在拖動ImageView時偵聽容器邊緣

Question

我有一個大於顯示容器的圖像。圖像在容器內可拖動，目前它可以在容器中的任何位置拖動。我想停止圖像的頂部與容器頂部匹配時被拖動。

我的代碼：

@Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
      Bundle savedInstanceState) { 
     View rootView = inflater.inflate(R.layout.fragment_main, container, 
       false); 

     frame = (ViewGroup) rootView.findViewById(R.id.frame1); 


     imageView = (ImageView) rootView.findViewById(R.id.imageView1); 

     imageView.setOnTouchListener(new OnTouchListener() { 

      @Override 
      public boolean onTouch(View v, MotionEvent event) { 

       final int X = (int) event.getRawX(); 
       final int Y = (int) event.getRawY(); 

       LayoutParams layoutParams = (LayoutParams) imageView.getLayoutParams(); 

       Log.d("Alert", imageView.getId() + " pressed"); 

       switch (event.getAction() & MotionEvent.ACTION_MASK) { 
       case MotionEvent.ACTION_DOWN: 
        RelativeLayout.LayoutParams lParams = (RelativeLayout.LayoutParams) imageView.getLayoutParams(); 
        _xDelta = X - lParams.leftMargin; 
        _yDelta = Y - lParams.topMargin; 
        break; 
       case MotionEvent.ACTION_UP: 
        //Do Nothing 
        break; 
       case MotionEvent.ACTION_POINTER_DOWN: 
        //Do Nothing 
        break; 
       case MotionEvent.ACTION_POINTER_UP: 
        //Do Nothing 
        break; 
       case MotionEvent.ACTION_MOVE: 
        layoutParams = (RelativeLayout.LayoutParams) imageView.getLayoutParams(); 
        layoutParams.leftMargin = X - _xDelta; 
        layoutParams.topMargin = Y - _yDelta; 
        v.setLayoutParams(layoutParams); 
        break; 
       } 
       frame.invalidate(); 
       return true; 
      } 
     }); 


     return rootView; 
    } 
} 


<RelativeLayout 
    android:id="@+id/frame1" 
    android:layout_width="wrap_content" 
    android:layout_height="130dp" 
    android:layout_alignParentBottom="true" 
    android:layout_alignParentLeft="true" 
    android:layout_alignParentRight="true" 
    android:background="#000" > 

    <ImageView 
     android:id="@+id/imageView1" 
     android:layout_width="wrap_content" 
     android:layout_height="match_parent" 
     android:layout_alignParentLeft="true" 
     android:layout_alignParentTop="true" 
     android:scaleType="matrix" 
     android:src="@drawable/image1" /> 

</RelativeLayout> 

我想阻止正在進一步拖累比例如容器的圖像的頂部邊框的圖片應不超過佈局容器的頂部被拖進。

Answer 1

經過了一段時間我的代碼修補後，我終於想出了工作解決方案，我的問題虐待代碼在這裏。

View frame; 
    ImageView imageView; 

    //stores position of finger during drag operation 
    private int _xDelta; 
    private int _yDelta; 

    //Stores the boundaries of the Frame 
    private int frameWidth; 
    private int frameHeight; 

    public PlaceholderFragment() { 

    } 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
      Bundle savedInstanceState) { 
     View rootView = inflater.inflate(R.layout.fragment_main, container, 
       false); 

     frame = (View) rootView.findViewById(R.id.frame1); 
     imageView = (ImageView) rootView.findViewById(R.id.imageView1);  

     //Get frame width and height once it has been drawn. 
     frame.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() { 

      @Override 
      public void onGlobalLayout() { 
       // set global variables 
       frameWidth = getView().getWidth(); 
       frameHeight = getView().getHeight(); 
       //Log.e("Framewidth", "" + frameWidth); 
       Log.e("FrameHeight", "" + frameHeight); 



      } 
     });  

     //ontouch listener that controls the Drag functionality of the keyboard. 
     imageView.setOnTouchListener(new OnTouchListener() { 

      @Override 
      public boolean onTouch(View v, MotionEvent event) { 

       //get x and y cords of the user touch 
       final int X = (int) event.getRawX(); 
       final int Y = (int) event.getRawY(); 

       LayoutParams layoutParams = (LayoutParams) imageView.getLayoutParams(); 

       switch (event.getAction() & MotionEvent.ACTION_MASK) { 
       case MotionEvent.ACTION_DOWN: 
        RelativeLayout.LayoutParams lParams = (RelativeLayout.LayoutParams) imageView.getLayoutParams(); 
        _xDelta = X - lParams.leftMargin; 
        _yDelta = Y - lParams.topMargin; 
        break; 
       case MotionEvent.ACTION_UP: 
        //Do Nothing 
        break; 
       case MotionEvent.ACTION_POINTER_DOWN: 
        //Do Nothing 
        break; 
       case MotionEvent.ACTION_POINTER_UP: 
        //Do Nothing 
        break; 
       case MotionEvent.ACTION_MOVE: 
        layoutParams = (RelativeLayout.LayoutParams) imageView.getLayoutParams(); 
        Log.e("Test", "" + imageView.getX() + " , " + imageView.getY());  

        layoutParams.leftMargin = X - _xDelta; 
        layoutParams.topMargin = Y - _yDelta; 

        //stops the outer edges of the image from being dragged past the 
        //frames outer edges. 
        if(((int)layoutParams.topMargin) >= 1) { 
         layoutParams.topMargin = 0; 
         if(((int)layoutParams.leftMargin) >= 1){ 
          layoutParams.leftMargin = 0; 
         }else if(((int)layoutParams.leftMargin) <= -291){ 
          layoutParams.leftMargin = -290; 
         } 
        } else if(((int)layoutParams.topMargin) <= -70) { 
         layoutParams.topMargin = -68; 
         if(((int)layoutParams.leftMargin) >= 1){ 
          layoutParams.leftMargin = 0; 
         }else if(((int)layoutParams.leftMargin) <= -291){ 
          layoutParams.leftMargin = -290; 
         } 
        } else if(((int)layoutParams.leftMargin) >= 1){ 
         layoutParams.leftMargin = 0; 
        } else if(((int)layoutParams.leftMargin) <= -291) { 
         layoutParams.leftMargin = -290; 
        } 

        v.setLayoutParams(layoutParams); 
        break; 
       } 
       frame.invalidate(); 
       return true; 
      } 
     }); 


     return rootView; 
    } 
} 

這是一個大項目來創建自定義INPUTMETHOD的智能手錶

的第一部分