How to rotate the image without changing its size?

问题

I am developing an android app where I have to rotate a circular image around another circular image, but when I am running this the size of my circular image gets automatically changing continuously. So please help me how to solve this. Here is my code

public class JobSearch extends Activity implements OnTouchListener {
    private ImageView dialer;
    private float y=0;
    public boolean onTouch(View v, MotionEvent event) {
        double r=Math.atan2(event.getX()-dialer.getWidth()/2, dialer.getHeight()/2-event.getY());
        int rotation=(int)Math.toDegrees(r);
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                break;
            case MotionEvent.ACTION_MOVE:
                //x=event.getX();
                y=event.getY();
                updateRotation(rotation);
                break;
            case MotionEvent.ACTION_UP:
                break;
        }//switch       
     return true;    
    }//onTouch
    private void updateRotation(double rot){
        float newRot=new Float(rot);
        Bitmap bitmap=BitmapFactory.decodeResource(getResources(),R.drawable.round_button_big);
        Matrix matrix=new Matrix();
        matrix.postRotate(newRot);//,bitmap.getWidth()/2,bitmap.getHeight()/2);
        Bitmap reDrawnBitmap=Bitmap.createBitmap(bitmap,0,0,bitmap.getWidth(),bitmap.getHeight(),matrix,true);
        dialer.setImageBitmap(reDrawnBitmap);
        if(newRot>=-5 && newRot<=5)
            Toast.makeText(this,"12 O\'Clock",Toast.LENGTH_SHORT).show();
        if(newRot>=85 && newRot<=95)
            Toast.makeText(this,"3 O\'Clock",Toast.LENGTH_SHORT).show();
        if(newRot>=175 || newRot<=-175)
            Toast.makeText(this,"6 O\'Clock",Toast.LENGTH_SHORT).show();
        if(newRot>=-95 && newRot<=-85)
            Toast.makeText(this,"9 O\'Clock",Toast.LENGTH_SHORT).show();
    }
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        dialer = (ImageView) findViewById(R.id.big_button);
        dialer.setOnTouchListener(this);
    }//onCreate
}

回答1:

Try this code for Rotating Image -

public class bitmaptest extends Activity {
@Override
public void onCreate(Bundle icicle) {
    super.onCreate(icicle);
    LinearLayout linLayout = new LinearLayout(this);

    // load the origial BitMap (500 x 500 px)
    Bitmap bitmapOrg = BitmapFactory.decodeResource(getResources(),
           R.drawable.android);

    int width = bitmapOrg.width();
    int height = bitmapOrg.height();
    int newWidth = 200;
    int newHeight = 200;

    // calculate the scale - in this case = 0.4f
    float scaleWidth = ((float) newWidth) / width;
    float scaleHeight = ((float) newHeight) / height;

    // createa matrix for the manipulation
    Matrix matrix = new Matrix();
    // resize the bit map
    matrix.postScale(scaleWidth, scaleHeight);
    // rotate the Bitmap
    matrix.postRotate(45);

    // recreate the new Bitmap
    Bitmap resizedBitmap = Bitmap.createBitmap(bitmapOrg, 0, 0,
                      width, height, matrix, true);

    // make a Drawable from Bitmap to allow to set the BitMap
    // to the ImageView, ImageButton or what ever
    BitmapDrawable bmd = new BitmapDrawable(resizedBitmap);

    ImageView imageView = new ImageView(this);

    // set the Drawable on the ImageView
    imageView.setImageDrawable(bmd);

    // center the Image
    imageView.setScaleType(ScaleType.CENTER);

    // add ImageView to the Layout
    linLayout.addView(imageView,
            new LinearLayout.LayoutParams(
                  LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT
            )
    );

    // set LinearLayout as ContentView
    setContentView(linLayout);
}
}

And, also see this Tutorial

回答2:

This this one; worked for me perfectly.

private Bitmap rotateBitmap(Bitmap bitmap, int rotationAngleDegree){

        int w = bitmap.getWidth();
        int h = bitmap.getHeight();

        int newW=w, newH=h;
        if (rotationAngleDegree==90 || rotationAngleDegree==270){
            newW = h;
            newH = w;
        }
        Bitmap rotatedBitmap = Bitmap.createBitmap(newW,newH, bitmap.getConfig());
        Canvas canvas = new Canvas(rotatedBitmap);

        Rect rect = new Rect(0,0,newW, newH);
        Matrix matrix = new Matrix();
        float px = rect.exactCenterX();
        float py = rect.exactCenterY();
        matrix.postTranslate(-bitmap.getWidth()/2, -bitmap.getHeight()/2);
        matrix.postRotate(rotationAngleDegree);
        matrix.postTranslate(px, py);
        canvas.drawBitmap(bitmap, matrix, new Paint( Paint.ANTI_ALIAS_FLAG | Paint.DITHER_FLAG | Paint.FILTER_BITMAP_FLAG ));
        matrix.reset();

        return rotatedBitmap;
    }

回答3:

This is my code to rotate image around itself and slowly reduce the speed

rotateAnimation1 = new RotateAnimation(0, 360,
                    Animation.RELATIVE_TO_SELF, 0.5f,
                    Animation.RELATIVE_TO_SELF, 0.5f);
            rotateAnimation1.setInterpolator(new LinearInterpolator());
            rotateAnimation1.setDuration(duration);
            rotateAnimation1.setRepeatCount(0);
            imgBottle.startAnimation(rotateAnimation1);

            flagSpinAvailable = false;

            rotateAnimation1.setAnimationListener(new AnimationListener() {
                public void onAnimationStart(Animation anim) {
                };

                public void onAnimationRepeat(Animation anim) {
                };

                public void onAnimationEnd(Animation anim) {
                    duration = duration + 70;
                    startMoving();
                };
            });

回答4:

this is the code of rotate the image

Bitmap bMap = BitmapFactory.decodeResource(getResources(),R.drawable.test);
Matrix mat = new Matrix();
mat.postRotate(90);
Bitmap bMapRotate = Bitmap.createBitmap(bMap, 0, 0,
                         bMap.getWidth(), bMap.getHeight(), mat, true);
BitmapDrawable bmd = new BitmapDrawable(bMapRotate);
image.setImageBitmap(bMapRotate);
image.setImageDrawable(bmd);

来源：https://stackoverflow.com/questions/8923920/how-to-rotate-the-image-without-changing-its-size