Const TArray to string

Development Programming & Scripting
1

I am trying to compress an image, convert it to a string, add it to a JSON object (with some other properties) and then send it via TCP.

Here is how I compress the image:

TArray<uint8> CompressedData;

FImageUtils::CompressImageArray(
		1024,
		1024,
		ColorBuffer,
		CompressedData
);
		
	server.Process(CompressedData);

My Process function definition looks like this:

void Process(const TArray<uint8> data);

Now, since I need to send JSON (using rapidjson), I need to convert it to a string.
I have tried:

FString frameAsFString =  StringFromBinaryArray(data);
string frameAsString(TCHAR_TO_UTF8(*frameAsFString));

Where StringFromBinaryArray is from Rama:

FString TCPMessengerServer::StringFromBinaryArray(const TArray<uint8>& BinaryArray)
{
	//Create a string from a byte array!
	const std::string cstr(reinterpret_cast<const char*>(BinaryArray.GetData()), BinaryArray.Num());

	//FString can take in the c_str() of a std::string
	return FString(cstr.c_str());
}

But the frameAsString looks like this: “?PNG\r\n\u001A\n”

I then tried:

string s(*data.GetData(), sizeof(data));

But from that, frameAsString looks like this:

\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u00
10\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u
0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010
\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u00
10\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u
0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010
\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u00
10\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u
0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010\u0010
\u0010\u0010\u0010\u0010

I don’t think that I am getting the actual image data… just the address or something.
How can I get the actual image data from my const TArray data and convert it to a string so that I can send as JSON?

2

What are you looking for in the string format? FString has ToBlob and ToHexBlob - either of those work for you?

3

Hmm, I still can’t get it to work… how would I get the image data into a string? Here is what I tried:

FString frameAsFString = StringFromBinaryArray(data);
uint8 pixelData[sizeof(data.GetData())];
frameAsFString.ToHexBlob(frameAsFString, pixelData, sizeof(data.GetData()));
string frameAsString(TCHAR_TO_UTF8(pixelData)); //frameAsString is empty…

4

If your data contains zeros what’s to stop the characters being considered terminators? Are you looking for a raw binary blob of data (strings don’t map well to this) or can you handle something a little more readable like a string of hex values (“ab3fcd00”).

5

I have converted my image data to hex and it works, but really not the fastest solution.

6

If you have control of the receiver one solution I’ve seen floating around in these forums is to +1 on every element in the array (and -1 on receipt), you may need to deal with overflow.