gistfile1.txt

package im.wsb.example

import java.lang.reflect.Field;

import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.ViewConfiguration;
import android.widget.AbsListView;
import android.widget.ListView;

public class ProperTouchSlopListView extends ListView {

  private static final int X_DRAGGING_RANGE = 90;

  private final int mDefaultTouchSlop;
  private Field mTouchSlopField;
  private boolean mClampingX;
  private boolean mClampingY;
  private MotionEvent mDownEvent;
  private boolean mReflectionIsBroken;

  public ProperTouchSlopListView(Context context) {
    this(context, null);
  }

  public ProperTouchSlopListView(Context context, AttributeSet attrs) {
    this(context, attrs, 0);
  }

  public ProperTouchSlopListView(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    mDefaultTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();
    try {
      mTouchSlopField = AbsListView.class.getDeclaredField("mTouchSlop");
      mTouchSlopField.setAccessible(true);
    } catch (NoSuchFieldException e) {
      mReflectionIsBroken = true;
    }
  }

  private void setAllowBuiltinInterceptBehavior(boolean allow) {
    if (mTouchSlopField == null) {
      return;
    }
    try {
      mTouchSlopField.set(this, allow ? mDefaultTouchSlop : Integer.MAX_VALUE);
    } catch (IllegalAccessException e) {
      mReflectionIsBroken = true;
    }
  }

  private void checkClamping(MotionEvent down, MotionEvent current) {
    float dX = down.getX() - current.getX();
    float dY = down.getY() - current.getY();
    if (mClampingY || mClampingX) {
      return;
    }
    double distance = Math.sqrt(dX * dX + dY * dY);
    boolean exitedSlop = distance > mDefaultTouchSlop;
    double angle = Math.toDegrees(Math.atan(Math.abs(dY / dX)));
    if (exitedSlop) {
      if (angle <= X_DRAGGING_RANGE / 2) {
        mClampingX = true;
      } else {
        mClampingY = true;
      }
    }
  }

  @Override
  public boolean onInterceptTouchEvent(MotionEvent ev) {
    switch (ev.getActionMasked()) {
      case MotionEvent.ACTION_DOWN:
        mClampingX = false;
        mClampingY = false;
        mDownEvent = MotionEvent.obtain(ev);
        break;
      case MotionEvent.ACTION_MOVE:
        checkClamping(mDownEvent, ev);
        break;
    }
    setAllowBuiltinInterceptBehavior(mReflectionIsBroken || mClampingY);
    return super.onInterceptTouchEvent(ev);
  }
}