/**
* Read the next PNG chunk from the input stream given. If unable to read a chunk, return null.
*/
static PngChunk readNextFromStream(LEDataInputStream stream) {
try {
int headerLength = LENGTH_FIELD_LENGTH + TYPE_FIELD_LENGTH;
byte[] headerBytes = new byte[headerLength];
int result = stream.read(headerBytes, 0, headerLength);
stream.unread(headerBytes);
if (result != headerLength) return null;
PngChunk tempChunk = new PngChunk(headerBytes);
int chunkLength = tempChunk.getSize();
byte[] chunk = new byte[chunkLength];
result = stream.read(chunk, 0, chunkLength);
if (result != chunkLength) return null;
switch (tempChunk.getChunkType()) {
case CHUNK_IHDR:
return new PngIhdrChunk(chunk);
case CHUNK_PLTE:
return new PngPlteChunk(chunk);
case CHUNK_IDAT:
return new PngIdatChunk(chunk);
case CHUNK_IEND:
return new PngIendChunk(chunk);
case CHUNK_tRNS:
return new PngTrnsChunk(chunk);
default:
return new PngChunk(chunk);
}
} catch (IOException e) {
return null;
}
}
@Override
boolean isFileFormat(LEDataInputStream stream) {
try {
byte[] signature = new byte[3];
stream.read(signature);
stream.unread(signature);
return signature[0] == 'G' && signature[1] == 'I' && signature[2] == 'F';
} catch (Exception e) {
return false;
}
}
boolean isFileFormat(LEDataInputStream stream) {
try {
byte[] header = new byte[18];
stream.read(header);
stream.unread(header);
int infoHeaderSize =
(header[14] & 0xFF)
| ((header[15] & 0xFF) << 8)
| ((header[16] & 0xFF) << 16)
| ((header[17] & 0xFF) << 24);
return header[0] == 0x42 && header[1] == 0x4D && infoHeaderSize == BMPHeaderFixedSize;
} catch (Exception e) {
return false;
}
}
