C

Streaming Compression

See more Compression Examples

Compress and decompress using a stream. C

#include <C_CkFileAccess.h>
#include <C_CkCompression.h>
#include <C_CkStream.h>
#include <C_CkTask.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkFileAccess fac;
    HCkCompression compress;
    HCkStream streamC;
    HCkStream streamD;
    BOOL bFilesEqual;
    HCkStream streamA;
    HCkTask task;
    const char *decompressedText;

    success = FALSE;

    // This example assumes the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    fac = CkFileAccess_Create();
    compress = CkCompression_Create();
    CkCompression_putAlgorithm(compress,"deflate");

    streamC = CkStream_Create();

    // This example sets the source and sink of the stream to files.
    // A stream can have use other streams as a source or sink,
    // or the application can itself be the source/sink by directly
    // reading or writing a stream.  (See below for an example of this..)
    CkStream_putSourceFile(streamC,"qa_data/hamlet.xml");
    CkStream_putSinkFile(streamC,"qa_output/hamlet_compressed.dat");

    // Compress from source to sink.
    success = CkCompression_CompressStream(compress,streamC);
    if (success != TRUE) {
        printf("%s\n",CkCompression_lastErrorText(compress));
        CkFileAccess_Dispose(fac);
        CkCompression_Dispose(compress);
        CkStream_Dispose(streamC);
        return;
    }

    printf("File-to-file deflate compression successful.\n");
    // Note: The FileSize method returns a signed 32-bit integer.  If the file is potentially larger than 2GB, call FileSizeStr instead to return
    // the size of the file as a string, then convert to an integer value.
    printf("Original size = %d\n",CkFileAccess_FileSize(fac,CkStream_sourceFile(streamC)));
    printf("Compressed size = %d\n",CkFileAccess_FileSize(fac,CkStream_sinkFile(streamC)));

    // Now do file-to-file decompression
    streamD = CkStream_Create();
    CkStream_putSourceFile(streamD,"qa_output/hamlet_compressed.dat");
    CkStream_putSinkFile(streamD,"qa_output/hamlet_restored.xml");

    // Decompress from source to sink.
    success = CkCompression_DecompressStream(compress,streamD);
    if (success != TRUE) {
        printf("%s\n",CkCompression_lastErrorText(compress));
        CkFileAccess_Dispose(fac);
        CkCompression_Dispose(compress);
        CkStream_Dispose(streamC);
        CkStream_Dispose(streamD);
        return;
    }

    printf("File-to-file deflate decompression successful.\n");

    // Let's double-check to see that the files are equal in size and content:

    bFilesEqual = CkFileAccess_FileContentsEqual(fac,CkStream_sourceFile(streamC),CkStream_sinkFile(streamD));
    if (bFilesEqual != TRUE) {
        printf("The output file is not equal to the input file!\n");
    }
    else {
        printf("The file was successfully compressed and decompressed.\n");
    }

    // ---------------------------------------------------------------------
    // Now let's decompress again, but this time w/ the application reading
    // the decompressed data directly from a stream.
    streamA = CkStream_Create();

    CkStream_putSourceFile(streamA,"qa_output/hamlet_compressed.dat");

    // Start decompressing in a background thread.
    task = CkCompression_DecompressStreamAsync(compress,streamA);
    success = CkTask_Run(task);

    // Read decompressed data from streamA:

    while ((CkStream_getEndOfStream(streamA) != TRUE)) {
        if (CkStream_getDataAvailable(streamA) == TRUE) {
            decompressedText = CkStream_readString(streamA);
            printf("%s\n",decompressedText);
        }

    }

    // Let's make sure the background task finished and that the decompress was successful.
    // It should already be the case that the task is finished.
    while ((CkTask_getFinished(task) != TRUE)) {
        CkTask_SleepMs(task,20);
    }

    // The decompressor may have finished, but it is possible that data
    // remains to be flushed.  
    if (CkStream_getDataAvailable(streamA) == TRUE) {
        decompressedText = CkStream_readString(streamA);
        printf("%s\n",decompressedText);
    }

    // Did streamA succeed in reading the entire file?
    if (CkTask_getTaskSuccess(task) != TRUE) {
        printf("async decompress failed:\n");
        printf("%s\n",CkTask_resultErrorText(task));
        success = FALSE;
    }

    printf("The async decompress was successful.\n");


    CkFileAccess_Dispose(fac);
    CkCompression_Dispose(compress);
    CkStream_Dispose(streamC);
    CkStream_Dispose(streamD);
    CkStream_Dispose(streamA);

    }