缩放和滚动后HitArea的偏移量

时间:2012-06-13 09:43:20

标签: math android-layout

缩放和滚动后getHitRect的偏移量是多少。可以计算缩放后命中区域的偏移量 - (event.getX()/ ZoomLayout.mScaleFactor + ZoomLayout.mClipBound.left)但是我还没有想到缩放和滚动后命中区域的偏移量。

public class ZoomLayout extends RelativeLayout implements OnDoubleTapListener, OnGestureListener{


//ScalingFactor i.e. Amount of Zoom
static float mScaleFactor = 1.0f;

// Maximum and Minimum Zoom
private static float MIN_ZOOM = 1.0f;
private static float MAX_ZOOM = 2.0f;

//Different Operation to be used 
    private final int NONE_OPERATION=0;
    private final int DRAG_OPERATION=1;
    private final int ZOOM_OPERATION=2;
    private float mWidth= 1280;
    private float mHeight=800; 

// Mode to select the operation
    private int mode;

//Track X and Y coordinate of the finger when it first touches the screen
    private float mInitialX = 0f;
    private float mInitialY = 0f;

// Track the Bound of the Image after zoom to calculate the offset  
static Rect mClipBound;

// mDetector to detect the scaleGesture for the pinch Zoom  
private ScaleGestureDetector mDetector;

// mDoubleTapDetector to detect the double tap 
private GestureDetector mDoubleTapDetector;

//Pivot point for Scaling
static float gx=0,gy=0;

boolean mdrag=false,mZoom=false;

public ZoomLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
        setWillNotDraw(false);
        mClipBound = new Rect();
        // Intialize ScaleGestureDetector
        mDetector = new ScaleGestureDetector(getContext(), new ZoomListener());
        mDoubleTapDetector = new GestureDetector(context,this);
        mDoubleTapDetector.setOnDoubleTapListener(this);
    }


    public ZoomLayout(Context context) {
        super(context);
        setWillNotDraw(false);
        mClipBound = new Rect();
        // Intialize ScaleGestureDetector
        mDetector = new ScaleGestureDetector(getContext(), new ZoomListener());
        mDoubleTapDetector = new GestureDetector(context,this);
        mDoubleTapDetector.setOnDoubleTapListener(this);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {

        // Handles all type of motion-events possible
        switch(event.getAction() ) {

        case MotionEvent.ACTION_DOWN:
            // Event occurs when the first finger is pressed on the Screen

            Log.d("ZoomPrint", "Event: Action_Down " );
            mInitialX = event.getX();
            mInitialY = event.getY();

        break;
        case MotionEvent.ACTION_POINTER_DOWN:
            //Event occurs when the second finger is pressed down

            Log.d("ZoomPrint", "Event: Action_Pointer_Down " );
            // If second finger is pressed on the screen with the first set the Mode to Zoom operation
            mode=ZOOM_OPERATION;

            break;  
        case MotionEvent.ACTION_POINTER_UP:
            Log.d("ZoomPrint", "Event: Action_Pointer_UP " );
            mdrag=true;

        case MotionEvent.ACTION_UP: 
            //Event occurs when all the finger are taken of the screen
            Log.d("ZoomPrint", "Event: Action_UP " );
            //If all the fingers are taken up there will be no operation 
            mode = NONE_OPERATION;
            mdrag=false;

            break;  


        }
        // give the event to the mDetector to get the scaling Factor
            mDetector.onTouchEvent(event);


        // give the event to the mDoubleTapDetector for the doubleTap 
            mDoubleTapDetector.onTouchEvent(event);

        if(!mdrag)
            invalidate();

    return true;
    }


    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        onTouchEvent(ev);
        return super.onInterceptTouchEvent(ev);
    //  return true;
    }







    @Override
    public ViewParent invalidateChildInParent(int[] location, Rect dirty) {
        return super.invalidateChildInParent(location, dirty);
    }




    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b)
    {
        int count = getChildCount();
        for(int i=0;i<count;i++){
            View child = getChildAt(i); 
            if(child.getVisibility()!=GONE){
                RelativeLayout.LayoutParams params = (RelativeLayout.LayoutParams)child.getLayoutParams();
                child.layout(
                    (int)(params.leftMargin ), 
                    (int)(params.topMargin ), 
                    (int)((params.leftMargin + child.getMeasuredWidth()) ), 
                    (int)((params.topMargin + child.getMeasuredHeight())) 
                    );
            }
        }
    }



    @Override
    protected void dispatchDraw(Canvas canvas) {

        //Save the canvas to set the scaling factor returned from detector
        canvas.save(Canvas.MATRIX_SAVE_FLAG);

        canvas.scale(mScaleFactor, mScaleFactor,gx,gy);     

        super.dispatchDraw(canvas);

        mClipBound = canvas.getClipBounds();

          canvas.restore();
    }



    private class ZoomListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {


            @Override
            public boolean onScale(ScaleGestureDetector detector) {
                // getting the scaleFactor from the detector
                mScaleFactor *= detector.getScaleFactor();              // gives the scaling factor from the previous scaling to the current
            //  Log.d("ZoomPrint", "detector scaling Factor" + mScaleFactor);

                gx = detector.getFocusX();
                gy = detector.getFocusY();
                // Limit the scale factor in the MIN and MAX bound
                mScaleFactor= Math.max(Math.min(mScaleFactor, MAX_ZOOM),MIN_ZOOM);
            //  Log.d("ZoomPrint", "Bounded scaling Factor" + mScaleFactor);

                /*//Force canvas to redraw itself only if the one event is to happen (say Zooming only ) else do not invalidate here for multi operations
                   As what we de for scrolling or panning will not reflect here. So we will add this in onDraw method 
                invalidate();*/
                 // Here we are only zooming so invalidate has to be done
            //  invalidate();
             //  requestLayout();

                // we have handle the onScale 
                return true;
            }



        }


        @Override
        public boolean onDoubleTap(MotionEvent e) {

        // Make the mScaleFactor to its normal value
            if(mScaleFactor>1.0f)
            {
                    mScaleFactor=1.0f;
            }
        // Force the canvas to redraw itself again as the changes has been occured.
        invalidate();
        requestLayout();
            return false;
        }


        @Override
        public boolean onDoubleTapEvent(MotionEvent e) {
        //  Log.d("ZoomPrint", "OnDoubleTapEvent");
            return false;
        }


        @Override
        public boolean onSingleTapConfirmed(MotionEvent e) {
        //  Log.d("ZoomPrint", "OnSingleTap");
            return false;
        }


        @Override
        public boolean onDown(MotionEvent e) {
            // TODO Auto-generated method stub
            return false;
        }


        @Override
        public boolean onFling(MotionEvent e1, MotionEvent e2,
                float velocityX, float velocityY) {
            return false;
        }


        @Override
        public void onLongPress(MotionEvent e) {

        }


     @Override
            public boolean onScroll(MotionEvent e1, MotionEvent e2,
                    float distanceX, float distanceY) {

                    int distX= (int) distanceX, distY =(int) distanceY;

        //Log.d("Print"," X " + this.mClipBound.left +" Y " + this.mClipBound.right + " b "+ this.mClipBound.bottom + " g" + this.mClipBound.top) ;

        Log.d("Print", "Scroll X " + distanceX + " Y " + distanceY);    

                if(this.mClipBound.left<=0)
                    this.scrollTo(-280, 0);
                else if(this.mClipBound.top<=0)
                    this.scrollTo(0, -250);
                    else if (this.mClipBound.right>=1047)
                        this.scrollTo(280, 0);
                    else if (this.mClipBound.bottom>=800)
                        this.scrollTo(0, 250);
                    else
                    this.scrollBy((int)distanceX,(int)distanceY);


                    return true;

            }


        @Override
        public void onShowPress(MotionEvent e) {

        }


        @Override
        public boolean onSingleTapUp(MotionEvent e) {
            return false;
        }

1 个答案:

答案 0 :(得分:1)

您需要在滚动功能期间翻译画布。我在我的代码中以这种方式完成了它:

canvas.translate(getScrollX(), getScrollY());

getScrollX和Y是滚动量。