Android Open Source - logback-android-ui Hint Spinner

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Copyright (C) 2011-2012 Vanderbilt University Permission is hereby granted, free of charge, to any person obtaining a copy of this data, including any software or models in source or binary form, as ...

Java Source Code

/*Copyright (C) 2010-2012 Institute for Software Integrated Systems (ISIS)
This software was developed by the Institute for Software Integrated
Systems (ISIS) at Vanderbilt University, Tennessee, USA for the 
Transformative Apps program under DARPA, Contract # HR011-10-C-0175.
The United States Government has unlimited rights to this software. 
The US government has the right to use, modify, reproduce, release, 
perform, display, or disclose computer software or computer software 
documentation in whole or in part, in any manner and for any 
purpose whatsoever, and to have or authorize others to do so.
 *///from   w  w w. ja v  a  2  s  .  c o  m
package edu.vu.isis.logger.ui;

import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import android.content.Context;
import android.database.DataSetObserver;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.Spinner;
import android.widget.SpinnerAdapter;
import android.widget.TextView;

/**
 * Allows a Spinner to show a hint/prompt instead of one of its choices whenever
 * the Spinner is waiting to be clicked.
 * 
 * @author Nick King
 */
public class HintSpinner extends Spinner {

  private String mHint;
  private Method setNextSelectedPositionInt;
  private Field mOldSelectedPosition;
  private boolean showHintOnce = false;
  private boolean alwaysShowHint = false;

  private static final Logger logger = LoggerFactory
      .getLogger("ui.hintspinner");

  public HintSpinner(Context context) {
    super(context);
    init();
  }

  public HintSpinner(Context context, AttributeSet attrs) {
    super(context, attrs);
    init();
  }

  public HintSpinner(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
    init();
  }

  private void init() {
    setHint((String) getPrompt());
    try {
      setNextSelectedPositionInt = AdapterView.class.getDeclaredMethod(
          "setNextSelectedPositionInt", int.class);
      setNextSelectedPositionInt.setAccessible(true);
      mOldSelectedPosition = AdapterView.class
          .getDeclaredField("mOldSelectedPosition");
      mOldSelectedPosition.setAccessible(true);
    } catch (NoSuchMethodException e) {
      logger.warn("setNextSelectedPositionInt method not found", e);
    } catch (NoSuchFieldException e) {
      logger.warn("mOldSelectedPosition field not found", e);
    }
  }

  public void setHint(String hint) {
    mHint = hint;
  }

  public void setAlwaysShowHint(boolean b) {
    alwaysShowHint = b;
  }

  public void setShowHintOnce(boolean b) {
    showHintOnce = b;
  }

  public void clearSelection() {
    try {
      // Setting the next selected position to be invalid should
      // have the same effect as "clearing" the selection
      if (setNextSelectedPositionInt != null) {
        setNextSelectedPositionInt.invoke(this,
            AdapterView.INVALID_POSITION);
      }

      /*
       * Setting the old selected position to be invalid will allow the
       * user to click the same selection as last time and still have a
       * callback event fired. Without this, if the user were to click the
       * dialog's item at position n, the selection were cleared, and the
       * user were to click the (now unselected) item at position n again,
       * the callback would not be fired because AdapterView checks to see
       * if the old selected position differs from the position that was
       * just selected before firing a callback.
       */
      if (mOldSelectedPosition != null) {
        mOldSelectedPosition.set(this, AdapterView.INVALID_POSITION);
      }
    } catch (IllegalArgumentException e) {
      logger.warn("", e);
    } catch (IllegalAccessException e) {
      logger.warn("", e);
    } catch (InvocationTargetException e) {
      logger.warn("", e);
    }
  }

  /**
   * This wraps a SpinnerAdapter, adding behavior to its getView() method.
   * Every other method is left as is, but we still have to implement the
   * large number of methods defined in the SpinnerAdapter interface.
   */
  @Override
  public void setAdapter(SpinnerAdapter adapter) {
    super.setAdapter(new HintSpinnerAdapter(adapter));
  }

  private class HintSpinnerAdapter implements SpinnerAdapter {

    private SpinnerAdapter mAdapter;

    public HintSpinnerAdapter(SpinnerAdapter adapter) {
      mAdapter = adapter;
    }

    @Override
    public void registerDataSetObserver(DataSetObserver observer) {
      mAdapter.registerDataSetObserver(observer);
    }

    @Override
    public void unregisterDataSetObserver(DataSetObserver observer) {
      mAdapter.unregisterDataSetObserver(observer);
    }

    @Override
    public int getCount() {
      return mAdapter.getCount();
    }

    @Override
    public Object getItem(int position) {
      return mAdapter.getItem(position);
    }

    @Override
    public long getItemId(int position) {
      return mAdapter.getItemId(position);
    }

    @Override
    public boolean hasStableIds() {
      return mAdapter.hasStableIds();
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
      View view = mAdapter.getView(position, convertView, parent);

      if (showHintOnce || alwaysShowHint) {
        // Set this false for next time (even if alwaysShowHint is true)
        showHintOnce = false;

        /*
         * It's possible that we're wrapping an adapter that doesn't
         * make TextViews. If the adapter *is* making TextViews, we'll
         * use their view instead of inflating a new one. Otherwise,
         * we'll inflate the default spinner item.
         */
        if (!(view instanceof TextView)) {
          view = LayoutInflater.from(getContext())
              .inflate(android.R.layout.simple_spinner_item,
                  parent, false);
        }
        ((TextView) view).setText(mHint);
      }

      return view;
    }

    @Override
    public int getItemViewType(int position) {
      return mAdapter.getItemViewType(position);
    }

    @Override
    public int getViewTypeCount() {
      return mAdapter.getViewTypeCount();
    }

    @Override
    public boolean isEmpty() {
      return mAdapter.isEmpty();
    }

    @Override
    public View getDropDownView(int position, View convertView,
        ViewGroup parent) {
      return mAdapter.getDropDownView(position, convertView, parent);
    }

  }

}

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