android - 如何在android中旋转带有固定点的图像以及触摸

Question

我一直在寻找这个问题的解决方案一天多了，但没有任何帮助，甚至这里的答案也没有帮助我。我的问题是我的图像在旋转，但旋转时位图大小没有变化。

这是我的代码

package dharam.rotate;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.os.Bundle;
import android.provider.ContactsContract.CommonDataKinds.Event;
import android.util.Log;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.View;
import android.view.Window;
import android.widget.ImageView;
import android.widget.TextView;

public class Rotate extends Activity {
    View baseView ;
    ImageView turntable;
    TextView bottomText;
    GestureDetector   gestureDetector;
    private float x , y;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    setContentView(R.layout.main);

    baseView = (View) findViewById(R.id.baseView);
    turntable = (ImageView) findViewById(R.id.turntable);

    turntable.setOnTouchListener(onTableTouched);
    baseView.setOnTouchListener(onTableTouched);
}

public android.view.View.OnTouchListener onTableTouched = new android.view.View.OnTouchListener() {
    public boolean onTouch(View v, MotionEvent evt) {
        double r = Math.atan2(evt.getX() - turntable.getWidth() / 2,
                (turntable.getHeight() / 2) - evt.getY());
        int rotation = (int) Math.toDegrees(r);
        Log.i("R is ", ""+r);
        if (evt.getAction() == MotionEvent.ACTION_DOWN) {
        }

        if (evt.getAction() == MotionEvent.ACTION_MOVE) {
            x= evt.getX();
            y= evt.getY();
            updateRotation(rotation);
        }

        if (evt.getAction() == MotionEvent.ACTION_UP) {
                //
        }
        return true;
    }
};
private void updateRotation(double rot) {
    float newRot = new Float(rot);
    Bitmap bitmap = BitmapFactory.decodeResource(getResources(),
    R.drawable.orsl_circle_transparent);
    Matrix matrix = new Matrix();
//        matrix.setTranslate(getWindowManager().getDefaultDisplay().getWidth()/2, getWindowManager().getDefaultDisplay().getHeight());
        matrix.postRotate(newRot,bitmap.getWidth()/2,bitmap.getHeight()/2);
//      matrix.setSinCos(newRot, newRot/2, 100, 100);
//      matrix.postRotate(newRot);
        Log.i("THE ROATTION ", "  "+    newRot);

    if(y>250)
    {
        Bitmap redrawnBitmap = Bitmap.createBitmap(bitmap, 0, 0, bitmap
                .getWidth(), bitmap.getHeight(), matrix, true);
        turntable.setImageBitmap(redrawnBitmap);
    }else
    {
        Bitmap  redrawnBitmap = Bitmap.createBitmap(bitmap, 0, 0, bitmap
                .getWidth(), bitmap.getHeight(), matrix, true);
         turntable.setImageBitmap(redrawnBitmap);
         Log.i("GUITAR _IMAGE", "");
    }

}

Answer 1

我想你想在用户触摸屏幕的地方旋转图像？如果是这样，像这个例子一样扩展 SimpleOnGestureListener:

public class MyGestureDetector extends SimpleOnGestureListener
{       

    @Override
    public void onLongPress(MotionEvent event)
    {
        int X = (int)event.getX();          
        int Y = (int)event.getY();

        ...Rotate the image
    }
}

获得触摸事件的屏幕坐标后，您可以围绕该点应用旋转动画 - 有关更多详细信息，请参见此处:http://developer.android.com/guide/topics/graphics/2d-graphics.html