeight/2) - center in viewport with offset
    // 2. scale(zoom) - apply zoom
    // 3. translate(-width/2, -height/2) - position canvas so (0,0) is at top-left
    //
    // To reverse:
    // 1. Subtract container center and offset
    // 2. Divide by zoom
    // 3. Add canvas center
    return {
      x: (screenX - containerWidth / 2 - offsetX) / zoom + width / 2,
      y: (screenY - containerHeight / 2 - offsetY) / zoom + height / 2,
    };
  },

  canvasToScreen: (canvasX, canvasY) => {
    const { zoom, offsetX, offsetY } = get();
    return {
      x: canvasX * zoom + offsetX,
      y: canvasY * zoom + offsetY,
    };
  },
    }),
    {
      name: 'canvas-view-storage',
      partialize: (state) => ({
        backgroundColor: state.backgroundColor,
        showGrid: state.showGrid,
        gridSize: state.gridSize,
        showRulers: state.showRulers,
        snapToGrid: state.snapToGrid,
        // Exclude: width, height, zoom, offsetX, offsetY, selection
      }),
    }
  )
);