Question

我需要实现这样的功能。用户滑动会离开列表视图的项目，并打开另一个活动。当用户开始向左滑动时，listview项目的背景颜色应该是绿色，当他完成滑动时，新的活动应该打开，项目的背景颜色应该变为白色。

我有SwipeDetector类来检测我的滑动事件：

public class SwipeDetector implements View.OnTouchListener {

    public static enum Action {
        LR, // Left to Right
        RL, // Right to Left
        TB, // Top to bottom
        BT, // Bottom to Top
        Start,
        Stop,
        None // when no action was detected
    }

    private static final String logTag = "SwipeDetector";
    private static final int MIN_DISTANCE = 100;
    private static final float HORIZONTAL_MIN_DISTANCE = 5;
    private static final float VERTICAL_MIN_DISTANCE = 100;
    private float downX, downY, upX, upY ,  stopX, stopY;
    private Action mSwipeDetected = Action.None;

    public boolean swipeDetected() {
        return mSwipeDetected != Action.None;
    }

    public Action getAction() {
        return mSwipeDetected;
    }

    public boolean onTouch(View v, MotionEvent event) {
        switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN: {
            downX = event.getX();
            downY = event.getY();
            mSwipeDetected = Action.Start;
            return false; // allow other events like Click to be processed
        }
        case MotionEvent.ACTION_MOVE: {
            upX = event.getX();
            upY = event.getY();

            float deltaX = downX - upX;
            float deltaY = downY - upY;

            // horizontal swipe detection
                    if (Math.abs(deltaX) > HORIZONTAL_MIN_DISTANCE) {
                        // left or right
                        if (deltaX <= 0) {
                            Log.i(logTag, "Swipe Left to Right");
                            mSwipeDetected = Action.LR;
                            return true;
                        }
                        if (deltaX > 0) { 
                            Log.i(logTag, "Swipe Right to Left");
                            mSwipeDetected = Action.RL;
                            return true;
                        }
                    } else 

                    // vertical swipe detection
                    if (Math.abs(deltaY) > VERTICAL_MIN_DISTANCE) 
                    {
                        // top or down
                        if (deltaY < 0) {
                            Log.i(logTag, "Swipe Top to Bottom");
                            mSwipeDetected = Action.TB;
                            return false;
                        }
                        if (deltaY > 0) 
                        {
                            Log.i(logTag, "Swipe Bottom to Top");
                            mSwipeDetected = Action.BT;
                            return false;
                        }
                    } 
                    Log.i("delta X", Float.toString(deltaX));
                    return true;
        }
        case MotionEvent.ACTION_UP:
        {

             stopX = event.getX();
             stopY = event.getY();
             float stopValue = upX-stopX;

             Log.i("StopX value",Float.toString(stopValue));
                 Log.i("StopX value",Float.toString(stopX));
                 Log.i("DownX value",Float.toString(downX));
                 Log.i("UpX value",Float.toString(upX));
               //
                 mSwipeDetected = Action.None;
             return false;
        }


        }
        return false;
    }
}

以及我如何在我的活动中使用它：

listView1.setOnItemClickListener(new OnItemClickListener() {
          public void onItemClick(AdapterView<?> parent, View view, int position, long id)
          {
                  if (swipeDetector.getAction()== swipeDetector.getAction().LR)
                  {
                      Log.i("start value", "it might be started");
                      view.setBackgroundColor(Color.GREEN);
                     Log.i("Swipe Action", getAction().toString());
                     Object listItem = listView1.getItemAtPosition(position);
                     Intent i = new Intent(getApplicationContext(),
                             InteractionsActivity.class);
                     startActivity(i);

                  } 
                  else if(!swipeDetector.swipeDetected())
                  {
                      Log.i("stop value", "it was stoped");
                        view.setBackgroundColor(Color.WHITE);
                  }
          }
      });

但是当我在SwipeDetector mSwipeDetected = Action.None;语句中注释行case MotionEvent.ACTION_UP:时，Activity会正常打开，但当我返回Activity时，listview项的背景颜色仍为绿色，Log.i("stop value", "it was stoped");:在我的活动else if语句中无法调用。当我取消注释它时，可以调用Log.i("stop value", "it was stoped");，但listview项目的背景颜色保持白色，新的Activity不会打开。我该如何实施呢？

Answer 1

当您打开活动而不是startActivity时，请使用startActivityForResult执行此操作。这意味着您将能够检测到其他活动何时完成并且用户已回到此活动。然后，您可以将颜色设置为白色。

请点击此处了解其工作原理：http://www.vogella.com/articles/AndroidIntent/article.html#usingintents_sub

在滑动时更改listview行背景颜色

1 个答案: