Android Jni用bitmap形式实现Image图片的黑白滤镜

    技术2022-07-10  146

    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 <jni.h> #include <string> #include <stdio.h> #include <pthread.h> #include <unistd.h> #include "AndroidLog.h" #include <android/bitmap.h> #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 JNICALL Java_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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