android - 我正在使用矩阵拖放图像，但它跨越了屏幕边界

Question

我正在使用矩阵拖放图像，但它跨越了屏幕边界。当我向上拖动时，它跨越了屏幕边界，以及如何将图像向下拖动到某个高度。

    public class MainActivity extends Activity {

        // mainLayout is the child of the HorizontalScrollView ...
        private LinearLayout mainLayout;

        // this is an array that holds the IDs of the drawables ...
        private int[] images = { R.drawable.dd, R.drawable.ss };


        int Measuredwidth = 0, MeasuredHeight = 0;
        float x = 0;


        View cell = null;
        Matrix matrix = new Matrix();
        Matrix savedMatrix = new Matrix();
        PointF startPoint = new PointF();

        static final int DRAG = 1;

        int mode = NONE;


        /** Called when the activity is first created. */
        @Override
        public void onCreate(Bundle icicle) {
            super.onCreate(icicle);

            setContentView(R.layout.activity_main);

            mainLayout = (LinearLayout) findViewById(R.id.linearLayout);

            for (int i = 0; i < images.length; i++) {

                cell = getLayoutInflater().inflate(R.layout.image, null);
                final ImageView img = (ImageView) cell.findViewById(R.id.imageView);
                img.setImageResource(images[i]);



                Point size = new Point();
                WindowManager w = getWindowManager();
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB_MR2) {
                    w.getDefaultDisplay().getSize(size);
                    MeasuredHeight = size.y;
                    Measuredwidth = size.x;
                } else {
                    Display d = w.getDefaultDisplay();
                    Measuredwidth = d.getWidth();
                    MeasuredHeight = d.getHeight();
                }

                AbsoluteLayout aalayout = (AbsoluteLayout) cell
                        .findViewById(R.id.absLayout);

                Button btn = (Button) cell.findViewById(R.id.button1);
                btn.setOnClickListener(new OnClickListener() {

                    @Override
                    public void onClick(View v) {
                        // TODO Auto-generated method stub
                        Toast.makeText(getApplicationContext(), "mcdk", 2000)
                                .show();

                    }
                });

                aalayout.setOnTouchListener(new View.OnTouchListener() {
                    public boolean onTouch(View v, MotionEvent event) {

                        System.out.println("matrix=" + savedMatrix.toString());
                        switch (event.getAction() & MotionEvent.ACTION_MASK) {
                        case MotionEvent.ACTION_DOWN:

                            System.out.println("imge dowm press");
                            savedMatrix.set(matrix);

                            startPoint.set(img.getLeft(), event.getY());

                            break;
                        case MotionEvent.ACTION_MOVE:

                            System.out.println("imgeup press");
                            float dx = event.getX() -startPoint.x;
                            float dy = event.getY() - startPoint.y;

                            System.out.println("startpointy: "+startPoint.y);

                            System.out.println("dy: "+event.getY());

                            matrix.set(savedMatrix);
                            int height = img.getHeight();
                            int h1 = height/1;


    //                      if (( event.getY() >10) && (event.getY() < h1)){
                                System.out.println("imge height: "+h1);
                                matrix.postTranslate(img.getLeft(), dy);

    //                      }



                            break;
                        }

                        img.setImageMatrix(matrix);
                        return true;
                    }

                });
                System.out.println("bmgbgklb");
                mainLayout.addView(cell);
            }
        }
    }