Android NDK return byte array of bitmap's pixels

Question

I have to do some processing of a bitmap, and I'm trying to use NDK to return a byte array to java by locking Bitmap pixels. After processing in java is done, I ( finally ) call another NDK function to unlock bitmap's pixels.

I've tryied a few things but no one has worked:

• returning to java the void* returned by lock pixels operation (casting it as jbyteArray), didn't work (sigsegv).
• Using a ByteBuffer also didnt work because its read only (I need to manipulate it from java).
• All other approaches that seem to work, will create a copy of the array... I'm trying to avoid this in order to reduce memory consumption.

Answer 1

Ive solved this by manipulating the array entirely inside native code. All Java code that used the byte[] has been moved to JNI.

According to my research, I think there is no way to manipulate the byte array of a Bitmap directly from Java. Of course you can manipulate a copy, but I dindt find any way to work directly with the native bitmap's data.

If someone finds a way, I would like to know it.

Regards!