android ndk开发（二）实现一个官方demo

实现了一个官方的demo：bitmap-plasma（水波纹）

源代码就在samples文件夹下，可以自己去找。

界面：

建立项目的步骤和配置环境不明白的可以去看：http://www.cnblogs.com/jycboy/p/5393727.html

一、activity代码：

package example.user.plasmatest;

import android.os.Bundle;
import android.app.Activity;
import android.os.Bundle;
import android.content.Context;
import android.view.View;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.view.Display;
import android.view.WindowManager;

public class MainActivity extends Activity
{
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        Display display = getWindowManager().getDefaultDisplay();
        setContentView(new PlasmaView(this, display.getWidth(), display.getHeight()));
    }

    /* load our native library */
    static {
        System.loadLibrary("plasma");
    }
}

class PlasmaView extends View {
    private Bitmap mBitmap;
    private long mStartTime;

    /* implementend by libplasma.so */
    private static native void renderPlasma(Bitmap  bitmap, long time_ms);

    public PlasmaView(Context context, int width, int height) {
        super(context);
        mBitmap = Bitmap.createBitmap(width, height, Bitmap.Config.RGB_565);
        mStartTime = System.currentTimeMillis();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        //canvas.drawColor(0xFFCCCCCC);
        renderPlasma(mBitmap, System.currentTimeMillis() - mStartTime);
        canvas.drawBitmap(mBitmap, 0, 0, null);
        // force a redraw, with a different time-based pattern.
        invalidate();
    }
}

　make project下，利用javah创建jni目录、.h头文件

在jni目录下创建c代码：

plasma.c:

/*
 * Copyright (C) 2010 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
#include "example_user_plasmatest_PlasmaView.h"
#include <jni.h>
#include <time.h>
#include <android/log.h>
#include <android/bitmap.h>

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

#define  LOG_TAG    "libplasma"
#define  LOGI(...)  __android_log_print(ANDROID_LOG_INFO,LOG_TAG,__VA_ARGS__)
#define  LOGE(...)  __android_log_print(ANDROID_LOG_ERROR,LOG_TAG,__VA_ARGS__)

/* Set to 1 to enable debug log traces. */
#define DEBUG 0

/* Set to 1 to optimize memory stores when generating plasma. */
#define OPTIMIZE_WRITES  1

/* Return current time in milliseconds */
static double now_ms(void)
{
    struct timeval tv;
    gettimeofday(&tv, NULL);
    return tv.tv_sec*. + tv.tv_usec/.;
}

/* We're going to perform computations for every pixel of the target
 * bitmap. floating-point operations are very slow on ARMv5, and not
 * too bad on ARMv7 with the exception of trigonometric functions.
 *
 * For better performance on all platforms, we're going to use fixed-point
 * arithmetic and all kinds of tricks
 */

typedef int32_t  Fixed;

#define  FIXED_BITS           16
#define  FIXED_ONE            (1 << FIXED_BITS)
#define  FIXED_AVERAGE(x,y)   (((x) + (y)) >> 1)

#define  FIXED_FROM_INT(x)    ((x) << FIXED_BITS)
#define  FIXED_TO_INT(x)      ((x) >> FIXED_BITS)

#define  FIXED_FROM_FLOAT(x)  ((Fixed)((x)*FIXED_ONE))
#define  FIXED_TO_FLOAT(x)    ((x)/(1.*FIXED_ONE))

#define  FIXED_MUL(x,y)       (((int64_t)(x) * (y)) >> FIXED_BITS)
#define  FIXED_DIV(x,y)       (((int64_t)(x) * FIXED_ONE) / (y))

#define  FIXED_DIV2(x)        ((x) >> 1)
#define  FIXED_AVERAGE(x,y)   (((x) + (y)) >> 1)

#define  FIXED_FRAC(x)        ((x) & ((1 << FIXED_BITS)-1))
#define  FIXED_TRUNC(x)       ((x) & ~((1 << FIXED_BITS)-1))

#define  FIXED_FROM_INT_FLOAT(x,f)   (Fixed)((x)*(FIXED_ONE*(f)))

typedef int32_t  Angle;

#define  ANGLE_BITS              9

#if ANGLE_BITS < 8
#  error ANGLE_BITS must be at least
#endif

#define  ANGLE_2PI               (1 << ANGLE_BITS)
#define  ANGLE_PI                (1 << (ANGLE_BITS-1))
#define  ANGLE_PI2               (1 << (ANGLE_BITS-2))
#define  ANGLE_PI4               (1 << (ANGLE_BITS-3))

#define  ANGLE_FROM_FLOAT(x)   (Angle)((x)*ANGLE_PI/M_PI)
#define  ANGLE_TO_FLOAT(x)     ((x)*M_PI/ANGLE_PI)

#if ANGLE_BITS <= FIXED_BITS
#  define  ANGLE_FROM_FIXED(x)     (Angle)((x) >> (FIXED_BITS - ANGLE_BITS))
#  define  ANGLE_TO_FIXED(x)       (Fixed)((x) << (FIXED_BITS - ANGLE_BITS))
#else
#  define  ANGLE_FROM_FIXED(x)     (Angle)((x) << (ANGLE_BITS - FIXED_BITS))
#  define  ANGLE_TO_FIXED(x)       (Fixed)((x) >> (ANGLE_BITS - FIXED_BITS))
#endif

static Fixed  angle_sin_tab[ANGLE_2PI+];

static void init_angles(void)
{
    int  nn;
    for (nn = ; nn < ANGLE_2PI+; nn++) {
        double  radians = nn*M_PI/ANGLE_PI;
        angle_sin_tab[nn] = FIXED_FROM_FLOAT(sin(radians));
    }
}

static __inline__ Fixed angle_sin( Angle  a )
{
    return angle_sin_tab[(uint32_t)a & (ANGLE_2PI-)];
}

static __inline__ Fixed angle_cos( Angle  a )
{
    return angle_sin(a + ANGLE_PI2);
}

static __inline__ Fixed fixed_sin( Fixed  f )
{
    return angle_sin(ANGLE_FROM_FIXED(f));
}

static __inline__ Fixed  fixed_cos( Fixed  f )
{
    return angle_cos(ANGLE_FROM_FIXED(f));
}

/* Color palette used for rendering the plasma */
#define  PALETTE_BITS   8
#define  PALETTE_SIZE   (1 << PALETTE_BITS)

#if PALETTE_BITS > FIXED_BITS
#  error PALETTE_BITS must be smaller than FIXED_BITS
#endif

static uint16_t  palette[PALETTE_SIZE];

static uint16_t  make565(int red, int green, int blue)
{
    return (uint16_t)( ((red   << ) & 0xf800) |
                       ((green << ) & 0x03e0) |
                       ((blue  >> ) & 0x001f) );
}

static void init_palette(void)
{
    int  nn, mm = ;
    /* fun with colors */
    for (nn = ; nn < PALETTE_SIZE/; nn++) {
        int  jj = (nn-mm)**/PALETTE_SIZE;
        palette[nn] = make565(, jj, -jj);
    }

    for ( mm = nn; nn < PALETTE_SIZE/; nn++ ) {
        int  jj = (nn-mm)**/PALETTE_SIZE;
        palette[nn] = make565(-jj, , jj);
    }

    for ( mm = nn; nn < PALETTE_SIZE*/; nn++ ) {
        int  jj = (nn-mm)**/PALETTE_SIZE;
        palette[nn] = make565(, -jj, );
    }

    for ( mm = nn; nn < PALETTE_SIZE; nn++ ) {
        int  jj = (nn-mm)**/PALETTE_SIZE;
        palette[nn] = make565(jj, , );
    }
}

static __inline__ uint16_t  palette_from_fixed( Fixed  x )
{
    if (x < ) x = -x;
    if (x >= FIXED_ONE) x = FIXED_ONE-;
    int  idx = FIXED_FRAC(x) >> (FIXED_BITS - PALETTE_BITS);
    return palette[idx & (PALETTE_SIZE-)];
}

/* Angles expressed as fixed point radians */

static void init_tables(void)
{
    init_palette();
    init_angles();
}

static void fill_plasma( AndroidBitmapInfo*  info, void*  pixels, double  t )
{
    Fixed yt1 = FIXED_FROM_FLOAT(t/.);
    Fixed yt2 = yt1;
    Fixed xt10 = FIXED_FROM_FLOAT(t/.);
    Fixed xt20 = xt10;

#define  YT1_INCR   FIXED_FROM_FLOAT(1/100.)
#define  YT2_INCR   FIXED_FROM_FLOAT(1/163.)

    int  yy;
    for (yy = ; yy < info->height; yy++) {
        uint16_t*  line = (uint16_t*)pixels;
        Fixed      base = fixed_sin(yt1) + fixed_sin(yt2);
        Fixed      xt1 = xt10;
        Fixed      xt2 = xt20;

        yt1 += YT1_INCR;
        yt2 += YT2_INCR;

#define  XT1_INCR  FIXED_FROM_FLOAT(1/173.)
#define  XT2_INCR  FIXED_FROM_FLOAT(1/242.)

#if OPTIMIZE_WRITES
        /* optimize memory writes by generating one aligned 32-bit store
         * for every pair of pixels.
         */
        uint16_t*  line_end = line + info->width;

        if (line < line_end) {
            if (((uint32_t)(uintptr_t)line & ) != ) {
                Fixed ii = base + fixed_sin(xt1) + fixed_sin(xt2);

                xt1 += XT1_INCR;
                xt2 += XT2_INCR;

                line[] = palette_from_fixed(ii >> );
                line++;
            }

            while (line +  <= line_end) {
                Fixed i1 = base + fixed_sin(xt1) + fixed_sin(xt2);
                xt1 += XT1_INCR;
                xt2 += XT2_INCR;

                Fixed i2 = base + fixed_sin(xt1) + fixed_sin(xt2);
                xt1 += XT1_INCR;
                xt2 += XT2_INCR;

                uint32_t  pixel = ((uint32_t)palette_from_fixed(i1 >> ) << ) |
                                  (uint32_t)palette_from_fixed(i2 >> );

                ((uint32_t*)line)[] = pixel;
                line += ;
            }

            if (line < line_end) {
                Fixed ii = base + fixed_sin(xt1) + fixed_sin(xt2);
                line[] = palette_from_fixed(ii >> );
                line++;
            }
        }
#else /* !OPTIMIZE_WRITES */
        int xx;
        for (xx = ; xx < info->width; xx++) {

            Fixed ii = base + fixed_sin(xt1) + fixed_sin(xt2);

            xt1 += XT1_INCR;
            xt2 += XT2_INCR;

            line[xx] = palette_from_fixed(ii / );
        }
#endif /* !OPTIMIZE_WRITES */

        // go to next line
        pixels = (char*)pixels + info->stride;
    }
}

/* simple stats management */
typedef struct {
    double  renderTime;
    double  frameTime;
} FrameStats;

#define  MAX_FRAME_STATS  200
#define  MAX_PERIOD_MS    1500

typedef struct {
    double  firstTime;
    double  lastTime;
    double  frameTime;

    int         firstFrame;
    int         numFrames;
    FrameStats  frames[ MAX_FRAME_STATS ];
} Stats;

static void
stats_init( Stats*  s )
{
    s->lastTime = now_ms();
    s->firstTime = .;
    s->firstFrame = ;
    s->numFrames  = ;
}

static void
stats_startFrame( Stats*  s )
{
    s->frameTime = now_ms();
}

static void
stats_endFrame( Stats*  s )
{
    double now = now_ms();
    double renderTime = now - s->frameTime;
    double frameTime  = now - s->lastTime;
    int nn;

    if (now - s->firstTime >= MAX_PERIOD_MS) {
        if (s->numFrames > ) {
            double minRender, maxRender, avgRender;
            double minFrame, maxFrame, avgFrame;
            int count;

            nn = s->firstFrame;
            minRender = maxRender = avgRender = s->frames[nn].renderTime;
            minFrame  = maxFrame  = avgFrame  = s->frames[nn].frameTime;
            for (count = s->numFrames; count > ; count-- ) {
                nn += ;
                if (nn >= MAX_FRAME_STATS)
                    nn -= MAX_FRAME_STATS;
                double render = s->frames[nn].renderTime;
                if (render < minRender) minRender = render;
                if (render > maxRender) maxRender = render;
                double frame = s->frames[nn].frameTime;
                if (frame < minFrame) minFrame = frame;
                if (frame > maxFrame) maxFrame = frame;
                avgRender += render;
                avgFrame  += frame;
            }
            avgRender /= s->numFrames;
            avgFrame  /= s->numFrames;

            LOGI("frame/s (avg,min,max) = (%.1f,%.1f,%.1f) "
                         "render time ms (avg,min,max) = (%.1f,%.1f,%.1f)\n",
                 ./avgFrame, ./maxFrame, ./minFrame,
                 avgRender, minRender, maxRender);
        }
        s->numFrames  = ;
        s->firstFrame = ;
        s->firstTime  = now;
    }

    nn = s->firstFrame + s->numFrames;
    if (nn >= MAX_FRAME_STATS)
        nn -= MAX_FRAME_STATS;

    s->frames[nn].renderTime = renderTime;
    s->frames[nn].frameTime  = frameTime;

    if (s->numFrames < MAX_FRAME_STATS) {
        s->numFrames += ;
    } else {
        s->firstFrame += ;
        if (s->firstFrame >= MAX_FRAME_STATS)
            s->firstFrame -= MAX_FRAME_STATS;
    }

    s->lastTime = now;
}

JNIEXPORT void JNICALL Java_example_user_plasmatest_PlasmaView_renderPlasma(JNIEnv * env, jobject  obj, jobject bitmap,  jlong  time_ms)
{
AndroidBitmapInfo  info;
void*              pixels;
int                ret;
static Stats       stats;
static int         init;

if (!init) {
init_tables();
stats_init(&stats);
init = ;
}

if ((ret = AndroidBitmap_getInfo(env, bitmap, &info)) < ) {
LOGE("AndroidBitmap_getInfo() failed ! error=%d", ret);
return;
}

if (info.format != ANDROID_BITMAP_FORMAT_RGB_565) {
LOGE("Bitmap format is not RGB_565 !");
return;
}

if ((ret = AndroidBitmap_lockPixels(env, bitmap, &pixels)) < ) {
LOGE("AndroidBitmap_lockPixels() failed ! error=%d", ret);
}

stats_startFrame(&stats);

/* Now fill the values with a nice little plasma */
fill_plasma(&info, pixels, time_ms );

AndroidBitmap_unlockPixels(env, bitmap);

stats_endFrame(&stats);
}
//
// Created by user on 2016/4/14.
//

修改build.gradle文件: 添加ndk{......}

defaultConfig {
    applicationId "example.user.plasmatest"
    minSdkVersion 15
    targetSdkVersion 23
    versionCode 1
    versionName "1.0"
    ndk{
        moduleName "plasma"
        ldLibs "log"
        ldLibs "jnigraphics"//新增
    }
}
修改Android.mk文件：
添加：LOCAL_LDLIBS    := -llog -ljnigraphics

这是我的Android.mk:

LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)

LOCAL_MODULE := plasma
LOCAL_LDFLAGS := -Wl,--build-id
LOCAL_LDLIBS := \
    -llog \
    -ljnigraphics \

LOCAL_SRC_FILES := \
    D:\as_workspace\NDKDemo2\plasmatest\src\main\jni\plasma.c \
    D:\as_workspace\NDKDemo2\plasmatest\src\main\jni\util.c \

LOCAL_C_INCLUDES += D:\as_workspace\NDKDemo2\plasmatest\src\main\jni
LOCAL_C_INCLUDES += D:\as_workspace\NDKDemo2\plasmatest\src\debug\jni

include $(BUILD_SHARED_LIBRARY)

运行即可。。。
遇到的问题：

问题一：Error:(383) undefined reference to `__android_log_print'：

1 修改 Android.mk 文件相关:

1	LOCAL_LDLIBS := -llog

2 如果使用 android studio，需要修改 gradle 脚本：

1 2 3 4 5 6 7 8

android { defaultConfig { ndk { moduleName "serial_port" ldLibs "log" } } }

也就是添加了一句：ldLibs "log"

问题二：Error:(377) undefined reference to `AndroidBitmap_getInfo'

修改Android.mk文件：
添加：LOCAL_LDLIBS    := -llog -ljnigraphics

修改 gradle 脚本如下：

ndk {
    moduleName "webcam"
    ldLibs "log"
    ldLibs "jnigraphics"
}

其实这句的意思就是增加动态链接库 jnigraphics ，这样就搞定了呢，是的，就是这样。

问题三：找不到appcompatActivity

这时候你的activity应该继承的是appcompatActivity，

解决方法一：修改成继承Activity就可以

解决方法二：javah -d jni -classpath D:\ide\android-sdk\platforms\android-22\android.jar;D:\ide\android-sdk\extras\android\support\v7\appcompat\libs\android-support-v7-appcompat.jar;..\..\build\intermediates\classes\debug

 在javah命令中加上android-support-v7-appcompat.jar这个的路径，在安装目录下，一级级找就可以。

几个很好的学习ndk的博客：

JNI官方规范中文版：http://blog.csdn.net/a345017062/article/category/1256568

Android 开发之 JNI入门 - NDK从入门到精通（说的很全）：http://www.hanshuliang.com/?post=3

http://blog.csdn.net/shulianghan/article/details/18964835（推荐）

NDK开发：http://blog.csdn.net/conowen/article/category/1127720

JNI实战：http://blog.csdn.net/yanbober/article/details/45309049（推荐）

极客学院的：http://wiki.jikexueyuan.com/project/jni-ndk-developer-guide/overview.html（推荐）