ClipData.java revision 1040dc465cbf5ca8f834a87c949e476abefa3f76
1/** 2 * Copyright (c) 2010, The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17package android.content; 18 19import android.content.res.AssetFileDescriptor; 20import android.graphics.Bitmap; 21import android.net.Uri; 22import android.os.Parcel; 23import android.os.Parcelable; 24import android.text.TextUtils; 25import android.util.Log; 26 27import java.io.FileInputStream; 28import java.io.FileNotFoundException; 29import java.io.IOException; 30import java.io.InputStreamReader; 31import java.util.ArrayList; 32 33/** 34 * Representation of a clipped data on the clipboard. 35 * 36 * <p>ClippedData is a complex type containing one or Item instances, 37 * each of which can hold one or more representations of an item of data. 38 * For display to the user, it also has a label and iconic representation.</p> 39 * 40 * <p>A ClipData is a sub-class of {@link ClipDescription}, which describes 41 * important meta-data about the clip. In particular, its {@link #getMimeType(int)} 42 * must return correct MIME type(s) describing the data in the clip. For help 43 * in correctly constructing a clip with the correct MIME type, use 44 * {@link #newPlainText(CharSequence, Bitmap, CharSequence)}, 45 * {@link #newUri(ContentResolver, CharSequence, Bitmap, Uri)}, and 46 * {@link #newIntent(CharSequence, Bitmap, Intent)}. 47 * 48 * <p>Each Item instance can be one of three main classes of data: a simple 49 * CharSequence of text, a single Intent object, or a Uri. See {@link Item} 50 * for more details. 51 * 52 * <a name="ImplementingPaste"></a> 53 * <h3>Implementing Paste or Drop</h3> 54 * 55 * <p>To implement a paste or drop of a ClippedData object into an application, 56 * the application must correctly interpret the data for its use. If the {@link Item} 57 * it contains is simple text or an Intent, there is little to be done: text 58 * can only be interpreted as text, and an Intent will typically be used for 59 * creating shortcuts (such as placing icons on the home screen) or other 60 * actions. 61 * 62 * <p>If all you want is the textual representation of the clipped data, you 63 * can use the convenience method {@link Item#coerceToText Item.coerceToText}. 64 * In this case there is generally no need to worry about the MIME types 65 * reported by {@link #getMimeType(int)}, since any clip item an always be 66 * converted to a string. 67 * 68 * <p>More complicated exchanges will be done through URIs, in particular 69 * "content:" URIs. A content URI allows the recipient of a ClippedData item 70 * to interact closely with the ContentProvider holding the data in order to 71 * negotiate the transfer of that data. The clip must also be filled in with 72 * the available MIME types; {@link #newUri(ContentResolver, CharSequence, Bitmap, Uri)} 73 * will take care of correctly doing this. 74 * 75 * <p>For example, here is the paste function of a simple NotePad application. 76 * When retrieving the data from the clipboard, it can do either two things: 77 * if the clipboard contains a URI reference to an existing note, it copies 78 * the entire structure of the note into a new note; otherwise, it simply 79 * coerces the clip into text and uses that as the new note's contents. 80 * 81 * {@sample development/samples/NotePad/src/com/example/android/notepad/NoteEditor.java 82 * paste} 83 * 84 * <p>In many cases an application can paste various types of streams of data. For 85 * example, an e-mail application may want to allow the user to paste an image 86 * or other binary data as an attachment. This is accomplished through the 87 * ContentResolver {@link ContentResolver#getStreamTypes(Uri, String)} and 88 * {@link ContentResolver#openTypedAssetFileDescriptor(Uri, String, android.os.Bundle)} 89 * methods. These allow a client to discover the type(s) of data that a particular 90 * content URI can make available as a stream and retrieve the stream of data. 91 * 92 * <p>For example, the implementation of {@link Item#coerceToText Item.coerceToText} 93 * itself uses this to try to retrieve a URI clip as a stream of text: 94 * 95 * {@sample frameworks/base/core/java/android/content/ClippedData.java coerceToText} 96 * 97 * <a name="ImplementingCopy"></a> 98 * <h3>Implementing Copy or Drag</h3> 99 * 100 * <p>To be the source of a clip, the application must construct a ClippedData 101 * object that any recipient can interpret best for their context. If the clip 102 * is to contain a simple text, Intent, or URI, this is easy: an {@link Item} 103 * containing the appropriate data type can be constructed and used. 104 * 105 * <p>More complicated data types require the implementation of support in 106 * a ContentProvider for describing and generating the data for the recipient. 107 * A common scenario is one where an application places on the clipboard the 108 * content: URI of an object that the user has copied, with the data at that 109 * URI consisting of a complicated structure that only other applications with 110 * direct knowledge of the structure can use. 111 * 112 * <p>For applications that do not have intrinsic knowledge of the data structure, 113 * the content provider holding it can make the data available as an arbitrary 114 * number of types of data streams. This is done by implementing the 115 * ContentProvider {@link ContentProvider#getStreamTypes(Uri, String)} and 116 * {@link ContentProvider#openTypedAssetFile(Uri, String, android.os.Bundle)} 117 * methods. 118 * 119 * <p>Going back to our simple NotePad application, this is the implementation 120 * it may have to convert a single note URI (consisting of a title and the note 121 * text) into a stream of plain text data. 122 * 123 * {@sample development/samples/NotePad/src/com/example/android/notepad/NotePadProvider.java 124 * stream} 125 * 126 * <p>The copy operation in our NotePad application is now just a simple matter 127 * of making a clip containing the URI of the note being copied: 128 * 129 * {@sample development/samples/NotePad/src/com/example/android/notepad/NotesList.java 130 * copy} 131 * 132 * <p>Note if a paste operation needs this clip as text (for example to paste 133 * into an editor), then {@link Item#coerceToText(Context)} will ask the content 134 * provider for the clip URI as text and successfully paste the entire note. 135 */ 136public class ClipData extends ClipDescription { 137 static final String[] MIMETYPES_TEXT_PLAIN = new String[] { MIMETYPE_TEXT_PLAIN }; 138 static final String[] MIMETYPES_TEXT_URILIST = new String[] { MIMETYPE_TEXT_URILIST }; 139 static final String[] MIMETYPES_TEXT_INTENT = new String[] { MIMETYPE_TEXT_INTENT }; 140 141 final Bitmap mIcon; 142 143 final ArrayList<Item> mItems = new ArrayList<Item>(); 144 145 /** 146 * Description of a single item in a ClippedData. 147 * 148 * <p>The types than an individual item can currently contain are:</p> 149 * 150 * <ul> 151 * <li> Text: a basic string of text. This is actually a CharSequence, 152 * so it can be formatted text supported by corresponding Android built-in 153 * style spans. (Custom application spans are not supported and will be 154 * stripped when transporting through the clipboard.) 155 * <li> Intent: an arbitrary Intent object. A typical use is the shortcut 156 * to create when pasting a clipped item on to the home screen. 157 * <li> Uri: a URI reference. This may be any URI (such as an http: URI 158 * representing a bookmark), however it is often a content: URI. Using 159 * content provider references as clips like this allows an application to 160 * share complex or large clips through the standard content provider 161 * facilities. 162 * </ul> 163 */ 164 public static class Item { 165 final CharSequence mText; 166 final Intent mIntent; 167 final Uri mUri; 168 169 /** 170 * Create an Item consisting of a single block of (possibly styled) text. 171 */ 172 public Item(CharSequence text) { 173 mText = text; 174 mIntent = null; 175 mUri = null; 176 } 177 178 /** 179 * Create an Item consisting of an arbitrary Intent. 180 */ 181 public Item(Intent intent) { 182 mText = null; 183 mIntent = intent; 184 mUri = null; 185 } 186 187 /** 188 * Create an Item consisting of an arbitrary URI. 189 */ 190 public Item(Uri uri) { 191 mText = null; 192 mIntent = null; 193 mUri = uri; 194 } 195 196 /** 197 * Create a complex Item, containing multiple representations of 198 * text, intent, and/or URI. 199 */ 200 public Item(CharSequence text, Intent intent, Uri uri) { 201 mText = text; 202 mIntent = intent; 203 mUri = uri; 204 } 205 206 /** 207 * Retrieve the raw text contained in this Item. 208 */ 209 public CharSequence getText() { 210 return mText; 211 } 212 213 /** 214 * Retrieve the raw Intent contained in this Item. 215 */ 216 public Intent getIntent() { 217 return mIntent; 218 } 219 220 /** 221 * Retrieve the raw URI contained in this Item. 222 */ 223 public Uri getUri() { 224 return mUri; 225 } 226 227 /** 228 * Turn this item into text, regardless of the type of data it 229 * actually contains. 230 * 231 * <p>The algorithm for deciding what text to return is: 232 * <ul> 233 * <li> If {@link #getText} is non-null, return that. 234 * <li> If {@link #getUri} is non-null, try to retrieve its data 235 * as a text stream from its content provider. If this succeeds, copy 236 * the text into a String and return it. If it is not a content: URI or 237 * the content provider does not supply a text representation, return 238 * the raw URI as a string. 239 * <li> If {@link #getIntent} is non-null, convert that to an intent: 240 * URI and returnit. 241 * <li> Otherwise, return an empty string. 242 * </ul> 243 * 244 * @param context The caller's Context, from which its ContentResolver 245 * and other things can be retrieved. 246 * @return Returns the item's textual representation. 247 */ 248//BEGIN_INCLUDE(coerceToText) 249 public CharSequence coerceToText(Context context) { 250 // If this Item has an explicit textual value, simply return that. 251 if (mText != null) { 252 return mText; 253 } 254 255 // If this Item has a URI value, try using that. 256 if (mUri != null) { 257 258 // First see if the URI can be opened as a plain text stream 259 // (of any sub-type). If so, this is the best textual 260 // representation for it. 261 FileInputStream stream = null; 262 try { 263 // Ask for a stream of the desired type. 264 AssetFileDescriptor descr = context.getContentResolver() 265 .openTypedAssetFileDescriptor(mUri, "text/*", null); 266 stream = descr.createInputStream(); 267 InputStreamReader reader = new InputStreamReader(stream, "UTF-8"); 268 269 // Got it... copy the stream into a local string and return it. 270 StringBuilder builder = new StringBuilder(128); 271 char[] buffer = new char[8192]; 272 int len; 273 while ((len=reader.read(buffer)) > 0) { 274 builder.append(buffer, 0, len); 275 } 276 return builder.toString(); 277 278 } catch (FileNotFoundException e) { 279 // Unable to open content URI as text... not really an 280 // error, just something to ignore. 281 282 } catch (IOException e) { 283 // Something bad has happened. 284 Log.w("ClippedData", "Failure loading text", e); 285 return e.toString(); 286 287 } finally { 288 if (stream != null) { 289 try { 290 stream.close(); 291 } catch (IOException e) { 292 } 293 } 294 } 295 296 // If we couldn't open the URI as a stream, then the URI itself 297 // probably serves fairly well as a textual representation. 298 return mUri.toString(); 299 } 300 301 // Finally, if all we have is an Intent, then we can just turn that 302 // into text. Not the most user-friendly thing, but it's something. 303 if (mIntent != null) { 304 return mIntent.toUri(Intent.URI_INTENT_SCHEME); 305 } 306 307 // Shouldn't get here, but just in case... 308 return ""; 309 } 310//END_INCLUDE(coerceToText) 311 } 312 313 /** 314 * Create a new clip. 315 * 316 * @param label Label to show to the user describing this clip. 317 * @param mimeTypes An array of MIME types this data is available as. 318 * @param icon Bitmap providing the user with an iconing representation of 319 * the clip. 320 * @param item The contents of the first item in the clip. 321 */ 322 public ClipData(CharSequence label, String[] mimeTypes, Bitmap icon, Item item) { 323 super(label, mimeTypes); 324 if (item == null) { 325 throw new NullPointerException("item is null"); 326 } 327 mIcon = icon; 328 mItems.add(item); 329 } 330 331 /** 332 * Create a new ClipData holding data of the type {@link #MIMETYPE_TEXT_PLAIN}. 333 * 334 * @param label User-visible label for the clip data. 335 * @param icon Iconic representation of the clip data. 336 * @param text The actual text in the clip. 337 * @return Returns a new ClipData containing the specified data. 338 */ 339 static public ClipData newPlainText(CharSequence label, Bitmap icon, CharSequence text) { 340 Item item = new Item(text); 341 return new ClipData(label, MIMETYPES_TEXT_PLAIN, icon, item); 342 } 343 344 /** 345 * Create a new ClipData holding an Intent with MIME type {@link #MIMETYPE_TEXT_INTENT}. 346 * 347 * @param label User-visible label for the clip data. 348 * @param icon Iconic representation of the clip data. 349 * @param intent The actual Intent in the clip. 350 * @return Returns a new ClipData containing the specified data. 351 */ 352 static public ClipData newIntent(CharSequence label, Bitmap icon, Intent intent) { 353 Item item = new Item(intent); 354 return new ClipData(label, MIMETYPES_TEXT_INTENT, icon, item); 355 } 356 357 /** 358 * Create a new ClipData holding a URI. If the URI is a content: URI, 359 * this will query the content provider for the MIME type of its data and 360 * use that as the MIME type. Otherwise, it will use the MIME type 361 * {@link #MIMETYPE_TEXT_URILIST}. 362 * 363 * @param resolver ContentResolver used to get information about the URI. 364 * @param label User-visible label for the clip data. 365 * @param icon Iconic representation of the clip data. 366 * @param uri The URI in the clip. 367 * @return Returns a new ClipData containing the specified data. 368 */ 369 static public ClipData newUri(ContentResolver resolver, CharSequence label, 370 Bitmap icon, Uri uri) { 371 Item item = new Item(uri); 372 String[] mimeTypes = null; 373 if ("content".equals(uri.getScheme())) { 374 String realType = resolver.getType(uri); 375 mimeTypes = resolver.getStreamTypes(uri, "*/*"); 376 if (mimeTypes == null) { 377 if (realType != null) { 378 mimeTypes = new String[] { realType, MIMETYPE_TEXT_URILIST }; 379 } 380 } else { 381 String[] tmp = new String[mimeTypes.length + (realType != null ? 2 : 1)]; 382 int i = 0; 383 if (realType != null) { 384 tmp[0] = realType; 385 i++; 386 } 387 System.arraycopy(mimeTypes, 0, tmp, i, mimeTypes.length); 388 tmp[i + mimeTypes.length] = MIMETYPE_TEXT_URILIST; 389 mimeTypes = tmp; 390 } 391 } 392 if (mimeTypes == null) { 393 mimeTypes = MIMETYPES_TEXT_URILIST; 394 } 395 return new ClipData(label, mimeTypes, icon, item); 396 } 397 398 /** 399 * Create a new ClipData holding an URI with MIME type {@link #MIMETYPE_TEXT_URILIST}. 400 * Unlike {@link #newUri(ContentResolver, CharSequence, Bitmap, Uri)}, nothing 401 * is inferred about the URI -- if it is a content: URI holding a bitmap, 402 * the reported type will still be uri-list. Use this with care! 403 * 404 * @param label User-visible label for the clip data. 405 * @param icon Iconic representation of the clip data. 406 * @param uri The URI in the clip. 407 * @return Returns a new ClipData containing the specified data. 408 */ 409 static public ClipData newRawUri(CharSequence label, Bitmap icon, Uri uri) { 410 Item item = new Item(uri); 411 return new ClipData(label, MIMETYPES_TEXT_URILIST, icon, item); 412 } 413 414 public void addItem(Item item) { 415 if (item == null) { 416 throw new NullPointerException("item is null"); 417 } 418 mItems.add(item); 419 } 420 421 public Bitmap getIcon() { 422 return mIcon; 423 } 424 425 public int getItemCount() { 426 return mItems.size(); 427 } 428 429 public Item getItem(int index) { 430 return mItems.get(index); 431 } 432 433 @Override 434 public int describeContents() { 435 return 0; 436 } 437 438 @Override 439 public void writeToParcel(Parcel dest, int flags) { 440 super.writeToParcel(dest, flags); 441 if (mIcon != null) { 442 dest.writeInt(1); 443 mIcon.writeToParcel(dest, flags); 444 } else { 445 dest.writeInt(0); 446 } 447 final int N = mItems.size(); 448 dest.writeInt(N); 449 for (int i=0; i<N; i++) { 450 Item item = mItems.get(i); 451 TextUtils.writeToParcel(item.mText, dest, flags); 452 if (item.mIntent != null) { 453 dest.writeInt(1); 454 item.mIntent.writeToParcel(dest, flags); 455 } else { 456 dest.writeInt(0); 457 } 458 if (item.mUri != null) { 459 dest.writeInt(1); 460 item.mUri.writeToParcel(dest, flags); 461 } else { 462 dest.writeInt(0); 463 } 464 } 465 } 466 467 ClipData(Parcel in) { 468 super(in); 469 if (in.readInt() != 0) { 470 mIcon = Bitmap.CREATOR.createFromParcel(in); 471 } else { 472 mIcon = null; 473 } 474 final int N = in.readInt(); 475 for (int i=0; i<N; i++) { 476 CharSequence text = TextUtils.CHAR_SEQUENCE_CREATOR.createFromParcel(in); 477 Intent intent = in.readInt() != 0 ? Intent.CREATOR.createFromParcel(in) : null; 478 Uri uri = in.readInt() != 0 ? Uri.CREATOR.createFromParcel(in) : null; 479 mItems.add(new Item(text, intent, uri)); 480 } 481 } 482 483 public static final Parcelable.Creator<ClipData> CREATOR = 484 new Parcelable.Creator<ClipData>() { 485 486 public ClipData createFromParcel(Parcel source) { 487 return new ClipData(source); 488 } 489 490 public ClipData[] newArray(int size) { 491 return new ClipData[size]; 492 } 493 }; 494} 495