RenderScript使用教程（二）

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本文介绍如何使用Android NDK中的RenderScript进行灰度转换，包括编写rs脚本文件、NDK调用代码及编译过程，并展示了最终的运行效果。

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RenderScript使用教程（二）

NDK中使用RenderScript

编写一个rs脚本文件

实现灰度转换的代码

#pragma version(1)
#pragma rs java_package_name(com.example.android.rs.hellocomputendk)
const static float3 gMonoMult = {0.299f, 0.587f, 0.114f};
void root(const uchar4 *v_in, uchar4 *v_out) {
    float4 f4 = rsUnpackColor8888(*v_in);

    float3 mono = dot(f4.rgb, gMonoMult);
    *v_out = rsPackColorTo8888(mono);
}

编写NDK调用代码

#include <jni.h>
#include <android/log.h>
#include <android/bitmap.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <RenderScript.h>
#include "ScriptC_mono.h"
#include "demo_ndk_rs_wps_cn_rsndkdemo_MainActivity.h"

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

using namespace android::RSC;

extern "C" JNIEXPORT void JNICALL
Java_demo_ndk_rs_wps_cn_rsndkdemo_MainActivity_nativeMono(JNIEnv * env, jclass, jstring pathObj, jint X, jint Y, jobject jbitmapIn, jobject jbitmapOut) {

    void* inputPtr = nullptr;
    void* outputPtr = nullptr;

    AndroidBitmap_lockPixels(env, jbitmapIn, &inputPtr);
    AndroidBitmap_lockPixels(env, jbitmapOut, &outputPtr);

    const char * path = env->GetStringUTFChars(pathObj, nullptr);
    sp<RS> rs = new RS();
    rs->init(path);
    env->ReleaseStringUTFChars(pathObj, path);

    sp<const Element> e = Element::RGBA_8888(rs);

    sp<const Type> t = Type::create(rs, e, X, Y, 0);

    sp<Allocation> inputAlloc = Allocation::createTyped(rs, t, RS_ALLOCATION_MIPMAP_NONE,
                                                        RS_ALLOCATION_USAGE_SHARED | RS_ALLOCATION_USAGE_SCRIPT,
                                                        inputPtr);
    sp<Allocation> outputAlloc = Allocation::createTyped(rs, t, RS_ALLOCATION_MIPMAP_NONE,
                                                         RS_ALLOCATION_USAGE_SHARED | RS_ALLOCATION_USAGE_SCRIPT,
                                                         outputPtr);

    inputAlloc->copy2DRangeFrom(0, 0, X, Y, inputPtr);
    ScriptC_mono* sc = new ScriptC_mono(rs);
    sc->forEach_root(inputAlloc, outputAlloc);
    outputAlloc->copy2DRangeTo(0, 0, X, Y, outputPtr);


    AndroidBitmap_unlockPixels(env, jbitmapIn);
    AndroidBitmap_unlockPixels(env, jbitmapOut);

}

编写编译mk文件

android.mk文件如下：

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)


LOCAL_MODULE := rstest-compute
LOCAL_SRC_FILES:=main.cpp mono.rs
LOCAL_C_INCLUDES += D:/Android/android-ndk-r14b-windows-x86_64/android-ndk-r14b/toolchains/renderscript/prebuilt/windows-x86_64/platform/rs/cpp \
    D:/Android/android-ndk-r14b-windows-x86_64/android-ndk-r14b/toolchains/renderscript/prebuilt/windows-x86_64/platform/rs


LOCAL_CFLAGS := -std=c++11
LOCAL_LDFLAGS := -Wl,-Bsymbolic


#LOCAL_RENDERSCRIPT_COMPATIBILITY := true
LOCAL_SHARED_LIBRARIES := RSSupport blasV8 RSSupportIO
LOCAL_STATIC_LIBRARIES := RScpp_static
LOCAL_LDLIBS := -llog -ljnigraphics -lz -ldl

include $(BUILD_SHARED_LIBRARY)

$(call import-module,android/renderscript)

这里注意LOCAL_C_INCLUDES 请写你本地对应NDK有关rs头文件的目录。
application.mk文件如下：

APP_ABI := armeabi-v7a
APP_PLATFORM := android-19
APP_STL := stlport_static

编译代码

这里需要注意必须使用linux系统或者babun去编译文件，因为在window命令行下有NDK有一个bug，具体请查看编译以及注意事项请查看该链接。

Java调用测试

private Bitmap mBitmapIn;
    private Bitmap mBitmapOut;
    private ImageView iv_show;
    private ImageView iv_input;

    // Used to load the 'native-lib' library on application startup.
    static {
        System.loadLibrary("rstest-compute");
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mBitmapIn = ((BitmapDrawable)getResources().getDrawable(R.drawable.ic_launcher)).getBitmap();
        mBitmapOut = Bitmap.createBitmap(mBitmapIn.getWidth(), mBitmapIn.getHeight(), mBitmapIn.getConfig());

        nativeMono(this.getCacheDir().toString(),
                mBitmapIn.getWidth(), mBitmapIn.getHeight(),
                mBitmapIn, mBitmapOut);

        iv_show = (ImageView) findViewById(R.id.iv_show);
        iv_input = (ImageView) findViewById(R.id.iv_input);
        iv_input.setImageBitmap(mBitmapIn);
        iv_show.setImageBitmap(mBitmapOut);

    }


    /**
     * A native method that is implemented by the 'native-lib' native library,
     * which is packaged with this application.
     */
    native void nativeMono(String cacheDir, int X, int Y, Bitmap in, Bitmap out);

运行效果如下：

这里写图片描述