theseus/bundled-addons/pdf-editor/lib/tools.js

// Pointer behaviour for every tool.
//
// The editor is modal: one tool is armed, and what a drag does depends only on
// which. The alternative — inferring intent from what is under the cursor — is
// what makes PDF annotators infuriating, because a drag meant to draw a box
// selects a paragraph instead. Modality is enforced in CSS (see the
// body[data-mode] rules): with a drawing tool armed, the text and form layers
// stop taking pointer events entirely, so a drag cannot be stolen.
//
// The text-markup tools are the deliberate exception. Highlight, underline and
// strikeout all work BY selecting text — the text layer stays live, the browser
// does the selection, and on release we convert the selection's client rects
// into user space. Rebuilding text selection over pdf.js's span soup would be
// worse at it.
//
// Placing something one-shot — a text stamp, a signature — drops straight back
// to the select tool with the new mark selected. Staying armed means the next
// click stamps a second copy, which is almost never what was wanted, and it
// puts the thing just placed immediately within reach of a nudge or a resize.

import { boundsOf, normBox, translatePatch, resizeBox, scaleToBox } from "./shape.js";

const MIN_DRAG = 3;          // CSS px before a press counts as a drag
const DOUBLE_CLICK_MS = 450; // window for a second click on the same mark
const SIG_WIDTH_PT = 170;    // default placed width of a signature

/** Tools that mark up existing text rather than drawing free-hand. */
export const TEXT_MARKUP = new Set(["highlight", "underline", "strikeout"]);
/** Tools that place something with a single click. */
const STAMP_TOOLS = new Set(["text", "signature"]);

export class Tools {
  constructor({ strip, model, host }) {
    this.strip = strip;
    this.model = model;
    // host (editor.js): { toast, onChange, selectTool, onSelectionChange,
    //                     editText, openSignaturePad, signature }
    this.host = host;
    this.tool = "select";
    this.color = "#ffd400";
    this.width = 2.5;
    this.fill = false;          // shapes: outline only, or filled
    this.fillOpacity = 0.25;
    this.selected = null;
    this.drag = null;
    // Opening a second document builds a second Tools over the same container.
    // Without a way to unbind, the first one stays subscribed, keeps pointing
    // at a torn-down strip, and throws on the next click — so every listener
    // goes on one signal and destroy() drops the lot.
    this._abort = new AbortController();
    const opts = { signal: this._abort.signal };
    const c = strip.container;
    c.addEventListener("pointerdown", (e) => this.onDown(e), opts);
    c.addEventListener("pointermove", (e) => this.onMove(e), opts);
    window.addEventListener("pointerup", (e) => this.onUp(e), opts);
  }

  destroy() {
    this._abort.abort();
    this.drag = null;
    this.selected = null;
  }

  get mode() {
    if (this.tool === "select") return "select";
    if (TEXT_MARKUP.has(this.tool)) return "highlight";
    if (STAMP_TOOLS.has(this.tool)) return "stamp";
    return "draw";
  }

  setTool(t) {
    this.tool = t;
    this._setSelected(null);
    document.body.dataset.mode = this.mode;
    this.host.onChange?.();
  }

  /** The one place selection changes, so the host never misses one. */
  _setSelected(id) {
    this.selected = id;
    this.strip.refreshAllOverlays(id);
    this.host.onSelectionChange?.(id);
  }
  select(id) { this._setSelected(id); }

  setColor(c) {
    this.color = c;
    const a = this.model.annot(this.selected);
    if (a && a.kind !== "redact") this.patchSelected({ color: c });
  }
  setFill(on) {
    this.fill = !!on;
    const a = this.model.annot(this.selected);
    if (a && (a.kind === "rect" || a.kind === "ellipse")) this.patchSelected({ fill: this.fill });
  }
  setWidth(w) {
    this.width = w;
    const a = this.model.annot(this.selected);
    if (a && a.kind !== "text" && a.kind !== "redact") this.patchSelected({ width: w });
  }

  /** Change the selected mark, as one undo step. */
  patchSelected(patch) {
    if (!this.selected) return false;
    const ok = this.model.moveAnnot(this.selected, patch);
    this.strip.refreshAllOverlays(this.selected);
    this.host.onSelectionChange?.(this.selected);
    this.host.onChange?.();
    return ok;
  }

  deleteSelected() {
    if (!this.selected) return false;
    const ok = this.model.removeAnnot(this.selected);
    this._setSelected(null);
    this.host.onChange?.();
    return ok;
  }

  /** Drop a copy of the selected mark, offset so it is visibly a second one. */
  duplicateSelected() {
    const a = this.model.annot(this.selected);
    if (!a) return null;
    const off = 12;
    const copy = { ...structuredClone(a), ...translatePatch(a, off, -off) };
    delete copy.id;
    delete copy._w;
    const made = this.model.addAnnot(copy);
    this._setSelected(made.id);
    this.host.onChange?.();
    return made;
  }

  // ---- pointer ------------------------------------------------------
  onDown(e) {
    if (e.button !== 0) return;

    // A resize handle is checked before anything else: it sits outside the
    // mark's own bounds, so the page under it may not even be the page the
    // mark is on.
    if (this.tool === "select") {
      const handle = e.target?.closest?.(".handle")?.dataset?.handle;
      if (handle && this.selected) {
        const a = this.model.annot(this.selected);
        const ov = a && this.strip.overlayFor(a.page);
        if (a && ov?.viewport) {
          const view = this.strip.views.get(a.page);
          const r = view.pv.div.getBoundingClientRect();
          const [hx, hy] = ov.toPdf(e.clientX - r.left, e.clientY - r.top);
          this.drag = {
            kind: "resize", uid: a.page, id: a.id, handle,
            x0: hx, y0: hy, orig: structuredClone(a), from: boundsOf(a),
            cx: e.clientX, cy: e.clientY, moved: false,
          };
          e.preventDefault();
          return;
        }
      }
    }

    const hit = this.strip.pageAt(e.clientX, e.clientY);
    if (!hit) return;
    const ov = this.strip.overlayFor(hit.uid);
    if (!ov || !ov.viewport) return;

    if (TEXT_MARKUP.has(this.tool)) return;   // let the browser select text

    const [x, y] = ov.toPdf(hit.vx, hit.vy);

    if (this.tool === "select") {
      const id = e.target?.closest?.(".mark")?.dataset?.id || null;
      // Double-click is detected here rather than from a `dblclick` listener.
      // Selecting a mark calls preventDefault() on the pointerdown, and that
      // suppresses the compatibility mouse events the browser would otherwise
      // synthesise a dblclick from — so the native event never arrives.
      const now = Date.now();
      const double = !!id && this._lastClick?.id === id && now - this._lastClick.t < DOUBLE_CLICK_MS;
      this._lastClick = id ? { id, t: now } : null;

      this._setSelected(id);
      if (!id) return;
      e.preventDefault();
      if (double) {
        const a = this.model.annot(id);
        if (a?.kind === "text") { this.host.editText?.(id, null); return; }
      }
      this.drag = { kind: "move", uid: hit.uid, id, x0: x, y0: y,
                    orig: structuredClone(this.model.annot(id)), cx: e.clientX, cy: e.clientY, moved: false };
      return;
    }

    if (this.tool === "text") {
      this.host.editText?.(null, { uid: hit.uid, x, y });
      e.preventDefault();
      return;
    }
    if (this.tool === "signature") {
      this._placeSignature(hit.uid, x, y);
      e.preventDefault();
      return;
    }

    // Drawing tools: start a drag with a live preview.
    this.drag = { kind: this.tool, uid: hit.uid, x0: x, y0: y, x, y,
                  pts: this.tool === "pen" ? [[x, y]] : null,
                  cx: e.clientX, cy: e.clientY, moved: false };
    e.preventDefault();
  }

  onMove(e) {
    const d = this.drag;
    if (!d) return;
    const ov = this.strip.overlayFor(d.uid);
    if (!ov || !ov.viewport) return;
    const view = this.strip.views.get(d.uid);
    if (!view) { this.drag = null; return; }
    const rect = view.pv.div.getBoundingClientRect();
    // A drag that wanders off the page stays on it. Marks outside the page
    // box are invisible in any PDF reader, so letting one be drawn there
    // would only produce something that disappears on save.
    const cx = Math.min(Math.max(e.clientX, rect.left), rect.right);
    const cy = Math.min(Math.max(e.clientY, rect.top), rect.bottom);
    const [x, y] = ov.toPdf(cx - rect.left, cy - rect.top);
    d.x = x; d.y = y;
    if (!d.moved && Math.hypot(e.clientX - (d.cx ?? e.clientX), e.clientY - (d.cy ?? e.clientY)) > MIN_DRAG) d.moved = true;

    if (d.kind === "move") {
      const a = this.model.annot(d.id);
      if (!a) return;
      // Live and un-journalled; the whole gesture is committed once on release
      // so undo steps back over the drag, not over each mouse move.
      Object.assign(a, translatePatch(d.orig, x - d.x0, y - d.y0));
      d.moved = true;
      this.strip.refreshOverlay(d.uid, d.id);
      return;
    }
    if (d.kind === "resize") {
      const a = this.model.annot(d.id);
      if (!a) return;
      // Always mapped from the ORIGINAL geometry, never from the last frame,
      // so a drag back to where it started restores the mark exactly.
      if (d.handle === "p1" || d.handle === "p2") {
        Object.assign(a, d.handle === "p1" ? { x1: x, y1: y } : { x2: x, y2: y });
      } else {
        const uniform = d.orig.kind === "text" || d.orig.kind === "signature";
        const to = resizeBox(d.from, d.handle, x - d.x0, y - d.y0, { uniform });
        Object.assign(a, scaleToBox(d.orig, d.from, to));
      }
      d.moved = true;
      this.strip.refreshOverlay(d.uid, d.id);
      return;
    }
    if (d.kind === "pen") { d.pts.push([x, y]); }
    this.strip.setPreview(d.uid, this._previewAnnot(d));
  }

  onUp(e) {
    if (TEXT_MARKUP.has(this.tool)) { this._commitTextMarkup(); return; }
    const d = this.drag;
    this.drag = null;
    if (!d) return;
    this.strip.setPreview(null, null);

    if (d.kind === "move" || d.kind === "resize") {
      const a = this.model.annot(d.id);
      if (!a || !d.moved) { this.strip.refreshOverlay(d.uid, this.selected); return; }
      this._commitLiveEdit(a, d.orig);
      this._setSelected(d.id);
      this.host.onChange?.();
      return;
    }

    const a = this._previewAnnot(d, true);
    if (a) {
      const made = this.model.addAnnot(a);
      this._setSelected(made.id);
    } else {
      this.strip.refreshAllOverlays(this.selected);
    }
    this.host.onChange?.();
  }

  // A live drag mutates the mark in place so the screen keeps up. To land it
  // on the undo stack as ONE step, put the original back and re-apply the
  // result through the model.
  _commitLiveEdit(a, orig) {
    const after = structuredClone(a);
    Object.assign(a, orig);
    const patch = {};
    for (const k of Object.keys(after)) {
      if (k !== "id" && k !== "page" && k !== "kind") patch[k] = after[k];
    }
    this.model.moveAnnot(a.id, patch);
  }

  // The mark a drag currently describes. `final` rejects degenerate ones so a
  // stray click does not leave an invisible zero-size rectangle behind.
  _previewAnnot(d, final = false) {
    const common = { page: d.uid, color: this.color, width: this.width };
    switch (d.kind) {
      case "pen": {
        if (final && d.pts.length < 2) return null;
        return { kind: "pen", ...common, pts: d.pts.slice() };
      }
      case "arrow": case "line": {
        if (final && !d.moved) return null;
        return { kind: d.kind, ...common, x1: d.x0, y1: d.y0, x2: d.x, y2: d.y };
      }
      case "rect": case "ellipse": case "redact": {
        const b = normBox(d.x0, d.y0, d.x, d.y);
        if (final && (b.w < 2 || b.h < 2)) return null;
        if (d.kind === "redact") return { kind: "redact", page: d.uid, ...b };
        return { kind: d.kind, ...common, ...b, fill: !!this.fill, opacity: this.fillOpacity ?? 0.25 };
      }
      default: return null;
    }
  }

  // ---- text markup --------------------------------------------------
  // Take the live selection's client rects, drop them onto whichever page each
  // one sits on, and convert to user space. A selection spanning a page break
  // therefore produces one mark per page, which is also what the PDF format
  // wants. Highlight, underline and strikeout differ only in `kind`.
  _commitTextMarkup() {
    const kind = this.tool;
    const sel = window.getSelection();
    if (!sel || sel.isCollapsed || sel.rangeCount === 0) return;
    const byPage = new Map();
    for (let i = 0; i < sel.rangeCount; i++) {
      for (const cr of sel.getRangeAt(i).getClientRects()) {
        if (cr.width < 0.5 || cr.height < 0.5) continue;
        const hit = this.strip.pageAt(cr.left + cr.width / 2, cr.top + cr.height / 2);
        if (!hit) continue;
        const ov = this.strip.overlayFor(hit.uid);
        if (!ov || !ov.viewport) continue;
        const r = this.strip.views.get(hit.uid).pv.div.getBoundingClientRect();
        const [ax, ay] = ov.toPdf(cr.left - r.left, cr.top - r.top);
        const [bx, by] = ov.toPdf(cr.right - r.left, cr.bottom - r.top);
        const box = normBox(ax, ay, bx, by);
        if (box.w < 0.5 || box.h < 0.5) continue;
        if (!byPage.has(hit.uid)) byPage.set(hit.uid, []);
        byPage.get(hit.uid).push(box);
      }
    }
    if (!byPage.size) return;
    let last = null;
    for (const [uid, rects] of byPage) {
      last = this.model.addAnnot({
        kind, page: uid, color: this.color,
        opacity: kind === "highlight" ? 0.38 : 1,
        width: kind === "highlight" ? undefined : Math.max(0.8, this.width * 0.55),
        rects: mergeRows(rects),
      });
    }
    sel.removeAllRanges();
    this._setSelected(last ? last.id : null);
    this.host.onChange?.();
  }

  // ---- stamps -------------------------------------------------------
  /** Place a new text mark, or rewrite an existing one, as one undo step. */
  placeText({ uid, x, y }, props) {
    if (!String(props.text || "").trim()) return null;
    const a = this.model.addAnnot({
      kind: "text", page: uid, color: this.color, x, y,
      size: props.size, text: props.text, bold: !!props.bold, italic: !!props.italic,
    });
    this._afterStamp(a);
    return a;
  }

  updateText(id, props) {
    const a = this.model.annot(id);
    if (!a) return null;
    if (!String(props.text || "").trim()) { this.deleteSelected(); return null; }
    this.model.moveAnnot(id, {
      text: props.text, size: props.size, bold: !!props.bold, italic: !!props.italic,
    });
    delete a._w;                       // width changed; let the renderer re-measure
    this._setSelected(id);
    this.host.onChange?.();
    return a;
  }

  async _placeSignature(uid, x, y) {
    let sig = this.host.signature();
    if (!sig) {
      sig = await this.host.openSignaturePad();
      if (!sig) return;
    }
    const w = SIG_WIDTH_PT;
    const h = w * (sig.aspect || 0.34);
    const a = this.model.addAnnot({
      kind: "signature", page: uid, color: this.color === "#ffd400" ? "#1a1f2b" : this.color,
      width: 1.6, x, y: y - h, w, h, strokes: sig.strokes,
    });
    this._afterStamp(a);
  }

  // Drop back to select with the new mark live, so it can be nudged, resized
  // or deleted straight away and a second click does not stamp a duplicate.
  _afterStamp(a) {
    this.host.selectTool?.("select");
    this._setSelected(a.id);
    this.host.onChange?.();
  }

  /** Bounds of the current selection, for the status line. */
  selectedBounds() {
    const a = this.model.annot(this.selected);
    return a ? boundsOf(a) : null;
  }
}

// Client rects for a text selection come one per text run, so a single
// highlighted line arrives as a dozen slivers. Merging the ones that share a
// baseline turns them back into one band per line — fewer objects in the saved
// file, and no seams where two slivers overlap at 38% opacity.
function mergeRows(rects) {
  const rows = [];
  for (const r of rects.slice().sort((a, b) => b.y - a.y || a.x - b.x)) {
    const row = rows.find((q) => Math.abs((q.y + q.h / 2) - (r.y + r.h / 2)) < Math.min(q.h, r.h) * 0.5);
    if (!row) { rows.push({ ...r }); continue; }
    const x0 = Math.min(row.x, r.x), x1 = Math.max(row.x + row.w, r.x + r.w);
    const y0 = Math.min(row.y, r.y), y1 = Math.max(row.y + row.h, r.y + r.h);
    row.x = x0; row.w = x1 - x0; row.y = y0; row.h = y1 - y0;
  }
  return rows;
}