ZipEntry Dart Reference Documentation
CkZipEntry
Current Version: 11.6.1
Chilkat.ZipEntry
Inspect filenames, stored ZIP paths, comments, timestamps, CRC values,
attributes, sizes, compression method, and compression level.
Use
Extract a selected file entry to disk, inflate its contents into memory,
or read the uncompressed data into Chilkat objects.
Access the raw compressed entry data when an application needs ZIP-level
control rather than only the inflated contents.
Update an entry's contents from strings, byte data, files, or in-memory
data sources before writing the ZIP archive.
Walk through entries returned from
For an extended overview, see
ZipEntry Overview.
Inspect, extract, update, and iterate individual entries inside a ZIP archive.
Chilkat.ZipEntry represents a single item associated with a
Chilkat.Zip archive. An entry may be a file already stored in an
opened ZIP, a referenced filesystem file waiting to be compressed, an
in-memory text or binary entry, or a directory entry. It provides access to
entry-level metadata, compressed and uncompressed data, timestamps,
attributes, CRC values, encryption information, and extraction or replacement
operations for that specific ZIP item.
Entry metadata
Entry type and state
EntryType to understand whether the entry comes from an
existing ZIP, a filesystem reference, memory data, or a directory.
Extract one entry
Read compressed data
Replace or append data
Iterate archive entries
Chilkat.Zip methods to
inspect, filter, extract, or modify ZIP contents one item at a time.
Chilkat.Zip object, obtain a
ZipEntry using methods such as EntryAt,
EntryOf, EntryMatching, or
FirstEntry, then inspect metadata, extract contents, update the
entry, or continue iterating through the archive. Use
Chilkat.Zip for whole-archive operations and
ZipEntry for operations on one specific archive item.
Object Creation
// pubspec.yaml:
// dependencies:
// chilkat: ^11.6.1
import 'package:chilkat/chilkat.dart';
// Once per process, before any other Chilkat call:
Chilkat.unlockBundle('Anything for 30-day trial'); // shorthand for CkGlobal().unlockBundle(..)
final zipEntry = CkZipEntry();
// ... the native object is released when `zipEntry` is garbage collected, or now with zipEntry.dispose().Creates the underlying native Chilkat object. Use a CkZipEntry only from the isolate that created it: Chilkat objects cannot be sent between isolates. Every call is synchronous; in a Flutter app, run long operations (network, large files) inside Isolate.run, creating the Chilkat objects inside the isolate.
Releases the native object immediately instead of waiting for garbage collection (useful for a large CkBinData or an open socket). Calling it more than once is harmless; any other use of the object afterwards throws a StateError. isDisposed tells whether it has been called.
Errors
A method that can fail throws a ChilkatException: a method whose only outcome is success or failure returns void and throws on failure; a method producing a String or an object returns it and throws where Chilkat would have returned null. The exception carries the object's LastErrorText at the time of the failure (lastErrorText), the class and method names (className, methodName) and a one-line message. Properties never throw, and methods that answer a question (has..., is..., ...) return a plain bool.
try {
zipEntry.someMethod(...);
} on ChilkatException catch (e) {
print(e); // CkZipEntry.someMethod failed: <reason>
print(e.lastErrorText); // the full Chilkat log of the failed call
}Properties
Comment
String get comment
set comment(String value)
Gets or sets the comment stored in the ZIP archive for this entry.
topCompressedLength
int get compressedLength
The compressed size of this entry, in bytes.
For mapped entries (entries already contained within an opened ZIP archive), this property contains the actual compressed size stored within the ZIP.
For file entries or data entries that have not yet been written to a ZIP archive, compression has not yet occurred. In these cases, this property contains:
- The current uncompressed data size for data entries.
- The cached filesystem file size for referenced file entries.
After the ZIP archive is written, the entries become mapped entries, and this property then reflects the actual compressed size stored in the ZIP archive.
topCompressedLength64
int get compressedLength64
The compressed size of this entry, in bytes, as a 64-bit integer.
For mapped entries (entries already contained within an opened ZIP archive), this property contains the actual compressed size stored within the ZIP.
For file entries or data entries that have not yet been written to a ZIP archive, compression has not yet occurred. In these cases, this property contains:
- The current uncompressed data size for data entries.
- The cached filesystem file size for referenced file entries.
After the ZIP archive is written, the entries become mapped entries, and this property then reflects the actual compressed size stored in the ZIP archive.
Use this property when sizes may exceed the range of a 32-bit integer.
topCompressedLengthStr
String get compressedLengthStr
The compressed size of this entry as a decimal string.
For mapped entries (entries already contained within an opened ZIP archive), this property contains the actual compressed size stored within the ZIP.
For file entries or data entries that have not yet been written to a ZIP archive, compression has not yet occurred. In these cases, this property contains:
- The current uncompressed data size for data entries.
- The cached filesystem file size for referenced file entries.
After the ZIP archive is written, the entries become mapped entries, and this property then reflects the actual compressed size stored in the ZIP archive.
This property is useful when sizes may exceed the range of a 32-bit integer.
topCompressionLevel
int get compressionLevel
set compressionLevel(int value)
Gets or sets the compression level for this entry.
A value of 0 means no compression, and a value of
9 means maximum compression.
The default value is 6.
CompressionMethod
int get compressionMethod
set compressionMethod(int value)
Gets or sets the compression method used for this entry.
-
0means no compression. -
8means Deflate compression.
Deflate is the standard compression algorithm used by common ZIP utilities such as WinZip.
topCrc
int get crc
DebugLogFilePath
String get debugLogFilePath
set debugLogFilePath(String value)
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.
EncryptionKeyLen
int get encryptionKeyLen
The AES encryption key length for this entry.
If this entry is AES encrypted, the value is 128,
192, or 256.
If this entry is not AES encrypted, the value is 0.
EntryID
int get entryID
A unique identifier assigned to this entry while the ZIP object is instantiated in memory.
This ID can be used to retrieve the same entry later with
Zip.EntryById.
EntryType
int get entryType
Indicates the origin and current state of this ZIP entry.
-
0— Mapped Entry: an entry that already exists in an open ZIP file. -
1— File Entry: a file in the local filesystem that has been referenced, but not yet read or compressed. -
2— Data Entry: an entry containing uncompressed data already held in memory. -
3— Null Entry: an entry that no longer exists in the ZIP archive. -
4— New Directory Entry: a directory entry added to the ZIP object.
When the ZIP archive is written by calling WriteZip or
WriteToMemory, entries are transformed into mapped entries.
In other words, after writing, they point to compressed data contained
in the newly created or rewritten ZIP archive.
FileDateTimeStr
String get fileDateTimeStr
set fileDateTimeStr(String value)
Gets or sets the local last-modified date/time for this ZIP entry in RFC 822 string format.
Example RFC 822 date/time strings:
Tue, 15 Nov 1994 12:45:26 GMT
Fri, 05 Jan 2024 18:30:00 -0500
The timezone may be specified either as a named timezone such as
GMT, or as a numeric UTC offset such as
-0500.
FileName
String get fileName
set fileName(String value)
Gets or sets the filename, including any relative path, stored for this entry inside the ZIP archive.
Changing this property changes the path/name that will appear in the ZIP archive. It does not rename a source file in the local filesystem.
FileNameHex
String get fileNameHex
Returns the raw filename bytes found in the ZIP entry, encoded as a hexadecimal string.
This can be useful for diagnosing filename encoding issues.
topHeartbeatMs
int get heartbeatMs
set heartbeatMs(int value)
The interval in milliseconds between each AbortCheck event callback, which enables an application to abort certain method calls before they complete. By default, HeartbeatMs is set to 0, meaning no AbortCheck event callbacks will trigger.
IsAesEncrypted
bool get isAesEncrypted
Indicates whether this ZIP entry is AES encrypted.
This property can be trueOpenZip, OpenBd, or
OpenFromMemory.
If the entry is not AES encrypted, the property is
false
IsDirectory
bool get isDirectory
Indicates whether this ZIP entry is a directory entry.
The value is truefalse
LastErrorHtml
String get lastErrorHtml
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.
topLastErrorText
String get lastErrorText
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.
LastErrorXml
String get lastErrorXml
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.
topLastMethodSuccess
bool get lastMethodSuccess
set lastMethodSuccess(bool value)
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. Note: This property does not apply to methods that return integer values or to boolean-returning methods where the boolean does not indicate success or failure.
TextFlag
bool get textFlag
set textFlag(bool value)
Gets or sets the text flag in the internal file attributes for this ZIP entry.
This flag indicates whether the entry contents should be considered text rather than binary data.
The flag is informational and does not need to be accurate for normal ZIP processing. It is provided for compatibility with applications that may be sensitive to this attribute.
topUncompressedLength
int get uncompressedLength
The uncompressed size of this entry, in bytes.
topUncompressedLength64
int get uncompressedLength64
The uncompressed size of this entry, in bytes, as a 64-bit integer.
Use this property when the uncompressed size may exceed the range of a 32-bit integer.
topUncompressedLengthStr
String get uncompressedLengthStr
The uncompressed size of this ZIP entry as a decimal string.
This is useful when the uncompressed size may be larger than what can safely be represented by a 32-bit integer.
topVerboseLogging
bool get verboseLogging
set verboseLogging(bool value)
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.
Version
String get version
Methods
AppendString
Appends text data to this ZIP entry's file contents.
The text is converted to bytes using the character encoding specified
by charset, such as utf-8,
utf-16, or ansi.
If this entry is already a Data Entry
(EntryType = 2), then the encoded bytes are appended
directly to the existing uncompressed in-memory data.
If this entry is not already a Data Entry, then the entry is first converted into a Data Entry before the new text data is appended.
-
If the entry is a mapped entry
(
EntryType = 0), the compressed ZIP entry data is first inflated into memory. The new text data is then appended, and the entry becomes a Data Entry containing the combined uncompressed data. -
If the entry is a file entry
(
EntryType = 1), the referenced filesystem file is first loaded into memory. The new text data is then appended, and the entry becomes a Data Entry containing the combined data.
After this method is called, the entry contents exist entirely as uncompressed in-memory data associated with the ZipEntry object.
Returns normally on success; throws a ChilkatException on failure.
CopyToBase64
Returns the compressed data for this ZIP entry as a Base64-encoded string.
This method can only be used when the entry already contains compressed data, meaning the entry is a mapped entry.
This is possible for entries from a ZIP archive that has already been opened, or after writing a ZIP archive while it remains open.
Throws a ChilkatException on failure (where the description says null is returned, the Dart method throws instead).
CopyToHex
Returns the compressed data for this ZIP entry as a hexadecimal encoded string.
This method can only be used when the entry already contains compressed data, meaning the entry is a mapped entry.
This is possible for entries from a ZIP archive that has already been opened, or after writing a ZIP archive while it remains open.
Throws a ChilkatException on failure (where the description says null is returned, the Dart method throws instead).
Extract
Extracts this ZIP entry beneath the specified base directory.
The entry is extracted according to the relative path stored in the ZIP archive.
For example, if the entry filename is
docs/readme.txt and dirPath is
c:/temp/output, the file is extracted to
c:/temp/output/docs/readme.txt.
Use ExtractInto instead if the file should be extracted
directly into a specific directory regardless of the path stored in
the ZIP archive.
Returns normally on success; throws a ChilkatException on failure.
ExtractInto
Extracts this entry directly into the specified directory, ignoring any path information stored in the ZIP entry.
For example, if the entry filename is
docs/readme.txt and dirPath is
c:/temp/output, the file is extracted to
c:/temp/output/readme.txt.
If this entry is a directory entry, nothing is extracted. To create
the directory represented by a directory entry, use
Extract instead.
Returns normally on success; throws a ChilkatException on failure.
GetNext
Updates this ZipEntry object so that it represents the
next entry in the same ZIP archive.
The next entry may be either a file entry or a directory entry.
Returns truefalse
Returns normally on success; throws a ChilkatException on failure.
GetNextMatch
Updates this ZipEntry object so that it represents the
next entry in the ZIP archive matching the specified wildcard pattern.
The wildcard character * matches zero or more characters.
Matching is performed against the full stored filename, including any
relative path.
The matching entry may be either a file entry or a directory entry.
Returns truefalse
Returns normally on success; throws a ChilkatException on failure.
ReplaceString
Replaces this ZIP entry's existing contents with new text data.
The text is converted to bytes using the character encoding specified
by charset, such as utf-8 or
ansi.
The resulting bytes become the complete contents of the entry.
Returns normally on success; throws a ChilkatException on failure.
SetDt
Sets the last-modified date/time for this ZIP entry.
The dt argument is a CkDateTime object
containing the date/time to store for the entry.
UnzipToBd
Unzips this entry directly into a BinData object.
The uncompressed bytes are written to binData.
Returns normally on success; throws a ChilkatException on failure.
UnzipToSb
Unzips this entry as text and appends the result to a
StringBuilder.
The srcCharset argument specifies how the uncompressed
bytes should be interpreted, such as utf-8,
utf-16, or windows-1252.
The lineEndingBehavior argument controls line-ending
conversion:
-
0— leave line endings unchanged. -
1— convert all line endings to bare LF. -
2— convert all line endings to CRLF.
Returns normally on success; throws a ChilkatException on failure.
UnzipToStream
Unzips this entry to a stream.
If called synchronously, the toStream must have a sink,
such as a file or another stream object.
If called asynchronously, the foreground thread can read from the stream while the unzip operation writes to it.
Returns normally on success; throws a ChilkatException on failure.
UnzipToString
Inflates this entry and returns the uncompressed data as a string.
The srcCharset argument specifies how the uncompressed
bytes should be interpreted, such as utf-8,
utf-16, or windows-1252.
The lineEndingBehavior argument controls line-ending
conversion:
-
0— leave line endings unchanged. -
1— convert all line endings to bare LF. -
2— convert all line endings to CRLF.
Throws a ChilkatException on failure (where the description says null is returned, the Dart method throws instead).
Events
All Chilkat methods are synchronous: the call returns when the work is done. During a call, CkZipEntry raises three events so your application can show progress and offer a way out. Each event is a nullable callback property on the object; assign a function to receive it, or null to stop receiving it:
final zipEntry = CkZipEntry();
zipEntry.onPercentDone = (pct) {
print('$pct%');
return false; // return true to abort the method in progress
};
zipEntry.onProgressInfo = (name, value) => print('$name: $value');
zipEntry.heartbeatMs = 250; // raise onAbortCheck 4 times per second during Chilkat calls
zipEntry.onAbortCheck = () => _userPressedCancel;AbortCheck fires at regular intervals controlled by the HeartbeatMs property (0, the default, disables it); PercentDone fires when an operation's completion percentage is known; ProgressInfo delivers named progress values. Returning true from onAbortCheck or onPercentDone aborts the running method, which then throws a ChilkatException.
Events fire on the thread that called the method, before that method returns. An exception thrown inside a callback aborts the running method and is rethrown from it once the native library has returned. In a Flutter app the callbacks run inside the worker isolate that owns the object; forward progress to the UI through a SendPort, and let onAbortCheck read a flag the UI sets the same way.
AbortCheck
bool Function()? onAbortCheck
Enables a method call to be aborted by triggering the AbortCheck event at intervals defined by the HeartbeatMs property. If HeartbeatMs is set to its default value of 0, no events will occur. For instance, set HeartbeatMs to 200 to trigger 5 AbortCheck events per second.
Example:
zipEntry.heartbeatMs = 250; // call onAbortCheck 4 times per second
var cancelRequested = false;
zipEntry.onAbortCheck = () => cancelRequested;
// ... set cancelRequested = true (e.g. from a message received on a ReceivePort) to abort the method in progressPercentDone
bool Function(int pctDone)? onPercentDone
This provides the percentage completion for any method involving network communications or time-consuming processing, assuming the progress can be measured as a percentage. This event is triggered only when it's possible and logical to express the operation's progress as a percentage. The pctDone argument will range from 1 to 100. For methods that finish quickly, the number of PercentDone callbacks may vary, but the final callback will have pctDone equal to 100. For longer operations, callbacks will not exceed one per percentage point (e.g., 1, 2, 3, ..., 98, 99, 100).
The PercentDone callback also acts as an AbortCheck event. For fast methods where PercentDone fires, an AbortCheck event may not trigger since the PercentDone callback already provides an opportunity to abort. For longer operations, where time between PercentDone callbacks is extended, AbortCheck callbacks enable more responsive operation termination.
To abort the operation, set the abort output argument to true. This will cause the method to terminate and return a failure status or corresponding failure value.
Example:
zipEntry.onPercentDone = (pct) {
// pct ranges from 1 to 100.
print('Percent done: $pct');
return false; // return true to abort the method in progress
};ProgressInfo
void Function(String name, String value)? onProgressInfo
This event callback provides tag name/value pairs that detail what occurs during a method call. To discover existing tag names, create code to handle the event, emit the pairs, and review them. Most tag names are self-explanatory.
Note: Some Chilkat methods don't fire any ProgressInfo events.
Example:
zipEntry.onProgressInfo = (name, value) => print('$name: $value');