Android---21---ImageView

MainActivity.java:

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.drawable.BitmapDrawable;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.View.OnTouchListener;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.LinearLayout;

public class MainActivity extends Activity {

	//定义一个访问图片的数组
	int images[] = new int[] { R.drawable.yy00, R.drawable.yy01,
			R.drawable.yy02, R.drawable.yy03, R.drawable.yy04, R.drawable.yy05,
			R.drawable.yy06, R.drawable.yy07, R.drawable.yy08, R.drawable.yy09,
			R.drawable.yy11, R.drawable.yy12, R.drawable.yy13,

	};
	//定义当前的图片
	int currentimage = 2;
	private int alpha = 255;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		final Button plus = (Button) findViewById(R.id.plus);
		final Button minus = (Button) findViewById(R.id.minus);
		final ImageView imageView = (ImageView) findViewById(R.id.image1);
		final ImageView imageView2 = (ImageView) findViewById(R.id.image2);
		Button next = (Button) findViewById(R.id.next);

		next.setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
				imageView.setImageResource(images[++currentimage
						% images.length]);
			}
		});

		OnClickListener listener = new OnClickListener() {

			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
				if (v == plus) {
					alpha += 20;
				}
				if (v == minus) {
					alpha -= 20;
				}
				if (alpha >= 255) {
					alpha = 255;
				}
				if (alpha <= 0) {
					alpha = 0;
				}
				imageView.setAlpha(alpha);
			}
		};
		//改变透明度
		plus.setOnClickListener(listener);
		minus.setOnClickListener(listener);

		imageView.setOnTouchListener(new OnTouchListener() {

			@Override
			public boolean onTouch(View v, MotionEvent event) {
				// TODO Auto-generated method stub
				BitmapDrawable bitmapDrawable = (BitmapDrawable) imageView
						.getDrawable();
				//获取第一个图片显示框中的位图
				Bitmap bitmap = bitmapDrawable.getBitmap();
				//bitmap图片实际大小与第一个ImageView的缩放比例
				double scale = bitmap.getWidth() / 320.0;
				//获取需要显示的图片的开始点
				int x = (int) (event.getX() * scale);
				int y = (int) (event.getY() * scale);
				if (x + 120 > bitmap.getWidth()) {
					x = bitmap.getWidth() - 120;
				}
				if (y + 120 > bitmap.getHeight()) {
					y = bitmap.getHeight() - 120;
				}
				// 显示图片的指定区域
				imageView2.setImageBitmap(Bitmap.createBitmap(bitmap, x, y,
						120, 120));
				imageView2.setAlpha(alpha);
				return false;
			}
		});
	}
}

activity_main.xml:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.imageviewdemo.MainActivity" >

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:orientation="horizontal" >

        <Button
            android:id="@+id/plus"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="增大透明度" />

        <Button
            android:id="@+id/minus"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="降低透明度" />

        <Button
            android:id="@+id/next"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="下一张" />
    </LinearLayout>
    <!-- 定义显示图片整体的ImageView -->

    <ImageView
        android:id="@+id/image1"
        android:layout_width="fill_parent"
        android:layout_height="240px"
        android:scaleType="fitCenter"
        android:src="@drawable/yy01" />
<!-- 定义显示局部图片的imageView -->
    <ImageView
        android:id="@+id/image2"
        android:layout_width="120dp"
        android:layout_height="120dp"
        android:layout_marginTop="10dp"
        android:background="#00f" />

</LinearLayout>