Java tutorial
package ch.arnab.simplelauncher; /* * Created by Thomas Barrasso on 9/11/12. * Copyright (c) 2012 Loupe Inc. * * 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. */ import android.content.Context; import android.content.res.Resources; import android.os.Build; import android.os.Bundle; import android.os.Handler; import android.support.v4.app.Fragment; import android.util.TypedValue; import android.view.Gravity; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.view.animation.AnimationUtils; import android.widget.AdapterView; import android.widget.FrameLayout; import android.widget.GridView; import android.widget.LinearLayout; import android.widget.ListAdapter; import android.widget.ListView; import android.widget.ProgressBar; import android.widget.TextView; /** * Based on {@link android.app.ListFragment} but adapted for {@link GridView}. */ public class GridFragment extends Fragment { static final int INTERNAL_EMPTY_ID = 0x00ff0001; static final int INTERNAL_PROGRESS_CONTAINER_ID = 0x00ff0002; static final int INTERNAL_LIST_CONTAINER_ID = 0x00ff0003; final private Handler mHandler = new Handler(); final private Runnable mRequestFocus = new Runnable() { public void run() { mGrid.focusableViewAvailable(mGrid); } }; 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); } }; ListAdapter mAdapter; GridView mGrid; View mEmptyView; TextView mStandardEmptyView; View mProgressContainer; View mGridContainer; CharSequence mEmptyText; boolean mGridShown; public GridFragment() { } /** * 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 android.R.id#list android.R.id.list} and can optionally * have a sibling view id {@link android.R.id#empty android.R.id.empty} * that is to be shown when the grid is empty. * * <p>If you are overriding this method with your own custom content, * consider including the standard layout {@link android.R.layout#list_content} * in your layout file, so that you continue to retain all of the standard * behavior of ListFragment. 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) { final Context context = getActivity(); FrameLayout root = new FrameLayout(context); // ------------------------------------------------------------------ LinearLayout pframe = new LinearLayout(context); pframe.setId(INTERNAL_PROGRESS_CONTAINER_ID); pframe.setOrientation(LinearLayout.VERTICAL); pframe.setVisibility(View.GONE); pframe.setGravity(Gravity.CENTER); ProgressBar progress = new ProgressBar(context, null, android.R.attr.progressBarStyleLarge); pframe.addView(progress, new FrameLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT)); root.addView(pframe, new FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT)); // ------------------------------------------------------------------ FrameLayout lframe = new FrameLayout(context); lframe.setId(INTERNAL_LIST_CONTAINER_ID); TextView tv = new TextView(getActivity()); tv.setId(INTERNAL_EMPTY_ID); tv.setGravity(Gravity.CENTER); lframe.addView(tv, new FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT)); GridView lv = new GridView(getActivity()); lv.setId(android.R.id.list); lv.setDrawSelectorOnTop(false); lv.setColumnWidth(convertDpToPixels(60, getActivity())); lv.setStretchMode(GridView.STRETCH_COLUMN_WIDTH); lv.setNumColumns(GridView.AUTO_FIT); lv.setHorizontalSpacing(convertDpToPixels(20, getActivity())); lv.setVerticalSpacing(convertDpToPixels(20, getActivity())); lv.setSmoothScrollbarEnabled(true); // disable overscroll if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.GINGERBREAD) { lv.setOverScrollMode(ListView.OVER_SCROLL_NEVER); } lframe.addView(lv, new FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT)); root.addView(lframe, new FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT)); // ------------------------------------------------------------------ root.setLayoutParams(new FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT)); return root; } /** * Attach to grid view once the view hierarchy has been created. */ @Override public void onViewCreated(View view, Bundle savedInstanceState) { super.onViewCreated(view, savedInstanceState); ensureGrid(); } /** * Detach from {@link GridView} */ @Override public void onDestroyView() { mHandler.removeCallbacks(mRequestFocus); mGrid = null; mGridShown = false; mEmptyView = mProgressContainer = mGridContainer = null; mStandardEmptyView = null; super.onDestroyView(); } public static int convertDpToPixels(float dp, Context context) { Resources resources = context.getResources(); return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp, resources.getDisplayMetrics()); } /** * 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 g The {@link GridView} where the click happened * @param v The view that was clicked within the {@link GridView} * @param position The position of the view in the grid * @param id The row id of the item that was clicked */ public void onGridItemClick(GridView g, View v, int position, long id) { } /** * Provide the cursor for the {@link GridView}. */ public void setGridAdapter(ListAdapter adapter) { final boolean hadAdapter = (mAdapter != null); mAdapter = adapter; if (mGrid != null) { mGrid.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)); } } } /** * Set the currently selected grid item to the specified * position with the adapter's data * * @param position */ public void setSelection(int position) { ensureGrid(); mGrid.setSelection(position); } /** * Get the position of the currently selected grid item. */ public int getSelectedItemPosition() { ensureGrid(); return mGrid.getSelectedItemPosition(); } /** * Get the cursor row ID of the currently selected grid item. */ public long getSelectedItemId() { ensureGrid(); return mGrid.getSelectedItemId(); } /** * Get the activity's {@link GridView} widget. */ public GridView getGridView() { ensureGrid(); return mGrid; } /** * The default content for a ListFragment 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) { ensureGrid(); if (mStandardEmptyView == null) { throw new IllegalStateException("Can't be used with a custom content view"); } mStandardEmptyView.setText(text); if (mEmptyText == null) { mGrid.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>Applications do not normally need to use this themselves. The default * behavior of ListFragment is to start with the grid not being shown, only * showing it once an adapter is given with {@link #setGridAdapter(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) { ensureGrid(); 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 {@link GridView}. */ public ListAdapter getGridAdapter() { return mAdapter; } private void ensureGrid() { if (mGrid != null) { return; } View root = getView(); if (root == null) { throw new IllegalStateException("Content view not yet created"); } if (root instanceof GridView) { mGrid = (GridView) root; } else { mStandardEmptyView = (TextView) root.findViewById(INTERNAL_EMPTY_ID); if (mStandardEmptyView == null) { mEmptyView = root.findViewById(android.R.id.empty); } else { mStandardEmptyView.setVisibility(View.GONE); } mProgressContainer = root.findViewById(INTERNAL_PROGRESS_CONTAINER_ID); mGridContainer = root.findViewById(INTERNAL_LIST_CONTAINER_ID); View rawGridView = root.findViewById(android.R.id.list); if (!(rawGridView instanceof GridView)) { if (rawGridView == null) { throw new RuntimeException( "Your content must have a GridView whose id attribute is " + "'android.R.id.list'"); } throw new RuntimeException( "Content has view with id attribute 'android.R.id.list' " + "that is not a GridView class"); } mGrid = (GridView) rawGridView; if (mEmptyView != null) { mGrid.setEmptyView(mEmptyView); } else if (mEmptyText != null) { mStandardEmptyView.setText(mEmptyText); mGrid.setEmptyView(mStandardEmptyView); } } mGridShown = true; mGrid.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); } }