动脑学院 - Java 和 JNI方式处理图片比较

约定不等于承诺〃 2022-07-17 03:09 120阅读 0赞

MainAcitivty:

/** 
     * @projectName:JavaNdkComp 
     * @fileName:MainActivity.java 
     * @packageName:club.younge.demo 
     * @date:2016年8月28日下午11:10:29 
     * @copyright (c) 2016, heqy@finansir.nt All Rights Reserved. 
     * 
     */
    
    package club.younge.demo;
    
    import android.app.Activity;
    import android.graphics.Bitmap;
    import android.graphics.BitmapFactory;
    import android.graphics.Bitmap.Config;
    import android.media.Image;
    import android.os.Bundle;
    import android.view.View;
    import android.widget.ImageView;
    import android.widget.Toast;
    import club.younge.java.JavaImageUtils;
    import club.younge.ndk.NdkImageUtils;
    
    /**
     * @className:MainActivity
     * @function: TODO ADD FUNCTION.
     * @reason: TODO ADD REASON.
     * @date: 2016年8月28日 下午11:10:29
     * @author Younge
     * @version
     * @since JDK 1.8
     * @see
     */
    public class MainActivity extends Activity {
    	private ImageView imageView;
    	private Bitmap mBitmap;
    	@Override
    	protected void onCreate(Bundle savedInstanceState) {
    		super.onCreate(savedInstanceState);
    		setContentView(R.layout.main);
    		imageView = (ImageView) findViewById(R.id.imageView);
    		mBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.xy);
    	}
    
    	public void srcImage(View view) {
    		imageView.setImageBitmap(mBitmap);
    	}
    
    	public void javaImage(View view) {
    		long start = System.currentTimeMillis();
    		Bitmap bitmap = JavaImageUtils.getBitMap(mBitmap);
    		imageView.setImageBitmap(bitmap);
    		long end = System.currentTimeMillis();
    		Toast.makeText(this, "耗时："+ (end -start) +"ms", Toast.LENGTH_SHORT).show();
    	}
    
    	public void ndkImage(View view) {
    		int width = mBitmap.getWidth();
    		int height = mBitmap.getHeight();
    		int[] buffer = new int[width*height];
    		mBitmap.getPixels(buffer, 0, width, 0, 0, width, height);
    		long start = System.currentTimeMillis();
    		int[] result = NdkImageUtils.getImage(buffer, width, height);
    		Bitmap bitmap = Bitmap.createBitmap(result, 0, width, width, height, Config.ARGB_8888);
    		imageView.setImageBitmap(bitmap);
    		long end = System.currentTimeMillis();
    		Toast.makeText(this, "耗时："+ (end -start) +"ms", Toast.LENGTH_SHORT).show();
    	}
    }

JavaImageUtils:

/** 
     * @projectName:JavaNdkComp 
     * @fileName:JavaImageUtils.java 
     * @packageName:club.younge.java 
     * @date:2016年8月28日下午11:12:57 
     * @copyright (c) 2016, heqy@finansir.nt All Rights Reserved. 
     * 
     */  
      
    package club.younge.java;
    
    import android.graphics.Bitmap;
    import android.graphics.Bitmap.Config;
    import android.graphics.Color;
    
    /** 
     * @className:JavaImageUtils 
     * @function: TODO ADD FUNCTION.  
     * @reason:   TODO ADD REASON. 
     * @date:     2016年8月28日 下午11:12:57
     * @author   Younge 
     * @version   
     * @since    JDK 1.8 
     * @see       
     */
    public class JavaImageUtils {
    	public static Bitmap getBitMap(Bitmap bitmap){
    		if(bitmap == null) return null;
    		int width = bitmap.getWidth();
    		int height = bitmap.getHeight();
    		Bitmap result = Bitmap.createBitmap(width, height, Config.ARGB_8888);
    		int color, a, r, g, b, rt, gt, bt;
    		float bright = 0.2f;
    		float contrast = 0.2f;
    		int bri = (int)(256*bright);
    		for (int x = 0; x < width; x++) {
    			for (int y = 0; y < height; y++) {
    				color = bitmap.getPixel(x, y);
    				a = Color.alpha(color);
    				r = Color.red(color);
    				g = Color.green(color);
    				b = Color.blue(color);
    				//更改亮度，统一增加一个值，变得更白更亮
    			    rt = r + bri;
    			    gt = g + bri;
    			    bt = b + bri;
    			    
    			    r = rt > 255 ? 255:(rt < 0 ? 0: rt); //事实在目前情况下，不会出现rt小于0的情况，此处这么写是为了统一后边
    			    g = gt > 255 ? 255:(gt < 0 ? 0: gt);
    			    b = bt > 255 ? 255:(bt < 0 ? 0: bt);
    			    
    			    //更改对比度, 以128中间值为分界点，白的更白，黑的更黑，增加对比度
    			    
    			    r = r - 128;
    			    g = g - 128;
    			    b = b - 128;
    			    
    			    rt = (int) (r*(1 + contrast)) + 128;
    			    gt = (int) (g*(1 + contrast)) + 128;
    			    bt = (int) (b*(1 + contrast)) + 128;
    			    
    			    r = rt > 255 ? 255:(rt < 0 ? 0: rt); 
    			    g = gt > 255 ? 255:(gt < 0 ? 0: gt);
    			    b = bt > 255 ? 255:(bt < 0 ? 0: bt);
    			    
    			    color = Color.argb(a, r, g, b);	
    			    
    			    result.setPixel(x, y, color);
    			}
    			
    		}
    		
    		return result;
    	}
    }

NdkImageUtils:

/** 
     * @projectName:JavaNdkComp 
     * @fileName:NdkImageUtils.java 
     * @packageName:club.younge.ndk 
     * @date:2016年8月28日下午11:13:12 
     * @copyright (c) 2016, heqy@finansir.nt All Rights Reserved. 
     * 
     */  
      
    package club.younge.ndk;
    
    /** 
     * @className:NdkImageUtils 
     * @function: TODO ADD FUNCTION.  
     * @reason:   TODO ADD REASON. 
     * @date:     2016年8月28日 下午11:13:12
     * @author   Younge 
     * @version   
     * @since    JDK 1.8 
     * @see       
     */
    public class NdkImageUtils {
    	static{
    		System.loadLibrary("Image");
    	}
    	public static native int[] getImage(int[] buffer, int width, int height);
    }

生成的JNI头文件，club\_younge\_ndk\_NdkImageUtils.h：

/* DO NOT EDIT THIS FILE - it is machine generated */
    #include <jni.h>
    /* Header for class club_younge_ndk_NdkImageUtils */
    
    #ifndef _Included_club_younge_ndk_NdkImageUtils
    #define _Included_club_younge_ndk_NdkImageUtils
    #ifdef __cplusplus
    extern "C" {
    #endif
    /*
     * Class:     club_younge_ndk_NdkImageUtils
     * Method:    getImage
     * Signature: ([III)[I
     */
    JNIEXPORT jintArray JNICALL Java_club_younge_ndk_NdkImageUtils_getImage
      (JNIEnv *, jclass, jintArray, jint, jint);
    
    #ifdef __cplusplus
    }
    #endif
    #endif

实现类，编辑实现类时，右键，Android tools -> add Native support, 然后右键Properties -> c/c++ general -> paths and symbols 若为添加包含的头文件路径，需要添加包含的头文件路径，这样在CPP文件中才会出现代码提示，确保不那么容易出现错误。club\_younge\_ndk\_NdkImageUtils.cpp：

/* DO NOT EDIT THIS FILE - it is machine generated */
    #include <stdlib.h>
    #include <jni.h>
    #include "club_younge_ndk_NdkImageUtils.h"
    /* Header for class club_younge_ndk_NdkImageUtils */
    
    
    /*
     * Class:     club_younge_ndk_NdkImageUtils
     * Method:    getImage
     * Signature: ([III)[I
     */
    JNIEXPORT jintArray JNICALL Java_club_younge_ndk_NdkImageUtils_getImage
      (JNIEnv *env, jclass clazz, jintArray buffer, jint width, jint height){
    	jint *buf = (jint*)env->GetIntArrayElements(buffer, 0);
    	jsize len = env->GetArrayLength(buffer);
    	jint resultBuf[len];
    	jintArray result = env->NewIntArray(len);
    	int color, a, r, g, b, rt, gt, bt;
    	int bright = (int)(0.2f*256);
    	float contrast = 0.2f;
    	for(int x = 0; x < width; x++){
    		for(int y = 0; y < height; y++){
    			color = buf[y*width + x];
    			a = color  >> 24;
    			r = (color >> 16) & 0xFF;
    			g = (color >> 8) & 0xFF;
    			b = color & 0xFF;
    
    			//改变亮度
    			rt = r + bright;
    			gt = g + bright;
    			bt = b + bright;
    
    			r = rt > 255 ? 255 : rt;
    			g = gt > 255 ? 255 : gt;
    			b = bt > 255 ? 255 : bt;
    			//改变对比度
    			r = r - 128;
    			g = g - 128;
    			b = b - 128;
    
    			rt = (int) (r*(1 + contrast)) + 128;
    			gt = (int) (g*(1 + contrast)) + 128;
    			bt = (int) (b*(1 + contrast)) + 128;
    
    			r = rt > 255 ? 255 : (rt < 0 ? 0 : rt);
    			g = gt > 255 ? 255 : (gt < 0 ? 0 : gt);
    			b = bt > 255 ? 255 : (bt < 0 ? 0 : bt);
    
    			color = a << 24 | r << 16 | g << 8 | b;
    			resultBuf[y*width + x] = color;
    		}
    	}
    
    	env->ReleaseIntArrayElements(buffer,buf,0);
    	env->SetIntArrayRegion(result, 0, len, resultBuf);
    
    	return result;
    }

测试结果：java:1579ms, jni:470ms, 性能提升3倍多一点。若用大图超过1M，JNI调用直接崩溃退出，报Fatal signal 11 (SIGSEGV) at 0x00000000 (code=1)。

Github: [源码][Link 1]

[Link 1]: https://github.com/heqingyong/JavaNdKImage