feuerwerk/src/editor/graph/AnnotationView.ts

import { Graphics, Rectangle, Text, TextStyle } from 'pixi.js';
import type { AnnotationKind, GraphAnnotation } from '../../core/graph';
import { readableTextColor, Theme, truncate, Widget } from '../../ui';

/** Height of a group's title bar – the same as a node's, so the two line up in the eye. */
export const ANNOTATION_TITLE_HEIGHT = 24;
/** Side of the square at the bottom right corner that resizes the box. */
export const RESIZE_HANDLE = 14;
const PAD = 8;

/**
 * One group or comment, drawn behind the nodes in graph coordinates.
 *
 * A group is hit on its title bar and its resize handle only: its body has to stay transparent to
 * the pointer, or a rubber band could never be drawn across the nodes it holds. A comment frames
 * nothing, so it is grabbed anywhere.
 */
export class AnnotationView extends Widget {
  private readonly box = new Graphics();
  private readonly caption: Text;
  selected = false;

  constructor(
    public annotation: GraphAnnotation,
    readonly kind: AnnotationKind,
  ) {
    super();
    this.addChild(this.box);
    this.caption = new Text({ text: '', style: this.captionStyle(0xffffff) });
    this.caption.position.set(PAD, kind === 'group' ? 0 : PAD);
    this.addChild(this.caption);
    this.cursor = Theme.hoverCursor;
    this.sync(annotation);
  }

  sync(annotation: GraphAnnotation): void {
    this.annotation = annotation;
    this.position.set(annotation.x, annotation.y);
    this.resize(annotation.w, annotation.h);
    // `resize` puts the full rectangle back every time, changed size or not, so this comes after it.
    this.applyHitArea();
    this.redraw();
  }

  get color(): number {
    return this.annotation.color ?? Theme.colors.annotation;
  }

  /** Black or white, picked from the fill it sits on – the price of letting the picker run free. */
  get textColor(): number {
    return readableTextColor(this.color);
  }

  private captionStyle(color: number): TextStyle {
    return new TextStyle({
      fontFamily: Theme.font,
      fontSize: Theme.fontSize,
      fill: color,
      fontWeight: this.kind === 'group' ? '600' : '400',
      wordWrap: this.kind === 'note',
      wordWrapWidth: Math.max(this.w - PAD * 2, 1),
      lineHeight: Theme.fontSize + 4,
    });
  }

  /** Where the box answers the pointer: the title bar of a group, the whole card of a comment. */
  private applyHitArea(): void {
    if (this.kind === 'note') {
      this.hitArea = new Rectangle(0, 0, this.w, this.h);
      return;
    }
    this.hitArea = {
      contains: (x: number, y: number) =>
        (x >= 0 && x <= this.w && y >= 0 && y <= ANNOTATION_TITLE_HEIGHT) || this.handleAt(x, y),
    };
  }

  /** Whether this local point is on the corner that resizes – outside the hit area for a group,
   *  so the canvas asks for it before it asks who is under the pointer. */
  handleAt(x: number, y: number): boolean {
    return x >= this.w - RESIZE_HANDLE && x <= this.w && y >= this.h - RESIZE_HANDLE && y <= this.h;
  }

  override redraw(): void {
    const c = Theme.colors;
    const color = this.color;
    const text = this.textColor;
    this.box.clear();
    if (this.kind === 'group') {
      // Translucent body, solid title: the nodes inside must stay readable, the title must not.
      this.box.roundRect(0, 0, this.w, this.h, Theme.radius).fill({ color, alpha: 0.12 });
      this.box.roundRect(0, 0, this.w, ANNOTATION_TITLE_HEIGHT, Theme.radius).fill(color);
      this.box.rect(0, ANNOTATION_TITLE_HEIGHT - Theme.radius, this.w, Theme.radius).fill(color);
    } else {
      this.box.roundRect(0, 0, this.w, this.h, Theme.radius).fill(color);
    }
    this.box
      .roundRect(0.5, 0.5, this.w - 1, this.h - 1, Theme.radius)
      .stroke({ width: this.selected ? 2 : 1, color: this.selected ? c.nodeSelected : color, alpha: 0.9 });
    // A corner that can be grabbed says so, in the text colour of the box it belongs to.
    this.box
      .moveTo(this.w - RESIZE_HANDLE, this.h - 2)
      .lineTo(this.w - 2, this.h - RESIZE_HANDLE)
      .moveTo(this.w - RESIZE_HANDLE / 2, this.h - 2)
      .lineTo(this.w - 2, this.h - RESIZE_HANDLE / 2)
      .stroke({ width: 1, color: text, alpha: 0.5 });

    this.caption.style = this.captionStyle(text);
    this.caption.text =
      this.kind === 'group'
        ? truncate(this.annotation.text, this.caption.style, Math.max(this.w - PAD * 2, 1))
        : this.annotation.text;
    if (this.kind === 'group') this.caption.y = (ANNOTATION_TITLE_HEIGHT - this.caption.height) / 2;
  }

  /** What the last redraw put on screen, for the checks. */
  drawnText(): string {
    return this.caption.text;
  }
}