UI组件之ProgressBar及其子类（二）SeekBar拖动条和RatingBar星级评分条的使用

拖动条采用拖动滑块的位置来表示数值

SeekBar的常用xml属性值：

重要的android：thumb制定一个Drawable对象，改变滑块外观

通过滑块来改变图片的透明度：

main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/root"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <ImageView
        android:id="@+id/imageView1"
        android:layout_width="wrap_content"
        android:layout_height="300dp"
        android:src="@drawable/lijiang" />
<!--  android:thumb 是滑块的图片， android:progressDrawable是滑条的图片 -->
    <SeekBar
        android:id="@+id/seekBar1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:max="255"
        android:progress="255"
        android:thumb="@drawable/ic_launcher" />

    <TextView
        android:id="@+id/textView1"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"

        android:textSize="25dp" />

    <TextView
        android:id="@+id/textView2"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"

        android:textSize="25dp" />

</LinearLayout>

MainActivity.java

package com.example.seekbartest;

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ImageView;
import android.widget.SeekBar;
import android.widget.SeekBar.OnSeekBarChangeListener;
import android.widget.TextView;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
       final ImageView image =(ImageView) findViewById(R.id.imageView1);
       SeekBar seekbar=(SeekBar) findViewById(R.id.seekBar1);
       final TextView textView1 = (TextView) this.findViewById(R.id.textView1);
       final TextView textView2 = (TextView) this.findViewById(R.id.textView2);
       //设置拖动条的状态改变监听器
       seekbar.setOnSeekBarChangeListener(new OnSeekBarChangeListener(){
         //当拖动条的滑块位置发生改变时触发该方法
		@Override
		public void onProgressChanged(SeekBar seekBar, int progress,
				boolean fromUser) {
			// TODO Auto-generated method stub
			image.setAlpha(progress);//设置图片透明度
			textView1.setText("当前值:"+progress);
		}

		@Override
		public void onStartTrackingTouch(SeekBar seekBar) {
			// TODO Auto-generated method stub
			textView2.setText("拖动中...");
		}

		@Override
		public void onStopTrackingTouch(SeekBar seekBar) {
			// TODO Auto-generated method stub
			textView2.setText("拖动完毕");
		}

       });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

自定义拖动条比较好，留着以后借鉴：http://blog.csdn.net/imdxt1986/article/details/7609164

星级评分条的常用xml属性：

android:isIndicator:设置该评分条是否允许用户改变（true为不允许修改）

android:numStars：设置总共有多少个星级

android:rating设置星级评分条默认的星级

android:stepSize设置没吃最少需要改变多少个星级，0.5半个星星，1就是1个星星

使用星级评分改变图片透明度：

main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/root"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <ImageView
        android:id="@+id/imageView1"
        android:layout_width="wrap_content"
        android:layout_height="300dp"
        android:src="@drawable/lijiang" />

    <RatingBar
        android:id="@+id/ratingBar1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:max="255"
        android:numStars="6"
        android:progress="255"
        android:stepSize="0.5" />

</LinearLayout>

MainActivity.java

package com.example.ratingbartest;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ImageView;
import android.widget.RatingBar;
import android.widget.RatingBar.OnRatingBarChangeListener;
import android.widget.SeekBar;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        final ImageView image =(ImageView) findViewById(R.id.imageView1);
        RatingBar bar=(RatingBar) findViewById(R.id.ratingBar1);
       //设置星级评论条状态改变监听器
        bar.setOnRatingBarChangeListener(new OnRatingBarChangeListener(){

			@Override
			public void onRatingChanged(RatingBar ratingBar, float rating,
					boolean fromUser) {
				// TODO Auto-generated method stub
				image.setAlpha((int)(rating*255/6));//设置图片透明度
			}

        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}