andorid 进度条和图片的透明度

layout.xml

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

    <ImageView
        android:layout_width="80dp"
        android:layout_height="80dp"
        android:scaleType="center"
        android:background="#f00"
        android:src="@drawable/close"
        android:id="@+id/tc1"/>

    <SeekBar
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:max="255"
        android:progress="255"
        android:id="@+id/kz1"
        />
</LinearLayout>

Layout.java

package com.hanqi.application3;

import android.app.Activity;
import android.os.Bundle;
import android.widget.ImageView;
import android.widget.SeekBar;

/**
 * Created by Administrator on 2016/3/31.
 */
public class Layout extends Activity {

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

        final ImageView tc1 = (ImageView)findViewById(R.id.tc1);
        final SeekBar kz1 = (SeekBar)findViewById(R.id.kz1);

        kz1.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
            @Override
            public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {

                tc1.setImageAlpha(progress);
　　　　　　　　　　//如果最大值是100
　　　　　　　　　　//tc1.setImageAlpha(progress*255/100);

            }

            @Override
            public void onStartTrackingTouch(SeekBar seekBar) {

            }

            @Override
            public void onStopTrackingTouch(SeekBar seekBar) {

            }
        });

    }

}