Android Question Send and reveive an image using MQTT

[Juan Marrero]

Is it possible to send and receive images using MQTT? I've been trying to do so but always get an error saying that the object i used cannot be serialized with serializator.ConvertObjectToBytes. I've tried with ImageView, Bitmap, Object, InputStream and Type (with ImageView inside).

These are 2 examples of what I've tried:

'    Dim img As ImageView
          
'    img.Initialize("")
'    img.Bitmap = LoadBitmap(fd.FilePath, fd.ChosenName)
'
'    mqtt.Publish(mytopic, serializator.ConvertObjectToBytes(img))

     Dim iStream As InputStream         
     iStream = File.OpenInput(fd.FilePath, fd.ChosenName)
           
     mqtt.Publish(mytopic, serializator.ConvertObjectToBytes(iStream))

Also I can't receive the image in the server because I can't compare the object to an image because what the server receives is a Byte Array:

If obj Is Image Then 'The example uses CircleData that is a Type with basic data types

End If

 

[walterf25]

Is it possible to send and receive images using MQTT? I've been trying to do so but always get an error saying that the object i used cannot be serialized with serializator.ConvertObjectToBytes. I've tried with ImageView, Bitmap, Object, InputStream and Type (with ImageView inside).

These are 2 examples of what I've tried:

'    Dim img As ImageView
         
'    img.Initialize("")
'    img.Bitmap = LoadBitmap(fd.FilePath, fd.ChosenName)
'
'    mqtt.Publish(mytopic, serializator.ConvertObjectToBytes(img))

     Dim iStream As InputStream        
     iStream = File.OpenInput(fd.FilePath, fd.ChosenName)
          
     mqtt.Publish(mytopic, serializator.ConvertObjectToBytes(iStream))

Also I can't receive the image in the server because I can't compare the object to an image because what the server receives is a Byte Array:

If obj Is Image Then 'The example uses CircleData that is a Type with basic data types

End If

I've never used MQTT, but i'm assuming you can generate a checksum and check that on the other side when it's received, and compare it.

Just a thought!

Walter

 

[Erel]

Read the file into an array of bytes:

Dim data() As Byte = Bit.InputStreamToBytes(File.OpenInput(...))

Now send 'data'.

In the other side you can use InputStream.InitializeFromBytesArray together with Bitmap.Initialize2.

 

[Juan Marrero]

with or without using serialization?

 

[Erel]

It is up to you. Both are possible.

 

[Juan Marrero]

I used serialization because the MQTTExample uses it. It seems to be sending and receiving it but I'm having a hard time adding the image to a listview in b4j and to the customlistview in b4a. I'll post a new thread for this.