Websocket and arraybuffer
lazarus / 76-Pas2JS

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dennis_uniwin · 2023-06-27 09:13

Hello,

I started with the websocket demo and I am trying to make a websocket
connection to our own software.
So I have made sure that the websocket is created in the following
way:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i        
URL:='ws://'+aHost+':5001/ws/';    end;  try   
WS:=TJSWebsocket.New(url,'csr');    ws.binaryType:='arraybuffer';   
WS.onopen:=@DoOpen;    WS.onmessage:=@DoIncomingMessage;   
WS.onclose:=@DoClosed;  
The connection is made and I receive a message from out software. In
the DoIncomingMessage event I try to handle the received data.
This should be an ArrayBuffer. And I try to handle this in the
following way. Only myarray remains an array with a length of 0. So
obviously I am doing something wrong. Does someone know what it is I
am doing wrong? And the next question how do I cast the byte array to
a string?

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i var 
mystring: string;  myarray:TJSUint8Array;     begin     myarray :=
TJSUint8Array.new(TJSUint8Array.from(Msg.Data));    mystring :=
myarray.toLocaleString;    Writeln(mystring);   end;

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Thaddy · 2023-06-27 10:46

Since UTF8, UTF8 and UTF32 can at some point contain 4 bytes per
character, your buffer needs to assume SizeOf(Byte) * 4 in all
cases.... Basic...

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dennis_uniwin · 2023-06-27 13:18

I got it! I first had to make it an TJSObject and then a TJSUint8Array
and then I can create a readable string finally.
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i    
 myObject := toObject(Msg.Data);     myarray  :=
TJSUint8Array.new(myObject);         for i := 0 to myarray.byteLength
- 1 do begin       mystring:= mystring + Char(myarray.values[i]);   
 end;      Writeln('myString ' + mystring);