从头开始敲代码之《从BaseApplication/Activity开始（四）》

转载请注明出处：王亟亟的大牛之路

早上无聊看以前下的一大堆资料，发现一个用JNI实现的模糊效果，效果都差不多，但是对JNI的不熟悉让我不太推荐这种办法（不了解的总不方便，调试，修改都是）
然后在Git上找到个不错的实现，还是分2种的，应对于各种需要。

这一篇文章会介绍什么

1.模糊视图处理

2.线程操作优化

1.Renderscript
2.FastBlur

效果图

布局：

<?xml version="1.0" encoding="utf-8"?>

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ImageView
        android:id="@+id/picture"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:scaleType="centerCrop" />

    <LinearLayout
        android:id="@+id/controls"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#7f000000"
        android:orientation="vertical"
        android:layout_gravity="bottom"/>

    <TextView
        android:id="@+id/text"
        android:gravity="center_horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="测试用的字"
        android:textColor="@android:color/black"
        android:layout_gravity="center"
        android:textStyle="bold"
        android:textSize="48sp" />
</FrameLayout>

并不是自定义控件，而是对图像本身进行了操作。

1.创建了一个空的bitmap，把背景的一部分复制进去，之后我会对这个bitmap进行模糊处理并设置为TextView的背景。

2.通过这个bitmap保存Canvas的状态；

3.在父布局文件中把Canvas移动到TextView的位置；

4.把ImageView的内容绘到bitmap中；

5.此时，我们就有了一个和TextView一样大小的bitmap，它包含了ImageView的一部分内容，也就是TextView背后一层布局的内容；

6.创建一个Renderscript的实例；

7.把bitmap复制一份到Renderscript需要的数据片中；

8.创建Renderscript模糊处理的实例；

9.设置输入，半径范围然后进行模糊处理；

10.把处理后的结果复制回之前的bitmap中；

11.已经把bitmap进行模糊处理了，可以将它设置为TextView背景了；

2种形式在ViewPager中分别实现，RSBlurFragment，FastBlurFragment

FuzzyActivity（容器）

public class FuzzyActivity extends FragmentActivity {

        private CustomPagerAdapter pagerAdapter;
        private RSBlurFragment rsBlurFragment;
        private FastBlurFragment fastBlurFragment;

        private ViewPager viewPager;
        private ArrayList<Fragment> fragments ;

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_fuzzy_layout);
            fragments = new ArrayList<Fragment>();
            rsBlurFragment=new RSBlurFragment();
            fastBlurFragment=new FastBlurFragment();
            fragments.add(rsBlurFragment);
            fragments.add(fastBlurFragment);

            pagerAdapter =
                    new CustomPagerAdapter(
                            getSupportFragmentManager(),fragments);
            viewPager = (ViewPager) findViewById(R.id.pager);
            viewPager.setAdapter(pagerAdapter);
            viewPager.setPageTransformer(true, new ZoomOutPageTransformer());

            viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
                @Override
                public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
                }

                @Override
                public void onPageSelected(int position) {
                }

                @Override
                public void onPageScrollStateChanged(int state) {

                }
            });
        }

        public class CustomPagerAdapter extends FragmentStatePagerAdapter {
            private ArrayList<Fragment> fragments ;

            public CustomPagerAdapter(FragmentManager fm) {
                super(fm);

            }

            public CustomPagerAdapter(FragmentManager fm,ArrayList<Fragment> fragments) {
                super(fm);
                this.fragments=fragments;
            }

            @Override
            public Fragment getItem(int i) {
                return fragments.get(i);
            }

            @Override
            public int getCount() {
                return fragments.size();
            }

            @Override
            public CharSequence getPageTitle(int position) {
                return fragments.get(position).toString();
            }
        }
    }

RSBlurFragment

public class RSBlurFragment extends Fragment {
    private ImageView image;
    private TextView maimai;
    private TextView statusText;
    private CheckBox downScale;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.blur_layout, container, false);
        image = (ImageView) view.findViewById(R.id.picture);
        maimai = (TextView) view.findViewById(R.id.text);
        image.setImageResource(R.drawable.fuzzybg);
        statusText = addStatusText((ViewGroup) view.findViewById(R.id.controls));
        addCheckBoxes((ViewGroup) view.findViewById(R.id.controls));
        applyBlur();
        return view;
    }

    private void applyBlur() {
        image.getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
            @Override
            public boolean onPreDraw() {
                image.getViewTreeObserver().removeOnPreDrawListener(this);
                image.buildDrawingCache();

                Bitmap bmp = image.getDrawingCache();
                blur(bmp, maimai);
                return true;
            }
        });
    }

    @TargetApi(Build.VERSION_CODES.KITKAT)
    private void blur(Bitmap bkg, View view) {
        long startMs = System.currentTimeMillis();


        float scaleFactor = 1;
        float radius = 20;

        if (downScale.isChecked()) {
            scaleFactor = 8;
            radius = 2;
        }

        Bitmap overlay = Bitmap.createBitmap((int) (view.getMeasuredWidth() / scaleFactor),
                (int) (view.getMeasuredHeight() / scaleFactor), Bitmap.Config.ARGB_8888);

        Canvas canvas = new Canvas(overlay);

        canvas.translate(-view.getLeft() / scaleFactor, -view.getTop() / scaleFactor);
        canvas.scale(1 / scaleFactor, 1 / scaleFactor);
        Paint paint = new Paint();
        paint.setFlags(Paint.FILTER_BITMAP_FLAG);
        canvas.drawBitmap(bkg, 0, 0, paint);

        RenderScript rs = RenderScript.create(getActivity());

        Allocation overlayAlloc = Allocation.createFromBitmap(
                rs, overlay);

        ScriptIntrinsicBlur blur = ScriptIntrinsicBlur.create(
                rs, overlayAlloc.getElement());

        blur.setInput(overlayAlloc);

        blur.setRadius(radius);

        blur.forEach(overlayAlloc);

        overlayAlloc.copyTo(overlay);

        view.setBackground(new BitmapDrawable(
                getResources(), overlay));

        rs.destroy();
        statusText.setText(System.currentTimeMillis() - startMs + "ms");
    }

    @Override
    public String toString() {
        return "RenderScript";
    }

    private TextView addStatusText(ViewGroup container) {
        TextView result = new TextView(getActivity());
        result.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT));
        result.setTextColor(0xFFFFFFFF);
        container.addView(result);
        return result;
    }

    private void addCheckBoxes(ViewGroup container) {
        downScale = new CheckBox(getActivity());
        ViewGroup.LayoutParams lp = new FrameLayout.LayoutParams(FrameLayout.LayoutParams.WRAP_CONTENT, FrameLayout.LayoutParams.WRAP_CONTENT);
        downScale.setLayoutParams(lp);
        downScale.setText("Downscale before blur");
        downScale.setVisibility(View.VISIBLE);
        downScale.setTextColor(0xFFFFFFFF);
        downScale.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                applyBlur();
            }
        });
        container.addView(downScale);
    }
}

FastBlurFragment

public class FastBlurFragment extends Fragment {
    private final String DOWNSCALE_FILTER = "downscale_filter";

    private ImageView image;
    private TextView text;
    private CheckBox downScale;
    private TextView statusText;

    ExecutorService singleThreadExecutor = Executors.newSingleThreadExecutor();

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.blur_layout, container, false);
        image = (ImageView) view.findViewById(R.id.picture);
        text = (TextView) view.findViewById(R.id.text);
        image.setImageResource(R.drawable.fuzzybg);
        statusText = addStatusText((ViewGroup) view.findViewById(R.id.controls));
        addCheckBoxes((ViewGroup) view.findViewById(R.id.controls));

        if (savedInstanceState != null) {
            downScale.setChecked(savedInstanceState.getBoolean(DOWNSCALE_FILTER));
        }
        LogUtils.d("------<onCreateView  "+Thread.currentThread().getName());
        initImage();
        return view;
    }

    private void initImage(){
        singleThreadExecutor.execute(new SonThread());
    }

    private void applyBlur() {
        image.getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
            @Override
            public boolean onPreDraw() {
                image.getViewTreeObserver().removeOnPreDrawListener(this);
                image.buildDrawingCache();

                Bitmap bmp = image.getDrawingCache();
                blur(bmp, text);
                return true;
            }
        });
    }

    private void blur(Bitmap bkg, View view) {
        long startMs = System.currentTimeMillis();
        float scaleFactor = 1;
        float radius = 20;
        if (downScale.isChecked()) {
            scaleFactor = 8;
            radius = 2;
        }

        Bitmap overlay = Bitmap.createBitmap((int) (view.getMeasuredWidth()/scaleFactor),
                (int) (view.getMeasuredHeight()/scaleFactor), Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(overlay);
        canvas.translate(-view.getLeft()/scaleFactor, -view.getTop()/scaleFactor);
        canvas.scale(1 / scaleFactor, 1 / scaleFactor);
        Paint paint = new Paint();
        paint.setFlags(Paint.FILTER_BITMAP_FLAG);
        canvas.drawBitmap(bkg, 0, 0, paint);

        overlay = FastBlur.doBlur(overlay, (int) radius, true);
        view.setBackground(new BitmapDrawable(getResources(), overlay));
        statusText.setText(System.currentTimeMillis() - startMs + "ms");
    }

    @Override
    public String toString() {
        return "Fast blur";
    }

    private void addCheckBoxes(ViewGroup container) {

        downScale = new CheckBox(getActivity());
        FrameLayout.LayoutParams lp = new FrameLayout.LayoutParams(FrameLayout.LayoutParams.WRAP_CONTENT, FrameLayout.LayoutParams.WRAP_CONTENT);
        downScale.setLayoutParams(lp);
        downScale.setText("Downscale before blur");
        downScale.setVisibility(View.VISIBLE);
        downScale.setTextColor(0xFFFFFFFF);
        downScale.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                singleThreadExecutor.execute(new SonThread());
                LogUtils.d("------<addCheckBoxes  " + Thread.currentThread().getName());
            }
        });
        container.addView(downScale);
    }

    private TextView addStatusText(ViewGroup container) {
        TextView result = new TextView(getActivity());
        result.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT));
        result.setTextColor(0xFFFFFFFF);
        container.addView(result);
        return result;
    }

    @Override
    public void onSaveInstanceState(Bundle outState) {
        outState.putBoolean(DOWNSCALE_FILTER, downScale.isChecked());
        super.onSaveInstanceState(outState);
    }

    class SonThread implements Runnable{
        public void run() {
            LogUtils.d("------<sonThread  "+Thread.currentThread().getName());
            applyBlur();
        }
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        singleThreadExecutor.shutdown();
    }
}

运行效果：

顺便提一下版本的问题，ScriptIntrinsicBlur只支持API17以上，也可以用Renderscript的support lib降低一些API版本的要求

实现的理论在上面已经列明了，来说下为什么在FastBlur的实现过程中使用线程操作。

我们知道在Android中渲染一帧的时间应该不超过16ms（60fps），但如果在UI线程中做模糊处理就会让帧率降到了17fps。显然这是不可接受的，我们需要把这个操作移到子线程中操作了。

然后就是 说下 ExecutorService singleThreadExecutor = Executors.newSingleThreadExecutor();

少侠们我们一定要放弃new Thread …….一系列啊

诸如：

new Thread(new Runnable() {

    @Override
    public void run() {}

}).start();

1.每次新建对象性能差。
2. 线程缺乏统一管理，可能无限制新建线程，相互之间竞争，及可能占用过多系统资源导致死机或oom。
3. 缺乏更多功能，如定时执行、定期执行、线程中断。

用Executors提供四种线程池可以更好的方便我们去管理我们的线程

1.newCachedThreadPool创建一个可缓存线程池，如果线程池长度超过处理需要，可灵活回收空闲线程，若无可回收，则新建线程。

2.newFixedThreadPool 创建一个定长线程池，可控制线程最大并发数，超出的线程会在队列中等待。

3.newScheduledThreadPool 创建一个定长线程池，支持定时及周期性任务执行。

4.newSingleThreadExecutor 创建一个单线程化的线程池，它只会用唯一的工作线程来执行任务，保证所有任务按照指定顺序(FIFO, LIFO, 优先级)执行。

使用方法跟我代码中差不多但是，一定会更高效，更合理。

周末愉快！！
源码地址：http://yunpan.cn/cHfZLUjzGbZ4e 访问密码 b78e

分析的出处http://trickyandroid.com/advanced-blurring-techniques/