ClipData.java revision 3aef8e1d1b2f0b87d470bcccf37ba4ebb6560c45
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 contains a {@link ClipDescription}, which describes 41 * important meta-data about the clip. In particular, its 42 * {@link ClipDescription#getMimeType(int) getDescription().getMimeType(int)} 43 * must return correct MIME type(s) describing the data in the clip. For help 44 * in correctly constructing a clip with the correct MIME type, use 45 * {@link #newPlainText(CharSequence, CharSequence)}, 46 * {@link #newUri(ContentResolver, CharSequence, Uri)}, and 47 * {@link #newIntent(CharSequence, Intent)}. 48 * 49 * <p>Each Item instance can be one of three main classes of data: a simple 50 * CharSequence of text, a single Intent object, or a Uri. See {@link Item} 51 * for more details. 52 * 53 * <div class="special reference"> 54 * <h3>Developer Guides</h3> 55 * <p>For more information about using the clipboard framework, read the 56 * <a href="{@docRoot}guide/topics/clipboard/copy-paste.html">Copy and Paste</a> 57 * developer guide.</p> 58 * </div> 59 * 60 * <a name="ImplementingPaste"></a> 61 * <h3>Implementing Paste or Drop</h3> 62 * 63 * <p>To implement a paste or drop of a ClippedData object into an application, 64 * the application must correctly interpret the data for its use. If the {@link Item} 65 * it contains is simple text or an Intent, there is little to be done: text 66 * can only be interpreted as text, and an Intent will typically be used for 67 * creating shortcuts (such as placing icons on the home screen) or other 68 * actions. 69 * 70 * <p>If all you want is the textual representation of the clipped data, you 71 * can use the convenience method {@link Item#coerceToText Item.coerceToText}. 72 * In this case there is generally no need to worry about the MIME types 73 * reported by {@link ClipDescription#getMimeType(int) getDescription().getMimeType(int)}, 74 * since any clip item an always be converted to a string. 75 * 76 * <p>More complicated exchanges will be done through URIs, in particular 77 * "content:" URIs. A content URI allows the recipient of a ClippedData item 78 * to interact closely with the ContentProvider holding the data in order to 79 * negotiate the transfer of that data. The clip must also be filled in with 80 * the available MIME types; {@link #newUri(ContentResolver, CharSequence, Uri)} 81 * will take care of correctly doing this. 82 * 83 * <p>For example, here is the paste function of a simple NotePad application. 84 * When retrieving the data from the clipboard, it can do either two things: 85 * if the clipboard contains a URI reference to an existing note, it copies 86 * the entire structure of the note into a new note; otherwise, it simply 87 * coerces the clip into text and uses that as the new note's contents. 88 * 89 * {@sample development/samples/NotePad/src/com/example/android/notepad/NoteEditor.java 90 * paste} 91 * 92 * <p>In many cases an application can paste various types of streams of data. For 93 * example, an e-mail application may want to allow the user to paste an image 94 * or other binary data as an attachment. This is accomplished through the 95 * ContentResolver {@link ContentResolver#getStreamTypes(Uri, String)} and 96 * {@link ContentResolver#openTypedAssetFileDescriptor(Uri, String, android.os.Bundle)} 97 * methods. These allow a client to discover the type(s) of data that a particular 98 * content URI can make available as a stream and retrieve the stream of data. 99 * 100 * <p>For example, the implementation of {@link Item#coerceToText Item.coerceToText} 101 * itself uses this to try to retrieve a URI clip as a stream of text: 102 * 103 * {@sample frameworks/base/core/java/android/content/ClipData.java coerceToText} 104 * 105 * <a name="ImplementingCopy"></a> 106 * <h3>Implementing Copy or Drag</h3> 107 * 108 * <p>To be the source of a clip, the application must construct a ClippedData 109 * object that any recipient can interpret best for their context. If the clip 110 * is to contain a simple text, Intent, or URI, this is easy: an {@link Item} 111 * containing the appropriate data type can be constructed and used. 112 * 113 * <p>More complicated data types require the implementation of support in 114 * a ContentProvider for describing and generating the data for the recipient. 115 * A common scenario is one where an application places on the clipboard the 116 * content: URI of an object that the user has copied, with the data at that 117 * URI consisting of a complicated structure that only other applications with 118 * direct knowledge of the structure can use. 119 * 120 * <p>For applications that do not have intrinsic knowledge of the data structure, 121 * the content provider holding it can make the data available as an arbitrary 122 * number of types of data streams. This is done by implementing the 123 * ContentProvider {@link ContentProvider#getStreamTypes(Uri, String)} and 124 * {@link ContentProvider#openTypedAssetFile(Uri, String, android.os.Bundle)} 125 * methods. 126 * 127 * <p>Going back to our simple NotePad application, this is the implementation 128 * it may have to convert a single note URI (consisting of a title and the note 129 * text) into a stream of plain text data. 130 * 131 * {@sample development/samples/NotePad/src/com/example/android/notepad/NotePadProvider.java 132 * stream} 133 * 134 * <p>The copy operation in our NotePad application is now just a simple matter 135 * of making a clip containing the URI of the note being copied: 136 * 137 * {@sample development/samples/NotePad/src/com/example/android/notepad/NotesList.java 138 * copy} 139 * 140 * <p>Note if a paste operation needs this clip as text (for example to paste 141 * into an editor), then {@link Item#coerceToText(Context)} will ask the content 142 * provider for the clip URI as text and successfully paste the entire note. 143 */ 144public class ClipData implements Parcelable { 145 static final String[] MIMETYPES_TEXT_PLAIN = new String[] { 146 ClipDescription.MIMETYPE_TEXT_PLAIN }; 147 static final String[] MIMETYPES_TEXT_URILIST = new String[] { 148 ClipDescription.MIMETYPE_TEXT_URILIST }; 149 static final String[] MIMETYPES_TEXT_INTENT = new String[] { 150 ClipDescription.MIMETYPE_TEXT_INTENT }; 151 152 final ClipDescription mClipDescription; 153 154 final Bitmap mIcon; 155 156 final ArrayList<Item> mItems = new ArrayList<Item>(); 157 158 /** 159 * Description of a single item in a ClippedData. 160 * 161 * <p>The types than an individual item can currently contain are:</p> 162 * 163 * <ul> 164 * <li> Text: a basic string of text. This is actually a CharSequence, 165 * so it can be formatted text supported by corresponding Android built-in 166 * style spans. (Custom application spans are not supported and will be 167 * stripped when transporting through the clipboard.) 168 * <li> Intent: an arbitrary Intent object. A typical use is the shortcut 169 * to create when pasting a clipped item on to the home screen. 170 * <li> Uri: a URI reference. This may be any URI (such as an http: URI 171 * representing a bookmark), however it is often a content: URI. Using 172 * content provider references as clips like this allows an application to 173 * share complex or large clips through the standard content provider 174 * facilities. 175 * </ul> 176 */ 177 public static class Item { 178 final CharSequence mText; 179 final Intent mIntent; 180 final Uri mUri; 181 182 /** 183 * Create an Item consisting of a single block of (possibly styled) text. 184 */ 185 public Item(CharSequence text) { 186 mText = text; 187 mIntent = null; 188 mUri = null; 189 } 190 191 /** 192 * Create an Item consisting of an arbitrary Intent. 193 */ 194 public Item(Intent intent) { 195 mText = null; 196 mIntent = intent; 197 mUri = null; 198 } 199 200 /** 201 * Create an Item consisting of an arbitrary URI. 202 */ 203 public Item(Uri uri) { 204 mText = null; 205 mIntent = null; 206 mUri = uri; 207 } 208 209 /** 210 * Create a complex Item, containing multiple representations of 211 * text, intent, and/or URI. 212 */ 213 public Item(CharSequence text, Intent intent, Uri uri) { 214 mText = text; 215 mIntent = intent; 216 mUri = uri; 217 } 218 219 /** 220 * Retrieve the raw text contained in this Item. 221 */ 222 public CharSequence getText() { 223 return mText; 224 } 225 226 /** 227 * Retrieve the raw Intent contained in this Item. 228 */ 229 public Intent getIntent() { 230 return mIntent; 231 } 232 233 /** 234 * Retrieve the raw URI contained in this Item. 235 */ 236 public Uri getUri() { 237 return mUri; 238 } 239 240 /** 241 * Turn this item into text, regardless of the type of data it 242 * actually contains. 243 * 244 * <p>The algorithm for deciding what text to return is: 245 * <ul> 246 * <li> If {@link #getText} is non-null, return that. 247 * <li> If {@link #getUri} is non-null, try to retrieve its data 248 * as a text stream from its content provider. If this succeeds, copy 249 * the text into a String and return it. If it is not a content: URI or 250 * the content provider does not supply a text representation, return 251 * the raw URI as a string. 252 * <li> If {@link #getIntent} is non-null, convert that to an intent: 253 * URI and returnit. 254 * <li> Otherwise, return an empty string. 255 * </ul> 256 * 257 * @param context The caller's Context, from which its ContentResolver 258 * and other things can be retrieved. 259 * @return Returns the item's textual representation. 260 */ 261//BEGIN_INCLUDE(coerceToText) 262 public CharSequence coerceToText(Context context) { 263 // If this Item has an explicit textual value, simply return that. 264 if (mText != null) { 265 return mText; 266 } 267 268 // If this Item has a URI value, try using that. 269 if (mUri != null) { 270 271 // First see if the URI can be opened as a plain text stream 272 // (of any sub-type). If so, this is the best textual 273 // representation for it. 274 FileInputStream stream = null; 275 try { 276 // Ask for a stream of the desired type. 277 AssetFileDescriptor descr = context.getContentResolver() 278 .openTypedAssetFileDescriptor(mUri, "text/*", null); 279 stream = descr.createInputStream(); 280 InputStreamReader reader = new InputStreamReader(stream, "UTF-8"); 281 282 // Got it... copy the stream into a local string and return it. 283 StringBuilder builder = new StringBuilder(128); 284 char[] buffer = new char[8192]; 285 int len; 286 while ((len=reader.read(buffer)) > 0) { 287 builder.append(buffer, 0, len); 288 } 289 return builder.toString(); 290 291 } catch (FileNotFoundException e) { 292 // Unable to open content URI as text... not really an 293 // error, just something to ignore. 294 295 } catch (IOException e) { 296 // Something bad has happened. 297 Log.w("ClippedData", "Failure loading text", e); 298 return e.toString(); 299 300 } finally { 301 if (stream != null) { 302 try { 303 stream.close(); 304 } catch (IOException e) { 305 } 306 } 307 } 308 309 // If we couldn't open the URI as a stream, then the URI itself 310 // probably serves fairly well as a textual representation. 311 return mUri.toString(); 312 } 313 314 // Finally, if all we have is an Intent, then we can just turn that 315 // into text. Not the most user-friendly thing, but it's something. 316 if (mIntent != null) { 317 return mIntent.toUri(Intent.URI_INTENT_SCHEME); 318 } 319 320 // Shouldn't get here, but just in case... 321 return ""; 322 } 323//END_INCLUDE(coerceToText) 324 } 325 326 /** 327 * Create a new clip. 328 * 329 * @param label Label to show to the user describing this clip. 330 * @param mimeTypes An array of MIME types this data is available as. 331 * @param item The contents of the first item in the clip. 332 */ 333 public ClipData(CharSequence label, String[] mimeTypes, Item item) { 334 mClipDescription = new ClipDescription(label, mimeTypes); 335 if (item == null) { 336 throw new NullPointerException("item is null"); 337 } 338 mIcon = null; 339 mItems.add(item); 340 } 341 342 /** 343 * Create a new clip. 344 * 345 * @param description The ClipDescription describing the clip contents. 346 * @param item The contents of the first item in the clip. 347 */ 348 public ClipData(ClipDescription description, Item item) { 349 mClipDescription = description; 350 if (item == null) { 351 throw new NullPointerException("item is null"); 352 } 353 mIcon = null; 354 mItems.add(item); 355 } 356 357 /** 358 * Create a new ClipData holding data of the type 359 * {@link ClipDescription#MIMETYPE_TEXT_PLAIN}. 360 * 361 * @param label User-visible label for the clip data. 362 * @param text The actual text in the clip. 363 * @return Returns a new ClipData containing the specified data. 364 */ 365 static public ClipData newPlainText(CharSequence label, CharSequence text) { 366 Item item = new Item(text); 367 return new ClipData(label, MIMETYPES_TEXT_PLAIN, item); 368 } 369 370 /** 371 * Create a new ClipData holding an Intent with MIME type 372 * {@link ClipDescription#MIMETYPE_TEXT_INTENT}. 373 * 374 * @param label User-visible label for the clip data. 375 * @param intent The actual Intent in the clip. 376 * @return Returns a new ClipData containing the specified data. 377 */ 378 static public ClipData newIntent(CharSequence label, Intent intent) { 379 Item item = new Item(intent); 380 return new ClipData(label, MIMETYPES_TEXT_INTENT, item); 381 } 382 383 /** 384 * Create a new ClipData holding a URI. If the URI is a content: URI, 385 * this will query the content provider for the MIME type of its data and 386 * use that as the MIME type. Otherwise, it will use the MIME type 387 * {@link ClipDescription#MIMETYPE_TEXT_URILIST}. 388 * 389 * @param resolver ContentResolver used to get information about the URI. 390 * @param label User-visible label for the clip data. 391 * @param uri The URI in the clip. 392 * @return Returns a new ClipData containing the specified data. 393 */ 394 static public ClipData newUri(ContentResolver resolver, CharSequence label, 395 Uri uri) { 396 Item item = new Item(uri); 397 String[] mimeTypes = null; 398 if ("content".equals(uri.getScheme())) { 399 String realType = resolver.getType(uri); 400 mimeTypes = resolver.getStreamTypes(uri, "*/*"); 401 if (mimeTypes == null) { 402 if (realType != null) { 403 mimeTypes = new String[] { realType, ClipDescription.MIMETYPE_TEXT_URILIST }; 404 } 405 } else { 406 String[] tmp = new String[mimeTypes.length + (realType != null ? 2 : 1)]; 407 int i = 0; 408 if (realType != null) { 409 tmp[0] = realType; 410 i++; 411 } 412 System.arraycopy(mimeTypes, 0, tmp, i, mimeTypes.length); 413 tmp[i + mimeTypes.length] = ClipDescription.MIMETYPE_TEXT_URILIST; 414 mimeTypes = tmp; 415 } 416 } 417 if (mimeTypes == null) { 418 mimeTypes = MIMETYPES_TEXT_URILIST; 419 } 420 return new ClipData(label, mimeTypes, item); 421 } 422 423 /** 424 * Create a new ClipData holding an URI with MIME type 425 * {@link ClipDescription#MIMETYPE_TEXT_URILIST}. 426 * Unlike {@link #newUri(ContentResolver, CharSequence, Uri)}, nothing 427 * is inferred about the URI -- if it is a content: URI holding a bitmap, 428 * the reported type will still be uri-list. Use this with care! 429 * 430 * @param label User-visible label for the clip data. 431 * @param uri The URI in the clip. 432 * @return Returns a new ClipData containing the specified data. 433 */ 434 static public ClipData newRawUri(CharSequence label, Uri uri) { 435 Item item = new Item(uri); 436 return new ClipData(label, MIMETYPES_TEXT_URILIST, item); 437 } 438 439 /** 440 * Return the {@link ClipDescription} associated with this data, describing 441 * what it contains. 442 */ 443 public ClipDescription getDescription() { 444 return mClipDescription; 445 } 446 447 /** 448 * Add a new Item to the overall ClipData container. 449 */ 450 public void addItem(Item item) { 451 if (item == null) { 452 throw new NullPointerException("item is null"); 453 } 454 mItems.add(item); 455 } 456 457 /** @hide */ 458 public Bitmap getIcon() { 459 return mIcon; 460 } 461 462 /** 463 * Return the number of items in the clip data. 464 */ 465 public int getItemCount() { 466 return mItems.size(); 467 } 468 469 /** 470 * Return a single item inside of the clip data. The index can range 471 * from 0 to {@link #getItemCount()}-1. 472 */ 473 public Item getItemAt(int index) { 474 return mItems.get(index); 475 } 476 477 @Override 478 public int describeContents() { 479 return 0; 480 } 481 482 @Override 483 public void writeToParcel(Parcel dest, int flags) { 484 mClipDescription.writeToParcel(dest, flags); 485 if (mIcon != null) { 486 dest.writeInt(1); 487 mIcon.writeToParcel(dest, flags); 488 } else { 489 dest.writeInt(0); 490 } 491 final int N = mItems.size(); 492 dest.writeInt(N); 493 for (int i=0; i<N; i++) { 494 Item item = mItems.get(i); 495 TextUtils.writeToParcel(item.mText, dest, flags); 496 if (item.mIntent != null) { 497 dest.writeInt(1); 498 item.mIntent.writeToParcel(dest, flags); 499 } else { 500 dest.writeInt(0); 501 } 502 if (item.mUri != null) { 503 dest.writeInt(1); 504 item.mUri.writeToParcel(dest, flags); 505 } else { 506 dest.writeInt(0); 507 } 508 } 509 } 510 511 ClipData(Parcel in) { 512 mClipDescription = new ClipDescription(in); 513 if (in.readInt() != 0) { 514 mIcon = Bitmap.CREATOR.createFromParcel(in); 515 } else { 516 mIcon = null; 517 } 518 final int N = in.readInt(); 519 for (int i=0; i<N; i++) { 520 CharSequence text = TextUtils.CHAR_SEQUENCE_CREATOR.createFromParcel(in); 521 Intent intent = in.readInt() != 0 ? Intent.CREATOR.createFromParcel(in) : null; 522 Uri uri = in.readInt() != 0 ? Uri.CREATOR.createFromParcel(in) : null; 523 mItems.add(new Item(text, intent, uri)); 524 } 525 } 526 527 public static final Parcelable.Creator<ClipData> CREATOR = 528 new Parcelable.Creator<ClipData>() { 529 530 public ClipData createFromParcel(Parcel source) { 531 return new ClipData(source); 532 } 533 534 public ClipData[] newArray(int size) { 535 return new ClipData[size]; 536 } 537 }; 538} 539