JNA wrapper for Android NDK bitmap.h

AndroidBitmap.java

package io.github.ncruces.utils;

import android.graphics.Bitmap;

import androidx.annotation.IntDef;
import androidx.annotation.NonNull;
import androidx.annotation.RequiresApi;

import com.sun.jna.JNIEnv;
import com.sun.jna.Native;
import com.sun.jna.NativeLibrary;
import com.sun.jna.Pointer;
import com.sun.jna.Structure;
import com.sun.jna.ptr.PointerByReference;

import java.lang.annotation.Retention;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

import static com.sun.jna.Library.OPTION_ALLOW_OBJECTS;
import static java.lang.annotation.RetentionPolicy.SOURCE;
import static java.util.Objects.requireNonNull;

@RequiresApi(8)
@SuppressWarnings({"unused", "JniMissingFunction", "WeakerAccess"})
public final class AndroidBitmap {
    static {
        NativeLibrary lib = NativeLibrary.getInstance("jnigraphics",
                                                      Collections.singletonMap(OPTION_ALLOW_OBJECTS, true));
        Native.register(AndroidBitmap.class, lib);
    }

    private AndroidBitmap() {}

    public static Info getInfo(Bitmap bitmap) {
        requireNonNull(bitmap);
        Info info = new Info();
        info.setAutoWrite(false);
        check(AndroidBitmap_getInfo(JNIEnv.CURRENT, bitmap, info));
        return info;
    }

    public static Pointer lockPixels(Bitmap bitmap) {
        requireNonNull(bitmap);
        PointerByReference ptr = new PointerByReference();
        check(AndroidBitmap_lockPixels(JNIEnv.CURRENT, bitmap, ptr));
        return ptr.getValue();
    }

    public static void unlockPixels(Bitmap bitmap) {
        requireNonNull(bitmap);
        check(AndroidBitmap_unlockPixels(JNIEnv.CURRENT, bitmap));
    }

    @Retention(SOURCE)
    @IntDef({Format.NONE, Format.RGBA_8888, Format.RGB_565, Format.RGBA_4444, Format.A_8})
    public @interface Format {
        int NONE = 0;
        int RGBA_8888 = 1;
        int RGB_565 = 4;
        int RGBA_4444 = 7;
        int A_8 = 8;
    }

    public static final class Info extends Structure {
        public int width;
        public int height;
        public int stride;
        public @Format int format;
        public int flags;

        public Info() {}

        @Override
        protected @NonNull List<String> getFieldOrder() {
            return Arrays.asList("width", "height", "stride", "format", "flags");
        }
    }

    private static native @Result int AndroidBitmap_getInfo(JNIEnv env, Bitmap jbitmap, Info info);
    private static native @Result int AndroidBitmap_lockPixels(JNIEnv env, Bitmap jbitmap, PointerByReference addrPtr);
    private static native @Result int AndroidBitmap_unlockPixels(JNIEnv env, Bitmap jbitmap);

    @Retention(SOURCE)
    @IntDef({Result.SUCCESS, Result.BAD_PARAMETER, Result.JNI_EXCEPTION, Result.ALLOCATION_FAILED})
    private @interface Result {
        int SUCCESS = 0;
        int BAD_PARAMETER = -1;
        int JNI_EXCEPTION = -2;
        int ALLOCATION_FAILED = -3;
    }

    private static void check(@Result int result) {
        switch (result) {
            case Result.SUCCESS: break;
            case Result.BAD_PARAMETER: throw new IllegalArgumentException();
            case Result.JNI_EXCEPTION: throw new RuntimeException();
            case Result.ALLOCATION_FAILED: throw new OutOfMemoryError();
        }
    }
}