如何在android中模糊主布局的背景图像？

Question

我只是想让背景图像看起来模糊（如散焦），我使用了 alpha，但它不仅将 alpha 设置为我的背景图像，还设置了整个内容...有什么方法可以设置仅对我的背景图像产生模糊效果！！！..

需要帮助提前谢谢！！..

Answer 1

请使用下面的教程来模糊背景

1. 导航抽屉： https://github.com/charbgr/BlurNavigationDrawer

2. 片段： https://github.com/tvbarthel/BlurDialogFragment

3. 图像：如果要在布局中模糊图像： https://github.com/kikoso/android-stackblur

4. 布局： https://github.com/PomepuyN/BlurEffectForAndroidDesign

   公共类 MainActivity 扩展 Activity {

   private static final String BLURRED_IMG_PATH = "blurred_image.png";
   private static final int TOP_HEIGHT = 700;
   private ListView mList;
   private ImageView mBlurredImage;
   private View headerView;
   private ImageView mNormalImage;
   private ScrollableImageView mBlurredImageHeader;
   private Switch mSwitch;
   private float alpha;
   
   @Override
   protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS);
       setContentView(R.layout.activity_main);
   
       // Get the screen width
       final int screenWidth = ImageUtils.getScreenWidth(this);
   
       // Find the view
       mBlurredImage = (ImageView) findViewById(R.id.blurred_image);
       mNormalImage = (ImageView) findViewById(R.id.normal_image);
       mBlurredImageHeader = (ScrollableImageView) findViewById(R.id.blurred_image_header);
       mSwitch = (Switch) findViewById(R.id.background_switch);
       mList = (ListView) findViewById(R.id.list);
   
       // prepare the header ScrollableImageView
       mBlurredImageHeader.setScreenWidth(screenWidth);
   
       // Action for the switch
       mSwitch.setOnCheckedChangeListener(new OnCheckedChangeListener() {
   
           @Override
           public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
               if (isChecked) {
                   mBlurredImage.setAlpha(alpha);
               } else {
                   mBlurredImage.setAlpha(0f);
   
               }
   
           }
       });
   
       // Try to find the blurred image
       final File blurredImage = new File(getFilesDir() + BLURRED_IMG_PATH);
       if (!blurredImage.exists()) {
   
           // launch the progressbar in ActionBar
           setProgressBarIndeterminateVisibility(true);
   
           new Thread(new Runnable() {
   
               @Override
               public void run() {
   
                   // No image found => let's generate it!
                   BitmapFactory.Options options = new BitmapFactory.Options();
                   options.inSampleSize = 2;
                   Bitmap image = BitmapFactory.decodeResource(getResources(), R.drawable.image, options);
                   Bitmap newImg = Blur.fastblur(MainActivity.this, image, 12);
                   ImageUtils.storeImage(newImg, blurredImage);
                   runOnUiThread(new Runnable() {
   
                       @Override
                       public void run() {
                           updateView(screenWidth);
   
                           // And finally stop the progressbar
                           setProgressBarIndeterminateVisibility(false);
                       }
                   });
   
               }
           }).start();
   
       } else {
   
           // The image has been found. Let's update the view
           updateView(screenWidth);
   
       }
   
       String[] strings = getResources().getStringArray(R.array.list_content);
   
       // Prepare the header view for our list
       headerView = new View(this);
       headerView.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, TOP_HEIGHT));
       mList.addHeaderView(headerView);
       mList.setAdapter(new ArrayAdapter<String>(this, R.layout.list_item, strings));
       mList.setOnScrollListener(new OnScrollListener() {
   
           @Override
           public void onScrollStateChanged(AbsListView view, int scrollState) {
   
           }
   
           /**
            * Listen to the list scroll. This is where magic happens ;)
            */
           @Override
           public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
   
               // Calculate the ratio between the scroll amount and the list
               // header weight to determinate the top picture alpha
               alpha = (float) -headerView.getTop() / (float) TOP_HEIGHT;
               // Apply a ceil
               if (alpha > 1) {
                   alpha = 1;
               }
   
               // Apply on the ImageView if needed
               if (mSwitch.isChecked()) {
                   mBlurredImage.setAlpha(alpha);
               }
   
               // Parallax effect : we apply half the scroll amount to our
               // three views
               mBlurredImage.setTop(headerView.getTop() / 2);
               mNormalImage.setTop(headerView.getTop() / 2);
               mBlurredImageHeader.handleScroll(headerView.getTop() / 2);
   
           }
       });
   }
   
   private void updateView(final int screenWidth) {
       Bitmap bmpBlurred = BitmapFactory.decodeFile(getFilesDir() + BLURRED_IMG_PATH);
       bmpBlurred = Bitmap.createScaledBitmap(bmpBlurred, screenWidth, (int) (bmpBlurred.getHeight()
               * ((float) screenWidth) / (float) bmpBlurred.getWidth()), false);
   
       mBlurredImage.setImageBitmap(bmpBlurred);
   
       mBlurredImageHeader.setoriginalImage(bmpBlurred);
   }
   

   }

Answer 2

Kotlin 代码，使用视图效果库：

1- 在 build.gradle 中添加库：

    implementation 'com.github.mirrajabi:view-effects:e355a1bac4'

2- 模糊根视图或视图的背景，这里Constraint Layout模糊了20%

 ViewFilter.getInstance(this)
        .setRenderer(  BlurRenderer(20))
        .applyFilterOnView(  root_constraintLayout,
            root_constraintLayout    )

我用于模糊背景的 github 存储库：link