如何在不改变大小的情况下旋转图像？

Question

我正在开发一个 android 应用程序，我必须在其中围绕另一个圆形图像旋转一个圆形图像，但是当我运行它时，我的圆形图像的大小会自动连续变化。所以请帮助我如何解决这个问题。这是我的代码

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
}

Answer 1

这个这个;完美地为我工作。

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;
    }

Answer 2

试试这个代码旋转图像 -

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);
}
}

另外，请参阅Tutorial

Answer 3

这是我围绕自身旋转图像并慢慢降低速度的代码

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();
                };
            });

Answer 4

这是旋转图像的代码

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);