ZipStream Class

Properties   Methods   Events   Config Settings   Errors  

The ZipStream class is used to perform compression or decompression.

Syntax

ZipStream

Remarks

The ZipStream class provides a way to compress and decompress streamed data.

Data may be operated on in multiple ways as discussed below. The StreamFormat property specifies the algorithm to us. Possible values are:

• Deflate
• Zlib
• Gzip

CompressBlock and DecompressBlock

The CompressBlock and DecompressBlock methods operate on blocks (chunks) of data. The methods may be used to compress and decompress data as it becomes available.

Note that when using blocks of data the OutputData property is not applicable. Instead data is made available through the CompressedData and DecompressedData events.

If all data is available ahead of time CompressData and DecompressData may be called instead.

Compress Data

Set InputData to the current block to be compressed. Next call CompressBlock to compress the current block. Note that CompressBlock takes a LastBlock parameter. If the block of data is the final block to be compressed set this to True. For all other blocks set this to False.

During compression the CompressedData event will fire with the compressed data. Note that this event may not fire for every call to CompressBlock due to the way the compression algorithm operates. For example:

zipstream.InputDataB = MyDecompressedData; zipstream.CompressBlock(); Data is accumulated inside the CompressedData event: private static void Zipstream_OnCompressedData(object sender, ZipstreamCompressedDataEventArgs e) { DoSomethingWith(e.DataB); }

Note that OutputData is not applicable when compressing block data.

Decompress Data

Set InputData to the current block to be decompressed. Next call DecompressBlock to decompress the current block.

During decompression the DecompressedData event will fire with the decompressed data. Note that this event may not fire for every call to DecompressBlock due to the way the decompression algorithm operates. For example:

zipstream.InputDataB = MyCompressedData; zipstream.DecompressBlock(); Data is accumulated inside the DecompressedData event: private static void Zipstream_OnDecompressedData(object sender, ZipstreamDecompressedDataEventArgs e) { DoSomethingWith(e.DataB); }

Note that OutputData is not applicable when decompressing block data.

CompressData and DecompressData

The CompressData and DecompressData methods operate on the complete blob of data. The entire compressed or decompressed data must be set to InputData before calling either method.

To compress and decompress data in blocks (chunks) see CompressBlock and DecompressBlock.

Compress Data

Set InputData to the decompressed data. This should be the entire data to be compressed. Next call CompressData. After compression OutputData will hold the compressed data. For example:

zipstream.InputDataB = MyDecompressedData; zipstream.CompressData(); MyCompressedData = zipstream.OutputDataB;

In addition to OutputData, the compressed data may also be accumulated within the CompressedData event.

Decompress Data

Set InputData to the compressed data. This should be the entire data to be decompressed. Next call DecompressData. After decompression OutputData will hold the decompressed data. For example:

zipstream.InputDataB = MyCompressedData; zipstream.DecompressData(); MyDecompressedData = zipstream.OutputDataB;

In addition to OutputData, the compressed data may also be accumulated within the DecompressedData event.

Property List

The following is the full list of the properties of the class with short descriptions. Click on the links for further details.

Method List

The following is the full list of the methods of the class with short descriptions. Click on the links for further details.

Event List

The following is the full list of the events fired by the class with short descriptions. Click on the links for further details.

Config Settings

The following is a list of config settings for the class with short descriptions. Click on the links for further details.

CompressionLevel Property (ZipStream Class)

The compression level to use.

Syntax

• C++
• C
• Qt

ANSI (Cross Platform)
int GetCompressionLevel();
int SetCompressionLevel(int iCompressionLevel);

Unicode (Windows)
INT GetCompressionLevel();
INT SetCompressionLevel(INT iCompressionLevel);

int ipworkszip_zipstream_getcompressionlevel(void* lpObj);
int ipworkszip_zipstream_setcompressionlevel(void* lpObj, int iCompressionLevel);

int GetCompressionLevel();
int SetCompressionLevel(int iCompressionLevel);

Default Value

4

Remarks

The compression level to use, from 1 to 6. Higher values will cause the component to compress better; lower values will cause the component to compress faster.

When GetCompressionStream is invoked the stream will be created with the specified compression level. After a stream has been created it is independent of the control, and changing CompressionLevel will have no effect on existing streams.

Data Type

Integer

InputData Property (ZipStream Class)

Specifies the data to compress or decompress.

Syntax

• C++
• C
• Qt

ANSI (Cross Platform)
int GetInputData(char* &lpInputData, int &lenInputData);
int SetInputData(const char* lpInputData, int lenInputData);

Unicode (Windows)
INT GetInputData(LPSTR &lpInputData, INT &lenInputData);
INT SetInputData(LPCSTR lpInputData, INT lenInputData);

int ipworkszip_zipstream_getinputdata(void* lpObj, char** lpInputData, int* lenInputData);
int ipworkszip_zipstream_setinputdata(void* lpObj, const char* lpInputData, int lenInputData);

QByteArray GetInputData();
int SetInputData(QByteArray qbaInputData);

Default Value

""

Remarks

This property specifies the data to compress or decompress.

When decompressing this should be set to the compressed data before calling DecompressData or DecompressBlock.

When compressing this should be set to the decompressed data before calling CompressData or CompressBlock.

Data Type

Binary String

OutputData Property (ZipStream Class)

The output data after compression or decompression.

Syntax

• C++
• C
• Qt

ANSI (Cross Platform)
int GetOutputData(char* &lpOutputData, int &lenOutputData);

Unicode (Windows)
INT GetOutputData(LPSTR &lpOutputData, INT &lenOutputData);

int ipworkszip_zipstream_getoutputdata(void* lpObj, char** lpOutputData, int* lenOutputData);

QByteArray GetOutputData();

Default Value

""

Remarks

This property holds the compressed or decompressed data after CompressData or DecompressData is called.

This property is not applicable when calling CompressBlock or DecompressBlock.

This property is read-only and not available at design time.

Data Type

Binary String

StreamFormat Property (ZipStream Class)

The stream format to use.

Syntax

• C++
• C
• Qt

ANSI (Cross Platform)
int GetStreamFormat();
int SetStreamFormat(int iStreamFormat);

Unicode (Windows)
INT GetStreamFormat();
INT SetStreamFormat(INT iStreamFormat);

SF_DEFLATE(0), 
SF_ZLIB(1), 
SF_GZIP(2)

int ipworkszip_zipstream_getstreamformat(void* lpObj);
int ipworkszip_zipstream_setstreamformat(void* lpObj, int iStreamFormat);

int GetStreamFormat();
int SetStreamFormat(int iStreamFormat);

Default Value

0

Remarks

The stream format to use, by default Deflate.

All three stream formats use the Deflate algorithm specified in RFC 1951, which is the same algorithm used by Zip. The Zlib stream format adds a two-byte header and an Adler-32 checksum; the Gzip format adds a longer header and a CRC checksum, and is identical to the Gzip file format.

Caution: The terms zlib and deflate are sometimes used interchangeably (which is technically incorrect).

Data Type

Integer

CompressBlock Method (ZipStream Class)

Compresses a block of data.

Syntax

• C++
• C
• Qt

ANSI (Cross Platform)
int CompressBlock(int bLastBlock);

Unicode (Windows)
INT CompressBlock(BOOL bLastBlock);

int ipworkszip_zipstream_compressblock(void* lpObj, int bLastBlock);

int CompressBlock(bool bLastBlock);

Remarks

This method compresses the block of data specified by InputData.

The CompressBlock and DecompressBlock methods operate on blocks (chunks) of data. The methods may be used to compress and decompress data as it becomes available.

Note that when using blocks of data the OutputData property is not applicable. Instead data is made available through the CompressedData and DecompressedData events.

If all data is available ahead of time CompressData and DecompressData may be called instead.

Compress Data

Set InputData to the current block to be compressed. Next call CompressBlock to compress the current block. Note that CompressBlock takes a LastBlock parameter. If the block of data is the final block to be compressed set this to True. For all other blocks set this to False.

During compression the CompressedData event will fire with the compressed data. Note that this event may not fire for every call to CompressBlock due to the way the compression algorithm operates. For example:

zipstream.InputDataB = MyDecompressedData; zipstream.CompressBlock(); Data is accumulated inside the CompressedData event: private static void Zipstream_OnCompressedData(object sender, ZipstreamCompressedDataEventArgs e) { DoSomethingWith(e.DataB); }

Note that OutputData is not applicable when compressing block data.

Decompress Data

Set InputData to the current block to be decompressed. Next call DecompressBlock to decompress the current block.

During decompression the DecompressedData event will fire with the decompressed data. Note that this event may not fire for every call to DecompressBlock due to the way the decompression algorithm operates. For example:

zipstream.InputDataB = MyCompressedData; zipstream.DecompressBlock(); Data is accumulated inside the DecompressedData event: private static void Zipstream_OnDecompressedData(object sender, ZipstreamDecompressedDataEventArgs e) { DoSomethingWith(e.DataB); }

Note that OutputData is not applicable when decompressing block data.

Error Handling (C++)

This method returns a result code; 0 indicates success, while a non-zero error code indicates that this method encountered an error during its execution. If an error occurs, the GetLastError() method can be called to retrieve the associated error message. (Note: This method's result code can also be obtained by calling the GetLastErrorCode() method after it returns.)

CompressData Method (ZipStream Class)

Compresses the specified data.

Syntax

• C++
• C
• Qt

ANSI (Cross Platform)
int CompressData();

Unicode (Windows)
INT CompressData();

int ipworkszip_zipstream_compressdata(void* lpObj);

int CompressData();

Remarks

This method compresses the data specified by InputData. After calling this method OutputData holds the compressed data.

The CompressData and DecompressData methods operate on the complete blob of data. The entire compressed or decompressed data must be set to InputData before calling either method.

To compress and decompress data in blocks (chunks) see CompressBlock and DecompressBlock.

Compress Data

Set InputData to the decompressed data. This should be the entire data to be compressed. Next call CompressData. After compression OutputData will hold the compressed data. For example:

zipstream.InputDataB = MyDecompressedData; zipstream.CompressData(); MyCompressedData = zipstream.OutputDataB;

In addition to OutputData, the compressed data may also be accumulated within the CompressedData event.

Decompress Data

Set InputData to the compressed data. This should be the entire data to be decompressed. Next call DecompressData. After decompression OutputData will hold the decompressed data. For example:

zipstream.InputDataB = MyCompressedData; zipstream.DecompressData(); MyDecompressedData = zipstream.OutputDataB;

In addition to OutputData, the compressed data may also be accumulated within the DecompressedData event.

Error Handling (C++)

This method returns a result code; 0 indicates success, while a non-zero error code indicates that this method encountered an error during its execution. If an error occurs, the GetLastError() method can be called to retrieve the associated error message. (Note: This method's result code can also be obtained by calling the GetLastErrorCode() method after it returns.)

Config Method (ZipStream Class)

Sets or retrieves a configuration setting.

Syntax

• C++
• C
• Qt

ANSI (Cross Platform)
char* Config(const char* lpszConfigurationString);

Unicode (Windows)
LPWSTR Config(LPCWSTR lpszConfigurationString);

char* ipworkszip_zipstream_config(void* lpObj, const char* lpszConfigurationString);

QString Config(const QString& qsConfigurationString);

Remarks

Config is a generic method available in every class. It is used to set and retrieve configuration settings for the class.

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the class, access to these internal properties is provided through the Config method.

To set a configuration setting named PROPERTY, you must call Config("PROPERTY=VALUE"), where VALUE is the value of the setting expressed as a string. For boolean values, use the strings "True", "False", "0", "1", "Yes", or "No" (case does not matter).

To read (query) the value of a configuration setting, you must call Config("PROPERTY"). The value will be returned as a string.

Error Handling (C++)

This method returns a String value; after it returns, call the GetLastErrorCode() method to obtain its result code; 0 indicates success, while a non-zero error code indicates that this method encountered an error during its execution. If an error occurs, the GetLastError() method can be called to retrieve the associated error message.

DecompressBlock Method (ZipStream Class)

Decompresses a block of data.

Syntax

• C++
• C
• Qt

ANSI (Cross Platform)
int DecompressBlock();

Unicode (Windows)
INT DecompressBlock();

int ipworkszip_zipstream_decompressblock(void* lpObj);

int DecompressBlock();

Remarks

This method decompresses the block of data specified by InputData.

The CompressBlock and DecompressBlock methods operate on blocks (chunks) of data. The methods may be used to compress and decompress data as it becomes available.

Note that when using blocks of data the OutputData property is not applicable. Instead data is made available through the CompressedData and DecompressedData events.

If all data is available ahead of time CompressData and DecompressData may be called instead.

Compress Data

Set InputData to the current block to be compressed. Next call CompressBlock to compress the current block. Note that CompressBlock takes a LastBlock parameter. If the block of data is the final block to be compressed set this to True. For all other blocks set this to False.

During compression the CompressedData event will fire with the compressed data. Note that this event may not fire for every call to CompressBlock due to the way the compression algorithm operates. For example:

zipstream.InputDataB = MyDecompressedData; zipstream.CompressBlock(); Data is accumulated inside the CompressedData event: private static void Zipstream_OnCompressedData(object sender, ZipstreamCompressedDataEventArgs e) { DoSomethingWith(e.DataB); }

Note that OutputData is not applicable when compressing block data.

Decompress Data

Set InputData to the current block to be decompressed. Next call DecompressBlock to decompress the current block.

During decompression the DecompressedData event will fire with the decompressed data. Note that this event may not fire for every call to DecompressBlock due to the way the decompression algorithm operates. For example:

zipstream.InputDataB = MyCompressedData; zipstream.DecompressBlock(); Data is accumulated inside the DecompressedData event: private static void Zipstream_OnDecompressedData(object sender, ZipstreamDecompressedDataEventArgs e) { DoSomethingWith(e.DataB); }

Note that OutputData is not applicable when decompressing block data.

Error Handling (C++)

This method returns a result code; 0 indicates success, while a non-zero error code indicates that this method encountered an error during its execution. If an error occurs, the GetLastError() method can be called to retrieve the associated error message. (Note: This method's result code can also be obtained by calling the GetLastErrorCode() method after it returns.)

DecompressData Method (ZipStream Class)

Decompresses the specified data.

Syntax

• C++
• C
• Qt

ANSI (Cross Platform)
int DecompressData();

Unicode (Windows)
INT DecompressData();

int ipworkszip_zipstream_decompressdata(void* lpObj);

int DecompressData();

Remarks

This method decompresses the data specified by InputData. After calling this method OutputData holds the decompressed data.

The CompressData and DecompressData methods operate on the complete blob of data. The entire compressed or decompressed data must be set to InputData before calling either method.

To compress and decompress data in blocks (chunks) see CompressBlock and DecompressBlock.

Compress Data

Set InputData to the decompressed data. This should be the entire data to be compressed. Next call CompressData. After compression OutputData will hold the compressed data. For example:

zipstream.InputDataB = MyDecompressedData; zipstream.CompressData(); MyCompressedData = zipstream.OutputDataB;

In addition to OutputData, the compressed data may also be accumulated within the CompressedData event.

Decompress Data

Set InputData to the compressed data. This should be the entire data to be decompressed. Next call DecompressData. After decompression OutputData will hold the decompressed data. For example:

zipstream.InputDataB = MyCompressedData; zipstream.DecompressData(); MyDecompressedData = zipstream.OutputDataB;

In addition to OutputData, the compressed data may also be accumulated within the DecompressedData event.

Error Handling (C++)

This method returns a result code; 0 indicates success, while a non-zero error code indicates that this method encountered an error during its execution. If an error occurs, the GetLastError() method can be called to retrieve the associated error message. (Note: This method's result code can also be obtained by calling the GetLastErrorCode() method after it returns.)

Reset Method (ZipStream Class)

Resets the class.

Syntax

• C++
• C
• Qt

ANSI (Cross Platform)
int Reset();

Unicode (Windows)
INT Reset();

int ipworkszip_zipstream_reset(void* lpObj);

int Reset();

Remarks

Reset resets the state of the class. All properties will be set to their default values, and any files open will be closed.

Error Handling (C++)

This method returns a result code; 0 indicates success, while a non-zero error code indicates that this method encountered an error during its execution. If an error occurs, the GetLastError() method can be called to retrieve the associated error message. (Note: This method's result code can also be obtained by calling the GetLastErrorCode() method after it returns.)

CompressedData Event (ZipStream Class)

This event fires with compressed data.

Syntax

• C++
• C
• Qt

ANSI (Cross Platform)
virtual int FireCompressedData(ZipStreamCompressedDataEventParams *e);

typedef struct {
  const char *Data;
  int lenData;
  int reserved;
} ZipStreamCompressedDataEventParams;


Unicode (Windows)
virtual INT FireCompressedData(ZipStreamCompressedDataEventParams *e);

typedef struct {
  LPCSTR Data;
  INT lenData;
  INT reserved;
} ZipStreamCompressedDataEventParams;

#define EID_ZIPSTREAM_COMPRESSEDDATA 1

virtual INT IPWORKSZIP_CALL FireCompressedData(LPSTR &lpData, INT &lenData);

class ZipStreamCompressedDataEventParams {
public:
  const QByteArray &Data();

  int EventRetVal();
  void SetEventRetVal(int iRetVal);
};

// To handle, connect one or more slots to this signal.
void CompressedData(ZipStreamCompressedDataEventParams *e);

// Or, subclass ZipStream and override this emitter function.
virtual int FireCompressedData(ZipStreamCompressedDataEventParams *e) {...}

Remarks

The CompressedData event fires as compressed data is available when CompressData or CompressBlock is called. This may fire one or more times when data is compressed.

Data holds the current block of compressed data.

DecompressedData Event (ZipStream Class)

This event fires with decompressed data.

Syntax

• C++
• C
• Qt

ANSI (Cross Platform)
virtual int FireDecompressedData(ZipStreamDecompressedDataEventParams *e);

typedef struct {
  const char *Data;
  int lenData;
  int reserved;
} ZipStreamDecompressedDataEventParams;


Unicode (Windows)
virtual INT FireDecompressedData(ZipStreamDecompressedDataEventParams *e);

typedef struct {
  LPCSTR Data;
  INT lenData;
  INT reserved;
} ZipStreamDecompressedDataEventParams;

#define EID_ZIPSTREAM_DECOMPRESSEDDATA 2

virtual INT IPWORKSZIP_CALL FireDecompressedData(LPSTR &lpData, INT &lenData);

class ZipStreamDecompressedDataEventParams {
public:
  const QByteArray &Data();

  int EventRetVal();
  void SetEventRetVal(int iRetVal);
};

// To handle, connect one or more slots to this signal.
void DecompressedData(ZipStreamDecompressedDataEventParams *e);

// Or, subclass ZipStream and override this emitter function.
virtual int FireDecompressedData(ZipStreamDecompressedDataEventParams *e) {...}

Remarks

The DecompressedData event fires as compressed data is available when DecompressData or DecompressBlock is called. This may fire one or more times as data is decompressed.

Data holds the current block of decompressed data.

Error Event (ZipStream Class)

Information about errors during data delivery.

Syntax

• C++
• C
• Qt

ANSI (Cross Platform)
virtual int FireError(ZipStreamErrorEventParams *e);

typedef struct {
  int ErrorCode;
  const char *Description;
  int reserved;
} ZipStreamErrorEventParams;


Unicode (Windows)
virtual INT FireError(ZipStreamErrorEventParams *e);

typedef struct {
  INT ErrorCode;
  LPCWSTR Description;
  INT reserved;
} ZipStreamErrorEventParams;

#define EID_ZIPSTREAM_ERROR 3

virtual INT IPWORKSZIP_CALL FireError(INT &iErrorCode, LPSTR &lpszDescription);

class ZipStreamErrorEventParams {
public:
  int ErrorCode();

  const QString &Description();

  int EventRetVal();
  void SetEventRetVal(int iRetVal);
};

// To handle, connect one or more slots to this signal.
void Error(ZipStreamErrorEventParams *e);

// Or, subclass ZipStream and override this emitter function.
virtual int FireError(ZipStreamErrorEventParams *e) {...}

Remarks

The Error event is fired in case of exceptional conditions during message processing. Normally the class fails with an error.

ErrorCode contains an error code and Description contains a textual description of the error. For a list of valid error codes and their descriptions, please refer to the Error Codes section.

Config Settings (ZipStream Class)

No configuration settings defined.

Trappable Errors (ZipStream Class)

Error Handling (C++)

Call the GetLastErrorCode() method to obtain the last called method's result code; 0 indicates success, while a non-zero error code indicates that this method encountered an error during its execution. Known error codes are listed below. If an error occurs, the GetLastError() method can be called to retrieve the associated error message.

ZipStream Errors

	101   The data is of an invalid or unsupported format.
	111   Can't open file for read.
	150   An I/O error has occurred (details follow).