Blob Class
| Inherits: | Stream |
This class is used to store data in the memory (unlike File which is stored on the disk). The blob uses either an Unigine allocator (if #define USE_MEMORY is set, by default) or a system allocator.
Example
The code below illustrates the following process:
- Packing data to a blob and saving compressed data to a file
- Reading and uncompressing data from the file to the destination blob
- Reading data from the destination blob
Source code (UnigineScript)
// creating a source blob to store data
Blob blob1 = new Blob();
// creating a file to save our blob's data to
File file = new File("test.dat", "w+");
// clearing a blob
blob1.clear();
// writing data to a blob (prefix, vector and postfix)
blob1.writeChar('B');
blob1.writeVec3(vec3(0.1f, 0.2f, 0.3f));
blob1.writeChar('E');
// compressing blob's data with low compression and saving it to the file
blob1.compress(file, 0);
// closing the file
file.close();
// deleting a blob
delete blob1;
// opening the data file for reading
file.open("test.dat", "r");
// creating a second blob
Blob blob2 = new Blob();
// reading and decompressing data from the file
blob2.decompress(file);
// closing the file
file.close();
delete file;
// setting current position to the beginning of the blob
blob2.seekSet(0);
// reading data from a blob (prefix, vector and postfix)
int pref = blob2.readChar();
vec3 v = blob2.readVec3();
int postf = blob2.readChar();
// reporting the decoded blob data and SHA1 checksum
log.message("\nDESTINATION: [%c] vec(%f, %f, %f) [%c] - SHA1 checksum (%s)", pref, v.x, v.y, v.z, postf, blob2.getSHA1());
// deleting a blob
delete blob2;Blob Class
Members
static Blob(int size = 0)
Constructor. Creates a new blob of the specified size.Arguments
- int size - Blob size.
Blob cast(Stream stream)
Casts a Blob out of the Stream instance.Arguments
- Stream stream - Stream.
Return value
Blob.void set(int offset, int value)
Sets the value of the specified byte in the blob.Arguments
- int offset - The offset in the blob.
- int value - The byte value.
int get(int offset)
Returns the value of the specified byte in the blob.Arguments
- int offset - The offset, in bytes.
Return value
The byte value.int getc()
Returns the next symbol from the blob.Return value
The blob symbol.String getCRC32()
Returns the 32-bit CRC checksum.Return value
The 32-bit CRC checksum.String getMD5()
Returns a 128-bit MD5 checksum.Return value
128-bit MD5 checksum.String getSHA1()
Returns a 160-bit SHA1 checksum.Return value
160-bit SHA1 checksum.String getSHA256()
Returns a 256-bit SHA256 checksum.Return value
256-bit SHA256 checksum.int getSize()
Returns the current size of the blob.Return value
The size of the blob.void allocate(int size)
Allocates the required memory without resizing the blob.Notice
The blob will be resized dynamically when the allocated memory is filled.
Arguments
- int size - Size of the allocated memory, in bytes.
void clear()
Clears the size of the blob to 0.int compress(Stream dest, int quality)
Compresses the blob and writes it into the given stream.Notice
This method uses zlib compression which is better than Lz4 (see the compressLz4() method), but significantly slower.
Arguments
- Stream dest - Destination stream.
- int quality - Compression quality (0 is for a fast compression, 1 is for a small size).
Return value
1 if the data is successfully compressed; otherwise, 0.int compressLz4(Stream dest, int quality)
Compresses the blob with Lz4 algorithm and writes it into the given stream.Arguments
- Stream dest - Destination stream.
- int quality - Compression quality (0 is for a fast compression, 1 is for a small size).
Return value
1 if the data is successfully compressed; otherwise, 0.int decode(string src)
Decodes a base64 encoded string into the blob.Arguments
- string src - Source base64 encoded string.
Return value
Returns 1 if the data is decoded successfully; otherwise, 0.int decodeZBase32(string src)
Decodes a Zbase32 encoded string into the blob.Arguments
- string src - Source Zbase32 encoded string.
Return value
Returns 1 if the data is decoded successfully; otherwise, 0.int decompress(Stream src)
Reads and decompresses a previously compressed blob from a given stream.Arguments
- Stream src - Stream to read data from.
Return value
1 if the blob is decompressed successfully; otherwise, 0.int decompressLz4(Stream src)
Reads and decompresses a previously compressed blob with Lz4 algorithm from a given stream.Arguments
- Stream src - Source stream to read data from.
Return value
1 if the blob is successfully decompressed; otherwise, 0.StringStack<256> encode()
Encodes the blob into the base64 encoded string.Return value
Base64 encoded string.int eof()
Checks if the end of the blob has been reached.Return value
1 if the end of blob is reached; otherwise, 0.int flush()
Flushes the blob. This function has an empty body; it is created for Blob class to have the same number of methods as the File class has.Return value
Returns 1 if the blob is successfully flushed; otherwise, 0.void reserve(int size)
Reserves the blob, i.e. allocates (size * 1.5) bytes without resizing the blob.Notice
The blob will be resized dynamically when the allocated memory is filled.
Arguments
- int size - The size of the allocated memory, in bytes.
void resize(int size)
Allocates the required memory and resizes the blob.Arguments
- int size - The size of the blob, in bytes.
int seekCur(int offset)
Seeks the position relative to the current offset.Arguments
- int offset - The offset from the current position of the indicator, in bytes.
Return value
Returns 1 if the new blob position indicator is successfully set; otherwise, 0.int seekEnd(int offset)
Seeks the position relative to the end of the blob.Arguments
- int offset - The offset from the end of the blob, in bytes.
Return value
Returns 1 if the blob position indicator is successfully set; otherwise, 0.int seekSet(int offset)
Seeks the position relative to the start of blob.Arguments
- int offset - The offset from the beginning of the blob, in bytes.
Return value
Returns 1 if the blob position indicator is successfully set; otherwise, 0.int tell()
Returns the current blob offset.Return value
The blob offset.Last update: 2018-08-10
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