android - 如何限制缩小android

Question

缩小时(放大后)如何限制图像的大小，我希望图像的最小尺寸与正常尺寸相同，但比正常尺寸小，看图片附件截图 . 这是我的初始化变量:

private static final String TAG = "Touch";
    @SuppressWarnings("unused")
    private static final float MIN_ZOOM = 1f,MAX_ZOOM = 1f;

    // These matrices will be used to scale points of the image
    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 = 1f; 

这里是我的源代码:

@Override
    public boolean onTouch(View v, MotionEvent event) {
        // TODO Auto-generated method stub
        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());
                mode = DRAG;
                break;

            case MotionEvent.ACTION_UP: // first finger lifted

            case MotionEvent.ACTION_POINTER_UP: // second finger lifted
                mode = NONE;
                break;

            case MotionEvent.ACTION_POINTER_DOWN: // first and second finger down
                oldDist = spacing(event);
                Log.d(TAG, "oldDist=" + oldDist);
                if (oldDist > 5f) {
                    savedMatrix.set(matrix);
                    midPoint(mid, event);
                    mode = ZOOM;
                }
                break;

            case MotionEvent.ACTION_MOVE:
                if (mode == DRAG) 
                { 
                    matrix.set(savedMatrix);
                    //matrix.postTranslate(0,0);
                    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);
                    if (newDist > 5f) 
                    {
                        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);
                        Log.d(TAG, "scale=" + scale);
                    }
                }
                break;
        }

        view.setImageMatrix(matrix); // display the transformation on screen
        return true; // indicate event was handled                      
    }


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

    /** Show an event in the LogCat view, for debugging */
    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("]");
    }

Answer 1

public void checkZoom(){
    float[] values = new float[9];
    matrix.getValues(values);

    float scaleX = values[Matrix.MSCALE_X];
    float scaleY = values[Matrix.MSCALE_Y];
    if(scaleX > MAX_ZOOM) {
    scaleX = MAX_ZOOM;
    } else if(scaleX < MIN_ZOOM) {
    scaleX = MIN_ZOOM;
    }

    if(scaleY > MAX_ZOOM) {
    scaleY = MAX_ZOOM;
    } else if(scaleY < MIN_ZOOM) {
    scaleY = MIN_ZOOM;
    }

    values[Matrix.MSCALE_X] = scaleX;
    values[Matrix.MSCALE_Y] = scaleY; 
    matrix.setValues(values);
}