Android学习之seekbar拖动条

设置屏幕亮度

main.xml:

 

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical" android:layout_width="fill_parent"
  android:layout_height="fill_parent">
  <ImageView 
    android:id="@+id/pic"
    android:src="@drawable/android_book"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"/> 
  <SeekBar 
    android:id="@+id/seekbar" 
    android:layout_width="fill_parent"
    android:layout_height="wrap_content" />
</LinearLayout>

 

MySeekBarDemo.java:

 

import android.app.Activity;
import android.os.Bundle;
import android.view.WindowManager;
import android.widget.SeekBar;

public class MySeekBarDemo extends Activity {
  private SeekBar seekbar = null;

  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    super.setContentView(R.layout.main);
    this.seekbar = (SeekBar) super.findViewById(R.id.seekbar); // 取得组件
    this.seekbar.setMax(100);
    this.seekbar
        .setOnSeekBarChangeListener(new OnSeekBarChangeListenerImpl());
  }

  private class OnSeekBarChangeListenerImpl implements
      SeekBar.OnSeekBarChangeListener {
    @Override
    public void onStartTrackingTouch(SeekBar seekBar) {
    }

    @Override
    public void onProgressChanged(SeekBar seekBar, int progress,
        boolean fromUser) {
      MySeekBarDemo.this.setScreenBrightness((float) seekBar
          .getProgress() / 100);
    }

    @Override
    public void onStopTrackingTouch(SeekBar seekBar) {
    }
  }
  private void setScreenBrightness(float num) { // 0 ~ 1表示亮度
    WindowManager.LayoutParams layoutParams = super.getWindow().getAttributes() ; // 取得屏幕的属性
    layoutParams.screenBrightness = num ; // 设置屏幕亮度
    super.getWindow().setAttributes(layoutParams) ; // 重新设置窗口的属性
  }
}