C#

Transition from Compression.BeginCompressBytes to FirstChunk/LastChunk

Provides instructions for replacing deprecated BeginCompressBytes method calls with using FirstChunk and LastChunk properties. C#

bool success = false;

Chilkat.FileAccess facSrc = new Chilkat.FileAccess();
Chilkat.FileAccess facDest = new Chilkat.FileAccess();

//  Open a large binary file for reading.
success = facSrc.OpenForRead("qa_data/bmp/big.bmp");
if (success == false) {
    Debug.WriteLine(facSrc.LastErrorText);
    return;
}

//  If we compress in 64K chunks, find out how many blocks there will be.
int blockSize = 65536;
int numBlocks = facSrc.GetNumBlocks(blockSize);

//  Open an output file for the compressed data.
success = facDest.OpenForWrite("c:/temp/qa_output/compressedBmp.dat");
if (success == false) {
    Debug.WriteLine(facDest.LastErrorText);
    return;
}

Chilkat.Compression compress = new Chilkat.Compression();
compress.Algorithm = "deflate";

byte[] fileBytes = null;
byte[] compressedBytes = null;

//  ----------------------------------------------------------------------------------
//  This is the deprecated way of compressing in chunks using Begin/More/End methods..
//  ----------------------------------------------------------------------------------
int i = 0;
while (i < numBlocks) {
    fileBytes = facSrc.ReadBlock(i,blockSize);
    if (i == 0) {
        compressedBytes = compress.BeginCompressBytes(fileBytes);
    }
    else {
        compressedBytes = compress.MoreCompressBytes(fileBytes);
    }

    facDest.FileWrite(compressedBytes);

    i = i + 1;
}

//  At the very end, flush any remaining compressed bytes, if any.
compressedBytes = compress.EndCompressBytes();
facDest.FileWrite(compressedBytes);

facSrc.FileClose();
facDest.FileClose();

Debug.WriteLine("Finished compressing file.");

//  ----------------------------------------------------------------------------------
//  This is new way of compressing in chunks using FirstChunk and LastChunk properties
//  ----------------------------------------------------------------------------------

success = facSrc.OpenForRead("qa_data/bmp/big.bmp");
if (success == false) {
    Debug.WriteLine(facSrc.LastErrorText);
    return;
}

success = facDest.OpenForWrite("c:/temp/qa_output/compressedBmp2.dat");
if (success == false) {
    Debug.WriteLine(facDest.LastErrorText);
    return;
}

//  Assuming numBlocks > 1
compress.FirstChunk = true;
compress.LastChunk = false;

i = 0;
while (i < numBlocks) {
    fileBytes = facSrc.ReadBlock(i,blockSize);
    compressedBytes = compress.CompressBytes(fileBytes);

    facDest.FileWrite(compressedBytes);

    i = i + 1;

    compress.FirstChunk = false;
    if (i == (numBlocks - 1)) {
        compress.LastChunk = true;
    }

}

facSrc.FileClose();
facDest.FileClose();

Debug.WriteLine("Finished compressing file 2.");