mebjas

// Read the image
std::unique_ptr<Image> image = nullptr;
{
    std::string image_buffer;
    image_buffer.resize(fd_length);
    int remaining_length = read(fd, &image_buffer[0], length);
    if (remaining_length != 0) {
        return env->NewStringUTF("Failed to read full image");
    }

mebjas

class ImageFactory {
public:

    // Decodes the `image_buffer` and returns Image instance.
    //
    // Suggestion for readers: Use absl::string_view instead of string here.
    static std::unique_ptr<Image> FromString(const std::string& image_buffer);
    
    // Creates an instance of 'Image' from the file descriptor 'fd'.
    //

mebjas

#include "image.h"

#include <android/imagedecoder.h>

static std::unique_ptr<Image> ImageFactory::FromFd(int fd) {
    // First create decoder from fd.
    AImageDecoder* decoder;
    int result = AImageDecoder_createFromFd(fd, &decoder);
    if (result != ANDROID_IMAGE_DECODER_SUCCESS) {
        // More info: https://developer.android.com/ndk/reference/group/image-decoder#aimagedecoder_createfromfd

mebjas

#include <memory>

#include <assert.h>
#include <android/imagedecoder.h>

// Data class for ARGB image (owns the memory associated with the image).
// 
// Note for readers: Current implementation only allows read operations but can
// be extended to support write operations by overloading `()=` operator.
class Image {

mebjas

#include <jni.h>

// Corresponding to NativeImageLoader class in
// dev.minhazav.samples package.
extern "C" JNIEXPORT jstring JNICALL
Java_dev_minhazav_samples_NativeImageLoader_readFile(
    JNIEnv* env, jclass, jint fd) {
    if (fd < 0) {
        return env->NewStringUTF("Invalid fd");
    }

mebjas

/** Wrapper class for loading image in native layer. */
public final class NativeImageLoader {

    static {
        System.loadLibrary("image-loader-jni");
    }

    /** Reads the image represented by {@code fd} in native layer.
     *
     * <p>For apparently no reason!

mebjas

Context context = getApplicationContext();
ContentResolver contentResolver = context.getContentResolver();
try (AssetFileDescriptor assetFileDescriptor
    = contentResolver.openAssetFileDescriptor(imageUri, "r")) {
    ParcelFileDescriptor parcelFileDescriptor = assetFileDescriptor.getParcelFileDescriptor();
    int fd = parcelFileDescriptor.getFd();

    // TODO: Read file using the fd in native layer.
    // Important: Native layer shouldn't assume ownership of this fd and close it.

mebjas

public class MainActivity extends AppCompatActivity {

  private final ActivityResultLauncher<String[]> galleryActivityLauncher
      = registerForActivityResult(new ActivityResultContracts.OpenDocument(),
     this::onPickImage);

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

mebjas

let constraints: MediaTrackConstraints = {
    "torch": true,
    "advanced": [{ "torch": true }]
};

await html5Qrcode.applyVideoConstraints(constraints);
let settings = html5Qrcode.getRunningTrackSettings();

if (settings.torch === true) {
    // Torch was indeed enabled, succeess.

mebjas

/** Returns {@code true} if torch is supported. */
function isTorchSupported(html5Qrcode: Html5Qrcode): boolean {
    let settings = html5Qrcode.getRunningTrackSettings();
    return "torch" in settings;
}