Create your first annotation

Continue with the same core instance from Getting started. In this tutorial, you will add application buttons that draw a rectangle and turn selected PDF text into a highlight.

NOTE

InkLayer Core is headless: it does not ship a toolbar or sidebar. You build those controls in your framework and call the same methods shown here.

Draw a rectangle

Add a button outside the Viewer hosts. InkLayer Core is headless, so your application owns this button and decides where it appears:

<button id="rectangle" type="button">Rectangle</button>

Activate the Rectangle tool when the user clicks the button:

const rectangleButton = document.querySelector<HTMLButtonElement>('#rectangle')!

rectangleButton.onclick = () => {
  core.annotations.setTool('rectangle')
}

Click Rectangle, then drag on a PDF page. Core creates and selects the rectangle, then returns to the Select tool so the user can move or resize it.

Set the rectangle appearance (optional)

Set the appearance before activating the tool when you want a different default for new rectangles:

core.annotations.setToolAppearance('rectangle', {
  stroke: {
    color: '#175cd3', // Border color
    width: 2,         // Border width
    dash: []          // Empty means a solid line
  },
  fill: {
    color: '#84adff', // Fill color
    opacity: 0.18     // Fill opacity from 0 to 1
  }
})

Call this once during setup, before the user clicks Rectangle.

Highlight selected text

Text markup is created in two steps: first the user selects PDF text, then an application action turns that selection into a highlight.

Add one button for each step:

<button id="select-text" type="button">Select text</button>
<button id="highlight" type="button">Highlight selection</button>

Connect the buttons to Core:

const selectTextButton = document.querySelector<HTMLButtonElement>('#select-text')!
const highlightButton = document.querySelector<HTMLButtonElement>('#highlight')!

selectTextButton.onclick = () => {
  core.annotations.setTool('text-select')
}

highlightButton.onclick = () => {
  const active = core.viewer.getTextSelection()
  if (!active) return

  const selections = active.kind === 'page'
    ? [active.selection]
    : active.selection.fragments

  for (const selection of selections) {
    core.annotations.createTextMarkup('highlight', selection)
  }

  core.viewer.clearTextSelection()
}

Click Select text, drag across text in the PDF, then click Highlight selection. Core retains the PDF selection while focus moves to your button. A cross-page selection creates one page-scoped annotation for each selected page.

Replace highlight with underline or strikeout to create the other text markup types.

Inspect the result

Core stores every annotation created above in core.annotations.repository, the annotation data store for this instance:

const annotations = core.annotations.repository.getAll()
console.log(annotations)

getAll() returns detached, serializable annotation data rather than Konva nodes or page DOM. To send these values to a backend and restore them later, continue with Save and restore annotations.

When the page unmounts, keep the cleanup from Getting started and await core.destroy().