# useSetParagraphProps

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



Returns a function that updates the paragraph-wide properties of paragraphs by id: position, wrap width, transformation, indent, alignment, direction, and line height. The text style that varies along the text (font, size, color) is set through [useSelectionTextStyle](https://sdk.pdf.net/docs/v1/reference/useSelectionTextStyle) or [useProgrammaticEditor](https://sdk.pdf.net/docs/v1/reference/useProgrammaticEditor).

```ts
const setParagraphProps = useSetParagraphProps()

setParagraphProps(paragraphIds, props, options?)
```

`props` is a `ParagraphPropsUpdate`: any subset of the `ParagraphProps` fields below. The omitted fields keep their values.

| Prop            | Type               | Meaning                                                                                                                                                                                                       |
| --------------- | ------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `x`, `y`        | `number`           | The start of the first line's baseline in user space, as if `textIndent` was `0`. It is not a corner of the paragraph box: the box extends above the baseline.                                                |
| `width`         | `number \| 'auto'` | The width the text wraps at, in text space units. `'auto'` means the paragraph doesn't wrap and widens with its content.                                                                                      |
| `matrix`        | `ReadonlyMatrix2D` | The transformation from text space to user space (scaling, rotation, skewing) around the baseline start, as a PDF matrix `[a, b, c, d, e, f]`. `e` and `f` are ignored: `x` and `y` set the position.         |
| `textIndent`    | `number`           | In text space units, from the start edge of the lines. A positive value indents the first line; a negative value indents all lines but the first (a hanging indent). Clamped to the range the `width` allows. |
| `textAlign`     | `TextAlign`        | `'left'`, `'center'`, or `'right'`.                                                                                                                                                                           |
| `baseDirection` | `TextDirection`    | The base writing direction: `'ltr'` or `'rtl'`.                                                                                                                                                               |
| `lineHeight`    | `number`           | The distance between the baselines of adjacent lines, in text space units.                                                                                                                                    |

User space is the page coordinate system, in points, with the origin at the bottom-left corner of the page. Text space is the paragraph's own coordinate system: its x axis runs along the baseline, and `matrix` maps it to user space. With the identity matrix `[1, 0, 0, 1, 0, 0]`, both use the same units.

## Behavior [#behavior]

* Props equal to the current values are skipped, so a call that changes nothing creates no undo step.
* Pass `{ excludeFromHistory: true }` as `options` for changes that must not be undoable.
* The call throws `InvalidInputError` when an id doesn't identify an existing paragraph, or a value would break the layout: a non-finite number, a negative `width` or `lineHeight`, a `matrix` that isn't 6 finite numbers or flattens the text (a zero determinant), or an unknown `textAlign` or `baseDirection`. With no document loaded, it throws `DocumentNotLoadedError`.
* The current paragraph properties can be read from the `PlainTextParagraph` entries of [useProgrammaticEditor](https://sdk.pdf.net/docs/v1/reference/useProgrammaticEditor).

## Example [#example]

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

function useMakeColumn() {
  const setParagraphProps = useSetParagraphProps()

  // Wrap the paragraphs at a 240-point column and align them to the right.
  return (paragraphIds: string[]) =>
    setParagraphProps(paragraphIds, { width: 240, textAlign: 'right' })
}
```