在使用大图像时，如何使用JNI位图操作来帮助避免OOM? [英] How to use JNI bitmap operations for helping to avoid OOM when using large images?
本文介绍了在使用大图像时，如何使用JNI位图操作来帮助避免OOM?的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
背景
大多数情况下，在Android上使用OOM的原因是使用了太多位图和/或创建了大位图.
最近，我决定尝试JNI，以便通过将数据本身存储在JNI端来避免OOM.
在与JNI纠缠了一段时间之后，我在SO上创建了一些帖子以寻求帮助并分享我的知识，现在我决定与您分享更多代码.如果有人有兴趣阅读调查结果或做出贡献，请参阅以下帖子:
这次，我添加了存储，还原，裁剪和旋转位图的功能.添加更多选项应该很容易，并且如果其他人将自己的代码添加到更有用的功能中，我会很高兴.
所以我要显示的代码实际上是我创建的所有东西的合并.
用法示例代码:
Bitmap bitmap=BitmapFactory.decodeResource(getResources(),R.drawable.ic_launcher);
final int width=bitmap.getWidth(),height=bitmap.getHeight();
// store the bitmap in the JNI "world"
final JniBitmapHolder bitmapHolder=new JniBitmapHolder(bitmap);
// no need for the bitmap on the java "world", since the operations are done on the JNI "world"
bitmap.recycle();
// crop a center square from the bitmap, from (0.25,0.25) to (0.75,0.75) of the bitmap.
bitmapHolder.cropBitmap(width/4,height/4,width*3/4,height*3/4);
//rotate the bitmap:
bitmapHolder.rotateBitmapCcw90();
//get the output java bitmap , and free the one on the JNI "world"
bitmap=bitmapHolder.getBitmapAndFree();
该项目在github上可用
-
项目页面可在github 此处 上找到. /p>
-
可以随时提供建议和贡献.
重要提示
与 此处 所示的注释相同，以及:
-
此处编写的当前功能(在项目页面上有更多更新):
-
商店
-
还原
-
逆时针旋转90度
-
作物.
-
-
我为该代码采用的方法是内存效率(仅使用我需要的内存，并在不需要时释放它)和CPU效率(我尝试在任何时候使用指针和CPU内存缓存优化)可能).
-
为了获得最佳性能，我只进行了很少的验证，尤其是在JNI部分.最好是在Java世界"上管理验证.
-
我仍然应该添加许多缺失功能，我希望我能有时间添加它们.如果有人希望提供帮助，我也会很高兴为他们添加代码.这是我认为可能有用的功能:
-
获取当前位图信息
-
比例位图，包括选择使用哪种算法(最近邻居和双线性插值就足够了).
-
使用不同的位图格式
-
在JNI中进行解码，以避免从头开始创建Java位图(并且不要在Java世界中使用堆)，而要在完成所有操作后才结束. p>
-
人脸检测
-
以任何角度旋转，或至少以明显的角度旋转.目前，我只添加了逆时针旋转90度的功能.
-
解决方案
注意:这是一个有点旧的代码.要获取最新版本，请查看 github 上的项目页面.
jni/Android.mk
LOCAL_PATH := $(call my-dir)
#bitmap operations module
include $(CLEAR_VARS)
LOCAL_MODULE := JniBitmapOperations
LOCAL_SRC_FILES := JniBitmapOperations.cpp
LOCAL_LDLIBS := -llog
LOCAL_LDFLAGS += -ljnigraphics
include $(BUILD_SHARED_LIBRARY)
APP_OPTIM := debug
LOCAL_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();
}
}
Background
most of the times, getting OOM on android is due to using too many bitmaps and/or creating large bitmaps.
recently i've decided to try out JNI in order to allow avoiding OOM by storing the data itself on the JNI side.
after messing around with JNI for a while, i've created some posts on SO asking for help and sharing my knowledge, and i've now decided to share some more code with you. here are the posts in case anyone is interested in reading the findings or contributing :
this time, i've added the ability to store,restore, crop and rotate bitmaps. it should be easy to add more options and I would be happy if other people here would add their own code to more useful functions .
so the code i'm about to show is actually merging of all the things i've created.
Sample code of usage:
Bitmap bitmap=BitmapFactory.decodeResource(getResources(),R.drawable.ic_launcher);
final int width=bitmap.getWidth(),height=bitmap.getHeight();
// store the bitmap in the JNI "world"
final JniBitmapHolder bitmapHolder=new JniBitmapHolder(bitmap);
// no need for the bitmap on the java "world", since the operations are done on the JNI "world"
bitmap.recycle();
// crop a center square from the bitmap, from (0.25,0.25) to (0.75,0.75) of the bitmap.
bitmapHolder.cropBitmap(width/4,height/4,width*3/4,height*3/4);
//rotate the bitmap:
bitmapHolder.rotateBitmapCcw90();
//get the output java bitmap , and free the one on the JNI "world"
bitmap=bitmapHolder.getBitmapAndFree();
The project is available on github
project page is available on github here .
feel free to give advises and contribute.
Important notes
same notes as shown here, plus:
current features that are written here (more updated on the project page) :
store
restore
rotate 90 degrees CCW
crop.
the approach i've taken for this code is both memory efficiency (use only memory that i need, and free it when not needed), and CPU efficiency (i tried to use pointers and CPU memory cache optimizations whenever possible).
for best performance, i've done really few validations, especially on the JNI part. it might be best to manage the validations on the java "world".
there are still many missing features that i think should be added, and i hope that i will have the time to add them . if anyone wishes to contribute, i will be glad to add they code too. here are the functions that i think could be useful:
get current bitmap info
scale bitmaps, including choice of which algorithm to use (nearest neighbour and bilinear interpolation should be enough).
use different bitmap formats
do the decoding within JNI, to avoid creation of the java bitmap (and not use the heap on the java world) from the beginning, only at the end, when you finished with all of the operations.
face detection
rotation in any angle, or at least the obvious ones . currently i only added rotation of 90 degrees counter clock wise .
解决方案
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 module
include $(CLEAR_VARS)
LOCAL_MODULE := JniBitmapOperations
LOCAL_SRC_FILES := JniBitmapOperations.cpp
LOCAL_LDLIBS := -llog
LOCAL_LDFLAGS += -ljnigraphics
include $(BUILD_SHARED_LIBRARY)
APP_OPTIM := debug
LOCAL_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();
}
}
这篇关于在使用大图像时，如何使用JNI位图操作来帮助避免OOM?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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