ZipCrc Delphi DLL Reference Documentation
ZipCrc
Current Version: 10.1.2
Calculate a Zip CRC checksum for a file or in-memory data.
Create/Dispose
var myObject: HCkZipCrc; begin myObject := CkZipCrc_Create(); // ... CkZipCrc_Dispose(myObject); end;
Creates an instance of the HCkZipCrc object and returns a handle (i.e. a Pointer). The handle is passed in the 1st argument for the functions listed on this page.
Objects created by calling CkZipCrc_Create must be freed by calling this method. A memory leak occurs if a handle is not disposed by calling this function.
Properties
DebugLogFilePath
procedure CkZipCrc_putDebugLogFilePath(objHandle: HCkZipCrc; newPropVal: PWideChar); stdcall;
function CkZipCrc__debugLogFilePath(objHandle: HCkZipCrc): PWideChar; stdcall;
If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. This logging helps identify the context and history of Chilkat calls leading up to any crash or hang, aiding in debugging.
Enabling the VerboseLogging property provides more detailed information. This property is mainly used for debugging rare instances where a Chilkat method call causes a hang or crash, which should generally not happen.
Possible causes of hangs include:
- A timeout property set to 0, indicating an infinite timeout.
- A hang occurring within an event callback in the application code.
- An internal bug in the Chilkat code causing the hang.
See the notes about PWideChar memory ownership and validity.
LastErrorHtml
function CkZipCrc__lastErrorHtml(objHandle: HCkZipCrc): PWideChar; stdcall;
Provides HTML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
See the notes about PWideChar memory ownership and validity.
topLastErrorText
function CkZipCrc__lastErrorText(objHandle: HCkZipCrc): PWideChar; stdcall;
Provides plain text information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
See the notes about PWideChar memory ownership and validity.
LastErrorXml
function CkZipCrc__lastErrorXml(objHandle: HCkZipCrc): PWideChar; stdcall;
Provides XML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
See the notes about PWideChar memory ownership and validity.
topLastMethodSuccess
procedure CkZipCrc_putLastMethodSuccess(objHandle: HCkZipCrc; newPropVal: wordbool); stdcall;
Indicates the success or failure of the most recent method call: True means success, False means failure. This property remains unchanged by property setters or getters. This method is present to address challenges in checking for null or Nothing returns in certain programming languages.
topVerboseLogging
procedure CkZipCrc_putVerboseLogging(objHandle: HCkZipCrc; newPropVal: wordbool); stdcall;
If set to True, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is False. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.
topVersion
function CkZipCrc__version(objHandle: HCkZipCrc): PWideChar; stdcall;
Version of the component/library, such as "10.1.0"
See the notes about PWideChar memory ownership and validity.
Methods
BeginStream
Provides a way to calculate a CRC by streaming the data a chunk at a time. An application would start by calling BeginStream. Then it would add data by calling MoreData for each additional chunk. After the last chunk has been processed, the EndStream method is called to return the CRC.
topCalculateCrc
Calculates a 32-bit CRC for in-memory byte data. This is the 32-bit CRC that would be found in a Zip file header if a file containing the data was added to a zip archive. Returns the CRC32 of the data.
topCrcBd
Calculates a CRC32 for the bytes contained in bd.
topCrcSb
sb: HCkStringBuilder;
charset: PWideChar): LongWord; stdcall;
Calculates a CRC32 for the string contained in sb. The charset is the byte representation to be used for the sb when calculating the CRC32. It can be utf-8, utf-16, windows-1252, iso-8859-1, or any of the character encodings (charsets) listed at the link below.
topCrcString
str: PWideChar;
charset: PWideChar): LongWord; stdcall;
Calculates a CRC32 for a string. The charset is the byte representation to be used for the str when calculating the CRC32. It can be utf-8, utf-16, windows-1252, iso-8859-1, or any of the character encodings (charsets) listed at the link below.
topEndStream
Finalizes and returns the Zip CRC value calculated by calling BeginStream followed by multiple calls to MoreData.
topFileCrc
path: PWideChar): LongWord; stdcall;
Calculates the CRC32 of a file. The data contained in the file is streamed for the calculation to keep the memory footprint small and constant. Returns the CRC32 of the file.
FileCrcAsync (1)
Creates an asynchronous task to call the FileCrc method with the arguments provided.
Note: Async method event callbacks happen in the background thread. Accessing and updating UI elements existing in the main thread may require special considerations.
Returns nil on failure
topLoadTaskCaller
MoreData
Adds additional data to the CRC currently being calculated. (See BeginStream for more information.)
topToHex
crc: LongWord;
outStr: HCkString): wordbool; stdcall;
function CkZipCrc__toHex(objHandle: HCkZipCrc;
crc: LongWord): PWideChar; stdcall;
Converts a 32-bit integer to a hex string.
Returns True for success, False for failure.
See the notes about PWideChar memory ownership and validity.
topEvents
AbortCheck
Provides the opportunity for a method call to be aborted. The AbortCheck event is fired periodically based on the value of the HeartbeatMs property. If HeartbeatMs is 0, then no AbortCheck events will fire. As an example, to fire 5 AbortCheck events per second, set the HeartbeatMs property equal to 200. Return True to abort; return False to continue (not abort)
PercentDone
Provides the percentage completed for any method that involves network communications or time-consuming processing (assuming it is a method where a percentage completion can be measured). This event is only fired when it is possible to know a percentage completion, and when it makes sense to express the operation as a percentage completed. The pctDone argument will have a value from 1 to 100. For operations (Chilkat method calls) that complete very quickly, the number of PercentDone callbacks will vary, but the final callback should have a value of 100. For long running operations, no more than one callback per percentage point will occur (for example: 1, 2, 3, ... 98, 99, 100).
The PercentDone callback counts as an AbortCheck event. For method calls that complete quickly such that PercentDone events fire, it may be that AbortCheck events don't fire because the opportunity to abort is already provided in the PercentDone callback. For time consuming operations, where the amount of time between PercentDone callbacks are long, AbortCheck callbacks may be used to allow for the operation to be aborted in a more responsive manner.
Return True to abort; return False to continue (not abort)
ProgressInfo
A general name/value event that provides information about what is happening during a method call. To find out what information is available, write code to handle this event and log the name/value pairs. Most are self-explanatory.
TaskCompleted
Called in the background thread when an asynchronous task completes.