commonMain.org.jetbrains.letsPlot.util.pngj.DeflatedChunkReader.kt Maven / Gradle / Ivy
/*
* Copyright (c) 2023 JetBrains s.r.o.
* Use of this source code is governed by the MIT license that can be found in the LICENSE file.
*
* This file has been modified by JetBrains : Java code has been converted to Kotlin code.
*
* THE FOLLOWING IS THE COPYRIGHT OF THE ORIGINAL DOCUMENT:
*
* Copyright (c) 2009-2012, Hernán J. González.
* Licensed under the Apache License, Version 2.0.
*
* The original PNGJ library is written in Java and can be found here: [PNGJ](https://github.com/leonbloy/pngj).
*/
@file:Suppress("unused")
package org.jetbrains.letsPlot.util.pngj
import org.jetbrains.letsPlot.util.pngj.PngHelperInternal.readInt4fromBytes
import org.jetbrains.letsPlot.util.pngj.chunks.PngChunk.Companion.ID_FDAT
/**
*
* Specialization of ChunkReader, for IDAT-like chunks. These chunks are part of
* a set of similar chunks (contiguos normally, not necessariyl) which conforms
* a zlib stream
*/
internal abstract class DeflatedChunkReader(
clen: Int,
chunkid: String,
@Suppress("UNUSED_PARAMETER")
checkCrc: Boolean,
offsetInPng: Long,
iDatSet: DeflatedChunksSet
) : ChunkReader(clen, chunkid, offsetInPng, ChunkReaderMode.PROCESS) {
private val deflatedChunksSet: DeflatedChunksSet
private var alsoBuffer = false
private var skipBytes = false // fDAT (APNG) skips 4 bytes)
private lateinit var skippedBytes // only for fDAT
: ByteArray
private var seqNumExpected = -1 // only for fDAT
init {
deflatedChunksSet = iDatSet
if (chunkid == ID_FDAT) {
skipBytes = true
skippedBytes = ByteArray(4)
}
iDatSet.appendNewChunk(this)
}
/**
* Delegates to ChunkReaderDeflatedSet.processData()
*/
override fun processData(offsetInchunk: Int, buf: ByteArray, off: Int, len: Int) {
@Suppress("NAME_SHADOWING")
var off = off
@Suppress("NAME_SHADOWING")
var len = len
if (skipBytes && offsetInchunk < 4) { // only for APNG (sigh)
var oc = offsetInchunk
while (oc < 4 && len > 0) {
skippedBytes[oc] = buf[off]
oc++
off++
len--
}
}
if (len > 0) { // delegate to idatSet
deflatedChunksSet.processBytes(buf, off, len)
if (alsoBuffer) { // very rare!
arraycopy(buf, off, chunkRaw.data!!, read, len)
}
}
}
/**
* only a stupid check for fDAT (I wonder how many APGN readers do this)
*/
override fun chunkDone() {
if (skipBytes && chunkRaw.id == ID_FDAT) {
if (seqNumExpected >= 0) {
val seqNum = readInt4fromBytes(skippedBytes, 0)
if (seqNum != seqNumExpected) throw PngjInputException(
"bad chunk sequence for fDAT chunk $seqNum expected $seqNumExpected"
)
}
}
}
override val isFromDeflatedSet: Boolean
get() = true
/**
* In some rare cases you might want to also buffer the data?
*/
fun setAlsoBuffer() {
require(read > 0) { "too late" }
alsoBuffer = true
chunkRaw.allocData()
}
/** only relevant for fDAT */
fun setSeqNumExpected(seqNumExpected: Int) {
this.seqNumExpected = seqNumExpected
}
}