如何添加限制放大＆amp;缩小为imageview android

Question

我运行此代码的问题图像放大=无限！ 并缩小=无限！

我想添加放大限制＆amp;缩小..请帮助

问候。

这是我的班级代码：

Map.java

public class Map extends Fragment implements View.OnTouchListener {

private static final String TAG = "Touch";
@SuppressWarnings("unused")
private static final float MIN_ZOOM = 0.1f, MAX_ZOOM = 0.1f;

Matrix matrix = new Matrix();
Matrix savedMatrix = new Matrix();

// The 3 states (events) which the user is trying to perform
static final int NONE = 0;
static final int DRAG = 1;
static final int ZOOM = 2;
int mode = NONE;

// these PointF objects are used to record the point(s) the user is touching
PointF start = new PointF();
PointF mid = new PointF();
float oldDist = 0.1f;

public Map(){
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View v = inflater.inflate(R.layout.x_map, container, false);
    ImageView view = (ImageView) v.findViewById(R.id.imageView1);
    view.setOnTouchListener(this);
    return v;
}

@Override
public boolean onTouch(View v, MotionEvent event) {
    ImageView view = (ImageView) v;
    view.setScaleType(ImageView.ScaleType.MATRIX);
    float scale;

    dumpEvent(event);
    // Handle touch events here...

    switch (event.getAction() & MotionEvent.ACTION_MASK) {
        case MotionEvent.ACTION_DOWN: // first finger down only
            savedMatrix.set(matrix);
            start.set(event.getX(), event.getY());
            Log.d(TAG, "mode=DRAG"); // write to LogCat
            mode = DRAG;
            break;

        case MotionEvent.ACTION_UP:
        case MotionEvent.ACTION_POINTER_UP:

            mode = NONE;
            Log.d(TAG, "mode=NONE");
            break;

        case MotionEvent.ACTION_POINTER_DOWN:
            oldDist = spacing(event);
            Log.d(TAG, "oldDist=" + oldDist);
            if (oldDist > 0.1f) {
                savedMatrix.set(matrix);
                midPoint(mid, event);
                mode = ZOOM;
                Log.d(TAG, "mode=ZOOM");
            }
            break;

        case MotionEvent.ACTION_MOVE:

            if (mode == DRAG) {
                matrix.set(savedMatrix);
                matrix.postTranslate(event.getX() - start.x, event.getY()
                        - start.y); /*
                                 * create the transformation in the matrix
                                 * of points
                                 */
            } else if (mode == ZOOM) {
                // pinch zooming
                float newDist = spacing(event);
                Log.d(TAG, "newDist=" + newDist);
                if (newDist > 1f) {
                    matrix.set(savedMatrix);
                    scale = newDist / oldDist;
                /*
                 * setting the scaling of the matrix...if scale > 1 means
                 * zoom in...if scale < 1 means zoom out
                 */
                    matrix.postScale(scale, scale, mid.x, mid.y);
                }
            }
            break;
    }

    view.setImageMatrix(matrix); // display the transformation on screen

    return true;
}

private float spacing(MotionEvent event) {
    float x = event.getX(0) - event.getX(1);
    float y = event.getY(0) - event.getY(1);
    return (float) Math.sqrt(x * x + y * y);
}


private void midPoint(PointF point, MotionEvent event) {
    float x = event.getX(0) + event.getX(1);
    float y = event.getY(0) + event.getY(1);
    point.set(x / 2, y / 2);
}

private void dumpEvent(MotionEvent event) {
    String names[] = { "DOWN", "UP", "MOVE", "CANCEL", "OUTSIDE",
            "POINTER_DOWN", "POINTER_UP", "7?", "8?", "9?" };
    StringBuilder sb = new StringBuilder();
    int action = event.getAction();
    int actionCode = action & MotionEvent.ACTION_MASK;
    sb.append("event ACTION_").append(names[actionCode]);

    if (actionCode == MotionEvent.ACTION_POINTER_DOWN
            || actionCode == MotionEvent.ACTION_POINTER_UP) {
        sb.append("(pid ").append(
                action >> MotionEvent.ACTION_POINTER_ID_SHIFT);
        sb.append(")");
    }

    sb.append("[");
    for (int i = 0; i < event.getPointerCount(); i++) {
        sb.append("#").append(i);
        sb.append("(pid ").append(event.getPointerId(i));
        sb.append(")=").append((int) event.getX(i));
        sb.append(",").append((int) event.getY(i));
        if (i + 1 < event.getPointerCount())
            sb.append(";");
    }

    sb.append("]");
    Log.d("Touch Event", sb.toString());
    }
 }

这是我的布局：

map.xml

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >

<ImageView
    android:id="@+id/imageView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:src="@drawable/map" />

</FrameLayout>