# useSelectionTextStyle

Source: https://sdk.pdf.net/docs/v1/reference/useSelectionTextStyle



Returns the text style of the current selection and the functions for changing it: the data source for a text style toolbar. See [Building a PDF application](https://sdk.pdf.net/docs/v1/guides/building-a-pdf-application) for a toolbar built with it.

```ts
const { isApplicable, fontSize, textColor, fontFamily, isBold, isItalic, ... } =
  useSelectionTextStyle()
```

`isApplicable` is `true` when the selection holds text that can be styled: a text range or caret inside a paragraph, or whole selected paragraphs; hide the toolbar otherwise. Every other field is a selection prop: a `{ value, set }` pair where `value` holds the common value across the selection (`undefined` when the selected pieces disagree) and `set` applies a new value to the entire selection.

| Prop            | Value                               | Notes                                                                                                                                                       |
| --------------- | ----------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `fontSize`      | `number`, text space units          | Setting it also sets a proportional line height when the whole paragraph text is selected.                                                                  |
| `textColor`     | `ColorString`                       | `set` accepts common CSS color formats and normalizes them.                                                                                                 |
| `fontFamily`    | font family id                      | Also carries `options`: the available families, `regular` (always available) and `extracted` (from the document, possibly missing characters unused in it). |
| `isBold`        | `boolean`                           |                                                                                                                                                             |
| `isItalic`      | `boolean`                           |                                                                                                                                                             |
| `scriptType`    | `'super'`, `'sub'`, or `null`       | `set` takes `ScriptProps` (below), or `null` to return the text to the normal baseline.                                                                     |
| `textAlign`     | `'left'`, `'center'`, or `'right'`  | Applies to the whole paragraph.                                                                                                                             |
| `lineHeight`    | `number`, text space units          | Applies to the whole paragraph.                                                                                                                             |
| `letterSpacing` | `number`, text space units          | Setting `0` restores the default spacing.                                                                                                                   |
| `textIndent`    | `{ canIncrease, canDecrease, add }` | `add(delta)` shifts the indent of the selected paragraphs.                                                                                                  |

Text space is the paragraph's own coordinate system; for a paragraph that isn't scaled, its units equal user-space units (see [useSetParagraphProps](https://sdk.pdf.net/docs/v1/reference/useSetParagraphProps)). To set paragraph properties by id rather than through the selection, use that hook too.

`ScriptProps` is `{ type, fontSizeFraction?, verticalAlignFraction? }`:

| Field                   | Meaning                                                                                                                                       |
| ----------------------- | --------------------------------------------------------------------------------------------------------------------------------------------- |
| `type`                  | `'super'` for superscript or `'sub'` for subscript.                                                                                           |
| `fontSizeFraction`      | The script font size as a fraction of the surrounding font size, such as `0.6`. Defaults by `type` when omitted.                              |
| `verticalAlignFraction` | The baseline shift as a fraction of the surrounding font size: positive raises the text, negative lowers it. Defaults by `type` when omitted. |

## Example [#example]

```tsx
import { useSelectionTextStyle } from '@sdk-pdf/react'

function FontSizeInput() {
  const { isApplicable, fontSize } = useSelectionTextStyle()

  if (!isApplicable) return null

  return (
    <input
      type="number"
      // An empty value means the selection mixes different font sizes.
      value={fontSize.value ?? ''}
      onChange={(event) => fontSize.set(Number(event.currentTarget.value))}
    />
  )
}
```

After acting on the selection from a toolbar, return the focus with [useFocusSelection](https://sdk.pdf.net/docs/v1/reference/useFocusSelection).