e.tmp[3*i+0] = c1.R
		e.tmp[3*i+1] = c1.G
		e.tmp[3*i+2] = c1.B
		if c1.A != 0xff {
			last = i
		}
		e.tmp[3*256+i] = c1.A
	}
	e.writeChunk(e.tmp[:3*len(p)], "PLTE")
	if last != -1 {
		e.writeChunk(e.tmp[3*256:3*256+1+last], "tRNS")
	}
}

// An encoder is an io.Writer that satisfies writes by writing PNG IDAT chunks,

		rws.trailers = append(rws.trailers, k)
	}
}

// writeChunk writes chunks from the bufio.Writer. But because
// bufio.Writer may bypass its chunking, sometimes p may be
// arbitrarily large.
//
// writeChunk is also responsible (on the first chunk) for sending the
// HEADER response.
func (rws *http2responseWriterState) writeChunk(p []byte) (n int, err error) {
	if !rws.wroteHeader {
		rws.writeHeader(200)