NDK开发（八） ：JNI下Bitmap的使用

enum AndroidBitmapFormat {
    ANDROID_BITMAP_FORMAT_NONE      = 0,
    ANDROID_BITMAP_FORMAT_RGBA_8888 = 1,
    ANDROID_BITMAP_FORMAT_RGB_565   = 4,
    ANDROID_BITMAP_FORMAT_RGBA_4444 = 7,
    ANDROID_BITMAP_FORMAT_A_8       = 8,
};

typedef struct {
    //像素宽度
    uint32_t    width;
    //像素高度
    uint32_t    height;
    //每一行占几个字节
    uint32_t    stride;
    //像素格式
    int32_t     format;
    /** Unused. */
    uint32_t    flags;      // 0 for now
} AndroidBitmapInfo;

//获取bitmap的图片信息
int AndroidBitmap_getInfo(JNIEnv* env, jobject jbitmap,
                          AndroidBitmapInfo* info);
//获取像素信息
int AndroidBitmap_lockPixels(JNIEnv* env, jobject jbitmap, void** addrPtr);
//释放像素信息
int AndroidBitmap_unlockPixels(JNIEnv* env, jobject jbitmap);

enum {
    //调用成功
    ANDROID_BITMAP_RESULT_SUCCESS           = 0,
    //参数错误
    ANDROID_BITMAP_RESULT_BAD_PARAMETER     = -1,
    //出现异常
    ANDROID_BITMAP_RESULT_JNI_EXCEPTION     = -2,
   //分配失败
    ANDROID_BITMAP_RESULT_ALLOCATION_FAILED = -3,
};

public class JniBitmapDemo {
    private static final String TAG = "JniBitmapDemo";
    static {
        System.loadLibrary("bitmap");
    }

    public native void passBitmap(Bitmap bitmap);

    public void test() {
        Bitmap bitmap = Bitmap.createBitmap(1, 1, Bitmap.Config.ARGB_8888);
        bitmap.eraseColor(0xff336699); // AARRGGBB
        byte[] bytes = new byte[bitmap.getWidth() * bitmap.getHeight() * 4];
        Buffer dst = ByteBuffer.wrap(bytes);
        bitmap.copyPixelsToBuffer(dst);
        // ARGB_8888 真实的存储顺序是 R-G-B-A
        Log.d(TAG, "R: " + Integer.toHexString(bytes[0] & 0xff));
        Log.d(TAG, "G: " + Integer.toHexString(bytes[1] & 0xff));
        Log.d(TAG, "B: " + Integer.toHexString(bytes[2] & 0xff));
        Log.d(TAG, "A: " + Integer.toHexString(bytes[3] & 0xff));

        passBitmap(bitmap);
    }
}

add_library(
        bitmap
        SHARED
        bitmap.cpp)
target_link_libraries(
        bitmap
        jnigraphics
        ${log-lib})

#include <jni.h>
#include <android/bitmap.h>
#include <android/log.h>
#include <cstring>
#include "LogUtils.h"


extern "C"
JNIEXPORT void JNICALL
Java_com_lxk_ndkdemo_JniBitmapDemo_passBitmap(JNIEnv *env, jobject instance, jobject bitmap) {

    if (nullptr == bitmap) {
        LOGE("bitmap is null");
    }

    AndroidBitmapInfo info;
    int result;

    //获取图片信息
    result = AndroidBitmap_getInfo(env, bitmap, &info);

    if (result != ANDROID_BITMAP_RESUT_SUCCESS) {
        LOGE("AndroidBitmap_getInfo failed, result: %d", result);
        return;
    }

    LOGD("bitmap width: %d, height: %d, format: %d, stride: %d", info.width, info.height,
         info.format, info.stride);

    unsigned char *addrPtr;

    // 获取像素信息
    result = AndroidBitmap_lockPixels(env, bitmap, reinterpret_cast<void **>(&addrPtr));

    if (result != ANDROID_BITMAP_RESULT_SUCCESS) {
        LOGE("AndroidBitmap_lockPixels failed, result: %d", result);
        return;
    }

    // 执行图片操作的逻辑
    int length = info.stride * info.height;
    for (int i = 0; i < length; ++i) {
        LOGD("value: %x", addrPtr[i]);
    }

    // 像素信息不再使用后需要解除锁定
    result = AndroidBitmap_unlockPixels(env, bitmap);
    if (result != ANDROID_BITMAP_RESULT_SUCCESS) {
        LOGE("AndroidBitmap_unlockPixels failed, result: %d", result);
    }

}

new JniBitmapDemo().test();

target_link_libraries(
        bitmap
        jnigraphics
        ${log-lib})