Drawable.java revision c0053223bedf33581b0830fb87be32c1f26e5372
1/* 2 * Copyright (C) 2006 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.graphics.drawable; 18 19import org.xmlpull.v1.XmlPullParser; 20import org.xmlpull.v1.XmlPullParserException; 21 22import android.content.res.Resources; 23import android.content.res.TypedArray; 24import android.graphics.Bitmap; 25import android.graphics.BitmapFactory; 26import android.graphics.Canvas; 27import android.graphics.ColorFilter; 28import android.graphics.NinePatch; 29import android.graphics.PixelFormat; 30import android.graphics.PorterDuff; 31import android.graphics.PorterDuffColorFilter; 32import android.graphics.Rect; 33import android.graphics.Region; 34import android.util.AttributeSet; 35import android.util.DisplayMetrics; 36import android.util.StateSet; 37import android.util.TypedValue; 38import android.util.Xml; 39import android.view.View; 40 41import java.io.IOException; 42import java.io.InputStream; 43import java.lang.ref.WeakReference; 44import java.util.Arrays; 45 46/** 47 * A Drawable is a general abstraction for "something that can be drawn." Most 48 * often you will deal with Drawable as the type of resource retrieved for 49 * drawing things to the screen; the Drawable class provides a generic API for 50 * dealing with an underlying visual resource that may take a variety of forms. 51 * Unlike a {@link android.view.View}, a Drawable does not have any facility to 52 * receive events or otherwise interact with the user. 53 * 54 * <p>In addition to simple drawing, Drawable provides a number of generic 55 * mechanisms for its client to interact with what is being drawn: 56 * 57 * <ul> 58 * <li> The {@link #setBounds} method <var>must</var> be called to tell the 59 * Drawable where it is drawn and how large it should be. All Drawables 60 * should respect the requested size, often simply by scaling their 61 * imagery. A client can find the preferred size for some Drawables with 62 * the {@link #getIntrinsicHeight} and {@link #getIntrinsicWidth} methods. 63 * 64 * <li> The {@link #getPadding} method can return from some Drawables 65 * information about how to frame content that is placed inside of them. 66 * For example, a Drawable that is intended to be the frame for a button 67 * widget would need to return padding that correctly places the label 68 * inside of itself. 69 * 70 * <li> The {@link #setState} method allows the client to tell the Drawable 71 * in which state it is to be drawn, such as "focused", "selected", etc. 72 * Some drawables may modify their imagery based on the selected state. 73 * 74 * <li> The {@link #setLevel} method allows the client to supply a single 75 * continuous controller that can modify the Drawable is displayed, such as 76 * a battery level or progress level. Some drawables may modify their 77 * imagery based on the current level. 78 * 79 * <li> A Drawable can perform animations by calling back to its client 80 * through the {@link Callback} interface. All clients should support this 81 * interface (via {@link #setCallback}) so that animations will work. A 82 * simple way to do this is through the system facilities such as 83 * {@link android.view.View#setBackgroundDrawable(Drawable)} and 84 * {@link android.widget.ImageView}. 85 * </ul> 86 * 87 * Though usually not visible to the application, Drawables may take a variety 88 * of forms: 89 * 90 * <ul> 91 * <li> <b>Bitmap</b>: the simplest Drawable, a PNG or JPEG image. 92 * <li> <b>Nine Patch</b>: an extension to the PNG format allows it to 93 * specify information about how to stretch it and place things inside of 94 * it. 95 * <li> <b>Shape</b>: contains simple drawing commands instead of a raw 96 * bitmap, allowing it to resize better in some cases. 97 * <li> <b>Layers</b>: a compound drawable, which draws multiple underlying 98 * drawables on top of each other. 99 * <li> <b>States</b>: a compound drawable that selects one of a set of 100 * drawables based on its state. 101 * <li> <b>Levels</b>: a compound drawable that selects one of a set of 102 * drawables based on its level. 103 * <li> <b>Scale</b>: a compound drawable with a single child drawable, 104 * whose overall size is modified based on the current level. 105 * </ul> 106 * <p>For information and examples of creating drawable resources (XML or bitmap files that 107 * can be loaded in code), see <a 108 * href="{@docRoot}guide/topics/resources/drawable-resource.html">Drawable Resources</a>. 109 */ 110public abstract class Drawable { 111 private static final Rect ZERO_BOUNDS_RECT = new Rect(); 112 113 private int[] mStateSet = StateSet.WILD_CARD; 114 private int mLevel = 0; 115 private int mChangingConfigurations = 0; 116 private Rect mBounds = ZERO_BOUNDS_RECT; // lazily becomes a new Rect() 117 private WeakReference<Callback> mCallback = null; 118 private boolean mVisible = true; 119 120 /** 121 * Draw in its bounds (set via setBounds) respecting optional effects such 122 * as alpha (set via setAlpha) and color filter (set via setColorFilter). 123 * 124 * @param canvas The canvas to draw into 125 */ 126 public abstract void draw(Canvas canvas); 127 128 /** 129 * Specify a bounding rectangle for the Drawable. This is where the drawable 130 * will draw when its draw() method is called. 131 */ 132 public void setBounds(int left, int top, int right, int bottom) { 133 Rect oldBounds = mBounds; 134 135 if (oldBounds == ZERO_BOUNDS_RECT) { 136 oldBounds = mBounds = new Rect(); 137 } 138 139 if (oldBounds.left != left || oldBounds.top != top || 140 oldBounds.right != right || oldBounds.bottom != bottom) { 141 mBounds.set(left, top, right, bottom); 142 onBoundsChange(mBounds); 143 } 144 } 145 146 /** 147 * Specify a bounding rectangle for the Drawable. This is where the drawable 148 * will draw when its draw() method is called. 149 */ 150 public void setBounds(Rect bounds) { 151 setBounds(bounds.left, bounds.top, bounds.right, bounds.bottom); 152 } 153 154 /** 155 * Return a copy of the drawable's bounds in the specified Rect (allocated 156 * by the caller). The bounds specify where this will draw when its draw() 157 * method is called. 158 * 159 * @param bounds Rect to receive the drawable's bounds (allocated by the 160 * caller). 161 */ 162 public final void copyBounds(Rect bounds) { 163 bounds.set(mBounds); 164 } 165 166 /** 167 * Return a copy of the drawable's bounds in a new Rect. This returns the 168 * same values as getBounds(), but the returned object is guaranteed to not 169 * be changed later by the drawable (i.e. it retains no reference to this 170 * rect). If the caller already has a Rect allocated, call copyBounds(rect). 171 * 172 * @return A copy of the drawable's bounds 173 */ 174 public final Rect copyBounds() { 175 return new Rect(mBounds); 176 } 177 178 /** 179 * Return the drawable's bounds Rect. Note: for efficiency, the returned 180 * object may be the same object stored in the drawable (though this is not 181 * guaranteed), so if a persistent copy of the bounds is needed, call 182 * copyBounds(rect) instead. 183 * You should also not change the object returned by this method as it may 184 * be the same object stored in the drawable. 185 * 186 * @return The bounds of the drawable (which may change later, so caller 187 * beware). DO NOT ALTER the returned object as it may change the 188 * stored bounds of this drawable. 189 * 190 * @see #copyBounds() 191 * @see #copyBounds(android.graphics.Rect) 192 */ 193 public final Rect getBounds() { 194 if (mBounds == ZERO_BOUNDS_RECT) { 195 mBounds = new Rect(); 196 } 197 198 return mBounds; 199 } 200 201 /** 202 * Set a mask of the configuration parameters for which this drawable 203 * may change, requiring that it be re-created. 204 * 205 * @param configs A mask of the changing configuration parameters, as 206 * defined by {@link android.content.res.Configuration}. 207 * 208 * @see android.content.res.Configuration 209 */ 210 public void setChangingConfigurations(int configs) { 211 mChangingConfigurations = configs; 212 } 213 214 /** 215 * Return a mask of the configuration parameters for which this drawable 216 * may change, requiring that it be re-created. The default implementation 217 * returns whatever was provided through 218 * {@link #setChangingConfigurations(int)} or 0 by default. Subclasses 219 * may extend this to or in the changing configurations of any other 220 * drawables they hold. 221 * 222 * @return Returns a mask of the changing configuration parameters, as 223 * defined by {@link android.content.res.Configuration}. 224 * 225 * @see android.content.res.Configuration 226 */ 227 public int getChangingConfigurations() { 228 return mChangingConfigurations; 229 } 230 231 /** 232 * Set to true to have the drawable dither its colors when drawn to a device 233 * with fewer than 8-bits per color component. This can improve the look on 234 * those devices, but can also slow down the drawing a little. 235 */ 236 public void setDither(boolean dither) {} 237 238 /** 239 * Set to true to have the drawable filter its bitmap when scaled or rotated 240 * (for drawables that use bitmaps). If the drawable does not use bitmaps, 241 * this call is ignored. This can improve the look when scaled or rotated, 242 * but also slows down the drawing. 243 */ 244 public void setFilterBitmap(boolean filter) {} 245 246 /** 247 * Implement this interface if you want to create an animated drawable that 248 * extends {@link android.graphics.drawable.Drawable Drawable}. 249 * Upon retrieving a drawable, use 250 * {@link Drawable#setCallback(android.graphics.drawable.Drawable.Callback)} 251 * to supply your implementation of the interface to the drawable; it uses 252 * this interface to schedule and execute animation changes. 253 */ 254 public static interface Callback { 255 /** 256 * Called when the drawable needs to be redrawn. A view at this point 257 * should invalidate itself (or at least the part of itself where the 258 * drawable appears). 259 * 260 * @param who The drawable that is requesting the update. 261 */ 262 public void invalidateDrawable(Drawable who); 263 264 /** 265 * A Drawable can call this to schedule the next frame of its 266 * animation. An implementation can generally simply call 267 * {@link android.os.Handler#postAtTime(Runnable, Object, long)} with 268 * the parameters <var>(what, who, when)</var> to perform the 269 * scheduling. 270 * 271 * @param who The drawable being scheduled. 272 * @param what The action to execute. 273 * @param when The time (in milliseconds) to run. The timebase is 274 * {@link android.os.SystemClock#uptimeMillis} 275 */ 276 public void scheduleDrawable(Drawable who, Runnable what, long when); 277 278 /** 279 * A Drawable can call this to unschedule an action previously 280 * scheduled with {@link #scheduleDrawable}. An implementation can 281 * generally simply call 282 * {@link android.os.Handler#removeCallbacks(Runnable, Object)} with 283 * the parameters <var>(what, who)</var> to unschedule the drawable. 284 * 285 * @param who The drawable being unscheduled. 286 * @param what The action being unscheduled. 287 */ 288 public void unscheduleDrawable(Drawable who, Runnable what); 289 } 290 291 /** 292 * Implement this interface if you want to create an drawable that is RTL aware 293 */ 294 public static interface Callback2 extends Callback { 295 /** 296 * A Drawable can call this to get the resolved layout direction of the <var>who</var>. 297 * 298 * @param who The drawable being queried. 299 */ 300 public int getResolvedLayoutDirection(Drawable who); 301 } 302 303 /** 304 * Bind a {@link Callback} object to this Drawable. Required for clients 305 * that want to support animated drawables. 306 * 307 * @param cb The client's Callback implementation. 308 * 309 * @see #getCallback() 310 */ 311 public final void setCallback(Callback cb) { 312 mCallback = new WeakReference<Callback>(cb); 313 } 314 315 /** 316 * Return the current {@link Callback} implementation attached to this 317 * Drawable. 318 * 319 * @return A {@link Callback} instance or null if no callback was set. 320 * 321 * @see #setCallback(android.graphics.drawable.Drawable.Callback) 322 */ 323 public Callback getCallback() { 324 if (mCallback != null) { 325 return mCallback.get(); 326 } 327 return null; 328 } 329 330 /** 331 * Use the current {@link Callback} implementation to have this Drawable 332 * redrawn. Does nothing if there is no Callback attached to the 333 * Drawable. 334 * 335 * @see Callback#invalidateDrawable 336 * @see #getCallback() 337 * @see #setCallback(android.graphics.drawable.Drawable.Callback) 338 */ 339 public void invalidateSelf() { 340 final Callback callback = getCallback(); 341 if (callback != null) { 342 callback.invalidateDrawable(this); 343 } 344 } 345 346 /** 347 * Use the current {@link Callback} implementation to have this Drawable 348 * scheduled. Does nothing if there is no Callback attached to the 349 * Drawable. 350 * 351 * @param what The action being scheduled. 352 * @param when The time (in milliseconds) to run. 353 * 354 * @see Callback#scheduleDrawable 355 */ 356 public void scheduleSelf(Runnable what, long when) { 357 final Callback callback = getCallback(); 358 if (callback != null) { 359 callback.scheduleDrawable(this, what, when); 360 } 361 } 362 363 /** 364 * Use the current {@link Callback} implementation to have this Drawable 365 * unscheduled. Does nothing if there is no Callback attached to the 366 * Drawable. 367 * 368 * @param what The runnable that you no longer want called. 369 * 370 * @see Callback#unscheduleDrawable 371 */ 372 public void unscheduleSelf(Runnable what) { 373 final Callback callback = getCallback(); 374 if (callback != null) { 375 callback.unscheduleDrawable(this, what); 376 } 377 } 378 379 /** 380 * Use the current {@link android.graphics.drawable.Drawable.Callback2} implementation to get 381 * the resolved layout direction of this Drawable. 382 */ 383 public int getResolvedLayoutDirectionSelf() { 384 final Callback callback = getCallback(); 385 if (callback == null || !(callback instanceof Callback2)) { 386 return View.LAYOUT_DIRECTION_LTR; 387 } 388 return ((Callback2) callback).getResolvedLayoutDirection(this); 389 } 390 391 /** 392 * Specify an alpha value for the drawable. 0 means fully transparent, and 393 * 255 means fully opaque. 394 */ 395 public abstract void setAlpha(int alpha); 396 397 /** 398 * Specify an optional colorFilter for the drawable. Pass null to remove 399 * any filters. 400 */ 401 public abstract void setColorFilter(ColorFilter cf); 402 403 /** 404 * Specify a color and porterduff mode to be the colorfilter for this 405 * drawable. 406 */ 407 public void setColorFilter(int color, PorterDuff.Mode mode) { 408 setColorFilter(new PorterDuffColorFilter(color, mode)); 409 } 410 411 public void clearColorFilter() { 412 setColorFilter(null); 413 } 414 415 /** 416 * Indicates whether this view will change its appearance based on state. 417 * Clients can use this to determine whether it is necessary to calculate 418 * their state and call setState. 419 * 420 * @return True if this view changes its appearance based on state, false 421 * otherwise. 422 * 423 * @see #setState(int[]) 424 */ 425 public boolean isStateful() { 426 return false; 427 } 428 429 /** 430 * Specify a set of states for the drawable. These are use-case specific, 431 * so see the relevant documentation. As an example, the background for 432 * widgets like Button understand the following states: 433 * [{@link android.R.attr#state_focused}, 434 * {@link android.R.attr#state_pressed}]. 435 * 436 * <p>If the new state you are supplying causes the appearance of the 437 * Drawable to change, then it is responsible for calling 438 * {@link #invalidateSelf} in order to have itself redrawn, <em>and</em> 439 * true will be returned from this function. 440 * 441 * <p>Note: The Drawable holds a reference on to <var>stateSet</var> 442 * until a new state array is given to it, so you must not modify this 443 * array during that time.</p> 444 * 445 * @param stateSet The new set of states to be displayed. 446 * 447 * @return Returns true if this change in state has caused the appearance 448 * of the Drawable to change (hence requiring an invalidate), otherwise 449 * returns false. 450 */ 451 public boolean setState(final int[] stateSet) { 452 if (!Arrays.equals(mStateSet, stateSet)) { 453 mStateSet = stateSet; 454 return onStateChange(stateSet); 455 } 456 return false; 457 } 458 459 /** 460 * Describes the current state, as a union of primitve states, such as 461 * {@link android.R.attr#state_focused}, 462 * {@link android.R.attr#state_selected}, etc. 463 * Some drawables may modify their imagery based on the selected state. 464 * @return An array of resource Ids describing the current state. 465 */ 466 public int[] getState() { 467 return mStateSet; 468 } 469 470 /** 471 * If this Drawable does transition animations between states, ask that 472 * it immediately jump to the current state and skip any active animations. 473 */ 474 public void jumpToCurrentState() { 475 } 476 477 /** 478 * @return The current drawable that will be used by this drawable. For simple drawables, this 479 * is just the drawable itself. For drawables that change state like 480 * {@link StateListDrawable} and {@link LevelListDrawable} this will be the child drawable 481 * currently in use. 482 */ 483 public Drawable getCurrent() { 484 return this; 485 } 486 487 /** 488 * Specify the level for the drawable. This allows a drawable to vary its 489 * imagery based on a continuous controller, for example to show progress 490 * or volume level. 491 * 492 * <p>If the new level you are supplying causes the appearance of the 493 * Drawable to change, then it is responsible for calling 494 * {@link #invalidateSelf} in order to have itself redrawn, <em>and</em> 495 * true will be returned from this function. 496 * 497 * @param level The new level, from 0 (minimum) to 10000 (maximum). 498 * 499 * @return Returns true if this change in level has caused the appearance 500 * of the Drawable to change (hence requiring an invalidate), otherwise 501 * returns false. 502 */ 503 public final boolean setLevel(int level) { 504 if (mLevel != level) { 505 mLevel = level; 506 return onLevelChange(level); 507 } 508 return false; 509 } 510 511 /** 512 * Retrieve the current level. 513 * 514 * @return int Current level, from 0 (minimum) to 10000 (maximum). 515 */ 516 public final int getLevel() { 517 return mLevel; 518 } 519 520 /** 521 * Set whether this Drawable is visible. This generally does not impact 522 * the Drawable's behavior, but is a hint that can be used by some 523 * Drawables, for example, to decide whether run animations. 524 * 525 * @param visible Set to true if visible, false if not. 526 * @param restart You can supply true here to force the drawable to behave 527 * as if it has just become visible, even if it had last 528 * been set visible. Used for example to force animations 529 * to restart. 530 * 531 * @return boolean Returns true if the new visibility is different than 532 * its previous state. 533 */ 534 public boolean setVisible(boolean visible, boolean restart) { 535 boolean changed = mVisible != visible; 536 if (changed) { 537 mVisible = visible; 538 invalidateSelf(); 539 } 540 return changed; 541 } 542 543 public final boolean isVisible() { 544 return mVisible; 545 } 546 547 /** 548 * Return the opacity/transparency of this Drawable. The returned value is 549 * one of the abstract format constants in 550 * {@link android.graphics.PixelFormat}: 551 * {@link android.graphics.PixelFormat#UNKNOWN}, 552 * {@link android.graphics.PixelFormat#TRANSLUCENT}, 553 * {@link android.graphics.PixelFormat#TRANSPARENT}, or 554 * {@link android.graphics.PixelFormat#OPAQUE}. 555 * 556 * <p>Generally a Drawable should be as conservative as possible with the 557 * value it returns. For example, if it contains multiple child drawables 558 * and only shows one of them at a time, if only one of the children is 559 * TRANSLUCENT and the others are OPAQUE then TRANSLUCENT should be 560 * returned. You can use the method {@link #resolveOpacity} to perform a 561 * standard reduction of two opacities to the appropriate single output. 562 * 563 * <p>Note that the returned value does <em>not</em> take into account a 564 * custom alpha or color filter that has been applied by the client through 565 * the {@link #setAlpha} or {@link #setColorFilter} methods. 566 * 567 * @return int The opacity class of the Drawable. 568 * 569 * @see android.graphics.PixelFormat 570 */ 571 public abstract int getOpacity(); 572 573 /** 574 * Return the appropriate opacity value for two source opacities. If 575 * either is UNKNOWN, that is returned; else, if either is TRANSLUCENT, 576 * that is returned; else, if either is TRANSPARENT, that is returned; 577 * else, OPAQUE is returned. 578 * 579 * <p>This is to help in implementing {@link #getOpacity}. 580 * 581 * @param op1 One opacity value. 582 * @param op2 Another opacity value. 583 * 584 * @return int The combined opacity value. 585 * 586 * @see #getOpacity 587 */ 588 public static int resolveOpacity(int op1, int op2) { 589 if (op1 == op2) { 590 return op1; 591 } 592 if (op1 == PixelFormat.UNKNOWN || op2 == PixelFormat.UNKNOWN) { 593 return PixelFormat.UNKNOWN; 594 } 595 if (op1 == PixelFormat.TRANSLUCENT || op2 == PixelFormat.TRANSLUCENT) { 596 return PixelFormat.TRANSLUCENT; 597 } 598 if (op1 == PixelFormat.TRANSPARENT || op2 == PixelFormat.TRANSPARENT) { 599 return PixelFormat.TRANSPARENT; 600 } 601 return PixelFormat.OPAQUE; 602 } 603 604 /** 605 * Returns a Region representing the part of the Drawable that is completely 606 * transparent. This can be used to perform drawing operations, identifying 607 * which parts of the target will not change when rendering the Drawable. 608 * The default implementation returns null, indicating no transparent 609 * region; subclasses can optionally override this to return an actual 610 * Region if they want to supply this optimization information, but it is 611 * not required that they do so. 612 * 613 * @return Returns null if the Drawables has no transparent region to 614 * report, else a Region holding the parts of the Drawable's bounds that 615 * are transparent. 616 */ 617 public Region getTransparentRegion() { 618 return null; 619 } 620 621 /** 622 * Override this in your subclass to change appearance if you recognize the 623 * specified state. 624 * 625 * @return Returns true if the state change has caused the appearance of 626 * the Drawable to change (that is, it needs to be drawn), else false 627 * if it looks the same and there is no need to redraw it since its 628 * last state. 629 */ 630 protected boolean onStateChange(int[] state) { return false; } 631 /** Override this in your subclass to change appearance if you vary based 632 * on level. 633 * @return Returns true if the level change has caused the appearance of 634 * the Drawable to change (that is, it needs to be drawn), else false 635 * if it looks the same and there is no need to redraw it since its 636 * last level. 637 */ 638 protected boolean onLevelChange(int level) { return false; } 639 /** 640 * Override this in your subclass to change appearance if you recognize the 641 * specified state. 642 */ 643 protected void onBoundsChange(Rect bounds) {} 644 645 /** 646 * Return the intrinsic width of the underlying drawable object. Returns 647 * -1 if it has no intrinsic width, such as with a solid color. 648 */ 649 public int getIntrinsicWidth() { 650 return -1; 651 } 652 653 /** 654 * Return the intrinsic height of the underlying drawable object. Returns 655 * -1 if it has no intrinsic height, such as with a solid color. 656 */ 657 public int getIntrinsicHeight() { 658 return -1; 659 } 660 661 /** 662 * Returns the minimum width suggested by this Drawable. If a View uses this 663 * Drawable as a background, it is suggested that the View use at least this 664 * value for its width. (There will be some scenarios where this will not be 665 * possible.) This value should INCLUDE any padding. 666 * 667 * @return The minimum width suggested by this Drawable. If this Drawable 668 * doesn't have a suggested minimum width, 0 is returned. 669 */ 670 public int getMinimumWidth() { 671 final int intrinsicWidth = getIntrinsicWidth(); 672 return intrinsicWidth > 0 ? intrinsicWidth : 0; 673 } 674 675 /** 676 * Returns the minimum height suggested by this Drawable. If a View uses this 677 * Drawable as a background, it is suggested that the View use at least this 678 * value for its height. (There will be some scenarios where this will not be 679 * possible.) This value should INCLUDE any padding. 680 * 681 * @return The minimum height suggested by this Drawable. If this Drawable 682 * doesn't have a suggested minimum height, 0 is returned. 683 */ 684 public int getMinimumHeight() { 685 final int intrinsicHeight = getIntrinsicHeight(); 686 return intrinsicHeight > 0 ? intrinsicHeight : 0; 687 } 688 689 /** 690 * Return in padding the insets suggested by this Drawable for placing 691 * content inside the drawable's bounds. Positive values move toward the 692 * center of the Drawable (set Rect.inset). Returns true if this drawable 693 * actually has a padding, else false. When false is returned, the padding 694 * is always set to 0. 695 */ 696 public boolean getPadding(Rect padding) { 697 padding.set(0, 0, 0, 0); 698 return false; 699 } 700 701 /** 702 * Make this drawable mutable. This operation cannot be reversed. A mutable 703 * drawable is guaranteed to not share its state with any other drawable. 704 * This is especially useful when you need to modify properties of drawables 705 * loaded from resources. By default, all drawables instances loaded from 706 * the same resource share a common state; if you modify the state of one 707 * instance, all the other instances will receive the same modification. 708 * 709 * Calling this method on a mutable Drawable will have no effect. 710 * 711 * @return This drawable. 712 * @see ConstantState 713 * @see #getConstantState() 714 */ 715 public Drawable mutate() { 716 return this; 717 } 718 719 /** 720 * Create a drawable from an inputstream 721 */ 722 public static Drawable createFromStream(InputStream is, String srcName) { 723 return createFromResourceStream(null, null, is, srcName, null); 724 } 725 726 /** 727 * Create a drawable from an inputstream, using the given resources and 728 * value to determine density information. 729 */ 730 public static Drawable createFromResourceStream(Resources res, TypedValue value, 731 InputStream is, String srcName) { 732 return createFromResourceStream(res, value, is, srcName, null); 733 } 734 735 /** 736 * Create a drawable from an inputstream, using the given resources and 737 * value to determine density information. 738 */ 739 public static Drawable createFromResourceStream(Resources res, TypedValue value, 740 InputStream is, String srcName, BitmapFactory.Options opts) { 741 742 if (is == null) { 743 return null; 744 } 745 746 /* ugh. The decodeStream contract is that we have already allocated 747 the pad rect, but if the bitmap does not had a ninepatch chunk, 748 then the pad will be ignored. If we could change this to lazily 749 alloc/assign the rect, we could avoid the GC churn of making new 750 Rects only to drop them on the floor. 751 */ 752 Rect pad = new Rect(); 753 754 // Special stuff for compatibility mode: if the target density is not 755 // the same as the display density, but the resource -is- the same as 756 // the display density, then don't scale it down to the target density. 757 // This allows us to load the system's density-correct resources into 758 // an application in compatibility mode, without scaling those down 759 // to the compatibility density only to have them scaled back up when 760 // drawn to the screen. 761 if (opts == null) opts = new BitmapFactory.Options(); 762 opts.inScreenDensity = DisplayMetrics.DENSITY_DEVICE; 763 Bitmap bm = BitmapFactory.decodeResourceStream(res, value, is, pad, opts); 764 if (bm != null) { 765 byte[] np = bm.getNinePatchChunk(); 766 if (np == null || !NinePatch.isNinePatchChunk(np)) { 767 np = null; 768 pad = null; 769 } 770 return drawableFromBitmap(res, bm, np, pad, srcName); 771 } 772 return null; 773 } 774 775 /** 776 * Create a drawable from an XML document. For more information on how to 777 * create resources in XML, see 778 * <a href="{@docRoot}guide/topics/resources/drawable-resource.html">Drawable Resources</a>. 779 */ 780 public static Drawable createFromXml(Resources r, XmlPullParser parser) 781 throws XmlPullParserException, IOException { 782 AttributeSet attrs = Xml.asAttributeSet(parser); 783 784 int type; 785 while ((type=parser.next()) != XmlPullParser.START_TAG && 786 type != XmlPullParser.END_DOCUMENT) { 787 // Empty loop 788 } 789 790 if (type != XmlPullParser.START_TAG) { 791 throw new XmlPullParserException("No start tag found"); 792 } 793 794 Drawable drawable = createFromXmlInner(r, parser, attrs); 795 796 if (drawable == null) { 797 throw new RuntimeException("Unknown initial tag: " + parser.getName()); 798 } 799 800 return drawable; 801 } 802 803 /** 804 * Create from inside an XML document. Called on a parser positioned at 805 * a tag in an XML document, tries to create a Drawable from that tag. 806 * Returns null if the tag is not a valid drawable. 807 */ 808 public static Drawable createFromXmlInner(Resources r, XmlPullParser parser, AttributeSet attrs) 809 throws XmlPullParserException, IOException { 810 Drawable drawable; 811 812 final String name = parser.getName(); 813 814 if (name.equals("selector")) { 815 drawable = new StateListDrawable(); 816 } else if (name.equals("level-list")) { 817 drawable = new LevelListDrawable(); 818 /* Probably not doing this. 819 } else if (name.equals("mipmap")) { 820 drawable = new MipmapDrawable(); 821 */ 822 } else if (name.equals("layer-list")) { 823 drawable = new LayerDrawable(); 824 } else if (name.equals("transition")) { 825 drawable = new TransitionDrawable(); 826 } else if (name.equals("color")) { 827 drawable = new ColorDrawable(); 828 } else if (name.equals("shape")) { 829 drawable = new GradientDrawable(); 830 } else if (name.equals("scale")) { 831 drawable = new ScaleDrawable(); 832 } else if (name.equals("clip")) { 833 drawable = new ClipDrawable(); 834 } else if (name.equals("rotate")) { 835 drawable = new RotateDrawable(); 836 } else if (name.equals("animated-rotate")) { 837 drawable = new AnimatedRotateDrawable(); 838 } else if (name.equals("animation-list")) { 839 drawable = new AnimationDrawable(); 840 } else if (name.equals("inset")) { 841 drawable = new InsetDrawable(); 842 } else if (name.equals("bitmap")) { 843 drawable = new BitmapDrawable(r); 844 if (r != null) { 845 ((BitmapDrawable) drawable).setTargetDensity(r.getDisplayMetrics()); 846 } 847 } else if (name.equals("nine-patch")) { 848 drawable = new NinePatchDrawable(); 849 if (r != null) { 850 ((NinePatchDrawable) drawable).setTargetDensity(r.getDisplayMetrics()); 851 } 852 } else { 853 throw new XmlPullParserException(parser.getPositionDescription() + 854 ": invalid drawable tag " + name); 855 } 856 857 drawable.inflate(r, parser, attrs); 858 return drawable; 859 } 860 861 862 /** 863 * Create a drawable from file path name. 864 */ 865 public static Drawable createFromPath(String pathName) { 866 if (pathName == null) { 867 return null; 868 } 869 870 Bitmap bm = BitmapFactory.decodeFile(pathName); 871 if (bm != null) { 872 return drawableFromBitmap(null, bm, null, null, pathName); 873 } 874 875 return null; 876 } 877 878 /** 879 * Inflate this Drawable from an XML resource. 880 */ 881 public void inflate(Resources r, XmlPullParser parser, AttributeSet attrs) 882 throws XmlPullParserException, IOException { 883 884 TypedArray a = r.obtainAttributes(attrs, com.android.internal.R.styleable.Drawable); 885 inflateWithAttributes(r, parser, a, com.android.internal.R.styleable.Drawable_visible); 886 a.recycle(); 887 } 888 889 /** 890 * Inflate a Drawable from an XML resource. 891 * 892 * @throws XmlPullParserException 893 * @throws IOException 894 */ 895 void inflateWithAttributes(Resources r, XmlPullParser parser, 896 TypedArray attrs, int visibleAttr) 897 throws XmlPullParserException, IOException { 898 899 mVisible = attrs.getBoolean(visibleAttr, mVisible); 900 } 901 902 /** 903 * This abstract class is used by {@link Drawable}s to store shared constant state and data 904 * between Drawables. {@link BitmapDrawable}s created from the same resource will for instance 905 * share a unique bitmap stored in their ConstantState. 906 * 907 * <p> 908 * {@link #newDrawable(Resources)} can be used as a factory to create new Drawable instances 909 * from this ConstantState. 910 * </p> 911 * 912 * Use {@link Drawable#getConstantState()} to retrieve the ConstantState of a Drawable. Calling 913 * {@link Drawable#mutate()} on a Drawable should typically create a new ConstantState for that 914 * Drawable. 915 */ 916 public static abstract class ConstantState { 917 /** 918 * Create a new drawable without supplying resources the caller 919 * is running in. Note that using this means the density-dependent 920 * drawables (like bitmaps) will not be able to update their target 921 * density correctly. One should use {@link #newDrawable(Resources)} 922 * instead to provide a resource. 923 */ 924 public abstract Drawable newDrawable(); 925 /** 926 * Create a new Drawable instance from its constant state. This 927 * must be implemented for drawables that change based on the target 928 * density of their caller (that is depending on whether it is 929 * in compatibility mode). 930 */ 931 public Drawable newDrawable(Resources res) { 932 return newDrawable(); 933 } 934 /** 935 * Return a bit mask of configuration changes that will impact 936 * this drawable (and thus require completely reloading it). 937 */ 938 public abstract int getChangingConfigurations(); 939 } 940 941 /** 942 * Return a {@link ConstantState} instance that holds the shared state of this Drawable. 943 *q 944 * @return The ConstantState associated to that Drawable. 945 * @see ConstantState 946 * @see Drawable#mutate() 947 */ 948 public ConstantState getConstantState() { 949 return null; 950 } 951 952 private static Drawable drawableFromBitmap(Resources res, Bitmap bm, byte[] np, 953 Rect pad, String srcName) { 954 955 if (np != null) { 956 return new NinePatchDrawable(res, bm, np, pad, srcName); 957 } 958 959 return new BitmapDrawable(res, bm); 960 } 961} 962 963