# BinkPenBrush (`pen`)

A pressure-sensitive pen: variable width outline with round caps and a subtle taper at the end. The default brush for handwriting and signatures.

## Defaults

Read off `new BinkPenBrush()`. Every one of them is an `init` property of `BinkBrush`, set with an object initializer or `with`.

- **Color** = `#000000`
- **Width** = `4` (document units, reached at full pressure)
- **Opacity** = `1`
- **BlendMode** = `BinkBlendMode.Normal`
- **PressureCurve** = EaseInOut 0.2..1
- **Smoothing** = `0.5`
- **Spacing** = `0.25` (fraction of the width)
- **SimulatePressure** = `true`
- **TaperStart** = `0`
- **TaperEnd** = `6`

## Geometry

A filled, variable-width outline: the width follows the pressure curve, so a pen with pressure (or simulated pressure) draws thick and thin. Caps are round.

## Serialized

How `BinkSerializer` writes this brush into a stroke. Properties at their format default (opacity 1, smoothing 0.5, 
spacing 0.25, simulated pressure on, no taper, normal blend) are left out; a kind the reading registry does not 
know is loaded as a pen with these properties.

```json
{
  "kind": "pen",
  "color": "#000000",
  "width": 4,
  "taperEnd": 6,
  "pressure": {
    "curve": "easeinout",
    "min": 0.2,
    "max": 1
  }
}
```

## Usage

```razor
<BinkCanvas Brush="_brush" Height="400px" />

@code {
    private BinkBrush _brush = new BinkPenBrush();

    private void Recolor(string css) => _brush = _brush with { Color = BinkColor.Parse(css) };
}
```