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.actionbarsherlock.sample.hcgallery; import android.app.ActionBar; import android.app.Activity; 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.Build; import android.os.Bundle; import android.support.v4.app.Fragment; import android.support.v4.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.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; public class ContentFragment extends Fragment { private View mContentView; // The bitmap currently used by ImageView private Bitmap mBitmap = null; // Current action mode (contextual action bar, a.k.a. CAB) private ActionMode mCurrentActionMode; @Override public void onActivityCreated(Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); } @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); if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) { mContentView.setOnDragListener(new View.OnDragListener() { public boolean onDrag(View v, DragEvent event) { switch (event.getAction()) { case DragEvent.ACTION_DRAG_ENTERED: mContentView.setBackgroundColor(getResources().getColor(R.color.drag_active_color)); break; case DragEvent.ACTION_DRAG_EXITED: mContentView.setBackgroundColor(Color.TRANSPARENT); break; case DragEvent.ACTION_DRAG_STARTED: return processDragStarted(event); case DragEvent.ACTION_DROP: mContentView.setBackgroundColor(Color.TRANSPARENT); return processDrop(event, imageView); } return false; } }); // Keep the action bar visibility in sync with the system status bar. That is, when entering // 'lights out mode,' hide the action bar, and when exiting this mode, show the action bar. final Activity activity = getActivity(); mContentView.setOnSystemUiVisibilityChangeListener(new View.OnSystemUiVisibilityChangeListener() { public void onSystemUiVisibilityChange(int visibility) { ActionBar actionBar = activity.getActionBar(); if (actionBar != null) { mContentView.setSystemUiVisibility(visibility); if (visibility == View.STATUS_BAR_VISIBLE) { actionBar.show(); } else { actionBar.hide(); } } } }); // Show/hide the system status bar when single-clicking a photo. This is also called // 'lights out mode.' Activating and deactivating this mode also invokes the listener // defined above, which will show or hide the action bar accordingly. mContentView.setOnClickListener(new OnClickListener() { public void onClick(View v) { if (mContentView.getSystemUiVisibility() == View.STATUS_BAR_VISIBLE) { mContentView.setSystemUiVisibility(View.STATUS_BAR_HIDDEN); } else { mContentView.setSystemUiVisibility(View.STATUS_BAR_VISIBLE); } } }); } // 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); mContentView.setSelected(true); return true; } }); return mContentView; } 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.frag_title); titlesFrag.selectPosition(entryId); return true; } } } return false; } void updateContentAndRecycleBitmap(int category, int 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); } 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. */ 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. */ 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.share: shareCurrentPhoto(); actionMode.finish(); return true; } return false; } public void onDestroyActionMode(ActionMode actionMode) { mContentView.setSelected(false); mCurrentActionMode = null; } }; }