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# minimumTileExtendRect(forTileRect:sourceRGBASize:)

Returns the minimum source rect that must be sampled to render tileRect without edge artifacts.

```
class func minimumTileExtendRect(forTileRect tileRect: CGRect, sourceRGBASize: CGSize) -> CGRect
```

## Parameters

`tileRect`

The destination tile rect in full-image pixel coordinates.

`sourceRGBASize`

The dimensions of the full (un-tiled) source image.

## Return Value

A rect (in full-image pixel coordinates) covering the minimum required source region,
clamped to the image bounds.

## Discussion

When applying a bokeh blur near a tile boundary, the renderer needs pixels from outside the
destination tile. This method computes how far that border region extends. Pass the returned rect’s origin as tileExtendOffset
and allocate sourceTileRGBA with the returned rect’s size.

---

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