Android(安卓)Jni用bitmap形式实现Image图片的黑白滤镜

在Android的开发中，我们有时会对性能要求比较高。Android通过NDK为我们提供了c++开发的方式。我们可以通过c++完成核心的耗时的计算然后通过JNI的方式将处理完成的数据传给Java层。
今天，我们就用jni的方式对Bitmap进行处理，来实践NDK开发的方式。开发一个图片滤镜。
效果图：

1.CMakeLists.txt 配置

target_link_libraries( # Specifies the target library.                       native-lib                        jnigraphics//android提供的图像处理库                       # Links the target library to the log library                       # included in the NDK.                       ${log-lib} )

2.代码部分

Activity 部分：

 private void initview(){        source_img = (ImageView)findViewById(R.id.source_img);        operation_img = (ImageView)findViewById(R.id.operation_img);        Bitmap bitmap = BitmapFactory.decodeResource(getResources(),R.drawable.newpic);//        operation_img.setImageBitmap(rotateBitmap(bitmap));        operation_img.setImageBitmap(handleBitmap(bitmap));    }    /**     * 处理图片，此方法中会调用nativeProcessBitmap     * @param bitmap     * @return     */    private Bitmap handleBitmap(Bitmap bitmap) {        Bitmap bmp = bitmap.copy(Bitmap.Config.ARGB_8888, true);        nativeProcessBitmap(bmp);        return bmp;    }        /**     * 黑白特效     */    public native void nativeProcessBitmap(Bitmap bitmap);

2.jni 部分：

#include #include #include #include #include #include "AndroidLog.h"#include #define MAKE_RGB565(r,g,b) ((((r) >> 3) << 11) | (((g) >> 2) << 5) | ((b) >> 3))#define MAKE_ARGB(a,r,g,b) ((a&0xff)<<24) | ((r&0xff)<<16) | ((g&0xff)<<8) | (b&0xff)#define RGB565_R(p) ((((p) & 0xF800) >> 11) << 3)#define RGB565_G(p) ((((p) & 0x7E0 ) >> 5)  << 2)#define RGB565_B(p) ( ((p) & 0x1F  )        << 3)#define RGB8888_A(p) (p & (0xff<<24) >> 24 )#define RGB8888_R(p) (p & (0xff<<16) >> 16 )#define RGB8888_G(p) (p & (0xff<<8)  >> 8 )#define RGB8888_B(p) (p & (0xff) )#define RGBA_A(p) (((p) & 0xFF000000) >> 24)#define RGBA_R(p) (((p) & 0x00FF0000) >> 16)#define RGBA_G(p) (((p) & 0x0000FF00) >>  8)#define RGBA_B(p)  ((p) & 0x000000FF)#define MAKE_RGBA(r,g,b,a) (((a) << 24) | ((r) << 16) | ((g) << 8) | (b))extern "C" JNIEXPORT void JNICALLJava_com_xinrui_ndkapp_MainActivity_nativeProcessBitmap(JNIEnv *env,                                                                        jobject instance,                                                                        jobject bitmap) {    if (bitmap == NULL) {        LOGE("bitmap is null\n");        return;    }    AndroidBitmapInfo bitmapInfo;    memset(&bitmapInfo , 0 , sizeof(bitmapInfo));    // Need add "jnigraphics" into target_link_libraries in CMakeLists.txt    AndroidBitmap_getInfo(env , bitmap , &bitmapInfo);    // Lock the bitmap to get the buffer    void * pixels = NULL;    int res = AndroidBitmap_lockPixels(env, bitmap, &pixels);    // From top to bottom    int x = 0, y = 0;    for (y = 0; y < bitmapInfo.height; ++y) {        // From left to right        for (x = 0; x < bitmapInfo.width; ++x) {            int a = 0, r = 0, g = 0, b = 0;            void *pixel = NULL;            // Get each pixel by format            if(bitmapInfo.format == ANDROID_BITMAP_FORMAT_RGBA_8888)            {                pixel = ((uint32_t *)pixels) + y * bitmapInfo.width + x;                int r,g,b;                uint32_t v = *((uint32_t *)pixel);                r = RGB8888_R(v);                g = RGB8888_G(v);                b = RGB8888_B(v);                int sum = r+g+b;                *((uint32_t *)pixel) = MAKE_ARGB(0xff , sum/3, sum/3, sum/3);            }            else if (bitmapInfo.format == ANDROID_BITMAP_FORMAT_RGB_565) {                pixel = ((uint16_t *)pixels) + y * bitmapInfo.width + x;                int r,g,b;                uint16_t v = *((uint16_t *)pixel);                r = RGB565_R(v);                g = RGB565_G(v);                b = RGB565_B(v);                int sum = r+g+b;                *((uint16_t *)pixel) = MAKE_RGB565(sum/3, sum/3, sum/3);  }        }    }    AndroidBitmap_unlockPixels(env, bitmap);}

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