疯狂android讲义学习总结---ImageView

imageView  做图片浏览器
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<?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">

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

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

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

        <Button
            android:id="@+id/next"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="下一张" />
    </LinearLayout>

    <ImageView
        android:id="@+id/imageView1"
        android:layout_width="fill_parent"
        android:layout_height="240px"
        android:src="@drawable/lijiang"
        android:scaleType="fitCenter" />

    <ImageView
        android:id="@+id/imageView2"
        android:layout_width="120dp"
        android:layout_height="120dp"
        android:background="#00f"
        android:layout_marginTop="10dp"
        />

</LinearLayout>
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java代码：

package com.example.imageviewtest;

import android.os.Bundle;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.drawable.BitmapDrawable;
import android.util.Log;
import android.view.Menu;
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;

public class MainActivity extends Activity {
private int alpha=255;
private Button plus;
private Button minus;
private Button next;
private ImageView image;
private ImageView image2;
int currentImg=2;
//private BitmapDrawable bitmapdrawable;
//int [] images=new int[]{R.drawable.landscape,R.drawable.landscape1,R.drawable.landscape2,R.drawable.landscape3,R.drawable.landscape4,R.drawable.landscape5};
int [] images=new int[]{R.drawable.lijiang,R.drawable.qiao,R.drawable.shuangta,R.drawable.shui,R.drawable.xiangbi};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
plus=(Button)findViewById(R.id.upalpha);
minus=(Button)findViewById(R.id.lowalpha);
image=(ImageView)findViewById(R.id.imageView1);
next=(Button)findViewById(R.id.next);
image2=(ImageView)findViewById(R.id.imageView2);
OnClickListener listener=new OnClickListener()
{

@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
if(arg0==plus)
{
alpha+=20;
}
if(arg0==minus)
{
alpha-=20;
}
if(alpha>=255)
{
alpha=255;
}
if(alpha<0)
{
alpha=0;
}

image.setAlpha(alpha);
}

};
plus.setOnClickListener(listener);
minus.setOnClickListener(listener);
next.setOnClickListener(new OnClickListener()
{

@Override
public void onClick(View v) {
// TODO Auto-generated method stub

image.setImageResource(images[++currentImg%images.length]);

}

});

image.setOnTouchListener( new OnTouchListener() {

@Override
public boolean onTouch(View v, MotionEvent event) {
Log.i("Image","Test");
// TODO Auto-generated method stub
BitmapDrawable bitmapdrawable=(BitmapDrawable)image.getDrawable();
Bitmap bitmap=bitmapdrawable.getBitmap();
double scale=bitmap.getWidth()/320.0;
int x=(int) (event.getX()*scale);
int y=(int) (event.getY()*scale);

Log.i("Image","width"+bitmap.getWidth()+"height"+bitmap.getHeight());
Log.i("Image","x:"+x+"y:"+y);
if(x+120>bitmap.getWidth())
{
x=bitmap.getWidth()-120;
}
if(y+120>bitmap.getHeight())
{
y=bitmap.getHeight()-120;
}
Log.i("Image",""+x+" "+y);
image2.setImageBitmap(Bitmap.createBitmap(bitmap,x,y,120,120));
//alpha=0;
image2.setAlpha(alpha); // alpha 如果很小，会可能无法显示图片，原因是 图片透明了，所以无法看到图片。切记，。。

return false;
}

} );

}

@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;
}

}