Android Open Source - android-animation-task Rotation Gesture Detector

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License

The source code is released under:

GNU General Public License

Java Source Code

package gesture;
//from w w w . ja va2s.  c o  m
import android.view.MotionEvent;

public class RotationGestureDetector {
    private RotationGestureListener mListener;

    private float mX1, mY1, mX2, mY2;
    private int mPointerID1, mPointerID2;
    private float mFocusX, mFocusY;
    private float mAngle;

    public RotationGestureDetector(RotationGestureListener listener)
    {
        mListener = listener;
    }

    public boolean onTouchEvent(MotionEvent event) {
        int eventAction = event.getActionMasked();
        int pointerIndex = event.getActionIndex();
        int pointerId = event.getPointerId(pointerIndex);
        float x = event.getX(pointerIndex);
        float y = event.getY(pointerIndex);

        switch (eventAction) {
            case MotionEvent.ACTION_DOWN:
                mPointerID1 = pointerId;
                mPointerID2 = -1;
                mX1 = x;
                mY1 = y;
                break;

            case MotionEvent.ACTION_POINTER_DOWN:
                if (mPointerID1 == -1)
                {
                    mPointerID1 = pointerId;
                    mX1 = x;
                    mY1 = y;
                    if (mPointerID2 != -1)
                    {
                        int ptrIndex = event.findPointerIndex(mPointerID2);
                        mX2 = event.getX(ptrIndex);
                        mY2 = event.getY(ptrIndex);
                        mListener.onRotationBegin(this);
                    }
                }
                else if (mPointerID2 == -1)
                {
                    mPointerID2 = pointerId;
                    mX2 = x;
                    mY2 = y;
                    if (mPointerID1 != -1)
                    {
                        int ptrIndex = event.findPointerIndex(mPointerID1);
                        mX1 = event.getX(ptrIndex);
                        mY1 = event.getY(ptrIndex);
                        mListener.onRotationBegin(this);
                    }
                }
                break;

            case MotionEvent.ACTION_MOVE:
                if(mPointerID1 != -1 && mPointerID2 != -1)
                {
                    // 1
                    float x1 = event.getX(event.findPointerIndex(mPointerID1));
                    float y1 = event.getY(event.findPointerIndex(mPointerID1));
                    float x2 = event.getX(event.findPointerIndex(mPointerID2));
                    float y2 = event.getY(event.findPointerIndex(mPointerID2));

                    // 2
                    float angle1 = calcAngle(mX1, mY1, mX2, mY2);
                    float angle2 = calcAngle(x1, y1, x2, y2);

                    // 3
                    float deltaAngle = angle2 - angle1;
                    if (deltaAngle < -180.0f)
                    {
                        deltaAngle += 360.0f;
                    }
                    else if (deltaAngle > 180.0f)
                    {
                        deltaAngle -= 360.0f;
                    }
                    mAngle = deltaAngle;

                    // 4
                    mX2 = x2;
                    mY2 = y2;
                    mX1 = x1;
                    mY1 = y1;

                    // 5
                    mFocusX = calcCenter(x1, x2);
                    mFocusY = calcCenter(y1, y2);

                    // 6
                    mListener.onRotation(this);
                }
                break;

            case MotionEvent.ACTION_UP:
                mPointerID1 = -1;
                mPointerID2 = -1;
                break;

            case MotionEvent.ACTION_POINTER_UP:
                if (mPointerID1 == pointerId)
                {
                    mPointerID1 = -1;
                    if (mPointerID2 != -1)
                    {
                        mListener.onRotationEnd(this);
                    }
                }
                else if (mPointerID2 == pointerId)
                {
                    mPointerID2 = -1;
                    if (mPointerID1 != -1)
                    {
                        mListener.onRotationEnd(this);
                    }
                }
                break;
        }

        return true;
    }


    private float calcCenter(float p1, float p2)
    {
        return (p1 + p2) / 2;
    }

    private float calcAngle(float x1, float y1, float x2, float y2)
    {
        return (float)Math.toDegrees(Math.atan2((y2 - y1), (x2 - x1)));
    }

    public float getX1()
    {
        return mX1;
    }

    public float getY1()
    {
        return mY1;
    }

    public float getX2()
    {
        return mX2;
    }

    public float getY2()
    {
        return mY2;
    }

    public float getFocusX()
    {
        return mFocusX;
    }

    public float getFocusY()
    {
        return mFocusY;
    }

    public float getDeltaAngle()
    {
        return mAngle;
    }
}

Java Source Code List

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