How to use JNI bitmap operations for helping to avoid OOM when using large images? [closed]

NOTE: this is a bit old code. for the most updated one, check out the project page on github.

jni/Android.mk

LOCAL_PATH := $(call my-dir)#bitmap operations moduleinclude $(CLEAR_VARS)LOCAL_MODULE    := JniBitmapOperationsLOCAL_SRC_FILES := JniBitmapOperations.cppLOCAL_LDLIBS := -llogLOCAL_LDFLAGS += -ljnigraphicsinclude $(BUILD_SHARED_LIBRARY)APP_OPTIM := debugLOCAL_CFLAGS := -g#if you need to add more module, do the same as the one we started with (the one with the CLEAR_VARS)

jni/JniBitmapOperations.cpp

#include <jni.h>#include <jni.h>#include <android/log.h>#include <stdio.h>#include <android/bitmap.h>#include <cstring>#include <unistd.h>#define  LOG_TAG    "DEBUG"#define  LOGD(...)  __android_log_print(ANDROID_LOG_DEBUG,LOG_TAG,__VA_ARGS__)#define  LOGE(...)  __android_log_print(ANDROID_LOG_ERROR,LOG_TAG,__VA_ARGS__)extern "C"  {  JNIEXPORT jobject JNICALL Java_com_jni_bitmap_1operations_JniBitmapHolder_jniStoreBitmapData(JNIEnv * env, jobject obj, jobject bitmap);  JNIEXPORT jobject JNICALL Java_com_jni_bitmap_1operations_JniBitmapHolder_jniGetBitmapFromStoredBitmapData(JNIEnv * env, jobject obj, jobject handle);  JNIEXPORT void JNICALL Java_com_jni_bitmap_1operations_JniBitmapHolder_jniFreeBitmapData(JNIEnv * env, jobject obj, jobject handle);  JNIEXPORT void JNICALL Java_com_jni_bitmap_1operations_JniBitmapHolder_jniRotateBitmapCcw90(JNIEnv * env, jobject obj, jobject handle);  JNIEXPORT void JNICALL Java_com_jni_bitmap_1operations_JniBitmapHolder_jniCropBitmap(JNIEnv * env, jobject obj, jobject handle, uint32_t left, uint32_t top, uint32_t right, uint32_t bottom);  }class JniBitmap  {  public:    uint32_t* _storedBitmapPixels;    AndroidBitmapInfo _bitmapInfo;    JniBitmap()      {      _storedBitmapPixels = NULL;      }  };/**crops the bitmap within to be smaller. note that no validations are done*/ //JNIEXPORT void JNICALL Java_com_jni_bitmap_1operations_JniBitmapHolder_jniCropBitmap(JNIEnv * env, jobject obj, jobject handle, uint32_t left, uint32_t top, uint32_t right, uint32_t bottom)  {  JniBitmap* jniBitmap = (JniBitmap*) env->GetDirectBufferAddress(handle);  if (jniBitmap->_storedBitmapPixels == NULL)    return;  uint32_t* previousData = jniBitmap->_storedBitmapPixels;  uint32_t oldWidth = jniBitmap->_bitmapInfo.width;  uint32_t newWidth = right - left, newHeight = bottom - top;  uint32_t* newBitmapPixels = new uint32_t[newWidth * newHeight];  uint32_t* whereToGet = previousData + left + top * oldWidth;  uint32_t* whereToPut = newBitmapPixels;  for (int y = top; y < bottom; ++y)    {    memcpy(whereToPut, whereToGet, sizeof(uint32_t) * newWidth);    whereToGet += oldWidth;    whereToPut += newWidth;    }  //done copying , so replace old data with new one  delete[] previousData;  jniBitmap->_storedBitmapPixels = newBitmapPixels;  jniBitmap->_bitmapInfo.width = newWidth;  jniBitmap->_bitmapInfo.height = newHeight;  }/**rotates the inner bitmap data by 90 degress counter clock wise*/ //JNIEXPORT void JNICALL Java_com_jni_bitmap_1operations_JniBitmapHolder_jniRotateBitmapCcw90(JNIEnv * env, jobject obj, jobject handle)  {  JniBitmap* jniBitmap = (JniBitmap*) env->GetDirectBufferAddress(handle);  if (jniBitmap->_storedBitmapPixels == NULL)    return;  uint32_t* previousData = jniBitmap->_storedBitmapPixels;  AndroidBitmapInfo bitmapInfo = jniBitmap->_bitmapInfo;  uint32_t* newBitmapPixels = new uint32_t[bitmapInfo.height * bitmapInfo.width];  int whereToPut = 0;  // A.D D.C  // ...>...  // B.C A.B  for (int x = bitmapInfo.width - 1; x >= 0; --x)    for (int y = 0; y < bitmapInfo.height; ++y)      {      uint32_t pixel = previousData[bitmapInfo.width * y + x];      newBitmapPixels[whereToPut++] = pixel;      }  delete[] previousData;  jniBitmap->_storedBitmapPixels = newBitmapPixels;  uint32_t temp = bitmapInfo.width;  bitmapInfo.width = bitmapInfo.height;  bitmapInfo.height = temp;  }/**free bitmap*/  //JNIEXPORT void JNICALL Java_com_jni_bitmap_1operations_JniBitmapHolder_jniFreeBitmapData(JNIEnv * env, jobject obj, jobject handle)  {  JniBitmap* jniBitmap = (JniBitmap*) env->GetDirectBufferAddress(handle);  if (jniBitmap->_storedBitmapPixels == NULL)    return;  delete[] jniBitmap->_storedBitmapPixels;  jniBitmap->_storedBitmapPixels = NULL;  delete jniBitmap;  }/**restore java bitmap (from JNI data)*/  //JNIEXPORT jobject JNICALL Java_com_jni_bitmap_1operations_JniBitmapHolder_jniGetBitmapFromStoredBitmapData(JNIEnv * env, jobject obj, jobject handle)  {  JniBitmap* jniBitmap = (JniBitmap*) env->GetDirectBufferAddress(handle);  if (jniBitmap->_storedBitmapPixels == NULL)    {    LOGD("no bitmap data was stored. returning null...");    return NULL;    }  //  //creating a new bitmap to put the pixels into it - using Bitmap Bitmap.createBitmap (int width, int height, Bitmap.Config config) :  //  //LOGD("creating new bitmap...");  jclass bitmapCls = env->FindClass("android/graphics/Bitmap");  jmethodID createBitmapFunction = env->GetStaticMethodID(bitmapCls, "createBitmap", "(IILandroid/graphics/Bitmap$Config;)Landroid/graphics/Bitmap;");  jstring configName = env->NewStringUTF("ARGB_8888");  jclass bitmapConfigClass = env->FindClass("android/graphics/Bitmap$Config");  jmethodID valueOfBitmapConfigFunction = env->GetStaticMethodID(bitmapConfigClass, "valueOf", "(Ljava/lang/String;)Landroid/graphics/Bitmap$Config;");  jobject bitmapConfig = env->CallStaticObjectMethod(bitmapConfigClass, valueOfBitmapConfigFunction, configName);  jobject newBitmap = env->CallStaticObjectMethod(bitmapCls, createBitmapFunction, jniBitmap->_bitmapInfo.width, jniBitmap->_bitmapInfo.height, bitmapConfig);  //  // putting the pixels into the new bitmap:  //  int ret;  void* bitmapPixels;  if ((ret = AndroidBitmap_lockPixels(env, newBitmap, &bitmapPixels)) < 0)    {    LOGE("AndroidBitmap_lockPixels() failed ! error=%d", ret);    return NULL;    }  uint32_t* newBitmapPixels = (uint32_t*) bitmapPixels;  int pixelsCount = jniBitmap->_bitmapInfo.height * jniBitmap->_bitmapInfo.width;  memcpy(newBitmapPixels, jniBitmap->_storedBitmapPixels, sizeof(uint32_t) * pixelsCount);  AndroidBitmap_unlockPixels(env, newBitmap);  //LOGD("returning the new bitmap");  return newBitmap;  }/**store java bitmap as JNI data*/  //JNIEXPORT jobject JNICALL Java_com_jni_bitmap_1operations_JniBitmapHolder_jniStoreBitmapData(JNIEnv * env, jobject obj, jobject bitmap)  {  AndroidBitmapInfo bitmapInfo;  uint32_t* storedBitmapPixels = NULL;  //LOGD("reading bitmap info...");  int ret;  if ((ret = AndroidBitmap_getInfo(env, bitmap, &bitmapInfo)) < 0)    {    LOGE("AndroidBitmap_getInfo() failed ! error=%d", ret);    return NULL;    }  LOGD("width:%d height:%d stride:%d", bitmapInfo.width, bitmapInfo.height, bitmapInfo.stride);  if (bitmapInfo.format != ANDROID_BITMAP_FORMAT_RGBA_8888)    {    LOGE("Bitmap format is not RGBA_8888!");    return NULL;    }  //  //read pixels of bitmap into native memory :  //  //LOGD("reading bitmap pixels...");  void* bitmapPixels;  if ((ret = AndroidBitmap_lockPixels(env, bitmap, &bitmapPixels)) < 0)    {    LOGE("AndroidBitmap_lockPixels() failed ! error=%d", ret);    return NULL;    }  uint32_t* src = (uint32_t*) bitmapPixels;  storedBitmapPixels = new uint32_t[bitmapInfo.height * bitmapInfo.width];  int pixelsCount = bitmapInfo.height * bitmapInfo.width;  memcpy(storedBitmapPixels, src, sizeof(uint32_t) * pixelsCount);  AndroidBitmap_unlockPixels(env, bitmap);  JniBitmap *jniBitmap = new JniBitmap();  jniBitmap->_bitmapInfo = bitmapInfo;  jniBitmap->_storedBitmapPixels = storedBitmapPixels;  return env->NewDirectByteBuffer(jniBitmap, 0);  }

src/com/jni/bitmap_operations/JniBitmapHolder.java

package com.jni.bitmap_operations;import java.nio.ByteBuffer;import android.graphics.Bitmap;import android.util.Log;public class JniBitmapHolder  {  ByteBuffer _handler =null;  static    {    System.loadLibrary("JniBitmapOperations");    }  private native ByteBuffer jniStoreBitmapData(Bitmap bitmap);  private native Bitmap jniGetBitmapFromStoredBitmapData(ByteBuffer handler);  private native void jniFreeBitmapData(ByteBuffer handler);  private native void jniRotateBitmapCcw90(ByteBuffer handler);  private native void jniCropBitmap(ByteBuffer handler,final int left,final int top,final int right,final int bottom);  public JniBitmapHolder()    {}  public JniBitmapHolder(final Bitmap bitmap)    {    storeBitmap(bitmap);    }  public void storeBitmap(final Bitmap bitmap)    {    if(_handler!=null)      freeBitmap();    _handler=jniStoreBitmapData(bitmap);    }  public void rotateBitmapCcw90()    {    if(_handler==null)      return;    jniRotateBitmapCcw90(_handler);    }  public void cropBitmap(final int left,final int top,final int right,final int bottom)    {    if(_handler==null)      return;    jniCropBitmap(_handler,left,top,right,bottom);    }  public Bitmap getBitmap()    {    if(_handler==null)      return null;    return jniGetBitmapFromStoredBitmapData(_handler);    }  public Bitmap getBitmapAndFree()    {    final Bitmap bitmap=getBitmap();    freeBitmap();    return bitmap;    }  public void freeBitmap()    {    if(_handler==null)      return;    jniFreeBitmapData(_handler);    _handler=null;    }  @Override  protected void finalize() throws Throwable    {    super.finalize();    if(_handler==null)      return;    Log.w("DEBUG","JNI bitmap wasn't freed nicely.please rememeber to free the bitmap as soon as you can");    freeBitmap();    }  }