android - 淡入淡出動畫到底部導航視圖

Question

我是初學者到android。在這個項目中，我有BottomNavigationView。從一個視圖切換到另一個視圖時，我想將cross-fade動畫添加到此BottomNavigationView。以下是我的代碼。

bottom_nav.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:app="http://schemas.android.com/apk/res-auto" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent"> 

    <!-- Content Container --> 

    <android.support.design.widget.BottomNavigationView 
     android:id="@+id/bottom_navigation" 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     android:layout_alignParentBottom="true" 
     app:itemBackground="@color/colorWhite" 
     app:itemIconTint="@drawable/item_checked_color" 
     app:itemTextColor="@drawable/item_checked_color" 
     app:menu="@menu/bottom_navigation_main" /> 

</RelativeLayout> 

我包括上述xml文件activity_main.xml中

activity_main.xml中

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:app="http://schemas.android.com/apk/res-auto" 
    xmlns:tools="http://schemas.android.com/tools" 
    android:id="@+id/content_main" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:paddingTop="10dp"/> 

// other content 

<include 
      layout="@layout/bottom_nav" 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content" /> 

</RelativeLayout> 

MainActivity.java

public class MyDashboardActivity extends BaseActivity implements NavigationView.OnNavigationItemSelectedListener { 

private BottomNavigationView bottomNavigationView; 

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

bottomNavigationView = (BottomNavigationView)findViewById(R.id.bottom_navigation); 
     BottomNavigationViewHelper.disableShiftMode(bottomNavigationView); 


loadBottomNavigation(); 
} 

public void loadBottomNavigation(){ 


     Menu bottomMenu = bottomNavigationView.getMenu(); 
     if (bottomMenu != null){ 
      for (int i=0; i< bottomMenu.size(); i++){ 
       MenuItem bottomMenuItem = bottomMenu.getItem(i); 
       applyFontToMenuItem(bottomMenuItem); 

       MenuItem dashboard = bottomMenu.getItem(0); 
       dashboard.setChecked(true); 
       MenuItem expert = bottomMenu.getItem(2); 
       expert.setChecked(false); 
      } 
     } 

     bottomNavigationView.setOnNavigationItemSelectedListener(
       new BottomNavigationView.OnNavigationItemSelectedListener() { 
        @Override 
        public boolean onNavigationItemSelected(MenuItem item) { 
         switch (item.getItemId()){ 
          case R.id.action_1: 
           Intent intent = new Intent(getApplicationContext(), NewActivity.class); 
           intent.putExtra("idPatient", idPatient); 
           startActivity(intent); 

           break; 

          case R.id.action_2: 
           Intent intent1 = new Intent(MainActivity.this, FirstActivity.class); 
           intent1.putExtra("idPatient", idPatient); 
           startActivity(intent1); 

           break; 

          case R.id.action_3: 
           Intent intent2 = new Intent(MainActivity.this, SecondActivity.class); 
           String url = "https:rrrrrrr"; 
           String activityName = "MainActivity"; 
           intent2.putExtra("activity", activityName); 
           intent2.putExtra("linkUrl", url); 
           startActivity(intent2); 

           break; 


         } 
         return true; 
        } 
       }); 
    } 
} 

如何在視圖之間切換時添加cross-fade動畫？

Answer 1

從Android文檔...

https://developer.android.com/training/animation/crossfade.html

private View mContentView; 
    private View mLoadingView; 
    private int mShortAnimationDuration; 

    ... 

    private void crossfade() { 

     // Set the content view to 0% opacity but visible, so that it is visible 
     // (but fully transparent) during the animation. 
     mContentView.setAlpha(0f); 
     mContentView.setVisibility(View.VISIBLE); 

     // Animate the content view to 100% opacity, and clear any animation 
     // listener set on the view. 
     mContentView.animate() 
       .alpha(1f) 
       .setDuration(mShortAnimationDuration) 
       .setListener(null); 

     // Animate the loading view to 0% opacity. After the animation ends, 
     // set its visibility to GONE as an optimization step (it won't 
     // participate in layout passes, etc.) 
     mLoadingView.animate() 
       .alpha(0f) 
       .setDuration(mShortAnimationDuration) 
       .setListener(new AnimatorListenerAdapter() { 
        @Override 
        public void onAnimationEnd(Animator animation) { 
         mLoadingView.setVisibility(View.GONE); 
        } 
       }); 
    }