Java tutorial
/* * Copyright (C) 2011 The Android Open Source Project * * 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.heneryh.aquanotes.ui.livestock; import android.content.ClipData; import android.content.ClipData.Item; import android.content.ClipDescription; import android.content.Intent; import android.graphics.Bitmap; import android.graphics.Color; import android.net.Uri; import android.os.AsyncTask; import android.os.Bundle; import android.support.v4.app.Fragment; import android.view.ActionMode; import android.view.DragEvent; import android.view.LayoutInflater; import android.view.Menu; import android.view.MenuInflater; import android.view.MenuItem; import android.view.View; import android.view.View.OnClickListener; import android.view.ViewGroup; import android.view.Window; import android.view.WindowManager; import android.widget.ImageView; import android.widget.Toast; import java.io.File; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.util.StringTokenizer; import com.heneryh.aquanotes.R; /** Fragment that shows the content selected from the TitlesFragment. * When running on a screen size smaller than "large", this fragment is hosted in * ContentActivity. Otherwise, it appears side by side with the TitlesFragment * in LivestockActivity. */ public class ContentFragment extends Fragment { private View mContentView; private int mCategory = 0; private int mCurPosition = 0; private boolean mSystemUiVisible = true; private boolean mSoloFragment = false; // The bitmap currently used by ImageView private Bitmap mBitmap = null; // Current action mode (contextual action bar, a.k.a. CAB) private ActionMode mCurrentActionMode; /** This is where we initialize the fragment's UI and attach some * event listeners to UI components. */ @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { mContentView = inflater.inflate(R.layout.content_welcome, null); final ImageView imageView = (ImageView) mContentView.findViewById(R.id.image); mContentView.setDrawingCacheEnabled(false); // Handle drag events when a list item is dragged into the view mContentView.setOnDragListener(new View.OnDragListener() { public boolean onDrag(View view, DragEvent event) { switch (event.getAction()) { case DragEvent.ACTION_DRAG_ENTERED: view.setBackgroundColor(getResources().getColor(R.color.drag_active_color)); break; case DragEvent.ACTION_DRAG_EXITED: view.setBackgroundColor(Color.TRANSPARENT); break; case DragEvent.ACTION_DRAG_STARTED: return processDragStarted(event); case DragEvent.ACTION_DROP: view.setBackgroundColor(Color.TRANSPARENT); return processDrop(event, imageView); } return false; } }); // Show/hide the system status bar when single-clicking a photo. mContentView.setOnClickListener(new OnClickListener() { public void onClick(View view) { if (mCurrentActionMode != null) { // If we're in an action mode, don't toggle the action bar return; } if (mSystemUiVisible) { setSystemUiVisible(false); } else { setSystemUiVisible(true); } } }); // When long-pressing a photo, activate the action mode for selection, showing the // contextual action bar (CAB). mContentView.setOnLongClickListener(new View.OnLongClickListener() { public boolean onLongClick(View view) { if (mCurrentActionMode != null) { return false; } mCurrentActionMode = getActivity().startActionMode(mContentSelectionActionModeCallback); view.setSelected(true); return true; } }); return mContentView; } /** This is where we perform additional setup for the fragment that's either * not related to the fragment's layout or must be done after the layout is drawn. */ @Override public void onActivityCreated(Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); // Set member variable for whether this fragment is the only one in the activity Fragment listFragment = getFragmentManager().findFragmentById(R.id.titles_frag); mSoloFragment = listFragment == null ? true : false; if (mSoloFragment) { // The fragment is alone, so enable up navigation getActivity().getActionBar().setDisplayHomeAsUpEnabled(true); // Must call in order to get callback to onOptionsItemSelected() setHasOptionsMenu(true); } // Current position and UI visibility should survive screen rotations. if (savedInstanceState != null) { setSystemUiVisible(savedInstanceState.getBoolean("systemUiVisible")); if (mSoloFragment) { // Restoring these members is not necessary when this fragment // is combined with the TitlesFragment, because when the TitlesFragment // is restored, it selects the appropriate item and sends the event // to the updateContentAndRecycleBitmap() method itself mCategory = savedInstanceState.getInt("category"); mCurPosition = savedInstanceState.getInt("listPosition"); updateContentAndRecycleBitmap(mCategory, mCurPosition); } } if (mSoloFragment) { // String title = Directory.getCategory(mCategory).getEntry(mCurPosition).getName(); // ActionBar bar = getActivity().getActionBar(); // bar.setTitle(title); } } @Override public boolean onOptionsItemSelected(MenuItem item) { // This callback is used only when mSoloFragment == true (see onActivityCreated above) switch (item.getItemId()) { case android.R.id.home: // App icon in Action Bar clicked; go up Intent intent = new Intent(getActivity(), LivestockActivity.class); intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); // Reuse the existing instance startActivity(intent); return true; default: return super.onOptionsItemSelected(item); } } @Override public void onSaveInstanceState(Bundle outState) { super.onSaveInstanceState(outState); outState.putInt("listPosition", mCurPosition); outState.putInt("category", mCategory); outState.putBoolean("systemUiVisible", mSystemUiVisible); } /** Toggle whether the system UI (status bar / system bar) is visible. * This also toggles the action bar visibility. * @param show True to show the system UI, false to hide it. */ void setSystemUiVisible(boolean show) { mSystemUiVisible = show; Window window = getActivity().getWindow(); WindowManager.LayoutParams winParams = window.getAttributes(); View view = getView(); // ActionBar actionBar = getActivity().getActionBar(); if (show) { // Show status bar (remove fullscreen flag) window.setFlags(0, WindowManager.LayoutParams.FLAG_FULLSCREEN); // Show system bar view.setSystemUiVisibility(View.STATUS_BAR_VISIBLE); // Show action bar // actionBar.show(); } else { // Add fullscreen flag (hide status bar) window.setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN); // Hide system bar view.setSystemUiVisibility(View.STATUS_BAR_HIDDEN); // Hide action bar // actionBar.hide(); } window.setAttributes(winParams); } boolean processDragStarted(DragEvent event) { // Determine whether to continue processing drag and drop based on the // plain text mime type. ClipDescription clipDesc = event.getClipDescription(); if (clipDesc != null) { return clipDesc.hasMimeType(ClipDescription.MIMETYPE_TEXT_PLAIN); } return false; } boolean processDrop(DragEvent event, ImageView imageView) { // Attempt to parse clip data with expected format: category||entry_id. // Ignore event if data does not conform to this format. ClipData data = event.getClipData(); if (data != null) { if (data.getItemCount() > 0) { Item item = data.getItemAt(0); String textData = (String) item.getText(); if (textData != null) { StringTokenizer tokenizer = new StringTokenizer(textData, "||"); if (tokenizer.countTokens() != 2) { return false; } int category = -1; int entryId = -1; try { category = Integer.parseInt(tokenizer.nextToken()); entryId = Integer.parseInt(tokenizer.nextToken()); } catch (NumberFormatException exception) { return false; } updateContentAndRecycleBitmap(category, entryId); // Update list fragment with selected entry. // TitlesFragment titlesFrag = (TitlesFragment) // getFragmentManager().findFragmentById(R.id.titles_frag); // titlesFrag.selectPosition(entryId); return true; } } } return false; } /** * Sets the current image visible. * @param category Index position of the image category * @param position Index position of the image */ void updateContentAndRecycleBitmap(int category, int position) { mCategory = category; mCurPosition = position; if (mCurrentActionMode != null) { mCurrentActionMode.finish(); } if (mBitmap != null) { // This is an advanced call and should be used if you // are working with a lot of bitmaps. The bitmap is dead // after this call. mBitmap.recycle(); } // Get the bitmap that needs to be drawn and update the ImageView mBitmap = Directory.getCategory(category).getEntry(position).getBitmap(getResources()); ((ImageView) getView().findViewById(R.id.image)).setImageBitmap(mBitmap); } /** Share the currently selected photo using an AsyncTask to compress the image * and then invoke the appropriate share intent. */ void shareCurrentPhoto() { File externalCacheDir = getActivity().getExternalCacheDir(); if (externalCacheDir == null) { Toast.makeText(getActivity(), "Error writing to USB/external storage.", Toast.LENGTH_SHORT).show(); return; } // Prevent media scanning of the cache directory. final File noMediaFile = new File(externalCacheDir, ".nomedia"); try { noMediaFile.createNewFile(); } catch (IOException e) { } // Write the bitmap to temporary storage in the external storage directory (e.g. SD card). // We perform the actual disk write operations on a separate thread using the // {@link AsyncTask} class, thus avoiding the possibility of stalling the main (UI) thread. final File tempFile = new File(externalCacheDir, "tempfile.jpg"); new AsyncTask<Void, Void, Boolean>() { /** * Compress and write the bitmap to disk on a separate thread. * @return TRUE if the write was successful, FALSE otherwise. */ @Override protected Boolean doInBackground(Void... voids) { try { FileOutputStream fo = new FileOutputStream(tempFile, false); if (!mBitmap.compress(Bitmap.CompressFormat.JPEG, 60, fo)) { Toast.makeText(getActivity(), "Error writing bitmap data.", Toast.LENGTH_SHORT).show(); return Boolean.FALSE; } return Boolean.TRUE; } catch (FileNotFoundException e) { Toast.makeText(getActivity(), "Error writing to USB/external storage.", Toast.LENGTH_SHORT) .show(); return Boolean.FALSE; } } /** * After doInBackground completes (either successfully or in failure), we invoke an * intent to share the photo. This code is run on the main (UI) thread. */ @Override protected void onPostExecute(Boolean result) { if (result != Boolean.TRUE) { return; } Intent shareIntent = new Intent(Intent.ACTION_SEND); shareIntent.putExtra(Intent.EXTRA_STREAM, Uri.fromFile(tempFile)); shareIntent.setType("image/jpeg"); startActivity(Intent.createChooser(shareIntent, "Share photo")); } }.execute(); } /** * The callback for the 'photo selected' {@link ActionMode}. In this action mode, we can * provide contextual actions for the selected photo. We currently only provide the 'share' * action, but we could also add clipboard functions such as cut/copy/paste here as well. */ private ActionMode.Callback mContentSelectionActionModeCallback = new ActionMode.Callback() { public boolean onCreateActionMode(ActionMode actionMode, Menu menu) { actionMode.setTitle(R.string.photo_selection_cab_title); MenuInflater inflater = getActivity().getMenuInflater(); //inflater.inflate(R.menu.photo_context_menu, menu); return true; } public boolean onPrepareActionMode(ActionMode actionMode, Menu menu) { return false; } public boolean onActionItemClicked(ActionMode actionMode, MenuItem menuItem) { switch (menuItem.getItemId()) { case R.id.menu_share: shareCurrentPhoto(); actionMode.finish(); return true; } return false; } public void onDestroyActionMode(ActionMode actionMode) { mContentView.setSelected(false); mCurrentActionMode = null; } }; }