Android Question user-defined types - conversion to array of primitive bytes

brucePERU · Mar 22, 2020

Hello

I want to send packets TCP to a server in lazarus (object pascal) from types defined in B4A. The idea is to convert it to primitive byte array

B4X:

Type  TPackPosition(Hour As long, latitude As Double, longitude As double)
...
..
Dim Position as TPackPosition
Position.initialize
Position.Hour = DateTime.now
Position.Latitude = -16.46541
Position.Latitude = -70.487899

Dim obj As Object = Position
Dim buffer() as byte = obj
...
Stream.Write(buffer)

Please I need your great support,

Bruce

DonManfred · Mar 22, 2020

As far as i know there is no Pascal/Delphi implementation.

But using B4A/J/I you can use B4XSerializator. Here it is easy

B4X:

    Dim Position As TPackPosition
    Position.initialize
    Position.Hour = DateTime.now
    Position.Latitude = -16.46541
    Position.Latitude = -70.487899
    Dim ser As B4XSerializator ' RandomAccessFile library
    ser.ConvertObjectToBytesAsync(Position,"PosType")
    wait for PosType_ObjectToBytes (Success As Boolean, Bytes() As Byte)
    Log($"PosType_ObjectToBytes(${Success},${Bytes.Length})"$)
    Dim ser As B4XSerializator
    ser.ConvertBytesToObject(Bytes)
    wait for PosType_BytesToObject (Success As Boolean, NewObject As Object)
    Log($"PosType_BytesToObject(${Success}, ${NewObject})"$)

You can use RandomAccessfile to convert the Type to bytes.

B4X:

    Dim raf As RandomAccessFile
    raf.Initialize(File.DirInternal,"1.dat",False)
    raf.WriteB4XObject(Position,0)
    raf.Close

    Dim bytes() As Byte = File.ReadBytes(File.DirInternal,"1.dat")

Jeffrey Cameron · Mar 22, 2020

This has been discussed before for .NET -> https://www.b4x.com/android/forum/threads/serializing-deserializing-basic4android-net.32525/
I would suggest you just make a class that accepts the types and converts them to a byte stream before sending.

brucePERU · Mar 22, 2020

Hi DonManfred

B4X:

Dim Position As TPackPosition
    Position.initialize
    Position.Hour = DateTime.now
    Position.Latitude = -16.46541
    Position.Latitude = -70.487899
    Dim ser As B4XSerializator ' RandomAccessFile library
    ser.ConvertObjectToBytesAsync(Position,"PosType")
    wait for PosType_ObjectToBytes (Success As Boolean, Bytes() As Byte)
    Log($"PosType_ObjectToBytes(${Success},${Bytes.Length})"$)

which means the content of the variable "bytes"

Erel · Mar 23, 2020

Best solution is to use B4J on the PC. It will make this task trivial.

brucePERU said:
which means the content of the variable "bytes"

This is the format used by B4XSerializator. You can see the source code for more information: https://github.com/AnywhereSoftware...are/b4a/randomaccessfile/B4XSerializator.java

Android Question user-defined types - conversion to array of primitive bytes

brucePERU

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DonManfred

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Jeffrey Cameron

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Android Question user-defined types - conversion to array of primitive bytes

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