Blob
The Blob class lets you create and manipulate blob objects (4D.Blob).
Summary
4D.Blob.new()
4D.Blob.new*() : 4D.Blob
4D.Blob.new( blobScal : Blob ) : 4D.Blob
4D.Blob.new( blobObj : 4D.Blob ) : 4D.Blob
| Parameter | Type | Description | |
|---|---|---|---|
| blob | Blob or 4D.Blob | → | Blob to copy |
| Result | 4D.Blob | ← | New 4D.Blob |
Description
4D.Blob.new creates a new 4D.Blob object optionally encapsulating a copy of the data from another blob (scalar blob or 4D.Blob).
If the blob parameter is omitted, the method returns an empty 4D.Blob.
.size
.size* : number
Description
The .size property returns the size of a 4D.Blob, expressed in bytes.
.slice()
.slice*() : 4D.Blob
.slice( start : number ) : 4D.Blob
.slice( start : number; end : number ) : 4D.Blob
| Parameter | Type | Description | |
|---|---|---|---|
| start | number | → | index of the first byte to include in the new 4D.Blob. |
| end | number | → | index of the first byte that will not be included in the new 4D.Blob |
| Result | 4D.Blob | ← | New 4D.Blob |
Description
.slice() creates and returns a 4D.Blob that references data from a subset of the blob on which it's called. The original blob is not altered.
The start parameter is an index into the blob indicating the first byte to include in the new 4D.Blob. If you specify a negative value, 4D treats it as an offset from the end of the blob toward the beginning. For example, -10 would be the 10th from last byte in the blob. The default value is 0. If you specify a value for start that is larger than the size of the source blob, the returned 4D.Blob's size is 0, and it contains no data.
The end parameter is an index into the blob indicating the first byte that will not be included in the new 4D.Blob (i.e. the byte exactly at this index is not included). If you specify a negative value, 4D treats it as an offset from the end of the blob toward the beginning. For example, -10 would be the 10th from last byte in the blob. The default value is the size of the blob.
Example
var myBlob, myNewBlob : 4D.Blob
var is4DBlob : boolean
var myString : string
// Store text in a 4D.Blob
convertFromString("Hello, World!", "UTF-8", myBlob)
is4DBlob = instanceOf(myBlob, 4D.Blob) //True
myString = convertToString(myBlob, "UTF-8")
// myString contains "Hello, World!"
// Create a new 4D.Blob from myBlob
myNewBlob = myBlob.slice(0,5)
myString = convertToString(myNewBlob, "UTF-8")
// myString contains "Hello"