NDK--实现gif图片播放

typedef struct GifFileType {
    GifWord SWidth, SHeight;         /* 图片的宽，高 */
    GifWord SColorResolution;        /* How many colors can we generate? */
    GifWord SBackGroundColor;        /* Background color for virtual canvas */
    GifByteType AspectByte;      /* Used to compute pixel aspect ratio */
    ColorMapObject *SColorMap;       /* Global colormap, NULL if nonexistent. */
    int ImageCount;                  /* 帧数：一共多少张图片 */
    GifImageDesc Image;              /* Current image (low-level API) */
    SavedImage *SavedImages;         /* 图片数据数组：每一帧的图片数据 */
    int ExtensionBlockCount;         /* Count of extensions before image */
    ExtensionBlock *ExtensionBlocks; /* Extensions before image */    
    int Error;               /* Last error condition reported */
    void *UserData;                  /* 可以绑定我们自己的数据，类似于View的tag */
    void *Private;                   /* Don't mess with this! */
} GifFileType;

typedef struct SavedImage {
    GifImageDesc ImageDesc;          /* 图象标识符 */
    GifByteType *RasterBits;         /* 每个像素对应的压缩颜色 */
    int ExtensionBlockCount;         /* 扩展块个数 */
    ExtensionBlock *ExtensionBlocks; /* 扩展块数据 */
} SavedImage;

typedef struct GifImageDesc {
    GifWord Left, Top, Width, Height;   /* 内容偏移量. */
    bool Interlace;                     /* Sequential/Interlaced lines. */
    ColorMapObject *ColorMap;           /* 解压的RGB值 */
} GifImageDesc;

typedef struct ColorMapObject {
    int ColorCount;
    int BitsPerPixel;
    bool SortFlag;
    GifColorType *Colors;    /* on malloc(3) heap */
} ColorMapObject;

typedef struct GifColorType {
    GifByteType Red, Green, Blue; /* 三原色 */
} GifColorType;

typedef unsigned char GifByteType;

typedef struct ExtensionBlock {
    int ByteCount;
    GifByteType *Bytes; /* GifByteType就是char类型，之前用于存储三原色，这边第3个元素存储着延时时间的高8位，第二个元素存储着延时时间的低8位 */
    int Function;       /* The block function code */
#define CONTINUE_EXT_FUNC_CODE    0x00    /* continuation subblock */
#define COMMENT_EXT_FUNC_CODE     0xfe    /* comment */
#define GRAPHICS_EXT_FUNC_CODE    0xf9    /* graphics control (GIF89) */
#define PLAINTEXT_EXT_FUNC_CODE   0x01    /* plaintext */
#define APPLICATION_EXT_FUNC_CODE 0xff    /* application block */
} ExtensionBlock;

package com.aruba.gifapplication;

import android.graphics.Bitmap;

import java.io.FileDescriptor;

public class GifHandler {
    private long gifAddr;

    static {
        System.loadLibrary("native-lib");
    }

    public GifHandler(FileDescriptor fileDescriptor, long offset) {
        this.gifAddr = loadFd(fileDescriptor, offset);
    }

    /**
     * 加载gif资源文件
     *
     * @param fileDescriptor
     * @param offset
     * @return
     */
    private native long loadFd(FileDescriptor fileDescriptor, long offset);

    /**
     * 获取图片的宽
     *
     * @param ndkGif
     * @return
     */
    public native int getWidth(long ndkGif);

    /**
     * 获取图片的高
     *
     * @param ndkGif
     * @return
     */
    public native int getHeight(long ndkGif);

    public native int updateFrame(long ndkGif, Bitmap bitmap);

    public int getWidth() {
        return getWidth(gifAddr);
    }

    public int getHeight() {
        return getHeight(gifAddr);
    }

    /**
     * 更新bitmap到下一帧
     *
     * @param bitmap
     * @return
     */
    public int updateFrame(Bitmap bitmap) {
        return updateFrame(gifAddr, bitmap);
    }
}

#include <jni.h>
#include <string>
#include "gif_lib.h"
#include <android/log.h>
#include <android/bitmap.h>
#include <malloc.h>
#include <string.h>
#include <unistd.h>

#define  LOG_TAG    "aruba"
#define  argb(a, r, g, b) ( ((a) & 0xff) << 24 ) | ( ((b) & 0xff) << 16 ) | ( ((g) & 0xff) << 8 ) | ((r) & 0xff)
#define  LOGE(...)  __android_log_print(ANDROID_LOG_ERROR,LOG_TAG,__VA_ARGS__)
typedef struct GifBean {
    int current_frame;
    int total_frame;
    int *dealys;
} GifBean;
extern "C" {


//绘制一张图片
void drawFrame(GifFileType *gifFileType, GifBean *gifBean, AndroidBitmapInfo info, void *pixels) {
    //播放底层代码
//        拿到当前帧
    SavedImage savedImage = gifFileType->SavedImages[gifBean->current_frame];

    GifImageDesc frameInfo = savedImage.ImageDesc;
    //整幅图片的首地址
    int *px = (int *) pixels;
//    每一行的首地址
    int *line;

//   其中一个像素的位置  不是指针  在颜色表中的索引
    int pointPixel;
    GifByteType gifByteType;
    GifColorType gifColorType;
    ColorMapObject *colorMapObject = frameInfo.ColorMap;
    px = (int *) ((char *) px + info.stride * frameInfo.Top);
    for (int y = frameInfo.Top; y < frameInfo.Top + frameInfo.Height; ++y) {
        line = px;
        for (int x = frameInfo.Left; x < frameInfo.Left + frameInfo.Width; ++x) {
            pointPixel = (y - frameInfo.Top) * frameInfo.Width + (x - frameInfo.Left);
            gifByteType = savedImage.RasterBits[pointPixel];
            gifColorType = colorMapObject->Colors[gifByteType];
            line[x] = argb(255, gifColorType.Red, gifColorType.Green, gifColorType.Blue);
        }
        px = (int *) ((char *) px + info.stride);
    }


} ;

int fileRead(GifFileType *gif, GifByteType *bytes, int size) {
    FILE *file = (FILE *) gif->UserData;
    return fread(bytes, 1, size, file);
}

JNIEXPORT jlong JNICALL
Java_com_aruba_gifapplication_GifHandler_loadFd(JNIEnv *env, jobject instance,
                                                jobject fileDescriptor, jlong offset) {
    jclass clz = env->GetObjectClass(fileDescriptor);
    jfieldID jfieldID = env->GetFieldID(clz, "descriptor", "I");
    jint oldFd = env->GetIntField(fileDescriptor, jfieldID);
    const int fd = dup(oldFd);
    lseek64(fd, offset, SEEK_SET);
    FILE *file = fdopen(fd, "rb");
    int err;

    //用系统函数打开一个gif文件   返回一个结构体，这个结构体为句柄
    GifFileType *gifFileType = DGifOpen(file, fileRead, &err);

    DGifSlurp(gifFileType);
    GifBean *gifBean = (GifBean *) malloc(sizeof(GifBean));

    //清空内存地址
    memset(gifBean, 0, sizeof(GifBean));
    //绑定tag
    gifFileType->UserData = gifBean;

    gifBean->dealys = (int *) malloc(sizeof(int) * gifFileType->ImageCount);
    memset(gifBean->dealys, 0, sizeof(int) * gifFileType->ImageCount);
    gifBean->total_frame = gifFileType->ImageCount;
    ExtensionBlock *ext;
    for (int i = 0; i < gifFileType->ImageCount; ++i) {
        SavedImage frame = gifFileType->SavedImages[i];
        for (int j = 0; j < frame.ExtensionBlockCount; ++j) {
            if (frame.ExtensionBlocks[j].Function == GRAPHICS_EXT_FUNC_CODE) {
                ext = &frame.ExtensionBlocks[j];
                break;
            }
        }
        if (ext) {
            int frame_delay = 10 * (ext->Bytes[2] << 8 | ext->Bytes[1]);
            LOGE("时间  %d   ", frame_delay);
            gifBean->dealys[i] = frame_delay;

        }
    }
    LOGE("gif  长度大小    %d  ", gifFileType->ImageCount);
    return (jlong) gifFileType;
}

JNIEXPORT jint JNICALL
Java_com_aruba_gifapplication_GifHandler_getWidth(JNIEnv *env, jobject instance, jlong ndkGif) {
    GifFileType *gifFileType = (GifFileType *) ndkGif;
    return gifFileType->SWidth;
}

JNIEXPORT jint JNICALL
Java_com_aruba_gifapplication_GifHandler_getHeight(JNIEnv *env, jobject instance, jlong ndkGif) {

    GifFileType *gifFileType = (GifFileType *) ndkGif;
    return gifFileType->SHeight;

}

JNIEXPORT jint JNICALL
Java_com_aruba_gifapplication_GifHandler_updateFrame(JNIEnv *env, jobject instance, jlong ndkGif,
                                                     jobject bitmap) {
    //强转代表gif图片的结构体
    GifFileType *gifFileType = (GifFileType *) ndkGif;
    GifBean *gifBean = (GifBean *) gifFileType->UserData;
    AndroidBitmapInfo info;
    //代表一幅图片的像素数组
    void *pixels;
    AndroidBitmap_getInfo(env, bitmap, &info);
    //锁定bitmap  一幅图片--》二维 数组   ===一个二维数组
    AndroidBitmap_lockPixels(env, bitmap, &pixels);

    // TODO
    drawFrame(gifFileType, gifBean, info, pixels);

    //播放完成之后   循环到下一帧
    gifBean->current_frame += 1;
    LOGE("当前帧  %d  ", gifBean->current_frame);
    if (gifBean->current_frame >= gifBean->total_frame - 1) {
        gifBean->current_frame = 0;
        LOGE("重新过来  %d  ", gifBean->current_frame);
    }
    AndroidBitmap_unlockPixels(env, bitmap);
    return gifBean->dealys[gifBean->current_frame];
}


}

# For more information about using CMake with Android Studio, read the
# documentation: https://d.android.com/studio/projects/add-native-code.html

# Sets the minimum version of CMake required to build the native library.

cmake_minimum_required(VERSION 3.4.1)

# Creates and names a library, sets it as either STATIC
# or SHARED, and provides the relative paths to its source code.
# You can define multiple libraries, and CMake builds them for you.
# Gradle automatically packages shared libraries with your APK.

add_library( # Sets the name of the library.
        native-lib

        # Sets the library as a shared library.
        SHARED

        # Provides a relative path to your source file(s).
        native-lib.cpp
        dgif_lib.c
        gifalloc.c)

find_library( # Sets the name of the path variable.
        jnigraphics-lib

        # Specifies the name of the NDK library that
        # you want CMake to locate.
        jnigraphics)

# Searches for a specified prebuilt library and stores the path as a
# variable. Because CMake includes system libraries in the search path by
# default, you only need to specify the name of the public NDK library
# you want to add. CMake verifies that the library exists before
# completing its build.

find_library( # Sets the name of the path variable.
        log-lib

        # Specifies the name of the NDK library that
        # you want CMake to locate.
        log)

# Specifies libraries CMake should link to your target library. You
# can link multiple libraries, such as libraries you define in this
# build script, prebuilt third-party libraries, or system libraries.

target_link_libraries( # Specifies the target library.
        native-lib

        # Links the target library to the log library
        # included in the NDK.
        ${log-lib}
        ${jnigraphics-lib})

package com.aruba.gifapplication;

import android.content.res.AssetFileDescriptor;
import android.graphics.Bitmap;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.ImageView;

import java.io.File;

public class MainActivity extends AppCompatActivity {
    Bitmap bitmap;
    GifHandler gifHandler;
    ImageView imageView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        imageView = (ImageView) findViewById(R.id.image);
    }

    public void ndkLoadGif(View view) {
        AssetFileDescriptor assetFileDescriptor = getResources().openRawResourceFd(R.drawable.chi);
        gifHandler = new GifHandler(assetFileDescriptor.getFileDescriptor(), assetFileDescriptor.getStartOffset());
        //得到gif   width  height  生成Bitmap
        int width = gifHandler.getWidth();
        int height = gifHandler.getHeight();
        bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
        int nextFrame = gifHandler.updateFrame(bitmap);
        handler.sendEmptyMessageDelayed(1, nextFrame);

    }

    Handler handler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            int mNextFrame = gifHandler.updateFrame(bitmap);
            handler.sendEmptyMessageDelayed(1, mNextFrame);
            imageView.setImageBitmap(bitmap);
        }
    };

}