Android 改变图片大小解决方案

    /* 相关变量声明 */
    private ImageView mImageView;
    private Button mButton01;
    private Button mButton02;
    private FrameLayout layout1;
    private LinearLayout layoutImage;
    private Bitmap bmp;
    private int id=0;
    private int displayWidth;
    private int displayHeight;
    private float scaleWidth=1;
    private float scaleHeight=1;
    
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState)    {
        super.onCreate(savedInstanceState);
        /* 加载display.xml Layout */
        setContentView(R.layout.display);
        
        /* 取得屏幕分辨率大小 */
        DisplayMetrics dm=new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(dm);
        displayWidth=dm.widthPixels;
        displayHeight=dm.heightPixels; 
        
        /* 初始化相关变量 */
        Bundle bundle = this.getIntent().getExtras();
        Integer imageId = bundle.getInt("imageId");
        Log.i(TAG, "onCreate, imageId = " + imageId);
                       
        bmp=BitmapFactory.decodeResource(getResources(), imageId); 
        mImageView = (ImageView)findViewById(R.id.myImageView);
        mImageView.setImageBitmap(bmp);
        mImageView.setOnTouchListener(this);
        mImageView.setLongClickable(true);
        
        layout1 = (FrameLayout)findViewById(R.id.layout1);
        layoutImage = (LinearLayout)findViewById(R.id.layoutImage);
        mButton01 = (Button)findViewById(R.id.myButton1);
        mButton02 = (Button)findViewById(R.id.myButton2); 
        
        /* 缩小按钮onClickListener */
        mButton01.setOnClickListener(new Button.OnClickListener() {
            @Override
            public void onClick(View v) {
                small(); 
            }
        });
        
        /* 放大按钮onClickListener */
        mButton02.setOnClickListener(new Button.OnClickListener() {
            @Override       
            public void onClick(View v) {
                big();
            } 
        });
    }

    /* 图片缩小的method */
    private void small()    {
        int bmpWidth=bmp.getWidth(); 
        int bmpHeight=bmp.getHeight();
        
        Log.i(TAG, "bmpWidth = " + bmpWidth + ", bmpHeight = " + bmpHeight);
        
        /* 设置图片缩小的比例 */
        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)      {
            /* 如果是第一次按，就删除原来默认的ImageView */
            layoutImage.removeView(mImageView);
        } else {
            /* 如果不是第一次按，就删除上次放大缩小所产生的ImageView */
            layoutImage.removeView((ImageView)findViewById(id));
        } 
        
        /* 产生新的ImageView，放入reSize的Bitmap对象，再放入Layout中 */
        id++;
        ImageView imageView = new ImageView(this);
        imageView.setId(id);
        imageView.setImageBitmap(resizeBmp);
        layoutImage.addView(imageView);
        Log.i(TAG, "imageView.getWidth() = " + imageView.getWidth()
                + ", imageView.getHeight() = " + imageView.getHeight());
        setContentView(layout1);
        /* 因为图片放到最大时放大按钮会disable，所以在缩小时把它重设为enable */ 
        mButton02.setEnabled(true);
        mButton02.setTextColor(Color.MAGENTA);
    }
    
    /* 图片放大的method */
    private void big() {
        int bmpWidth=bmp.getWidth();
        int bmpHeight=bmp.getHeight();
        
        Log.i(TAG, "bmpWidth = " + bmpWidth + ", bmpHeight = " + bmpHeight);
        
        /* 设置图片放大的比例 */
        double scale=1.25;
        /* 计算这次要放大的比例 */
        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) {
            /* 如果是第一次按，就删除原来设置的ImageView */
            layoutImage.removeView(mImageView);
        } else {
            /* 如果不是第一次按，就删除上次放大缩小所产生的ImageView */ 
            layoutImage.removeView((ImageView)findViewById(id));
        }
        
        /* 产生新的ImageView，放入reSize的Bitmap对象，再放入Layout中 */
        id++;
        ImageView imageView = new ImageView(this);
        imageView.setId(id);
        imageView.setImageBitmap(resizeBmp);
        layoutImage.addView(imageView);
        setContentView(layout1);
        /* 如果再放大会超过屏幕大小，就把Button disable */
        if( scaleWidth * scale * bmpWidth > bmpWidth * 3 ||
            scaleHeight * scale * bmpHeight > bmpWidth * 3 ||
            scaleWidth * scale * bmpWidth > displayWidth * 5 ||
            scaleHeight * scale * bmpHeight > displayHeight * 5) {
                mButton02.setEnabled(false);
                mButton02.setTextColor(Color.GRAY);
            } else {
                mButton02.setEnabled(true);
                mButton02.setTextColor(Color.MAGENTA);
            }
        }