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/