Selection

The Selection plugin lets people select text with the pointer, and lets your application select the same text with code. It works from PDF text geometry, so selecting and highlighting text does not require extracting the literal text.

That distinction is useful for permissions: you can allow selection and text markups while keeping copy disabled.

Your first selection#

Register the interaction, selection, Stage, and render plugins. Then add a <SelectionLayer> above the rendered page:

Try it: drag over text, double-click a word, or triple-click a line. A selection can continue from one page to another. On a touch screen, long-press a word and drag the handles.

Registering interactionPlugin() is the whole wiring. It is the shared input system every tool speaks through: the Stage sends its pointer events there, the Selection plugin handles them, and <SelectionLayer> only draws the result.

This keeps input, selection state, and rendering separate. You can replace the highlight layer without changing how selection works.

At this point, the viewer reads glyph geometry only. It does not request page text until your application calls readText() or enables clipboard prefetch.

Select text with code#

useSelection() gives you the same capability used by pointer gestures. A programmatic selection updates the highlight and fires the same change signal:

For one page, pass its durable page object number (pon), a starting character index, and a character count:

selection.select({
  pon: page.pon,
  start: 20,
  count: 40,
});

Search results use this same character space, so selecting a result needs no text-offset conversion:

selection.select({
  pon: hit.pageObjectNumber,
  start: hit.charStart,
  count: hit.charCount,
});

For a range that crosses pages, use start and end positions:

selection.select({
  start: { pon: firstPage.pon, index: 120 },
  end: { pon: lastPage.pon, index: 35 },
});

Ranges are half-open: start is included and end is not. The range [20, 60) selects characters 20 through 59. These are PDF character indexes, not JavaScript string offsets.

Use selectAll() for the whole document and clear() to remove the current selection. An empty range also clears it.

Read the selection#

snapshot() is the complete read model. Its range can be saved and passed back to select() later:

const saved = selection.snapshot().range;
 
// Later, after navigation or another action
if (saved) selection.select(saved);

The snapshot also contains the per-page highlight segments, selection direction, and start/end geometry. For common UI, the smaller reads are easier:

selection.hasSelection();
selection.selectedPages();
selection.menuAnchor();
selection.segmentsForPage(page.pon);

Use onChange() when something should follow the selection while it changes. Use onCommit() when something should happen after a pointer gesture finishes, such as creating a markup or prefetching text for copy.

Copy selected text#

Selection and clipboard access are two separate operations:

const text = await selection.readText();

readText() returns data and does not touch the clipboard. It reads only the selected page ranges and caches each page’s text snapshot. Pages in a cross-page selection are joined with a newline. With no selection, it returns an empty string.

For a browser clipboard, use the React helpers:

import {
  SelectionClipboard,
  SelectionToken,
  copySelection,
  useSelection,
} from '@embedpdf/react/selection';
import { useSelector } from '@embedpdf/react/runtime';
 
function CopyButton() {
  const selection = useSelection();
  const hasSelection = useSelector(SelectionToken, (value) => value.hasSelection());
 
  return (
    <button
      disabled={!hasSelection || !selection.canCopy()}
      onClick={() => void copySelection(selection)}
    >
      Copy
    </button>
  );
}
 
// Mount once per document view to support ctrl/cmd+C and native Copy.
function DocumentView() {
  return <SelectionClipboard />;
}

<SelectionClipboard> prefetches selected text when the selection settles so the synchronous browser copy event can answer immediately. Keep that default when you want native Copy support. Use prefetch={false} when your UI calls copySelection() itself and you want text reads to happen only on demand.

Clipboard access stays in the web adapter. The Selection plugin itself is DOM-free, so readText() also works in Node, tests, native adapters, and other headless environments.

Add a selection menu#

<SelectionMenu> anchors one piece of UI to the end of the selection. It stays hidden while the user is dragging and appears when the selection settles:

Mount the menu in the Stage’s overlay prop. The Stage then keeps it attached to the selected text while the user scrolls or zooms.

The menu only handles placement. Its contents are yours: copy, comment, highlight, redact, or any action your product supports.

Selection on touch#

A finger has no caret to drag, so touch selection works the way it does everywhere else on a phone: long-press a word to select it, then drag the handles to grow the selection. Add <SelectionHandles> next to your menu in the Stage’s overlay:

import { SelectionHandles, SelectionLayer } from '@embedpdf/react/selection';
 
<Stage
  overlay={
    <>
      <SelectionMenu>
        <CopyButton />
      </SelectionMenu>
      <SelectionHandles />
    </>
  }
>
  {() => (
    <>
      <RenderLayer />
      <SelectionLayer />
    </>
  )}
</Stage>;

Each handle is a caret bar that forms the selection’s own edge, capped by a circle above the first line and below the last. The bar scales with zoom like the text; the circle stays the same size on screen. Dragging one extends from the opposite end, snapping to glyphs and crossing pages just like a pointer drag — the same onChange and onCommit signals fire.

Grabbing a handle never pans the Stage, and everywhere else a finger still scrolls and pinch-zooms normally. Pass color to match your theme, and token when the selection belongs to a secondary Stage.

Haptic feedback#

Register a feedback provider and a touch long-press that lands on a word gives the small tick people expect from a native selection:

import { feedbackPlugin, vibrationFeedback } from '@embedpdf/react/interaction';
 
const plugins = [
  // …
  interactionPlugin(),
  feedbackPlugin({ provider: vibrationFeedback }),
  selectionPlugin(),
];

It is optional and safe to leave in: without a provider nothing buzzes, and vibrationFeedback is a silent no-op wherever the Vibration API is missing — iOS Safari included, until Apple ships a web haptics API. Long-pressing blank space never fires, and a mouse double-click never does either. In a native shell, install a message handler and pass wkFeedback('yourHandlerName') instead.

Selection and copy permissions#

Selection geometry and literal text are separate resources:

The public checks mirror those permissions:

selection.canSelect(); // doc.text.select
selection.canCopy(); // doc.text.copy

Use them to hide or disable controls, but do not treat them as the security boundary. Both the local and cloud engines enforce the permissions too.

When canSelect() is false, the plugin does not request glyph geometry and pointer selection stays inactive. Programmatic select() and selectAll() throw PermissionDenied. clear() is always allowed.

When canCopy() is false, selection can still work normally. The user can select text and, with annotation permission, create highlights or underlines; readText() rejects with PermissionDenied, and no literal page text is returned.

For example, this policy allows markup without copy:

doc.text.select       allowed
doc.annotate.modify   allowed
doc.text.copy         denied

API at a glance#

Application code should import this public surface from @embedpdf/plugin-selection or its framework adapter. The /internal entry point is for framework and plugin integration and is not a public application contract.

Next steps#