MainActivity.java

package com.zhang.showPhoto; import android.app.ActionBar.LayoutParams;import android.app.Activity;import android.os.Bundle;import android.view.View;import android.view.View.OnClickListener;import android.view.animation.AnimationUtils;import android.widget.Button;import android.widget.ImageSwitcher;import android.widget.ImageView;import android.widget.ViewSwitcher.ViewFactory; public class MainActivity extends Activity { private int[] imagId=new int[]{ R.drawable.img01,R.drawable.img02,R.drawable.img03,R.drawable.img04, R.drawable.img05,R.drawable.img06,R.drawable.img07,R.drawable.img08, R.drawable.img09,R.drawable.img10 }; private int index=0; private ImageSwitcher imageSwitcher; private Button up,down; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); up=(Button) findViewById(R.id.bt1); down=(Button) findViewById(R.id.bt2); imageSwitcher=(ImageSwitcher) findViewById(R.id.imagSw1); imageSwitcher.setInAnimation(AnimationUtils.loadAnimation(this, android.R.anim.fade_in)); imageSwitcher.setOutAnimation(AnimationUtils.loadAnimation(this, android.R.anim.fade_out)); imageSwitcher.setFactory(new ViewFactory() { public View makeView() { ImageView imageView = new ImageView(MainActivity.this); imageView.setScaleType(ImageView.ScaleType.FIT_CENTER); imageView.setLayoutParams(new ImageSwitcher.LayoutParams( LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT )); return imageView; } }); imageSwitcher.setImageResource(imagId[index]); up.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { if(index>0){ index--; }else{ index=imagId.length-1; } imageSwitcher.setImageResource(imagId[index]); } }); down.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { if(index<imagId.length-1){ index++; }else{ index=0; } imageSwitcher.setImageResource(imagId[index]); } }); } }

main.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:background="@drawable/bg1" android:id="@+id/llayout" android:layout_width="fill_parent" android:layout_height="fill_parent" android:gravity="center" android:orientation="horizontal" > <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="上一张" android:id="@+id/bt1" /> <ImageSwitcher android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/imagSw1" android:layout_gravity="center" /> <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="下一张" android:id="@+id/bt2" /> </LinearLayout>

再来看一段代码

// 获取图片的宽高 BitmapFactory.Options opt = new BitmapFactory.Options(); opt.inJustDecodeBounds = true; try{ bitmapIn = BitmapFactory.decodeFile(Puzzle.user.CUSTOM_IMAGE[customImage], opt); }catch(Exception e){ if(D) Log.d(TAG,"error"); return; } int in_w=opt.outWidth,in_h=opt.outHeight; // 获取imageview的尺寸 注意imageview的宽高比要与原图相同 否则需要另行计算 full_w = imageview.getWidth() full_h = getHeight() // 计算缩放比例 带有四舍五入 int Size_rate=(in_w*in_h*10)/(full_w*full_h); if(Size_rate>10){ Size_rate+=5; Size_rate/=10; }else{ Size_rate=1; } // 重新设置opt 读取图片文件 opt.inSampleSize=Size_rate; opt.inJustDecodeBounds = false; opt.inScaled = false; opt.outWidth=full_w; opt.outHeight=full_h; bitmapIn = BitmapFactory.decodeFile(Puzzle.user.CUSTOM_IMAGE[customImage], opt);}