Drawable.java revision 908aecc3a63c5520d5b11da14a9383f885b7d126
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 android.graphics.Insets; 20import org.xmlpull.v1.XmlPullParser; 21import org.xmlpull.v1.XmlPullParserException; 22 23import android.content.res.Resources; 24import android.content.res.TypedArray; 25import android.graphics.Bitmap; 26import android.graphics.BitmapFactory; 27import android.graphics.Canvas; 28import android.graphics.ColorFilter; 29import android.graphics.NinePatch; 30import android.graphics.PixelFormat; 31import android.graphics.PorterDuff; 32import android.graphics.PorterDuffColorFilter; 33import android.graphics.Rect; 34import android.graphics.Region; 35import android.util.AttributeSet; 36import android.util.DisplayMetrics; 37import android.util.StateSet; 38import android.util.TypedValue; 39import android.util.Xml; 40import android.view.View; 41 42import java.io.IOException; 43import java.io.InputStream; 44import java.lang.ref.WeakReference; 45import java.util.Arrays; 46 47/** 48 * A Drawable is a general abstraction for "something that can be drawn." Most 49 * often you will deal with Drawable as the type of resource retrieved for 50 * drawing things to the screen; the Drawable class provides a generic API for 51 * dealing with an underlying visual resource that may take a variety of forms. 52 * Unlike a {@link android.view.View}, a Drawable does not have any facility to 53 * receive events or otherwise interact with the user. 54 * 55 * <p>In addition to simple drawing, Drawable provides a number of generic 56 * mechanisms for its client to interact with what is being drawn: 57 * 58 * <ul> 59 * <li> The {@link #setBounds} method <var>must</var> be called to tell the 60 * Drawable where it is drawn and how large it should be. All Drawables 61 * should respect the requested size, often simply by scaling their 62 * imagery. A client can find the preferred size for some Drawables with 63 * the {@link #getIntrinsicHeight} and {@link #getIntrinsicWidth} methods. 64 * 65 * <li> The {@link #getPadding} method can return from some Drawables 66 * information about how to frame content that is placed inside of them. 67 * For example, a Drawable that is intended to be the frame for a button 68 * widget would need to return padding that correctly places the label 69 * inside of itself. 70 * 71 * <li> The {@link #setState} method allows the client to tell the Drawable 72 * in which state it is to be drawn, such as "focused", "selected", etc. 73 * Some drawables may modify their imagery based on the selected state. 74 * 75 * <li> The {@link #setLevel} method allows the client to supply a single 76 * continuous controller that can modify the Drawable is displayed, such as 77 * a battery level or progress level. Some drawables may modify their 78 * imagery based on the current level. 79 * 80 * <li> A Drawable can perform animations by calling back to its client 81 * through the {@link Callback} interface. All clients should support this 82 * interface (via {@link #setCallback}) so that animations will work. A 83 * simple way to do this is through the system facilities such as 84 * {@link android.view.View#setBackgroundDrawable(Drawable)} and 85 * {@link android.widget.ImageView}. 86 * </ul> 87 * 88 * Though usually not visible to the application, Drawables may take a variety 89 * of forms: 90 * 91 * <ul> 92 * <li> <b>Bitmap</b>: the simplest Drawable, a PNG or JPEG image. 93 * <li> <b>Nine Patch</b>: an extension to the PNG format allows it to 94 * specify information about how to stretch it and place things inside of 95 * it. 96 * <li> <b>Shape</b>: contains simple drawing commands instead of a raw 97 * bitmap, allowing it to resize better in some cases. 98 * <li> <b>Layers</b>: a compound drawable, which draws multiple underlying 99 * drawables on top of each other. 100 * <li> <b>States</b>: a compound drawable that selects one of a set of 101 * drawables based on its state. 102 * <li> <b>Levels</b>: a compound drawable that selects one of a set of 103 * drawables based on its level. 104 * <li> <b>Scale</b>: a compound drawable with a single child drawable, 105 * whose overall size is modified based on the current level. 106 * </ul> 107 * 108 * <div class="special reference"> 109 * <h3>Developer Guides</h3> 110 * <p>For more information about how to use drawables, read the 111 * <a href="{@docRoot}guide/topics/graphics/2d-graphics.html">Canvas and Drawables</a> developer 112 * guide. For information and examples of creating drawable resources (XML or bitmap files that 113 * can be loaded in code), read the 114 * <a href="{@docRoot}guide/topics/resources/drawable-resource.html">Drawable Resources</a> 115 * document.</p></div> 116 */ 117public abstract class Drawable { 118 private static final Rect ZERO_BOUNDS_RECT = new Rect(); 119 120 private int[] mStateSet = StateSet.WILD_CARD; 121 private int mLevel = 0; 122 private int mChangingConfigurations = 0; 123 private Rect mBounds = ZERO_BOUNDS_RECT; // lazily becomes a new Rect() 124 private WeakReference<Callback> mCallback = null; 125 private boolean mVisible = true; 126 127 private int mLayoutDirection; 128 129 /** 130 * Draw in its bounds (set via setBounds) respecting optional effects such 131 * as alpha (set via setAlpha) and color filter (set via setColorFilter). 132 * 133 * @param canvas The canvas to draw into 134 */ 135 public abstract void draw(Canvas canvas); 136 137 /** 138 * Specify a bounding rectangle for the Drawable. This is where the drawable 139 * will draw when its draw() method is called. 140 */ 141 public void setBounds(int left, int top, int right, int bottom) { 142 Rect oldBounds = mBounds; 143 144 if (oldBounds == ZERO_BOUNDS_RECT) { 145 oldBounds = mBounds = new Rect(); 146 } 147 148 if (oldBounds.left != left || oldBounds.top != top || 149 oldBounds.right != right || oldBounds.bottom != bottom) { 150 mBounds.set(left, top, right, bottom); 151 onBoundsChange(mBounds); 152 } 153 } 154 155 /** 156 * Specify a bounding rectangle for the Drawable. This is where the drawable 157 * will draw when its draw() method is called. 158 */ 159 public void setBounds(Rect bounds) { 160 setBounds(bounds.left, bounds.top, bounds.right, bounds.bottom); 161 } 162 163 /** 164 * Return a copy of the drawable's bounds in the specified Rect (allocated 165 * by the caller). The bounds specify where this will draw when its draw() 166 * method is called. 167 * 168 * @param bounds Rect to receive the drawable's bounds (allocated by the 169 * caller). 170 */ 171 public final void copyBounds(Rect bounds) { 172 bounds.set(mBounds); 173 } 174 175 /** 176 * Return a copy of the drawable's bounds in a new Rect. This returns the 177 * same values as getBounds(), but the returned object is guaranteed to not 178 * be changed later by the drawable (i.e. it retains no reference to this 179 * rect). If the caller already has a Rect allocated, call copyBounds(rect). 180 * 181 * @return A copy of the drawable's bounds 182 */ 183 public final Rect copyBounds() { 184 return new Rect(mBounds); 185 } 186 187 /** 188 * Return the drawable's bounds Rect. Note: for efficiency, the returned 189 * object may be the same object stored in the drawable (though this is not 190 * guaranteed), so if a persistent copy of the bounds is needed, call 191 * copyBounds(rect) instead. 192 * You should also not change the object returned by this method as it may 193 * be the same object stored in the drawable. 194 * 195 * @return The bounds of the drawable (which may change later, so caller 196 * beware). DO NOT ALTER the returned object as it may change the 197 * stored bounds of this drawable. 198 * 199 * @see #copyBounds() 200 * @see #copyBounds(android.graphics.Rect) 201 */ 202 public final Rect getBounds() { 203 if (mBounds == ZERO_BOUNDS_RECT) { 204 mBounds = new Rect(); 205 } 206 207 return mBounds; 208 } 209 210 /** 211 * Set a mask of the configuration parameters for which this drawable 212 * may change, requiring that it be re-created. 213 * 214 * @param configs A mask of the changing configuration parameters, as 215 * defined by {@link android.content.res.Configuration}. 216 * 217 * @see android.content.res.Configuration 218 */ 219 public void setChangingConfigurations(int configs) { 220 mChangingConfigurations = configs; 221 } 222 223 /** 224 * Return a mask of the configuration parameters for which this drawable 225 * may change, requiring that it be re-created. The default implementation 226 * returns whatever was provided through 227 * {@link #setChangingConfigurations(int)} or 0 by default. Subclasses 228 * may extend this to or in the changing configurations of any other 229 * drawables they hold. 230 * 231 * @return Returns a mask of the changing configuration parameters, as 232 * defined by {@link android.content.res.Configuration}. 233 * 234 * @see android.content.res.Configuration 235 */ 236 public int getChangingConfigurations() { 237 return mChangingConfigurations; 238 } 239 240 /** 241 * Set to true to have the drawable dither its colors when drawn to a device 242 * with fewer than 8-bits per color component. This can improve the look on 243 * those devices, but can also slow down the drawing a little. 244 */ 245 public void setDither(boolean dither) {} 246 247 /** 248 * Set to true to have the drawable filter its bitmap when scaled or rotated 249 * (for drawables that use bitmaps). If the drawable does not use bitmaps, 250 * this call is ignored. This can improve the look when scaled or rotated, 251 * but also slows down the drawing. 252 */ 253 public void setFilterBitmap(boolean filter) {} 254 255 /** 256 * Implement this interface if you want to create an animated drawable that 257 * extends {@link android.graphics.drawable.Drawable Drawable}. 258 * Upon retrieving a drawable, use 259 * {@link Drawable#setCallback(android.graphics.drawable.Drawable.Callback)} 260 * to supply your implementation of the interface to the drawable; it uses 261 * this interface to schedule and execute animation changes. 262 */ 263 public static interface Callback { 264 /** 265 * Called when the drawable needs to be redrawn. A view at this point 266 * should invalidate itself (or at least the part of itself where the 267 * drawable appears). 268 * 269 * @param who The drawable that is requesting the update. 270 */ 271 public void invalidateDrawable(Drawable who); 272 273 /** 274 * A Drawable can call this to schedule the next frame of its 275 * animation. An implementation can generally simply call 276 * {@link android.os.Handler#postAtTime(Runnable, Object, long)} with 277 * the parameters <var>(what, who, when)</var> to perform the 278 * scheduling. 279 * 280 * @param who The drawable being scheduled. 281 * @param what The action to execute. 282 * @param when The time (in milliseconds) to run. The timebase is 283 * {@link android.os.SystemClock#uptimeMillis} 284 */ 285 public void scheduleDrawable(Drawable who, Runnable what, long when); 286 287 /** 288 * A Drawable can call this to unschedule an action previously 289 * scheduled with {@link #scheduleDrawable}. An implementation can 290 * generally simply call 291 * {@link android.os.Handler#removeCallbacks(Runnable, Object)} with 292 * the parameters <var>(what, who)</var> to unschedule the drawable. 293 * 294 * @param who The drawable being unscheduled. 295 * @param what The action being unscheduled. 296 */ 297 public void unscheduleDrawable(Drawable who, Runnable what); 298 } 299 300 /** 301 * Bind a {@link Callback} object to this Drawable. Required for clients 302 * that want to support animated drawables. 303 * 304 * @param cb The client's Callback implementation. 305 * 306 * @see #getCallback() 307 */ 308 public final void setCallback(Callback cb) { 309 mCallback = new WeakReference<Callback>(cb); 310 } 311 312 /** 313 * Return the current {@link Callback} implementation attached to this 314 * Drawable. 315 * 316 * @return A {@link Callback} instance or null if no callback was set. 317 * 318 * @see #setCallback(android.graphics.drawable.Drawable.Callback) 319 */ 320 public Callback getCallback() { 321 if (mCallback != null) { 322 return mCallback.get(); 323 } 324 return null; 325 } 326 327 /** 328 * Use the current {@link Callback} implementation to have this Drawable 329 * redrawn. Does nothing if there is no Callback attached to the 330 * Drawable. 331 * 332 * @see Callback#invalidateDrawable 333 * @see #getCallback() 334 * @see #setCallback(android.graphics.drawable.Drawable.Callback) 335 */ 336 public void invalidateSelf() { 337 final Callback callback = getCallback(); 338 if (callback != null) { 339 callback.invalidateDrawable(this); 340 } 341 } 342 343 /** 344 * Use the current {@link Callback} implementation to have this Drawable 345 * scheduled. Does nothing if there is no Callback attached to the 346 * Drawable. 347 * 348 * @param what The action being scheduled. 349 * @param when The time (in milliseconds) to run. 350 * 351 * @see Callback#scheduleDrawable 352 */ 353 public void scheduleSelf(Runnable what, long when) { 354 final Callback callback = getCallback(); 355 if (callback != null) { 356 callback.scheduleDrawable(this, what, when); 357 } 358 } 359 360 /** 361 * Use the current {@link Callback} implementation to have this Drawable 362 * unscheduled. Does nothing if there is no Callback attached to the 363 * Drawable. 364 * 365 * @param what The runnable that you no longer want called. 366 * 367 * @see Callback#unscheduleDrawable 368 */ 369 public void unscheduleSelf(Runnable what) { 370 final Callback callback = getCallback(); 371 if (callback != null) { 372 callback.unscheduleDrawable(this, what); 373 } 374 } 375 376 /** 377 * Returns the resolved layout direction for this Drawable. 378 * 379 * @return One of {@link View#LAYOUT_DIRECTION_LTR}, 380 * {@link View#LAYOUT_DIRECTION_RTL} 381 */ 382 public int getLayoutDirection() { 383 return mLayoutDirection; 384 } 385 386 /** 387 * Set the layout direction for this drawable. Should be a resolved direction as the 388 * Drawable as no capacity to do the resolution on his own. 389 * 390 * @param layoutDirection One of {@link View#LAYOUT_DIRECTION_LTR}, 391 * {@link View#LAYOUT_DIRECTION_RTL}, 392 * 393 */ 394 public void setLayoutDirection(int layoutDirection) { 395 if (getLayoutDirection() != layoutDirection) { 396 mLayoutDirection = layoutDirection; 397 } 398 } 399 400 /** 401 * Specify an alpha value for the drawable. 0 means fully transparent, and 402 * 255 means fully opaque. 403 */ 404 public abstract void setAlpha(int alpha); 405 406 /** 407 * Specify an optional colorFilter for the drawable. Pass null to remove 408 * any filters. 409 */ 410 public abstract void setColorFilter(ColorFilter cf); 411 412 /** 413 * Specify a color and porterduff mode to be the colorfilter for this 414 * drawable. 415 */ 416 public void setColorFilter(int color, PorterDuff.Mode mode) { 417 setColorFilter(new PorterDuffColorFilter(color, mode)); 418 } 419 420 public void clearColorFilter() { 421 setColorFilter(null); 422 } 423 424 /** 425 * Indicates whether this view will change its appearance based on state. 426 * Clients can use this to determine whether it is necessary to calculate 427 * their state and call setState. 428 * 429 * @return True if this view changes its appearance based on state, false 430 * otherwise. 431 * 432 * @see #setState(int[]) 433 */ 434 public boolean isStateful() { 435 return false; 436 } 437 438 /** 439 * Specify a set of states for the drawable. These are use-case specific, 440 * so see the relevant documentation. As an example, the background for 441 * widgets like Button understand the following states: 442 * [{@link android.R.attr#state_focused}, 443 * {@link android.R.attr#state_pressed}]. 444 * 445 * <p>If the new state you are supplying causes the appearance of the 446 * Drawable to change, then it is responsible for calling 447 * {@link #invalidateSelf} in order to have itself redrawn, <em>and</em> 448 * true will be returned from this function. 449 * 450 * <p>Note: The Drawable holds a reference on to <var>stateSet</var> 451 * until a new state array is given to it, so you must not modify this 452 * array during that time.</p> 453 * 454 * @param stateSet The new set of states to be displayed. 455 * 456 * @return Returns true if this change in state has caused the appearance 457 * of the Drawable to change (hence requiring an invalidate), otherwise 458 * returns false. 459 */ 460 public boolean setState(final int[] stateSet) { 461 if (!Arrays.equals(mStateSet, stateSet)) { 462 mStateSet = stateSet; 463 return onStateChange(stateSet); 464 } 465 return false; 466 } 467 468 /** 469 * Describes the current state, as a union of primitve states, such as 470 * {@link android.R.attr#state_focused}, 471 * {@link android.R.attr#state_selected}, etc. 472 * Some drawables may modify their imagery based on the selected state. 473 * @return An array of resource Ids describing the current state. 474 */ 475 public int[] getState() { 476 return mStateSet; 477 } 478 479 /** 480 * If this Drawable does transition animations between states, ask that 481 * it immediately jump to the current state and skip any active animations. 482 */ 483 public void jumpToCurrentState() { 484 } 485 486 /** 487 * @return The current drawable that will be used by this drawable. For simple drawables, this 488 * is just the drawable itself. For drawables that change state like 489 * {@link StateListDrawable} and {@link LevelListDrawable} this will be the child drawable 490 * currently in use. 491 */ 492 public Drawable getCurrent() { 493 return this; 494 } 495 496 /** 497 * Specify the level for the drawable. This allows a drawable to vary its 498 * imagery based on a continuous controller, for example to show progress 499 * or volume level. 500 * 501 * <p>If the new level you are supplying causes the appearance of the 502 * Drawable to change, then it is responsible for calling 503 * {@link #invalidateSelf} in order to have itself redrawn, <em>and</em> 504 * true will be returned from this function. 505 * 506 * @param level The new level, from 0 (minimum) to 10000 (maximum). 507 * 508 * @return Returns true if this change in level has caused the appearance 509 * of the Drawable to change (hence requiring an invalidate), otherwise 510 * returns false. 511 */ 512 public final boolean setLevel(int level) { 513 if (mLevel != level) { 514 mLevel = level; 515 return onLevelChange(level); 516 } 517 return false; 518 } 519 520 /** 521 * Retrieve the current level. 522 * 523 * @return int Current level, from 0 (minimum) to 10000 (maximum). 524 */ 525 public final int getLevel() { 526 return mLevel; 527 } 528 529 /** 530 * Set whether this Drawable is visible. This generally does not impact 531 * the Drawable's behavior, but is a hint that can be used by some 532 * Drawables, for example, to decide whether run animations. 533 * 534 * @param visible Set to true if visible, false if not. 535 * @param restart You can supply true here to force the drawable to behave 536 * as if it has just become visible, even if it had last 537 * been set visible. Used for example to force animations 538 * to restart. 539 * 540 * @return boolean Returns true if the new visibility is different than 541 * its previous state. 542 */ 543 public boolean setVisible(boolean visible, boolean restart) { 544 boolean changed = mVisible != visible; 545 if (changed) { 546 mVisible = visible; 547 invalidateSelf(); 548 } 549 return changed; 550 } 551 552 public final boolean isVisible() { 553 return mVisible; 554 } 555 556 /** 557 * Return the opacity/transparency of this Drawable. The returned value is 558 * one of the abstract format constants in 559 * {@link android.graphics.PixelFormat}: 560 * {@link android.graphics.PixelFormat#UNKNOWN}, 561 * {@link android.graphics.PixelFormat#TRANSLUCENT}, 562 * {@link android.graphics.PixelFormat#TRANSPARENT}, or 563 * {@link android.graphics.PixelFormat#OPAQUE}. 564 * 565 * <p>Generally a Drawable should be as conservative as possible with the 566 * value it returns. For example, if it contains multiple child drawables 567 * and only shows one of them at a time, if only one of the children is 568 * TRANSLUCENT and the others are OPAQUE then TRANSLUCENT should be 569 * returned. You can use the method {@link #resolveOpacity} to perform a 570 * standard reduction of two opacities to the appropriate single output. 571 * 572 * <p>Note that the returned value does <em>not</em> take into account a 573 * custom alpha or color filter that has been applied by the client through 574 * the {@link #setAlpha} or {@link #setColorFilter} methods. 575 * 576 * @return int The opacity class of the Drawable. 577 * 578 * @see android.graphics.PixelFormat 579 */ 580 public abstract int getOpacity(); 581 582 /** 583 * Return the appropriate opacity value for two source opacities. If 584 * either is UNKNOWN, that is returned; else, if either is TRANSLUCENT, 585 * that is returned; else, if either is TRANSPARENT, that is returned; 586 * else, OPAQUE is returned. 587 * 588 * <p>This is to help in implementing {@link #getOpacity}. 589 * 590 * @param op1 One opacity value. 591 * @param op2 Another opacity value. 592 * 593 * @return int The combined opacity value. 594 * 595 * @see #getOpacity 596 */ 597 public static int resolveOpacity(int op1, int op2) { 598 if (op1 == op2) { 599 return op1; 600 } 601 if (op1 == PixelFormat.UNKNOWN || op2 == PixelFormat.UNKNOWN) { 602 return PixelFormat.UNKNOWN; 603 } 604 if (op1 == PixelFormat.TRANSLUCENT || op2 == PixelFormat.TRANSLUCENT) { 605 return PixelFormat.TRANSLUCENT; 606 } 607 if (op1 == PixelFormat.TRANSPARENT || op2 == PixelFormat.TRANSPARENT) { 608 return PixelFormat.TRANSPARENT; 609 } 610 return PixelFormat.OPAQUE; 611 } 612 613 /** 614 * Returns a Region representing the part of the Drawable that is completely 615 * transparent. This can be used to perform drawing operations, identifying 616 * which parts of the target will not change when rendering the Drawable. 617 * The default implementation returns null, indicating no transparent 618 * region; subclasses can optionally override this to return an actual 619 * Region if they want to supply this optimization information, but it is 620 * not required that they do so. 621 * 622 * @return Returns null if the Drawables has no transparent region to 623 * report, else a Region holding the parts of the Drawable's bounds that 624 * are transparent. 625 */ 626 public Region getTransparentRegion() { 627 return null; 628 } 629 630 /** 631 * Override this in your subclass to change appearance if you recognize the 632 * specified state. 633 * 634 * @return Returns true if the state change has caused the appearance of 635 * the Drawable to change (that is, it needs to be drawn), else false 636 * if it looks the same and there is no need to redraw it since its 637 * last state. 638 */ 639 protected boolean onStateChange(int[] state) { return false; } 640 /** Override this in your subclass to change appearance if you vary based 641 * on level. 642 * @return Returns true if the level change has caused the appearance of 643 * the Drawable to change (that is, it needs to be drawn), else false 644 * if it looks the same and there is no need to redraw it since its 645 * last level. 646 */ 647 protected boolean onLevelChange(int level) { return false; } 648 /** 649 * Override this in your subclass to change appearance if you recognize the 650 * specified state. 651 */ 652 protected void onBoundsChange(Rect bounds) {} 653 654 /** 655 * Return the intrinsic width of the underlying drawable object. Returns 656 * -1 if it has no intrinsic width, such as with a solid color. 657 */ 658 public int getIntrinsicWidth() { 659 return -1; 660 } 661 662 /** 663 * Return the intrinsic height of the underlying drawable object. Returns 664 * -1 if it has no intrinsic height, such as with a solid color. 665 */ 666 public int getIntrinsicHeight() { 667 return -1; 668 } 669 670 /** 671 * Returns the minimum width suggested by this Drawable. If a View uses this 672 * Drawable as a background, it is suggested that the View use at least this 673 * value for its width. (There will be some scenarios where this will not be 674 * possible.) This value should INCLUDE any padding. 675 * 676 * @return The minimum width suggested by this Drawable. If this Drawable 677 * doesn't have a suggested minimum width, 0 is returned. 678 */ 679 public int getMinimumWidth() { 680 final int intrinsicWidth = getIntrinsicWidth(); 681 return intrinsicWidth > 0 ? intrinsicWidth : 0; 682 } 683 684 /** 685 * Returns the minimum height suggested by this Drawable. If a View uses this 686 * Drawable as a background, it is suggested that the View use at least this 687 * value for its height. (There will be some scenarios where this will not be 688 * possible.) This value should INCLUDE any padding. 689 * 690 * @return The minimum height suggested by this Drawable. If this Drawable 691 * doesn't have a suggested minimum height, 0 is returned. 692 */ 693 public int getMinimumHeight() { 694 final int intrinsicHeight = getIntrinsicHeight(); 695 return intrinsicHeight > 0 ? intrinsicHeight : 0; 696 } 697 698 /** 699 * Return in padding the insets suggested by this Drawable for placing 700 * content inside the drawable's bounds. Positive values move toward the 701 * center of the Drawable (set Rect.inset). Returns true if this drawable 702 * actually has a padding, else false. When false is returned, the padding 703 * is always set to 0. 704 */ 705 public boolean getPadding(Rect padding) { 706 padding.set(0, 0, 0, 0); 707 return false; 708 } 709 710 /** 711 * Return in insets the layout insets suggested by this Drawable for use with alignment 712 * operations during layout. 713 * 714 * @hide 715 */ 716 public Insets getLayoutInsets() { 717 return Insets.NONE; 718 } 719 720 /** 721 * Make this drawable mutable. This operation cannot be reversed. A mutable 722 * drawable is guaranteed to not share its state with any other drawable. 723 * This is especially useful when you need to modify properties of drawables 724 * loaded from resources. By default, all drawables instances loaded from 725 * the same resource share a common state; if you modify the state of one 726 * instance, all the other instances will receive the same modification. 727 * 728 * Calling this method on a mutable Drawable will have no effect. 729 * 730 * @return This drawable. 731 * @see ConstantState 732 * @see #getConstantState() 733 */ 734 public Drawable mutate() { 735 return this; 736 } 737 738 /** 739 * Create a drawable from an inputstream 740 */ 741 public static Drawable createFromStream(InputStream is, String srcName) { 742 return createFromResourceStream(null, null, is, srcName, null); 743 } 744 745 /** 746 * Create a drawable from an inputstream, using the given resources and 747 * value to determine density information. 748 */ 749 public static Drawable createFromResourceStream(Resources res, TypedValue value, 750 InputStream is, String srcName) { 751 return createFromResourceStream(res, value, is, srcName, null); 752 } 753 754 /** 755 * Create a drawable from an inputstream, using the given resources and 756 * value to determine density information. 757 */ 758 public static Drawable createFromResourceStream(Resources res, TypedValue value, 759 InputStream is, String srcName, BitmapFactory.Options opts) { 760 761 if (is == null) { 762 return null; 763 } 764 765 /* ugh. The decodeStream contract is that we have already allocated 766 the pad rect, but if the bitmap does not had a ninepatch chunk, 767 then the pad will be ignored. If we could change this to lazily 768 alloc/assign the rect, we could avoid the GC churn of making new 769 Rects only to drop them on the floor. 770 */ 771 Rect pad = new Rect(); 772 773 // Special stuff for compatibility mode: if the target density is not 774 // the same as the display density, but the resource -is- the same as 775 // the display density, then don't scale it down to the target density. 776 // This allows us to load the system's density-correct resources into 777 // an application in compatibility mode, without scaling those down 778 // to the compatibility density only to have them scaled back up when 779 // drawn to the screen. 780 if (opts == null) opts = new BitmapFactory.Options(); 781 opts.inScreenDensity = res.getDisplayMetrics().noncompatDensityDpi; 782 Bitmap bm = BitmapFactory.decodeResourceStream(res, value, is, pad, opts); 783 if (bm != null) { 784 byte[] np = bm.getNinePatchChunk(); 785 if (np == null || !NinePatch.isNinePatchChunk(np)) { 786 np = null; 787 pad = null; 788 } 789 int[] layoutBounds = bm.getLayoutBounds(); 790 Rect layoutBoundsRect = null; 791 if (layoutBounds != null) { 792 layoutBoundsRect = new Rect(layoutBounds[0], layoutBounds[1], 793 layoutBounds[2], layoutBounds[3]); 794 } 795 return drawableFromBitmap(res, bm, np, pad, layoutBoundsRect, srcName); 796 } 797 return null; 798 } 799 800 /** 801 * Create a drawable from an XML document. For more information on how to 802 * create resources in XML, see 803 * <a href="{@docRoot}guide/topics/resources/drawable-resource.html">Drawable Resources</a>. 804 */ 805 public static Drawable createFromXml(Resources r, XmlPullParser parser) 806 throws XmlPullParserException, IOException { 807 AttributeSet attrs = Xml.asAttributeSet(parser); 808 809 int type; 810 while ((type=parser.next()) != XmlPullParser.START_TAG && 811 type != XmlPullParser.END_DOCUMENT) { 812 // Empty loop 813 } 814 815 if (type != XmlPullParser.START_TAG) { 816 throw new XmlPullParserException("No start tag found"); 817 } 818 819 Drawable drawable = createFromXmlInner(r, parser, attrs); 820 821 if (drawable == null) { 822 throw new RuntimeException("Unknown initial tag: " + parser.getName()); 823 } 824 825 return drawable; 826 } 827 828 /** 829 * Create from inside an XML document. Called on a parser positioned at 830 * a tag in an XML document, tries to create a Drawable from that tag. 831 * Returns null if the tag is not a valid drawable. 832 */ 833 public static Drawable createFromXmlInner(Resources r, XmlPullParser parser, AttributeSet attrs) 834 throws XmlPullParserException, IOException { 835 Drawable drawable; 836 837 final String name = parser.getName(); 838 839 if (name.equals("selector")) { 840 drawable = new StateListDrawable(); 841 } else if (name.equals("level-list")) { 842 drawable = new LevelListDrawable(); 843 /* Probably not doing this. 844 } else if (name.equals("mipmap")) { 845 drawable = new MipmapDrawable(); 846 */ 847 } else if (name.equals("layer-list")) { 848 drawable = new LayerDrawable(); 849 } else if (name.equals("transition")) { 850 drawable = new TransitionDrawable(); 851 } else if (name.equals("color")) { 852 drawable = new ColorDrawable(); 853 } else if (name.equals("shape")) { 854 drawable = new GradientDrawable(); 855 } else if (name.equals("scale")) { 856 drawable = new ScaleDrawable(); 857 } else if (name.equals("clip")) { 858 drawable = new ClipDrawable(); 859 } else if (name.equals("rotate")) { 860 drawable = new RotateDrawable(); 861 } else if (name.equals("animated-rotate")) { 862 drawable = new AnimatedRotateDrawable(); 863 } else if (name.equals("animation-list")) { 864 drawable = new AnimationDrawable(); 865 } else if (name.equals("inset")) { 866 drawable = new InsetDrawable(); 867 } else if (name.equals("bitmap")) { 868 drawable = new BitmapDrawable(r); 869 if (r != null) { 870 ((BitmapDrawable) drawable).setTargetDensity(r.getDisplayMetrics()); 871 } 872 } else if (name.equals("nine-patch")) { 873 drawable = new NinePatchDrawable(); 874 if (r != null) { 875 ((NinePatchDrawable) drawable).setTargetDensity(r.getDisplayMetrics()); 876 } 877 } else { 878 throw new XmlPullParserException(parser.getPositionDescription() + 879 ": invalid drawable tag " + name); 880 } 881 882 drawable.inflate(r, parser, attrs); 883 return drawable; 884 } 885 886 887 /** 888 * Create a drawable from file path name. 889 */ 890 public static Drawable createFromPath(String pathName) { 891 if (pathName == null) { 892 return null; 893 } 894 895 Bitmap bm = BitmapFactory.decodeFile(pathName); 896 if (bm != null) { 897 return drawableFromBitmap(null, bm, null, null, null, pathName); 898 } 899 900 return null; 901 } 902 903 /** 904 * Inflate this Drawable from an XML resource. 905 */ 906 public void inflate(Resources r, XmlPullParser parser, AttributeSet attrs) 907 throws XmlPullParserException, IOException { 908 909 TypedArray a = r.obtainAttributes(attrs, com.android.internal.R.styleable.Drawable); 910 inflateWithAttributes(r, parser, a, com.android.internal.R.styleable.Drawable_visible); 911 a.recycle(); 912 } 913 914 /** 915 * Inflate a Drawable from an XML resource. 916 * 917 * @throws XmlPullParserException 918 * @throws IOException 919 */ 920 void inflateWithAttributes(Resources r, XmlPullParser parser, 921 TypedArray attrs, int visibleAttr) 922 throws XmlPullParserException, IOException { 923 924 mVisible = attrs.getBoolean(visibleAttr, mVisible); 925 } 926 927 /** 928 * This abstract class is used by {@link Drawable}s to store shared constant state and data 929 * between Drawables. {@link BitmapDrawable}s created from the same resource will for instance 930 * share a unique bitmap stored in their ConstantState. 931 * 932 * <p> 933 * {@link #newDrawable(Resources)} can be used as a factory to create new Drawable instances 934 * from this ConstantState. 935 * </p> 936 * 937 * Use {@link Drawable#getConstantState()} to retrieve the ConstantState of a Drawable. Calling 938 * {@link Drawable#mutate()} on a Drawable should typically create a new ConstantState for that 939 * Drawable. 940 */ 941 public static abstract class ConstantState { 942 /** 943 * Create a new drawable without supplying resources the caller 944 * is running in. Note that using this means the density-dependent 945 * drawables (like bitmaps) will not be able to update their target 946 * density correctly. One should use {@link #newDrawable(Resources)} 947 * instead to provide a resource. 948 */ 949 public abstract Drawable newDrawable(); 950 /** 951 * Create a new Drawable instance from its constant state. This 952 * must be implemented for drawables that change based on the target 953 * density of their caller (that is depending on whether it is 954 * in compatibility mode). 955 */ 956 public Drawable newDrawable(Resources res) { 957 return newDrawable(); 958 } 959 /** 960 * Return a bit mask of configuration changes that will impact 961 * this drawable (and thus require completely reloading it). 962 */ 963 public abstract int getChangingConfigurations(); 964 } 965 966 /** 967 * Return a {@link ConstantState} instance that holds the shared state of this Drawable. 968 *q 969 * @return The ConstantState associated to that Drawable. 970 * @see ConstantState 971 * @see Drawable#mutate() 972 */ 973 public ConstantState getConstantState() { 974 return null; 975 } 976 977 private static Drawable drawableFromBitmap(Resources res, Bitmap bm, byte[] np, 978 Rect pad, Rect layoutBounds, String srcName) { 979 980 if (np != null) { 981 return new NinePatchDrawable(res, bm, np, pad, layoutBounds, srcName); 982 } 983 984 return new BitmapDrawable(res, bm); 985 } 986} 987 988