通過拖動滑動塊來改變圖片透明度

1. 佈局文件

   <ImageView
       android:id="@+id/image"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:src="@drawable/dog1" />
       <SeekBar
           android:id="@+id/seekBar"
           android:layout_width="match_parent"
           android:layout_height="wrap_content"
           android:max="255"
           android:progress="255"
           android:thumb="@drawable/bar"
           />

   
   

2. Java控制亮度文件

   public class MainActivity extends AppCompatActivity {
       ImageView imageView ;
   
       @Override
       protected void onCreate(Bundle savedInstanceState) {
           super.onCreate(savedInstanceState);
           setContentView(R.layout.activity_main);
           imageView = (ImageView)findViewById(R.id.image);
           SeekBar seekBar = (SeekBar)findViewById(R.id.seekBar);
           //當拖動條的滑塊發生變化時觸發該方法
           seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
               @Override
               public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
                   imageView.setImageAlpha(progress);
               }
   
               @Override
               public void onStartTrackingTouch(SeekBar seekBar) {
   
               }
   
               @Override
               public void onStopTrackingTouch(SeekBar seekBar) {
   
               }
           });
       }
   }