立即跟隨手勢的Android ViewFlipper

Question

我在ViewFlipper上使用GestureDetector來實現showPrevious和showNext。 一切都很好。不過，我想要讓ViewFlipper動畫馬上跟隨手指姿勢，而不是在完成姿勢之後。 有何建議？

Answer 1

據我所知，你必須手動完成。下面的代碼應該指出你正確的方向。您必須添加動態動畫，以便視圖在翻轉過程中不閃爍。您需要做更多的事情，具體取決於viewflipper中的內容，但應該讓您開始。

public boolean onTouch(View v, MotionEvent event) { 
    switch (event.getAction()) 
    { 
     case MotionEvent.ACTION_DOWN: 
     { 
      //Gets the startpoint for you finger 
      pressDownPoint = event.getX(); 

      //Gets how many view there is in the viewflipper 
      flipperViewCount = flipper.getChildCount(); 

      //Checks if there is a view to the left of the current view 
//if there is, it positions it to the left of the current view 
      if (flipper.getDisplayedChild() > 0) 
      { 
       View leftChild = flipper.getChildAt(flipper.getDisplayedChild() - 1); 
       //You must set the left view to invisible or visible 
//or it will not move to the position you tell it 
       leftChild.setVisibility(View.INVISIBLE); 
       leftChild.layout(-screenWidth, 
         leftChild.getTop(), 0, 
         leftChild.getBottom()); 
      } 

      //Same as above but for the view to the right 
      if (flipper.getDisplayedChild() < flipperViewCount - 1) 
      { 
       View rightChild = flipper.getChildAt(flipper.getDisplayedChild() + 1); 
       rightChild.setVisibility(View.INVISIBLE); 
       rightChild.layout(screenWidth, 
         rightChild.getTop(), screenWidth * 2, 
         rightChild.getBottom()); 
      } 
      break; 
     } 
     case MotionEvent.ACTION_UP: 
     { 
      //Gets the absolute position on the screen 
      float releasePoint = event.getRawX(); 

      //Calculates if the fling is to the right or left 
//The screenDensity variable is simply the density of the device 
//Have in mind that this will not flipp the viewflipper if you drag 
//your finger less than about 0.5cm (depeding on the device) 
//In that case you need to make an animation that takes the view back 
//to its original position. Else it will just get stuck where you 
//let go with your finger. 
      if (Math.abs(pressDownPoint - releasePoint)/screenDensity > 30) 
      { 
       if (pressDownPoint > releasePoint) 
       { 
        myAnimLeft(); //Method with your animation 
        flipper.showNext(); 
       } 
       else 
       { 
        myAnimRight(); 
        flipper.showPrevious(); 
       } 
      } 
      break; 
     } 
     case MotionEvent.ACTION_MOVE: 
     { 
      View currentView = flipper.getCurrentView(); 

      //Moves the current view 
//screenWidth is based on the current devices screen width 
      currentView.layout((int)(event.getRawX() - pressDownPoint), 
        currentView.getTop(), (int)(event.getRawX() - pressDownPoint) + screenWidth, 
        currentView.getBottom()); 

      //Moves the view to the left if there is one 
      if (flipper.getDisplayedChild() > 0) 
      { 
       View leftChild = flipper.getChildAt(flipper.getDisplayedChild() - 1); 
       leftChild.layout((int)(event.getRawX() - pressDownPoint - screenWidth), 
         leftChild.getTop(), (int)(event.getRawX() - pressDownPoint), 
         leftChild.getBottom()); 

       //Sets the left view to visible so it shows 
       if (leftChild.getVisibility() == View.INVISIBLE) 
       { 
        leftChild.setVisibility(View.VISIBLE); 
       } 
      } 

      //Same as above but for the view to the right 
      if (flipper.getDisplayedChild() < flipperViewCount - 1) 
      { 
       View rightChild = flipper.getChildAt(flipper.getDisplayedChild() + 1); 
       rightChild.layout((int)(event.getRawX() - pressDownPoint + screenWidth), 
         rightChild.getTop(), (int)(event.getRawX() - pressDownPoint + (screenWidth * 2)), 
         rightChild.getBottom()); 

       if (rightChild.getVisibility() == View.INVISIBLE) 
       { 
        rightChild.setVisibility(View.VISIBLE); 
       } 
      } 
     } 

    } 
    return true; 
}