# BaseClip, Transform, and Style

## 1. `BaseClip`

```ts
interface BaseClip {
  id?: string;
  type: ClipType;
  start: number;
  duration: number;
  transform?: Transform;
  zIndex?: number;
  opacity?: number;
  style?: Style;
  animations?: Animation[];
  keyframes?: Keyframe[];
  transition?: Transition;
}
```

## 2. Field reference

### `id`
- Type: `string`
- Required: no
- Purpose: element identifier

### `type`
- Type: `ClipType`
- Required: yes

Currently supported:
- `video`
- `image`
- `text`
- `rect`
- `circle`
- `polygon`
- `code`
- `svg`
- `icon`
- `line`
- `path`
- `three`
- `audio`
- `subtitle`
- `layout`
- `template`

### `start`
- Type: `number`
- Unit: seconds
- Required: yes
- Purpose: clip start time

### `duration`
- Type: `number`
- Unit: seconds
- Required: yes
- Purpose: clip duration

### `transform`
- Type: `Transform`
- Required: no

### `zIndex`
- Type: `number`
- Required: no
- Default: `0`

### `opacity`
- Type: `number`
- Required: no
- Default: `1`
- Purpose: shorthand opacity for visible elements
- Compatibility rule: `style.opacity` has higher priority than top-level `opacity`

### `style`
- Type: `Style`
- Required: no

### `animations`
- Type: `Animation[]`
- Required: no

### `keyframes`
- Type: `Keyframe[]`
- Required: no

### `transition`
- Type: `Transition`
- Required: no

Notes:
- `transition` applies to visible elements
- `audio` does not run visual transitions

## 3. `Transform`

```ts
interface Transform {
  x?: number | string;
  y?: number | string;
  width?: number | string;
  height?: number | string;
  scale?: number | [number, number];
  rotation?: number;
  skew?: [number, number];
  anchor?: Anchor;
}
```

Currently effective at runtime:
- `x`
- `y`
- `width`
- `height`
- `scale`
- `rotation`
- `skew`
- `anchor`

## 4. Percentage coordinate rules

This is not a DOM-style top-left system. It uses a centered coordinate model.

Examples:
- `x: "50%"` means horizontal center
- `y: "50%"` means vertical center
- `x: "0%"` means far left
- `x: "100%"` means far right
- `y: "0%"` means top
- `y: "100%"` means bottom

## 5. `scale`

Supported forms:

```json
{ "scale": 1.2 }
```

```json
{ "scale": [1.2, 0.8] }
```

## 6. `anchor`

Supported values:
- `center`
- `top-left`
- `top`
- `top-right`
- `left`
- `right`
- `bottom-left`
- `bottom`
- `bottom-right`

## 7. `Style`

```ts
interface Style {
  opacity?: number;
  objectFit?: "fill" | "cover" | "contain";
  fill?: string | Gradient;
  stroke?: string;
  strokeWidth?: number;
  fontFamily?: string;
  fontSize?: number;
  fontWeight?: number | string;
  fontStyle?: "normal" | "italic";
  lineHeight?: number;
  letterSpacing?: number;
  textAlign?: "left" | "center" | "right";
  textWrap?: boolean;
  shadowColor?: string;
  shadowBlur?: number;
  shadowOffset?: [number, number];
  borderRadius?: number | [number, number, number, number];
  filters?: Filter[];
  cache?: boolean;
  cachePadding?: number | [number, number, number, number];
  composite?: boolean;
  compositeOperation?: GlobalCompositeOperation;
}
```

Currently effective at runtime:
- `opacity`
- `objectFit`
- `fill`
- `stroke`
- `strokeWidth`
- `fontFamily`
- `fontSize`
- `fontWeight`
- `fontStyle`
- `lineHeight`
- `letterSpacing`
- `textAlign`
- `textWrap`
- `shadowColor`
- `shadowBlur`
- `shadowOffset`
- `borderRadius`
- `filters`
- `cache`
- `cachePadding`
- `composite`
- `compositeOperation`

## 8. `filters`

Supported:
- `blur`
- `brightness`
- `contrast`
- `saturate`
- `hue`
- `grayscale`
- `sepia`
- `invert`

## 9. Shared style caveats

- `style.objectFit` is currently meaningful on `image` and `video`
- Allowed values are `fill`, `cover`, and `contain`
- Other clip types should not treat `objectFit` as an effective field