Java tutorial
/* * Copyright (C) 2013 Evgeny Shishkin * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.devspark.progressfragment; import android.os.Bundle; import android.os.Handler; import android.support.v4.app.Fragment; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.view.animation.AnimationUtils; import android.widget.AdapterView; import android.widget.GridView; import android.widget.ListAdapter; import android.widget.TextView; /** * The implementation of the fragment to display grid view. Based on {@link android.support.v4.app.ListFragment}. * If you are waiting for the initial data, you'll can displaying during this time an indeterminate progress indicator. * * @author e.shishkin. */ public class GridFragment extends Fragment { final private Handler mHandler = new Handler(); final private Runnable mRequestFocus = new Runnable() { public void run() { mGridView.focusableViewAvailable(mGridView); } }; final private AdapterView.OnItemClickListener mOnClickListener = new AdapterView.OnItemClickListener() { public void onItemClick(AdapterView<?> parent, View v, int position, long id) { onGridItemClick((GridView) parent, v, position, id); } }; private ListAdapter mAdapter; private GridView mGridView; private View mEmptyView; private TextView mStandardEmptyView; private View mProgressContainer; private View mGridContainer; private CharSequence mEmptyText; private boolean mGridShown; /** * Provide default implementation to return a simple grid view. Subclasses * can override to replace with their own layout. If doing so, the * returned view hierarchy <em>must</em> have a GridView whose id * is {@link com.devspark.progressfragment.R.id#grid R.id.grid} and can optionally * have a sibling view id {@link android.R.id#empty android.R.id.empty} * that is to be shown when the list is empty. * <p/> * <p>If you are overriding this method with your own custom content, * consider including the standard layout {@link com.devspark.progressfragment.R.layout#fragment_grid} * in your layout file, so that you continue to retain all of the standard * behavior of SherlockGridFragment. In particular, this is currently the only * way to have the built-in indeterminant progress state be shown. */ @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { return inflater.inflate(R.layout.fragment_grid, container, false); } /** * Attach to grid view once the view hierarchy has been created. */ @Override public void onViewCreated(View view, Bundle savedInstanceState) { super.onViewCreated(view, savedInstanceState); ensureList(); } /** * Detach from grid view. */ @Override public void onDestroyView() { mHandler.removeCallbacks(mRequestFocus); mGridView = null; mGridShown = false; mEmptyView = mProgressContainer = mGridContainer = null; mStandardEmptyView = null; super.onDestroyView(); } /** * This method will be called when an item in the grid is selected. * Subclasses should override. Subclasses can call * getGridView().getItemAtPosition(position) if they need to access the * data associated with the selected item. * * @param gridView The GridView where the click happened * @param v The view that was clicked within the ListView * @param position The position of the view in the list * @param id The row id of the item that was clicked */ public void onGridItemClick(GridView gridView, View v, int position, long id) { } /** * Set the currently selected grid item to the specified * position with the adapter's data * * @param position */ public void setSelection(int position) { ensureList(); mGridView.setSelection(position); } /** * Get the position of the currently selected grid item. */ public int getSelectedItemPosition() { ensureList(); return mGridView.getSelectedItemPosition(); } /** * Get the cursor row ID of the currently selected grid item. */ public long getSelectedItemId() { ensureList(); return mGridView.getSelectedItemId(); } /** * Get the activity's grid view widget. */ public GridView getGridView() { ensureList(); return mGridView; } /** * The default content for a SherlockGridFragment has a TextView that can * be shown when the grid is empty. If you would like to have it * shown, call this method to supply the text it should use. */ public void setEmptyText(CharSequence text) { ensureList(); if (mStandardEmptyView == null) { throw new IllegalStateException("Can't be used with a custom content view"); } mStandardEmptyView.setText(text); if (mEmptyText == null) { mGridView.setEmptyView(mStandardEmptyView); } mEmptyText = text; } /** * Control whether the grid is being displayed. You can make it not * displayed if you are waiting for the initial data to show in it. During * this time an indeterminant progress indicator will be shown instead. * <p/> * <p>Applications do not normally need to use this themselves. The default * behavior of SherlockGridFragment is to start with the grid not being shown, only * showing it once an adapter is given with {@link #setGridAdapter(android.widget.ListAdapter)}. * If the grid at that point had not been shown, when it does get shown * it will be do without the user ever seeing the hidden state. * * @param shown If true, the grid view is shown; if false, the progress * indicator. The initial value is true. */ public void setGridShown(boolean shown) { setGridShown(shown, true); } /** * Like {@link #setGridShown(boolean)}, but no animation is used when * transitioning from the previous state. */ public void setGridShownNoAnimation(boolean shown) { setGridShown(shown, false); } /** * Control whether the grid is being displayed. You can make it not * displayed if you are waiting for the initial data to show in it. During * this time an indeterminant progress indicator will be shown instead. * * @param shown If true, the grid view is shown; if false, the progress * indicator. The initial value is true. * @param animate If true, an animation will be used to transition to the * new state. */ private void setGridShown(boolean shown, boolean animate) { ensureList(); if (mProgressContainer == null) { throw new IllegalStateException("Can't be used with a custom content view"); } if (mGridShown == shown) { return; } mGridShown = shown; if (shown) { if (animate) { mProgressContainer .startAnimation(AnimationUtils.loadAnimation(getActivity(), android.R.anim.fade_out)); mGridContainer.startAnimation(AnimationUtils.loadAnimation(getActivity(), android.R.anim.fade_in)); } else { mProgressContainer.clearAnimation(); mGridContainer.clearAnimation(); } mProgressContainer.setVisibility(View.GONE); mGridContainer.setVisibility(View.VISIBLE); } else { if (animate) { mProgressContainer .startAnimation(AnimationUtils.loadAnimation(getActivity(), android.R.anim.fade_in)); mGridContainer.startAnimation(AnimationUtils.loadAnimation(getActivity(), android.R.anim.fade_out)); } else { mProgressContainer.clearAnimation(); mGridContainer.clearAnimation(); } mProgressContainer.setVisibility(View.VISIBLE); mGridContainer.setVisibility(View.GONE); } } /** * Get the ListAdapter associated with this activity's GridView. */ public ListAdapter getGridAdapter() { return mAdapter; } /** * Provide the cursor for the grid view. */ public void setGridAdapter(ListAdapter adapter) { boolean hadAdapter = mAdapter != null; mAdapter = adapter; if (mGridView != null) { mGridView.setAdapter(adapter); if (!mGridShown && !hadAdapter) { // The grid was hidden, and previously didn't have an // adapter. It is now time to show it. setGridShown(true, getView().getWindowToken() != null); } } } private void ensureList() { if (mGridView != null) { return; } View root = getView(); if (root == null) { throw new IllegalStateException("Content view not yet created"); } if (root instanceof GridView) { mGridView = (GridView) root; } else { View emptyView = root.findViewById(android.R.id.empty); if (emptyView != null) { if (emptyView instanceof TextView) { mStandardEmptyView = (TextView) emptyView; } else { mEmptyView = emptyView; } } else { mStandardEmptyView.setVisibility(View.GONE); } mProgressContainer = root.findViewById(R.id.progress_container); mGridContainer = root.findViewById(R.id.grid_container); View rawGridView = root.findViewById(R.id.grid); if (!(rawGridView instanceof GridView)) { throw new RuntimeException( "Content has view with id attribute 'R.id.grid' " + "that is not a GridView class"); } mGridView = (GridView) rawGridView; if (mGridView == null) { throw new RuntimeException( "Your content must have a GridView whose id attribute is " + "'R.id.grid'"); } if (mEmptyView != null) { mGridView.setEmptyView(mEmptyView); } else if (mEmptyText != null) { mStandardEmptyView.setText(mEmptyText); mGridView.setEmptyView(mStandardEmptyView); } } mGridShown = true; mGridView.setOnItemClickListener(mOnClickListener); if (mAdapter != null) { ListAdapter adapter = mAdapter; mAdapter = null; setGridAdapter(adapter); } else { // We are starting without an adapter, so assume we won't // have our data right away and start with the progress indicator. if (mProgressContainer != null) { setGridShown(false, false); } } mHandler.post(mRequestFocus); } }