ViewDragHelper.java revision 1538310a6c51ee7cbebc151df16798aa65f57f07
1/* 2 * Copyright (C) 2013 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 17 18package android.support.v4.widget; 19 20import android.content.Context; 21import android.support.v4.view.MotionEventCompat; 22import android.support.v4.view.VelocityTrackerCompat; 23import android.support.v4.view.ViewCompat; 24import android.view.MotionEvent; 25import android.view.VelocityTracker; 26import android.view.View; 27import android.view.ViewConfiguration; 28import android.view.ViewGroup; 29import android.view.animation.Interpolator; 30 31import java.util.Arrays; 32 33/** 34 * ViewDragHelper is a utility class for writing custom ViewGroups. It offers a number 35 * of useful operations and state tracking for allowing a user to drag and reposition 36 * views within their parent ViewGroup. 37 */ 38public class ViewDragHelper { 39 private static final String TAG = "ViewDragHelper"; 40 41 /** 42 * A null/invalid pointer ID. 43 */ 44 public static final int INVALID_POINTER = -1; 45 46 /** 47 * A view is not currently being dragged or animating as a result of a fling/snap. 48 */ 49 public static final int STATE_IDLE = 0; 50 51 /** 52 * A view is currently being dragged. The position is currently changing as a result 53 * of user input or simulated user input. 54 */ 55 public static final int STATE_DRAGGING = 1; 56 57 /** 58 * A view is currently settling into place as a result of a fling or 59 * predefined non-interactive motion. 60 */ 61 public static final int STATE_SETTLING = 2; 62 63 /** 64 * Edge flag indicating that the left edge should be affected. 65 */ 66 public static final int EDGE_LEFT = 1 << 0; 67 68 /** 69 * Edge flag indicating that the right edge should be affected. 70 */ 71 public static final int EDGE_RIGHT = 1 << 1; 72 73 /** 74 * Edge flag indicating that the top edge should be affected. 75 */ 76 public static final int EDGE_TOP = 1 << 2; 77 78 /** 79 * Edge flag indicating that the bottom edge should be affected. 80 */ 81 public static final int EDGE_BOTTOM = 1 << 3; 82 83 /** 84 * Edge flag set indicating all edges should be affected. 85 */ 86 public static final int EDGE_ALL = EDGE_LEFT | EDGE_TOP | EDGE_RIGHT | EDGE_BOTTOM; 87 88 /** 89 * Indicates that a check should occur along the horizontal axis 90 */ 91 public static final int DIRECTION_HORIZONTAL = 1 << 0; 92 93 /** 94 * Indicates that a check should occur along the vertical axis 95 */ 96 public static final int DIRECTION_VERTICAL = 1 << 1; 97 98 /** 99 * Indicates that a check should occur along all axes 100 */ 101 public static final int DIRECTION_ALL = DIRECTION_HORIZONTAL | DIRECTION_VERTICAL; 102 103 private static final int EDGE_SIZE = 20; // dp 104 105 private static final int BASE_SETTLE_DURATION = 256; // ms 106 private static final int MAX_SETTLE_DURATION = 600; // ms 107 108 // Current drag state; idle, dragging or settling 109 private int mDragState; 110 111 // Distance to travel before a drag may begin 112 private int mTouchSlop; 113 114 // Last known position/pointer tracking 115 private int mActivePointerId = INVALID_POINTER; 116 private float[] mInitialMotionX; 117 private float[] mInitialMotionY; 118 private float[] mLastMotionX; 119 private float[] mLastMotionY; 120 private int[] mInitialEdgesTouched; 121 private int[] mEdgeDragsInProgress; 122 private int[] mEdgeDragsLocked; 123 private int mPointersDown; 124 125 private VelocityTracker mVelocityTracker; 126 private float mMaxVelocity; 127 private float mMinVelocity; 128 129 private int mEdgeSize; 130 private int mTrackingEdges; 131 132 private ScrollerCompat mScroller; 133 134 private final Callback mCallback; 135 136 private View mCapturedView; 137 private boolean mReleaseInProgress; 138 139 private final ViewGroup mParentView; 140 141 /** 142 * A Callback is used as a communication channel with the ViewDragHelper back to the 143 * parent view using it. <code>on*</code>methods are invoked on siginficant events and several 144 * accessor methods are expected to provide the ViewDragHelper with more information 145 * about the state of the parent view upon request. The callback also makes decisions 146 * governing the range and draggability of child views. 147 */ 148 public static abstract class Callback { 149 /** 150 * Called when the drag state changes. See the <code>STATE_*</code> constants 151 * for more information. 152 * 153 * @param state The new drag state 154 * 155 * @see #STATE_IDLE 156 * @see #STATE_DRAGGING 157 * @see #STATE_SETTLING 158 */ 159 public void onViewDragStateChanged(int state) {} 160 161 /** 162 * Called when the captured view's position changes as the result of a drag or settle. 163 * 164 * @param changedView View whose position changed 165 * @param left New X coordinate of the left edge of the view 166 * @param top New Y coordinate of the top edge of the view 167 * @param dx Change in X position from the last call 168 * @param dy Change in Y position from the last call 169 */ 170 public void onViewPositionChanged(View changedView, int left, int top, int dx, int dy) {} 171 172 /** 173 * Called when a child view is captured for dragging or settling. The ID of the pointer 174 * currently dragging the captured view is supplied. If activePointerId is 175 * identified as {@link #INVALID_POINTER} the capture is programmatic instead of 176 * pointer-initiated. 177 * 178 * @param capturedChild Child view that was captured 179 * @param activePointerId Pointer id tracking the child capture 180 */ 181 public void onViewCaptured(View capturedChild, int activePointerId) {} 182 183 /** 184 * Called when the child view is no longer being actively dragged. 185 * The fling velocity is also supplied, if relevant. The velocity values may 186 * be clamped to system minimums or maximums. 187 * 188 * <p>Calling code may decide to fling or otherwise release the view to let it 189 * settle into place. It should do so using {@link #settleCapturedViewAt(int, int)} 190 * or {@link #flingCapturedView(int, int, int, int)}. If the Callback invokes 191 * one of these methods, the ViewDragHelper will enter {@link #STATE_SETTLING} 192 * and the view capture will not fully end until it comes to a complete stop. 193 * If neither of these methods is invoked before <code>onViewReleased</code> returns, 194 * the view will stop in place and the ViewDragHelper will return to 195 * {@link #STATE_IDLE}.</p> 196 * 197 * @param releasedChild The captured child view now being released 198 * @param xvel X velocity of the pointer as it left the screen in pixels per second. 199 * @param yvel Y velocity of the pointer as it left the screen in pixels per second. 200 */ 201 public void onViewReleased(View releasedChild, float xvel, float yvel) {} 202 203 /** 204 * Called when one of the subscribed edges in the parent view has been touched 205 * by the user while no child view is currently captured. 206 * 207 * @param edgeFlags A combination of edge flags describing the edge(s) currently touched 208 * @param pointerId ID of the pointer touching the described edge(s) 209 * @see #EDGE_LEFT 210 * @see #EDGE_TOP 211 * @see #EDGE_RIGHT 212 * @see #EDGE_BOTTOM 213 */ 214 public void onEdgeTouched(int edgeFlags, int pointerId) {} 215 216 /** 217 * Called when the given edge may become locked. This can happen if an edge drag 218 * was preliminarily rejected before beginning, but after {@link #onEdgeTouched(int, int)} 219 * was called. This method should return true to lock this edge or false to leave it 220 * unlocked. The default behavior is to leave edges unlocked. 221 * 222 * @param edgeFlags A combination of edge flags describing the edge(s) locked 223 * @return true to lock the edge, false to leave it unlocked 224 */ 225 public boolean onEdgeLock(int edgeFlags) { 226 return false; 227 } 228 229 /** 230 * Called when the user has started a deliberate drag away from one 231 * of the subscribed edges in the parent view while no child view is currently captured. 232 * 233 * @param edgeFlags A combination of edge flags describing the edge(s) dragged 234 * @param pointerId ID of the pointer touching the described edge(s) 235 * @see #EDGE_LEFT 236 * @see #EDGE_TOP 237 * @see #EDGE_RIGHT 238 * @see #EDGE_BOTTOM 239 */ 240 public void onEdgeDragStarted(int edgeFlags, int pointerId) {} 241 242 /** 243 * Called to determine the Z-order of child views. 244 * 245 * @param index the ordered position to query for 246 * @return index of the view that should be ordered at position <code>index</code> 247 */ 248 public int getOrderedChildIndex(int index) { 249 return index; 250 } 251 252 /** 253 * Return the magnitude of a draggable child view's horizontal range of motion in pixels. 254 * This method should return 0 for views that cannot move horizontally. 255 * 256 * @param child Child view to check 257 * @return range of horizontal motion in pixels 258 */ 259 public int getViewHorizontalDragRange(View child) { 260 return 0; 261 } 262 263 /** 264 * Return the magnitude of a draggable child view's vertical range of motion in pixels. 265 * This method should return 0 for views that cannot move vertically. 266 * 267 * @param child Child view to check 268 * @return range of vertical motion in pixels 269 */ 270 public int getViewVerticalDragRange(View child) { 271 return 0; 272 } 273 274 /** 275 * Called when the user's input indicates that they want to capture the given child view 276 * with the pointer indicated by pointerId. The callback should return true if the user 277 * is permitted to drag the given view with the indicated pointer. 278 * 279 * <p>ViewDragHelper may call this method multiple times for the same view even if 280 * the view is already captured; this indicates that a new pointer is trying to take 281 * control of the view.</p> 282 * 283 * <p>If this method returns true, a call to {@link #onViewCaptured(android.view.View, int)} 284 * will follow if the capture is successful.</p> 285 * 286 * @param child Child the user is attempting to capture 287 * @param pointerId ID of the pointer attempting the capture 288 * @return true if capture should be allowed, false otherwise 289 */ 290 public abstract boolean tryCaptureView(View child, int pointerId); 291 292 /** 293 * Restrict the motion of the dragged child view along the horizontal axis. 294 * The default implementation does not allow horizontal motion; the extending 295 * class must override this method and provide the desired clamping. 296 * 297 * 298 * @param child Child view being dragged 299 * @param left Attempted motion along the X axis 300 * @param dx Proposed change in position for left 301 * @return The new clamped position for left 302 */ 303 public int clampViewPositionHorizontal(View child, int left, int dx) { 304 return 0; 305 } 306 307 /** 308 * Restrict the motion of the dragged child view along the vertical axis. 309 * The default implementation does not allow vertical motion; the extending 310 * class must override this method and provide the desired clamping. 311 * 312 * 313 * @param child Child view being dragged 314 * @param top Attempted motion along the Y axis 315 * @param dy Proposed change in position for top 316 * @return The new clamped position for top 317 */ 318 public int clampViewPositionVertical(View child, int top, int dy) { 319 return 0; 320 } 321 } 322 323 /** 324 * Interpolator defining the animation curve for mScroller 325 */ 326 private static final Interpolator sInterpolator = new Interpolator() { 327 public float getInterpolation(float t) { 328 t -= 1.0f; 329 return t * t * t * t * t + 1.0f; 330 } 331 }; 332 333 private final Runnable mSetIdleRunnable = new Runnable() { 334 public void run() { 335 setDragState(STATE_IDLE); 336 } 337 }; 338 339 /** 340 * Factory method to create a new ViewDragHelper. 341 * 342 * @param forParent Parent view to monitor 343 * @param cb Callback to provide information and receive events 344 * @return a new ViewDragHelper instance 345 */ 346 public static ViewDragHelper create(ViewGroup forParent, Callback cb) { 347 return new ViewDragHelper(forParent.getContext(), forParent, cb); 348 } 349 350 /** 351 * Factory method to create a new ViewDragHelper. 352 * 353 * @param forParent Parent view to monitor 354 * @param sensitivity Multiplier for how sensitive the helper should be about detecting 355 * the start of a drag. Larger values are more sensitive. 1.0f is normal. 356 * @param cb Callback to provide information and receive events 357 * @return a new ViewDragHelper instance 358 */ 359 public static ViewDragHelper create(ViewGroup forParent, float sensitivity, Callback cb) { 360 final ViewDragHelper helper = create(forParent, cb); 361 helper.mTouchSlop = (int) (helper.mTouchSlop * (1 / sensitivity)); 362 return helper; 363 } 364 365 /** 366 * Apps should use ViewDragHelper.create() to get a new instance. 367 * This will allow VDH to use internal compatibility implementations for different 368 * platform versions. 369 * 370 * @param context Context to initialize config-dependent params from 371 * @param forParent Parent view to monitor 372 */ 373 private ViewDragHelper(Context context, ViewGroup forParent, Callback cb) { 374 if (forParent == null) { 375 throw new IllegalArgumentException("Parent view may not be null"); 376 } 377 if (cb == null) { 378 throw new IllegalArgumentException("Callback may not be null"); 379 } 380 381 mParentView = forParent; 382 mCallback = cb; 383 384 final ViewConfiguration vc = ViewConfiguration.get(context); 385 final float density = context.getResources().getDisplayMetrics().density; 386 mEdgeSize = (int) (EDGE_SIZE * density + 0.5f); 387 388 mTouchSlop = vc.getScaledTouchSlop(); 389 mMaxVelocity = vc.getScaledMaximumFlingVelocity(); 390 mMinVelocity = vc.getScaledMinimumFlingVelocity(); 391 mScroller = ScrollerCompat.create(context, sInterpolator); 392 } 393 394 /** 395 * Retrieve the current drag state of this helper. This will return one of 396 * {@link #STATE_IDLE}, {@link #STATE_DRAGGING} or {@link #STATE_SETTLING}. 397 * @return The current drag state 398 */ 399 public int getViewDragState() { 400 return mDragState; 401 } 402 403 /** 404 * Enable edge tracking for the selected edges of the parent view. 405 * The callback's {@link Callback#onEdgeTouched(int, int)} and 406 * {@link Callback#onEdgeDragStarted(int, int)} methods will only be invoked 407 * for edges for which edge tracking has been enabled. 408 * 409 * @param edgeFlags Combination of edge flags describing the edges to watch 410 * @see #EDGE_LEFT 411 * @see #EDGE_TOP 412 * @see #EDGE_RIGHT 413 * @see #EDGE_BOTTOM 414 */ 415 public void setEdgeTrackingEnabled(int edgeFlags) { 416 mTrackingEdges = edgeFlags; 417 } 418 419 /** 420 * Return the size of an edge. This is the range in pixels along the edges of this view 421 * that will actively detect edge touches or drags if edge tracking is enabled. 422 * 423 * @return The size of an edge in pixels 424 * @see #setEdgeTrackingEnabled(int) 425 */ 426 public int getEdgeSize() { 427 return mEdgeSize; 428 } 429 430 /** 431 * Capture a specific child view for dragging within the parent. The callback will be notified 432 * but {@link Callback#tryCaptureView(android.view.View, int)} will not be asked permission to 433 * capture this view. 434 * 435 * @param childView Child view to capture 436 * @param activePointerId ID of the pointer that is dragging the captured child view 437 */ 438 public void captureChildView(View childView, int activePointerId) { 439 if (childView.getParent() != mParentView) { 440 throw new IllegalArgumentException("captureChildView: parameter must be a descendant " + 441 "of the ViewDragHelper's tracked parent view (" + mParentView + ")"); 442 } 443 444 mCapturedView = childView; 445 mActivePointerId = activePointerId; 446 mCallback.onViewCaptured(childView, activePointerId); 447 setDragState(STATE_DRAGGING); 448 } 449 450 /** 451 * @return The currently captured view, or null if no view has been captured. 452 */ 453 public View getCapturedView() { 454 return mCapturedView; 455 } 456 457 /** 458 * @return The ID of the pointer currently dragging the captured view, 459 * or {@link #INVALID_POINTER}. 460 */ 461 public int getActivePointerId() { 462 return mActivePointerId; 463 } 464 465 /** 466 * @return The minimum distance in pixels that the user must travel to initiate a drag 467 */ 468 public int getTouchSlop() { 469 return mTouchSlop; 470 } 471 472 /** 473 * The result of a call to this method is equivalent to 474 * {@link #processTouchEvent(android.view.MotionEvent)} receiving an ACTION_CANCEL event. 475 */ 476 public void cancel() { 477 mActivePointerId = INVALID_POINTER; 478 clearMotionHistory(); 479 480 if (mVelocityTracker != null) { 481 mVelocityTracker.recycle(); 482 mVelocityTracker = null; 483 } 484 } 485 486 /** 487 * {@link #cancel()}, but also abort all motion in progress and snap to the end of any 488 * animation. 489 */ 490 public void abort() { 491 cancel(); 492 if (mDragState == STATE_SETTLING) { 493 final int oldX = mScroller.getCurrX(); 494 final int oldY = mScroller.getCurrY(); 495 mScroller.abortAnimation(); 496 final int newX = mScroller.getCurrX(); 497 final int newY = mScroller.getCurrY(); 498 mCallback.onViewPositionChanged(mCapturedView, newX, newY, newX - oldX, newY - oldY); 499 } 500 setDragState(STATE_IDLE); 501 } 502 503 /** 504 * Animate the view <code>child</code> to the given (left, top) position. 505 * If this method returns true, the caller should invoke {@link #continueSettling(boolean)} 506 * on each subsequent frame to continue the motion until it returns false. If this method 507 * returns false there is no further work to do to complete the movement. 508 * 509 * <p>This operation does not count as a capture event, though {@link #getCapturedView()} 510 * will still report the sliding view while the slide is in progress.</p> 511 * 512 * @param child Child view to capture and animate 513 * @param finalLeft Final left position of child 514 * @param finalTop Final top position of child 515 * @return true if animation should continue through {@link #continueSettling(boolean)} calls 516 */ 517 public boolean smoothSlideViewTo(View child, int finalLeft, int finalTop) { 518 mCapturedView = child; 519 mActivePointerId = INVALID_POINTER; 520 521 return forceSettleCapturedViewAt(finalLeft, finalTop, 0, 0); 522 } 523 524 /** 525 * Settle the captured view at the given (left, top) position. 526 * The appropriate velocity from prior motion will be taken into account. 527 * If this method returns true, the caller should invoke {@link #continueSettling(boolean)} 528 * on each subsequent frame to continue the motion until it returns false. If this method 529 * returns false there is no further work to do to complete the movement. 530 * 531 * @param finalLeft Settled left edge position for the captured view 532 * @param finalTop Settled top edge position for the captured view 533 * @return true if animation should continue through {@link #continueSettling(boolean)} calls 534 */ 535 public boolean settleCapturedViewAt(int finalLeft, int finalTop) { 536 if (!mReleaseInProgress) { 537 throw new IllegalStateException("Cannot settleCapturedViewAt outside of a call to " + 538 "Callback#onViewReleased"); 539 } 540 541 return forceSettleCapturedViewAt(finalLeft, finalTop, 542 (int) VelocityTrackerCompat.getXVelocity(mVelocityTracker, mActivePointerId), 543 (int) VelocityTrackerCompat.getYVelocity(mVelocityTracker, mActivePointerId)); 544 } 545 546 /** 547 * Settle the captured view at the given (left, top) position. 548 * 549 * @param finalLeft Target left position for the captured view 550 * @param finalTop Target top position for the captured view 551 * @param xvel Horizontal velocity 552 * @param yvel Vertical velocity 553 * @return true if animation should continue through {@link #continueSettling(boolean)} calls 554 */ 555 private boolean forceSettleCapturedViewAt(int finalLeft, int finalTop, int xvel, int yvel) { 556 final int startLeft = mCapturedView.getLeft(); 557 final int startTop = mCapturedView.getTop(); 558 final int dx = finalLeft - startLeft; 559 final int dy = finalTop - startTop; 560 561 if (dx == 0 && dy == 0) { 562 // Nothing to do. Send callbacks, be done. 563 mScroller.abortAnimation(); 564 setDragState(STATE_IDLE); 565 return false; 566 } 567 568 final int duration = computeSettleDuration(mCapturedView, dx, dy, xvel, yvel); 569 mScroller.startScroll(startLeft, startTop, dx, dy, duration); 570 571 setDragState(STATE_SETTLING); 572 return true; 573 } 574 575 private int computeSettleDuration(View child, int dx, int dy, int xvel, int yvel) { 576 xvel = clampMag(xvel, (int) mMinVelocity, (int) mMaxVelocity); 577 yvel = clampMag(yvel, (int) mMinVelocity, (int) mMaxVelocity); 578 final int absDx = Math.abs(dx); 579 final int absDy = Math.abs(dy); 580 final int absXVel = Math.abs(xvel); 581 final int absYVel = Math.abs(yvel); 582 final int addedVel = absXVel + absYVel; 583 final int addedDistance = absDx + absDy; 584 585 final float xweight = xvel != 0 ? (float) absXVel / addedVel : 586 (float) absDx / addedDistance; 587 final float yweight = yvel != 0 ? (float) absYVel / addedVel : 588 (float) absDy / addedDistance; 589 590 int xduration = computeAxisDuration(dx, xvel, mCallback.getViewHorizontalDragRange(child)); 591 int yduration = computeAxisDuration(dy, yvel, mCallback.getViewVerticalDragRange(child)); 592 593 return (int) (xduration * xweight + yduration * yweight); 594 } 595 596 private int computeAxisDuration(int delta, int velocity, int motionRange) { 597 if (delta == 0) { 598 return 0; 599 } 600 601 final int width = mParentView.getWidth(); 602 final int halfWidth = width / 2; 603 final float distanceRatio = Math.min(1f, (float) Math.abs(delta) / width); 604 final float distance = halfWidth + halfWidth * 605 distanceInfluenceForSnapDuration(distanceRatio); 606 607 int duration; 608 velocity = Math.abs(velocity); 609 if (velocity > 0) { 610 duration = 4 * Math.round(1000 * Math.abs(distance / velocity)); 611 } else { 612 final float range = (float) Math.abs(delta) / motionRange; 613 duration = (int) ((range + 1) * BASE_SETTLE_DURATION); 614 } 615 return Math.min(duration, MAX_SETTLE_DURATION); 616 } 617 618 /** 619 * Clamp the magnitude of value for absMin and absMax. 620 * If the value is below the minimum, it will be clamped to zero. 621 * If the value is above the maximum, it will be clamped to the maximum. 622 * 623 * @param value Value to clamp 624 * @param absMin Absolute value of the minimum significant value to return 625 * @param absMax Absolute value of the maximum value to return 626 * @return The clamped value with the same sign as <code>value</code> 627 */ 628 private int clampMag(int value, int absMin, int absMax) { 629 final int absValue = Math.abs(value); 630 if (absValue < absMin) return 0; 631 if (absValue > absMax) return value > 0 ? absMax : -absMax; 632 return value; 633 } 634 635 private float distanceInfluenceForSnapDuration(float f) { 636 f -= 0.5f; // center the values about 0. 637 f *= 0.3f * Math.PI / 2.0f; 638 return (float) Math.sin(f); 639 } 640 641 /** 642 * Settle the captured view based on standard free-moving fling behavior. 643 * The caller should invoke {@link #continueSettling(boolean)} on each subsequent frame 644 * to continue the motion until it returns false. 645 * 646 * @param minLeft Minimum X position for the view's left edge 647 * @param minTop Minimum Y position for the view's top edge 648 * @param maxLeft Maximum X position for the view's left edge 649 * @param maxTop Maximum Y position for the view's top edge 650 */ 651 public void flingCapturedView(int minLeft, int minTop, int maxLeft, int maxTop) { 652 if (!mReleaseInProgress) { 653 throw new IllegalStateException("Cannot flingCapturedView outside of a call to " + 654 "Callback#onViewReleased"); 655 } 656 657 mScroller.fling(mCapturedView.getLeft(), mCapturedView.getTop(), 658 (int) VelocityTrackerCompat.getXVelocity(mVelocityTracker, mActivePointerId), 659 (int) VelocityTrackerCompat.getYVelocity(mVelocityTracker, mActivePointerId), 660 minLeft, maxLeft, minTop, maxTop); 661 662 setDragState(STATE_SETTLING); 663 } 664 665 /** 666 * Move the captured settling view by the appropriate amount for the current time. 667 * If <code>continueSettling</code> returns true, the caller should call it again 668 * on the next frame to continue. 669 * 670 * @param deferCallbacks true if state callbacks should be deferred via posted message. 671 * Set this to true if you are calling this method from 672 * {@link android.view.View#computeScroll()} or similar methods 673 * invoked as part of layout or drawing. 674 * @return true if settle is still in progress 675 */ 676 public boolean continueSettling(boolean deferCallbacks) { 677 if (mDragState == STATE_SETTLING) { 678 boolean keepGoing = mScroller.computeScrollOffset(); 679 final int x = mScroller.getCurrX(); 680 final int y = mScroller.getCurrY(); 681 final int dx = x - mCapturedView.getLeft(); 682 final int dy = y - mCapturedView.getTop(); 683 684 if (dx != 0) { 685 mCapturedView.offsetLeftAndRight(dx); 686 } 687 if (dy != 0) { 688 mCapturedView.offsetTopAndBottom(dy); 689 } 690 691 if (dx != 0 || dy != 0) { 692 mCallback.onViewPositionChanged(mCapturedView, x, y, dx, dy); 693 } 694 695 if (keepGoing && x == mScroller.getFinalX() && y == mScroller.getFinalY()) { 696 // Close enough. The interpolator/scroller might think we're still moving 697 // but the user sure doesn't. 698 mScroller.abortAnimation(); 699 keepGoing = mScroller.isFinished(); 700 } 701 702 if (!keepGoing) { 703 if (deferCallbacks) { 704 mParentView.post(mSetIdleRunnable); 705 } else { 706 setDragState(STATE_IDLE); 707 } 708 } 709 } 710 711 return mDragState == STATE_SETTLING; 712 } 713 714 /** 715 * Like all callback events this must happen on the UI thread, but release 716 * involves some extra semantics. During a release (mReleaseInProgress) 717 * is the only time it is valid to call {@link #settleCapturedViewAt(int, int)} 718 * or {@link #flingCapturedView(int, int, int, int)}. 719 */ 720 private void dispatchViewReleased(float xvel, float yvel) { 721 mReleaseInProgress = true; 722 mCallback.onViewReleased(mCapturedView, xvel, yvel); 723 mReleaseInProgress = false; 724 725 if (mDragState == STATE_DRAGGING) { 726 // onViewReleased didn't call a method that would have changed this. Go idle. 727 setDragState(STATE_IDLE); 728 } 729 } 730 731 private void clearMotionHistory() { 732 if (mInitialMotionX == null) { 733 return; 734 } 735 Arrays.fill(mInitialMotionX, 0); 736 Arrays.fill(mInitialMotionY, 0); 737 Arrays.fill(mLastMotionX, 0); 738 Arrays.fill(mLastMotionY, 0); 739 Arrays.fill(mInitialEdgesTouched, 0); 740 Arrays.fill(mEdgeDragsInProgress, 0); 741 Arrays.fill(mEdgeDragsLocked, 0); 742 mPointersDown = 0; 743 } 744 745 private void clearMotionHistory(int pointerId) { 746 if (mInitialMotionX == null) { 747 return; 748 } 749 mInitialMotionX[pointerId] = 0; 750 mInitialMotionY[pointerId] = 0; 751 mLastMotionX[pointerId] = 0; 752 mLastMotionY[pointerId] = 0; 753 mInitialEdgesTouched[pointerId] = 0; 754 mEdgeDragsInProgress[pointerId] = 0; 755 mEdgeDragsLocked[pointerId] = 0; 756 mPointersDown &= ~(1 << pointerId); 757 } 758 759 private void ensureMotionHistorySizeForId(int pointerId) { 760 if (mInitialMotionX == null || mInitialMotionX.length <= pointerId) { 761 float[] imx = new float[pointerId + 1]; 762 float[] imy = new float[pointerId + 1]; 763 float[] lmx = new float[pointerId + 1]; 764 float[] lmy = new float[pointerId + 1]; 765 int[] iit = new int[pointerId + 1]; 766 int[] edip = new int[pointerId + 1]; 767 int[] edl = new int[pointerId + 1]; 768 769 if (mInitialMotionX != null) { 770 System.arraycopy(mInitialMotionX, 0, imx, 0, mInitialMotionX.length); 771 System.arraycopy(mInitialMotionY, 0, imy, 0, mInitialMotionY.length); 772 System.arraycopy(mLastMotionX, 0, lmx, 0, mLastMotionX.length); 773 System.arraycopy(mLastMotionY, 0, lmy, 0, mLastMotionY.length); 774 System.arraycopy(mInitialEdgesTouched, 0, iit, 0, mInitialEdgesTouched.length); 775 System.arraycopy(mEdgeDragsInProgress, 0, edip, 0, mEdgeDragsInProgress.length); 776 System.arraycopy(mEdgeDragsLocked, 0, edl, 0, mEdgeDragsLocked.length); 777 } 778 779 mInitialMotionX = imx; 780 mInitialMotionY = imy; 781 mLastMotionX = lmx; 782 mLastMotionY = lmy; 783 mInitialEdgesTouched = iit; 784 mEdgeDragsInProgress = edip; 785 mEdgeDragsLocked = edl; 786 } 787 } 788 789 private void saveInitialMotion(float x, float y, int pointerId) { 790 ensureMotionHistorySizeForId(pointerId); 791 mInitialMotionX[pointerId] = mLastMotionX[pointerId] = x; 792 mInitialMotionY[pointerId] = mLastMotionY[pointerId] = y; 793 mInitialEdgesTouched[pointerId] = getEdgesTouched((int) x, (int) y); 794 mPointersDown |= 1 << pointerId; 795 } 796 797 private void saveLastMotion(MotionEvent ev) { 798 final int pointerCount = MotionEventCompat.getPointerCount(ev); 799 for (int i = 0; i < pointerCount; i++) { 800 final int pointerId = MotionEventCompat.getPointerId(ev, i); 801 final float x = MotionEventCompat.getX(ev, i); 802 final float y = MotionEventCompat.getY(ev, i); 803 mLastMotionX[pointerId] = x; 804 mLastMotionY[pointerId] = y; 805 } 806 } 807 808 /** 809 * Check if the given pointer ID represents a pointer that is currently down (to the best 810 * of the ViewDragHelper's knowledge). 811 * 812 * <p>The state used to report this information is populated by the methods 813 * {@link #shouldInterceptTouchEvent(android.view.MotionEvent)} or 814 * {@link #processTouchEvent(android.view.MotionEvent)}. If one of these methods has not 815 * been called for all relevant MotionEvents to track, the information reported 816 * by this method may be stale or incorrect.</p> 817 * 818 * @param pointerId pointer ID to check; corresponds to IDs provided by MotionEvent 819 * @return true if the pointer with the given ID is still down 820 */ 821 public boolean isPointerDown(int pointerId) { 822 return (mPointersDown & 1 << pointerId) != 0; 823 } 824 825 void setDragState(int state) { 826 if (mDragState != state) { 827 mDragState = state; 828 mCallback.onViewDragStateChanged(state); 829 if (state == STATE_IDLE) { 830 mCapturedView = null; 831 } 832 } 833 } 834 835 /** 836 * Attempt to capture the view with the given pointer ID. The callback will be involved. 837 * This will put us into the "dragging" state. If we've already captured this view with 838 * this pointer this method will immediately return true without consulting the callback. 839 * 840 * @param toCapture View to capture 841 * @param pointerId Pointer to capture with 842 * @return true if capture was successful 843 */ 844 boolean tryCaptureViewForDrag(View toCapture, int pointerId) { 845 if (toCapture == mCapturedView && mActivePointerId == pointerId) { 846 // Already done! 847 return true; 848 } 849 if (toCapture != null && mCallback.tryCaptureView(toCapture, pointerId)) { 850 mActivePointerId = pointerId; 851 captureChildView(toCapture, pointerId); 852 return true; 853 } 854 return false; 855 } 856 857 /** 858 * Tests scrollability within child views of v given a delta of dx. 859 * 860 * @param v View to test for horizontal scrollability 861 * @param checkV Whether the view v passed should itself be checked for scrollability (true), 862 * or just its children (false). 863 * @param dx Delta scrolled in pixels along the X axis 864 * @param dy Delta scrolled in pixels along the Y axis 865 * @param x X coordinate of the active touch point 866 * @param y Y coordinate of the active touch point 867 * @return true if child views of v can be scrolled by delta of dx. 868 */ 869 protected boolean canScroll(View v, boolean checkV, int dx, int dy, int x, int y) { 870 if (v instanceof ViewGroup) { 871 final ViewGroup group = (ViewGroup) v; 872 final int scrollX = v.getScrollX(); 873 final int scrollY = v.getScrollY(); 874 final int count = group.getChildCount(); 875 // Count backwards - let topmost views consume scroll distance first. 876 for (int i = count - 1; i >= 0; i--) { 877 // TODO: Add versioned support here for transformed views. 878 // This will not work for transformed views in Honeycomb+ 879 final View child = group.getChildAt(i); 880 if (x + scrollX >= child.getLeft() && x + scrollX < child.getRight() && 881 y + scrollY >= child.getTop() && y + scrollY < child.getBottom() && 882 canScroll(child, true, dx, dy, x + scrollX - child.getLeft(), 883 y + scrollY - child.getTop())) { 884 return true; 885 } 886 } 887 } 888 889 return checkV && (ViewCompat.canScrollHorizontally(v, -dx) || 890 ViewCompat.canScrollVertically(v, -dy)); 891 } 892 893 /** 894 * Check if this event as provided to the parent view's onInterceptTouchEvent should 895 * cause the parent to intercept the touch event stream. 896 * 897 * @param ev MotionEvent provided to onInterceptTouchEvent 898 * @return true if the parent view should return true from onInterceptTouchEvent 899 */ 900 public boolean shouldInterceptTouchEvent(MotionEvent ev) { 901 final int action = MotionEventCompat.getActionMasked(ev); 902 final int actionIndex = MotionEventCompat.getActionIndex(ev); 903 904 if (action == MotionEvent.ACTION_DOWN) { 905 // Reset things for a new event stream, just in case we didn't get 906 // the whole previous stream. 907 cancel(); 908 } 909 910 if (mVelocityTracker == null) { 911 mVelocityTracker = VelocityTracker.obtain(); 912 } 913 mVelocityTracker.addMovement(ev); 914 915 switch (action) { 916 case MotionEvent.ACTION_DOWN: { 917 final float x = ev.getX(); 918 final float y = ev.getY(); 919 final int pointerId = MotionEventCompat.getPointerId(ev, 0); 920 saveInitialMotion(x, y, pointerId); 921 922 final View toCapture = findTopChildUnder((int) x, (int) y); 923 924 // Catch a settling view if possible. 925 if (toCapture == mCapturedView && mDragState == STATE_SETTLING) { 926 tryCaptureViewForDrag(toCapture, pointerId); 927 } 928 929 final int edgesTouched = mInitialEdgesTouched[pointerId]; 930 if ((edgesTouched & mTrackingEdges) != 0) { 931 mCallback.onEdgeTouched(edgesTouched & mTrackingEdges, pointerId); 932 } 933 break; 934 } 935 936 case MotionEventCompat.ACTION_POINTER_DOWN: { 937 final int pointerId = MotionEventCompat.getPointerId(ev, actionIndex); 938 final float x = MotionEventCompat.getX(ev, actionIndex); 939 final float y = MotionEventCompat.getY(ev, actionIndex); 940 941 saveInitialMotion(x, y, pointerId); 942 943 // A ViewDragHelper can only manipulate one view at a time. 944 if (mDragState == STATE_IDLE) { 945 final int edgesTouched = mInitialEdgesTouched[pointerId]; 946 if ((edgesTouched & mTrackingEdges) != 0) { 947 mCallback.onEdgeTouched(edgesTouched & mTrackingEdges, pointerId); 948 } 949 } else if (mDragState == STATE_SETTLING) { 950 // Catch a settling view if possible. 951 final View toCapture = findTopChildUnder((int) x, (int) y); 952 if (toCapture == mCapturedView) { 953 tryCaptureViewForDrag(toCapture, pointerId); 954 } 955 } 956 break; 957 } 958 959 case MotionEvent.ACTION_MOVE: { 960 // First to cross a touch slop over a draggable view wins. Also report edge drags. 961 final int pointerCount = MotionEventCompat.getPointerCount(ev); 962 for (int i = 0; i < pointerCount; i++) { 963 final int pointerId = MotionEventCompat.getPointerId(ev, i); 964 final float x = MotionEventCompat.getX(ev, i); 965 final float y = MotionEventCompat.getY(ev, i); 966 final float dx = x - mInitialMotionX[pointerId]; 967 final float dy = y - mInitialMotionY[pointerId]; 968 969 reportNewEdgeDrags(dx, dy, pointerId); 970 if (mDragState == STATE_DRAGGING) { 971 // Callback might have started an edge drag 972 break; 973 } 974 975 final View toCapture = findTopChildUnder((int) x, (int) y); 976 if (toCapture != null && checkTouchSlop(toCapture, dx, dy) && 977 tryCaptureViewForDrag(toCapture, pointerId)) { 978 break; 979 } 980 } 981 saveLastMotion(ev); 982 break; 983 } 984 985 case MotionEventCompat.ACTION_POINTER_UP: { 986 final int pointerId = MotionEventCompat.getPointerId(ev, actionIndex); 987 clearMotionHistory(pointerId); 988 break; 989 } 990 991 case MotionEvent.ACTION_UP: 992 case MotionEvent.ACTION_CANCEL: { 993 cancel(); 994 break; 995 } 996 } 997 998 return mDragState == STATE_DRAGGING; 999 } 1000 1001 /** 1002 * Process a touch event received by the parent view. This method will dispatch callback events 1003 * as needed before returning. The parent view's onTouchEvent implementation should call this. 1004 * 1005 * @param ev The touch event received by the parent view 1006 */ 1007 public void processTouchEvent(MotionEvent ev) { 1008 final int action = MotionEventCompat.getActionMasked(ev); 1009 final int actionIndex = MotionEventCompat.getActionIndex(ev); 1010 1011 if (action == MotionEvent.ACTION_DOWN) { 1012 // Reset things for a new event stream, just in case we didn't get 1013 // the whole previous stream. 1014 cancel(); 1015 } 1016 1017 if (mVelocityTracker == null) { 1018 mVelocityTracker = VelocityTracker.obtain(); 1019 } 1020 mVelocityTracker.addMovement(ev); 1021 1022 switch (action) { 1023 case MotionEvent.ACTION_DOWN: { 1024 final float x = ev.getX(); 1025 final float y = ev.getY(); 1026 final int pointerId = MotionEventCompat.getPointerId(ev, 0); 1027 final View toCapture = findTopChildUnder((int) x, (int) y); 1028 1029 saveInitialMotion(x, y, pointerId); 1030 1031 // Since the parent is already directly processing this touch event, 1032 // there is no reason to delay for a slop before dragging. 1033 // Start immediately if possible. 1034 tryCaptureViewForDrag(toCapture, pointerId); 1035 1036 final int edgesTouched = mInitialEdgesTouched[pointerId]; 1037 if ((edgesTouched & mTrackingEdges) != 0) { 1038 mCallback.onEdgeTouched(edgesTouched & mTrackingEdges, pointerId); 1039 } 1040 break; 1041 } 1042 1043 case MotionEventCompat.ACTION_POINTER_DOWN: { 1044 final int pointerId = MotionEventCompat.getPointerId(ev, actionIndex); 1045 final float x = MotionEventCompat.getX(ev, actionIndex); 1046 final float y = MotionEventCompat.getY(ev, actionIndex); 1047 1048 saveInitialMotion(x, y, pointerId); 1049 1050 // A ViewDragHelper can only manipulate one view at a time. 1051 if (mDragState == STATE_IDLE) { 1052 // If we're idle we can do anything! Treat it like a normal down event. 1053 1054 final View toCapture = findTopChildUnder((int) x, (int) y); 1055 tryCaptureViewForDrag(toCapture, pointerId); 1056 1057 final int edgesTouched = mInitialEdgesTouched[pointerId]; 1058 if ((edgesTouched & mTrackingEdges) != 0) { 1059 mCallback.onEdgeTouched(edgesTouched & mTrackingEdges, pointerId); 1060 } 1061 } else if (isCapturedViewUnder((int) x, (int) y)) { 1062 // We're still tracking a captured view. If the same view is under this 1063 // point, we'll swap to controlling it with this pointer instead. 1064 // (This will still work if we're "catching" a settling view.) 1065 1066 tryCaptureViewForDrag(mCapturedView, pointerId); 1067 } 1068 break; 1069 } 1070 1071 case MotionEvent.ACTION_MOVE: { 1072 if (mDragState == STATE_DRAGGING) { 1073 final int index = MotionEventCompat.findPointerIndex(ev, mActivePointerId); 1074 final float x = MotionEventCompat.getX(ev, index); 1075 final float y = MotionEventCompat.getY(ev, index); 1076 final int idx = (int) (x - mLastMotionX[mActivePointerId]); 1077 final int idy = (int) (y - mLastMotionY[mActivePointerId]); 1078 1079 dragTo(mCapturedView.getLeft() + idx, mCapturedView.getTop() + idy, idx, idy); 1080 1081 saveLastMotion(ev); 1082 } else { 1083 // Check to see if any pointer is now over a draggable view. 1084 final int pointerCount = MotionEventCompat.getPointerCount(ev); 1085 for (int i = 0; i < pointerCount; i++) { 1086 final int pointerId = MotionEventCompat.getPointerId(ev, i); 1087 final float x = MotionEventCompat.getX(ev, i); 1088 final float y = MotionEventCompat.getY(ev, i); 1089 final float dx = x - mInitialMotionX[pointerId]; 1090 final float dy = y - mInitialMotionY[pointerId]; 1091 1092 reportNewEdgeDrags(dx, dy, pointerId); 1093 if (mDragState == STATE_DRAGGING) { 1094 // Callback might have started an edge drag. 1095 break; 1096 } 1097 1098 final View toCapture = findTopChildUnder((int) x, (int) y); 1099 if (checkTouchSlop(toCapture, dx, dy) && 1100 tryCaptureViewForDrag(toCapture, pointerId)) { 1101 break; 1102 } 1103 } 1104 saveLastMotion(ev); 1105 } 1106 break; 1107 } 1108 1109 case MotionEventCompat.ACTION_POINTER_UP: { 1110 final int pointerId = MotionEventCompat.getPointerId(ev, actionIndex); 1111 if (mDragState == STATE_DRAGGING && pointerId == mActivePointerId) { 1112 // Try to find another pointer that's still holding on to the captured view. 1113 int newActivePointer = INVALID_POINTER; 1114 final int pointerCount = MotionEventCompat.getPointerCount(ev); 1115 for (int i = 0; i < pointerCount; i++) { 1116 final int id = MotionEventCompat.getPointerId(ev, i); 1117 if (id == mActivePointerId) { 1118 // This one's going away, skip. 1119 continue; 1120 } 1121 1122 final float x = MotionEventCompat.getX(ev, i); 1123 final float y = MotionEventCompat.getY(ev, i); 1124 if (findTopChildUnder((int) x, (int) y) == mCapturedView && 1125 tryCaptureViewForDrag(mCapturedView, id)) { 1126 newActivePointer = mActivePointerId; 1127 break; 1128 } 1129 } 1130 1131 if (newActivePointer == INVALID_POINTER) { 1132 // We didn't find another pointer still touching the view, release it. 1133 releaseViewForPointerUp(); 1134 } 1135 } 1136 clearMotionHistory(pointerId); 1137 break; 1138 } 1139 1140 case MotionEvent.ACTION_UP: { 1141 if (mDragState == STATE_DRAGGING) { 1142 releaseViewForPointerUp(); 1143 } 1144 cancel(); 1145 break; 1146 } 1147 1148 case MotionEvent.ACTION_CANCEL: { 1149 if (mDragState == STATE_DRAGGING) { 1150 dispatchViewReleased(0, 0); 1151 } 1152 cancel(); 1153 break; 1154 } 1155 } 1156 } 1157 1158 private void reportNewEdgeDrags(float dx, float dy, int pointerId) { 1159 int dragsStarted = 0; 1160 if (checkNewEdgeDrag(dx, dy, pointerId, EDGE_LEFT)) { 1161 dragsStarted |= EDGE_LEFT; 1162 } 1163 if (checkNewEdgeDrag(dy, dx, pointerId, EDGE_TOP)) { 1164 dragsStarted |= EDGE_TOP; 1165 } 1166 if (checkNewEdgeDrag(dx, dy, pointerId, EDGE_RIGHT)) { 1167 dragsStarted |= EDGE_RIGHT; 1168 } 1169 if (checkNewEdgeDrag(dy, dx, pointerId, EDGE_BOTTOM)) { 1170 dragsStarted |= EDGE_BOTTOM; 1171 } 1172 1173 if (dragsStarted != 0) { 1174 mEdgeDragsInProgress[pointerId] |= dragsStarted; 1175 mCallback.onEdgeDragStarted(dragsStarted, pointerId); 1176 } 1177 } 1178 1179 private boolean checkNewEdgeDrag(float delta, float odelta, int pointerId, int edge) { 1180 final float absDelta = Math.abs(delta); 1181 final float absODelta = Math.abs(odelta); 1182 1183 if ((mInitialEdgesTouched[pointerId] & edge) != edge || (mTrackingEdges & edge) == 0 || 1184 (mEdgeDragsLocked[pointerId] & edge) == edge || 1185 (mEdgeDragsInProgress[pointerId] & edge) == edge || 1186 (absDelta <= mTouchSlop && absODelta <= mTouchSlop)) { 1187 return false; 1188 } 1189 if (absDelta < absODelta * 0.5f && mCallback.onEdgeLock(edge)) { 1190 mEdgeDragsLocked[pointerId] |= edge; 1191 return false; 1192 } 1193 return (mEdgeDragsInProgress[pointerId] & edge) == 0 && absDelta > mTouchSlop; 1194 } 1195 1196 /** 1197 * Check if we've crossed a reasonable touch slop for the given child view. 1198 * If the child cannot be dragged along the horizontal or vertical axis, motion 1199 * along that axis will not count toward the slop check. 1200 * 1201 * @param child Child to check 1202 * @param dx Motion since initial position along X axis 1203 * @param dy Motion since initial position along Y axis 1204 * @return true if the touch slop has been crossed 1205 */ 1206 private boolean checkTouchSlop(View child, float dx, float dy) { 1207 if (child == null) { 1208 return false; 1209 } 1210 final boolean checkHorizontal = mCallback.getViewHorizontalDragRange(child) > 0; 1211 final boolean checkVertical = mCallback.getViewVerticalDragRange(child) > 0; 1212 1213 if (checkHorizontal && checkVertical) { 1214 return dx * dx + dy * dy > mTouchSlop * mTouchSlop; 1215 } else if (checkHorizontal) { 1216 return Math.abs(dx) > mTouchSlop; 1217 } else if (checkVertical) { 1218 return Math.abs(dy) > mTouchSlop; 1219 } 1220 return false; 1221 } 1222 1223 /** 1224 * Check if any pointer tracked in the current gesture has crossed 1225 * the required slop threshold. 1226 * 1227 * <p>This depends on internal state populated by 1228 * {@link #shouldInterceptTouchEvent(android.view.MotionEvent)} or 1229 * {@link #processTouchEvent(android.view.MotionEvent)}. You should only rely on 1230 * the results of this method after all currently available touch data 1231 * has been provided to one of these two methods.</p> 1232 * 1233 * @param directions Combination of direction flags, see {@link #DIRECTION_HORIZONTAL}, 1234 * {@link #DIRECTION_VERTICAL}, {@link #DIRECTION_ALL} 1235 * @return true if the slop threshold has been crossed, false otherwise 1236 */ 1237 public boolean checkTouchSlop(int directions) { 1238 final int count = mInitialMotionX.length; 1239 for (int i = 0; i < count; i++) { 1240 if (checkTouchSlop(directions, i)) { 1241 return true; 1242 } 1243 } 1244 return false; 1245 } 1246 1247 /** 1248 * Check if the specified pointer tracked in the current gesture has crossed 1249 * the required slop threshold. 1250 * 1251 * <p>This depends on internal state populated by 1252 * {@link #shouldInterceptTouchEvent(android.view.MotionEvent)} or 1253 * {@link #processTouchEvent(android.view.MotionEvent)}. You should only rely on 1254 * the results of this method after all currently available touch data 1255 * has been provided to one of these two methods.</p> 1256 * 1257 * @param directions Combination of direction flags, see {@link #DIRECTION_HORIZONTAL}, 1258 * {@link #DIRECTION_VERTICAL}, {@link #DIRECTION_ALL} 1259 * @param pointerId ID of the pointer to slop check as specified by MotionEvent 1260 * @return true if the slop threshold has been crossed, false otherwise 1261 */ 1262 public boolean checkTouchSlop(int directions, int pointerId) { 1263 if (!isPointerDown(pointerId)) { 1264 return false; 1265 } 1266 1267 final boolean checkHorizontal = (directions & DIRECTION_HORIZONTAL) == DIRECTION_HORIZONTAL; 1268 final boolean checkVertical = (directions & DIRECTION_VERTICAL) == DIRECTION_VERTICAL; 1269 1270 final float dx = mLastMotionX[pointerId] - mInitialMotionX[pointerId]; 1271 final float dy = mLastMotionY[pointerId] - mInitialMotionY[pointerId]; 1272 1273 if (checkHorizontal && checkVertical) { 1274 return dx * dx + dy * dy > mTouchSlop * mTouchSlop; 1275 } else if (checkHorizontal) { 1276 return Math.abs(dx) > mTouchSlop; 1277 } else if (checkVertical) { 1278 return Math.abs(dy) > mTouchSlop; 1279 } 1280 return false; 1281 } 1282 1283 /** 1284 * Check if any of the edges specified were initially touched in the currently active gesture. 1285 * If there is no currently active gesture this method will return false. 1286 * 1287 * @param edges Edges to check for an initial edge touch. See {@link #EDGE_LEFT}, 1288 * {@link #EDGE_TOP}, {@link #EDGE_RIGHT}, {@link #EDGE_BOTTOM} and 1289 * {@link #EDGE_ALL} 1290 * @return true if any of the edges specified were initially touched in the current gesture 1291 */ 1292 public boolean isEdgeTouched(int edges) { 1293 final int count = mInitialEdgesTouched.length; 1294 for (int i = 0; i < count; i++) { 1295 if (isEdgeTouched(edges, i)) { 1296 return true; 1297 } 1298 } 1299 return false; 1300 } 1301 1302 /** 1303 * Check if any of the edges specified were initially touched by the pointer with 1304 * the specified ID. If there is no currently active gesture or if there is no pointer with 1305 * the given ID currently down this method will return false. 1306 * 1307 * @param edges Edges to check for an initial edge touch. See {@link #EDGE_LEFT}, 1308 * {@link #EDGE_TOP}, {@link #EDGE_RIGHT}, {@link #EDGE_BOTTOM} and 1309 * {@link #EDGE_ALL} 1310 * @return true if any of the edges specified were initially touched in the current gesture 1311 */ 1312 public boolean isEdgeTouched(int edges, int pointerId) { 1313 return isPointerDown(pointerId) && (mInitialEdgesTouched[pointerId] & edges) != 0; 1314 } 1315 1316 private void releaseViewForPointerUp() { 1317 mVelocityTracker.computeCurrentVelocity(1000, mMaxVelocity); 1318 dispatchViewReleased(VelocityTrackerCompat.getXVelocity(mVelocityTracker, mActivePointerId), 1319 VelocityTrackerCompat.getYVelocity(mVelocityTracker, mActivePointerId)); 1320 } 1321 1322 private void dragTo(int left, int top, int dx, int dy) { 1323 int clampedX = left; 1324 int clampedY = top; 1325 final int oldLeft = mCapturedView.getLeft(); 1326 final int oldTop = mCapturedView.getTop(); 1327 if (dx != 0) { 1328 clampedX = mCallback.clampViewPositionHorizontal(mCapturedView, left, dx); 1329 mCapturedView.offsetLeftAndRight(clampedX - oldLeft); 1330 } 1331 if (dy != 0) { 1332 clampedY = mCallback.clampViewPositionVertical(mCapturedView, top, dy); 1333 mCapturedView.offsetTopAndBottom(clampedY - oldTop); 1334 } 1335 1336 if (dx != 0 || dy != 0) { 1337 final int clampedDx = clampedX - oldLeft; 1338 final int clampedDy = clampedY - oldTop; 1339 mCallback.onViewPositionChanged(mCapturedView, clampedX, clampedY, 1340 clampedDx, clampedDy); 1341 } 1342 } 1343 1344 /** 1345 * Determine if the currently captured view is under the given point in the 1346 * parent view's coordinate system. If there is no captured view this method 1347 * will return false. 1348 * 1349 * @param x X position to test in the parent's coordinate system 1350 * @param y Y position to test in the parent's coordinate system 1351 * @return true if the captured view is under the given point, false otherwise 1352 */ 1353 public boolean isCapturedViewUnder(int x, int y) { 1354 return isViewUnder(mCapturedView, x, y); 1355 } 1356 1357 /** 1358 * Determine if the supplied view is under the given point in the 1359 * parent view's coordinate system. 1360 * 1361 * @param view Child view of the parent to hit test 1362 * @param x X position to test in the parent's coordinate system 1363 * @param y Y position to test in the parent's coordinate system 1364 * @return true if the supplied view is under the given point, false otherwise 1365 */ 1366 public boolean isViewUnder(View view, int x, int y) { 1367 if (view == null) { 1368 return false; 1369 } 1370 return x >= view.getLeft() && 1371 x < view.getRight() && 1372 y >= view.getTop() && 1373 y < view.getBottom(); 1374 } 1375 1376 /** 1377 * Find the topmost child under the given point within the parent view's coordinate system. 1378 * The child order is determined using {@link Callback#getOrderedChildIndex(int)}. 1379 * 1380 * @param x X position to test in the parent's coordinate system 1381 * @param y Y position to test in the parent's coordinate system 1382 * @return The topmost child view under (x, y) or null if none found. 1383 */ 1384 public View findTopChildUnder(int x, int y) { 1385 final int childCount = mParentView.getChildCount(); 1386 for (int i = childCount - 1; i >= 0; i--) { 1387 final View child = mParentView.getChildAt(mCallback.getOrderedChildIndex(i)); 1388 if (x >= child.getLeft() && x < child.getRight() && 1389 y >= child.getTop() && y < child.getBottom()) { 1390 return child; 1391 } 1392 } 1393 return null; 1394 } 1395 1396 private int getEdgesTouched(int x, int y) { 1397 int result = 0; 1398 1399 if (x < mParentView.getLeft() + mEdgeSize) result |= EDGE_LEFT; 1400 if (y < mParentView.getTop() + mEdgeSize) result |= EDGE_TOP; 1401 if (x > mParentView.getRight() - mEdgeSize) result |= EDGE_RIGHT; 1402 if (y > mParentView.getBottom() - mEdgeSize) result |= EDGE_BOTTOM; 1403 1404 return result; 1405 } 1406} 1407