Develop Reference

CopyPixelsFromBuffer works. But decode its ByteArray returns null

Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
bitmap.copyPixelsFromBuffer(byteBuffer);
// bitmap is valid and can be displayed
I extracted the ByteArray from the valid byteBuffer. But it returns null when I tried to decodeByteArray. Can someone explain why it's the case.
byteBuffer.rewind();
byteBuffer.get(byteArray, 0, byteBuffer.capacity());
Bitmap bitmap = BitmapFactory.decodeByteArray(byteArray, 0 , byteArray.length);
// returns null

I believe the 2 functions do different things and expect different data.
copyPixelsFromBuffer()
is used to import raw pixel information into an existing Bitmap image which already has size and pixel depth configured.
BitmapFactory.decodeByteArray()
is used to create a bitmap from a byte array containing the full bitmap file data, not just the raw pixels. That's why the function doesn't take (or need) size and pixel depth information, because it gets it all from the bytes passed to it.

Cocos2dx: Garbled bitmap image from android

Note: Using the latest of cocos 2.x
Hi there. I'm trying to pass a bitmap through jni and convert it to a sprite to display, but the image created using CCTexture2d's initWithData is completely garbled. I've looked at other forum posts here, but even after following those as closely as possible, nothing works. Note that we are not going to use a path for the image (and it isn't an option).
There are a few issues that I will break down:
What kind of data is necessary?
The initWithData method has no documentation as to what kind of data it even takes- byte array? Pixel array? It seems other people have used byte array and got it working, so that is what we have gone with. This is the code to get the byte array, but are we supposed to use PNG or JPEG format?
ByteArrayOutputStream bAOS = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.PNG,100, bAOS);
byte[] bytes = bAOS.toByteArray();
Getting the data to cocos
We are using some other convenience methods to write jni messages as json data which gets converted to a CCDictionary. The Byte array gets turned into a CCArray of a bunch of ints, which we can then loop through and assign...to what kind of array? "byte" isn't a valid primitive in c++. Online I've seen an int array:
CCArray *bytes = (CCArray*)dictionary->objectForKey("bytes");
int byteArray[bytes->count()];
for (int i = 0; i < bytes->count(); i++) {
CCNumber *v = (CCNumber*)bytes->objectAtIndex(i);
byteArray[i] = v->getIntValue();
};
and I've tried a char array as well, but neither worked.
CCTexture2d? CCImage?
Ok, so now we have our supposed byte array, we can render the image. Do we use CCTexture2d or CCImage?
For CCTexture2d (we know the image is 20x20 px):
CCTexture2D *texture = new CCTexture2D();
texture->initWithData(byteArray,kCCTexture2DPixelFormat_RGBA8888,20,20,CCSizeMake(20,20));
The image is garbled.
For CCImage...what is the length? I've seen length calculated as the image witdth * image height, or as the actual length of the byte array. Your guess is as good as mine, as I have never gotten a CCImage to work.
CCImage *image = new CCImage();
image->initWithImageData(byteArray,length,CCImage::kFmtPng,20,20,8);
Once we have a CCImage, we can set it to a texture using CCTexture2d's initWithImage function.
Now that we have the Texture, making a sprite with it should be simple:
CCSprite *sprite = CCSprite::createWithTexture(texture);
Which works, in as much as a sprite is created. The image is trash though.
So, what exactly is wrong here?
How do we get the data from the bitmap?
How do we make the data something that cocos can render?
Texture2d or Image? What are the parameters?
For kicks, here is the image we are testing:
And here is the byte array as Android reports it:
[-119,80,78,71,13,10,26,10,0,0,0,13,73,72,68,82,0,0,0,40,0,0,0,40,8,2,0,0,0,3,-100,47,58,0,0,0,3,115,66,73,84,8,8,8,-37,-31,79,-32,0,0,0,-71,73,68,65,84,88,-123,-19,-44,-79,13,-125,48,16,-123,-31,-97,8,-118,-48,96,37,-108,40,-70,34,3,-48,-91,-124,81,24,-115,77,48,27,-64,6,-98,32,50,19,-112,5,48,-123,69,20,41,-36,-55,-35,-45,-13,-41,-100,-114,21,-30,-34,64,-45,48,-60,-74,-41,11,63,26,-123,21,86,88,97,-123,21,86,-8,-60,112,106,-101,-56,-90,-61,11,83,48,-10,6,39,44,38,-108,39,-51,16,9,11,69,-117,8,-127,-81,-89,-102,-66,99,-82,67,-11,116,108,35,97,88,-124,121,-81,109,-4,78,120,-66,-27,82,88,-31,-81,77,26,-35,-12,20,19,66,-32,-128,92,51,-71,21,46,47,-19,-15,-80,67,122,58,-61,-10,109,-86,114,-9,122,-40,-22,-19,-114,-121,23,-52,76,13,-19,102,-6,-52,-20,-67,112,73,57,-122,-22,-25,91,46,-123,21,-2,63,-8,3,120,-72,71,35,-19,75,10,-28,0,0,0,0,73,69,78,68,-82,66,96,-126]
And here is the result (the image is not 20 x 20 though- scaled by cocos to fit density, probably)
Any help would be greatly appreciated

cv::imencode required for outgoing byte[] in Android OpenCV?

I have been struggling with sending back a CV:Mat in JNI as a Java byte[] so that that it can be decoded successfully with BitmapFactory.decode(). When I first bring in my byte[] array(constructed using data from an Android Bitmap) from the Java side, I am able to successfully use it in the C++ OpenCV functions. I do this by building a Mat from the byte[] coming in and calling cv::imdecode on the Mat.
The problem comes when I return back to Android and attempt to use BitmapFactory to decode the byte array into an Android Bitmap. It returns null which indicates that there was a problem in the decoding. Am I incorrectly performing the operations before I return from JNI? Do I need to use cv::imencode since I had to use cv::imdecode on the entering byte[]?
Any and all help appreciated! Code sample is below where I convert the data I need from the Mat in JNI.
NOTE I am aware of using Apache Android_Bitmap functions, but using a byte array is a requirement I am currently working on.
//inData is a char* pointer that is set to a char* cast of the jbyte* pointer for the
// incoming Array.
cv::Mat inMat = cv::Mat(rows, columns, CV_8UC4, inData);
cv::Mat decodedMat = cv::imdecode(inMat, 1);
//convertImage is a function that changes the color space from BGR to Gray and then Gray to
//RGB.
convertImage(decodedMat, decodedMat);
cv::cvtColor(decodedMat, decodedMat, CV_RGB2RGBA);
jbyteArray jDataArray = env->NewByteArray(pixelDataLength);
env->SetByteArrayRegion(jDataArray,0,pixelDataLength,(jbyte*)decodedMat.data);
env->SetObjectField(in,dataArray,jDataArray);
env->ReleaseByteArrayElements(pixelData, bytePointerForIn, 0);

BitmapFactory expects the data provided to it to be in a known file format, but you are passing it raw pixels. You could make it work by calling cv::imencode, but perhaps a more natural solution for loading images from raw pixel data would be to create the original Java Bitmap object as mutable, and then calling the copyPixelsToBuffer and copyPixelsFromBuffer methods to get and set the pixel data in that object.

Solved! It was combination of my original version of sending in the bytes by using Bitmap.compress() and then on the returned pixels using copyPixelsFromBuffer. Thanks to Buddy for pointing me in the right direction.
Android:
//input was the original bitmap that was used to construct the byte[] array. I then used input.compress() in JPEG format to a Byte. Very important for it to be compressed in a format that will be recognized in cv::imdecode.
ByteArrayOutputStream bos = new ByteArrayOutputStream();
input.compress(CompressFormat.JPEG, 100, bos);
data1.pixelData = bos.toByteArray();
...
//Reconstruction after JNI call
ByteBuffer buffer2 = ByteBuffer.wrap(data1.pixelData);
Bitmap returnFromConvert = Bitmap.createBitmap(input.getWidth(),
input.getHeight(),Bitmap.Config.ARGB_8888);
returnFromConvert.copyPixelsFromBuffer(buffer2);

Android Bitmap factory returns null when trying to read a decoded Base64 jpeg

I have retrieved a jpeg image from a web service using an HTTP GET call, and I need to display it in an ImageView, but it is encoded in Base64. Therefore, I used the following code to convert it:
byte[] bytes = Base64.decode(imageStringInBase64, Base64.DEFAULT);
Bitmap bmp = BitmapFactory.decodeByteArray(bytes, 0, bytes.length);
However, I get the error: --- SkImageDecoder::Factory returned null
When logged to the console, imageStringInBase64 looks like this:
data:image/jpeg;base64,/9j/4AAQ ... a bunch of stuff ... /B6TTbssco

If data:image... is the value in imageStringInBase64 then that won't work. You need just the base64 encoded data (everything after the last comma).

Android : some problems when converting drawable image to byte array

I want to convert an image in my app to a Base64 encoded string. This image may be of any type like jpeg, png etc.
What I have done is, I converted the drawable to a Bitmap. Then I converted this Bitmap to ByteArrayOutputStream using compress metheod And I am converting this ByteArrayOutputStream to byte array. And then I am encoding it to Base64 using encodeToString().
I can display the image using the above method if the image is of PNG or JPEG.
ByteArrayOutputStream objByteOutput = new ByteArrayOutputStream();
imgBitmap.compress(CompressFormat.JPEG, 0, objByteOutput);
But the problem is if the image is in any other types than PNG or JPEG, how can I display the image?
Or please suggest me some another method to get byte array from Bitmap.
Thank you...

I'd suggest using
http://developer.android.com/reference/android/graphics/Bitmap.html#copyPixelsToBuffer(java.nio.Buffer)
and specify a ByteBuffer, then you can use .array() on the ByteBuffer if it is implemented (it's an optional method) or .get(byte[]) to get it if .array() doesn't exist.
Update:
In order to determine the size of the buffer to create you should use Bitmap.getByteCount(). However this is only present on API 12 and up, so you would need to use Bitmap.getWidth()*Bitmap.getHeight()*4 - the reason for 4 is that the Bitmap uses a series of pixels (internal representation may be less but shouldn't ever be more), each being an ARGB value with 0-255 hence 4 bytes per pixel.
You can get the same with Bitmap.getHeight() * Bitmap.getRowBytes() - here's some code I used to verify this worked:
BitmapDrawable bmd = (BitmapDrawable) getResources().getDrawable(R.drawable.icon);
Bitmap bm = bmd.getBitmap();
ByteBuffer byteBuff = ByteBuffer.allocate(bm.getWidth() * bm.getHeight() * 4);
byteBuff.rewind();
bm.copyPixelsToBuffer(byteBuff);
byte[] tmp = new byte[bm.getWidth() * bm.getHeight() * 4];
byteBuff.rewind();
byteBuff.get(tmp);
It's not nice code, but it gets the byte array out.