android图片缩小和放大Matrix

public class ex04_22 extends Activity{

private ImageView mImageView;
private Button btn1,btn2;
private TextView mTextView;
private AbsoluteLayout layout1;
private Bitmap bmp;
private int id=0;
private int displayWidth,displayHeight;
private float scaleWidth=1,scaleHeight=1;
private final static String filename=\”/data/data/ex04_22.lcs/ex04_22_2.png\”;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
//取得屏幕分辨率
DisplayMetrics dm=new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(dm);
displayWidth=dm.widthPixels;
displayHeight=dm.heightPixels-80;

bmp=BitmapFactory.decodeResource(this.getResources(),R.drawable.ex04_22_1);
layout1=(AbsoluteLayout)findViewById(R.id.layout1);
mImageView=(ImageView)findViewById(R.id.myImageView);
btn1=(Button)findViewById(R.id.myButton1);
btn1.setOnClickListener(new OnClickListener(){
public void onClick(View v){
small();
}
});
btn2=(Button)findViewById(R.id.myButton2);
btn2.setOnClickListener(new OnClickListener(){
public void onClick(View v){
big();
}
});
}
private void small(){
//获得Bitmap的高和宽
int bmpWidth=bmp.getWidth();
int bmpHeight=bmp.getHeight();
//设置缩小比例
double scale=0.8;
//计算出这次要缩小的比例
scaleWidth=(float)(scaleWidth*scale);
scaleHeight=(float)(scaleHeight*scale);
//产生resize后的Bitmap对象
Matrix matrix=new Matrix();
matrix.postScale(scaleWidth, scaleHeight);
Bitmap resizeBmp=Bitmap.createBitmap(bmp, 0, 0, bmpWidth, bmpHeight, matrix, true);
if(id==0){
layout1.removeView(mImageView);
}
else{
layout1.removeView((ImageView)findViewById(id));

}
id++;
ImageView imageView=new ImageView(this);
imageView.setId(id);
imageView.setImageBitmap(resizeBmp);
layout1.addView(imageView);
setContentView(layout1);
btn2.setEnabled(true);
}
private void big(){
//获得Bitmap的高和宽
int bmpWidth=bmp.getWidth();
int bmpHeight=bmp.getHeight();
//设置缩小比例
double scale=1.25;
//计算出这次要缩小的比例
scaleWidth=(float)(scaleWidth*scale);
scaleHeight=(float)(scaleHeight*scale);
//产生resize后的Bitmap对象
Matrix matrix=new Matrix();
matrix.postScale(scaleWidth, scaleHeight);
Bitmap resizeBmp=Bitmap.createBitmap(bmp, 0, 0, bmpWidth, bmpHeight, matrix, true);
if(id==0){
layout1.removeView(mImageView);
}
else{
layout1.removeView((ImageView)findViewById(id));

}
id++;
ImageView imageView=new ImageView(this);
imageView.setId(id);
imageView.setImageBitmap(resizeBmp);
layout1.addView(imageView);
setContentView(layout1);
if(scaleWidth*scale*bmpWidth>displayWidth||scaleHeight*scale*scaleHeight>displayHeight){
btn2.setEnabled(false);
}
}
}
xml文件
<?xml version=\”1.0\” encoding=\”utf-8\”?>
<AbsoluteLayout
android:id=\”@+id/layout1\”
android:layout_width=\”fill_parent\”
android:layout_height=\”fill_parent\”
xmlns:android=\”http://schemas.android.com/apk/res/android\”
>
<ImageView
android:id=\”@+id/myImageView\”
android:layout_width=\”200px\”
android:layout_height=\”150px\”
android:src=\”@drawable/ex04_22_1\”
android:layout_x=\”0px\”
android:layout_y=\”0px\”
>
</ImageView>
<Button
android:id=\”@+id/myButton1\”
android:layout_width=\”90px\”
android:layout_height=\”60px\”
android:text=\”缩小\”
android:textSize=\”18sp\”
android:layout_x=\”20px\”
android:layout_y=\”372px\”
>
</Button>
<Button
android:id=\”@+id/myButton2\”
android:layout_width=\”90px\”
android:layout_height=\”60px\”
android:text=\”放大\”
android:textSize=\”18sp\”
android:layout_x=\”210px\”
android:layout_y=\”372px\”
>
</Button>
</AbsoluteLayout>