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.util.Log; 25import android.view.MotionEvent; 26import android.view.VelocityTracker; 27import android.view.View; 28import android.view.ViewConfiguration; 29import android.view.ViewGroup; 30import android.view.animation.Interpolator; 31 32import java.util.Arrays; 33 34/** 35 * ViewDragHelper is a utility class for writing custom ViewGroups. It offers a number 36 * of useful operations and state tracking for allowing a user to drag and reposition 37 * views within their parent ViewGroup. 38 */ 39public class ViewDragHelper { 40 private static final String TAG = "ViewDragHelper"; 41 42 /** 43 * A null/invalid pointer ID. 44 */ 45 public static final int INVALID_POINTER = -1; 46 47 /** 48 * A view is not currently being dragged or animating as a result of a fling/snap. 49 */ 50 public static final int STATE_IDLE = 0; 51 52 /** 53 * A view is currently being dragged. The position is currently changing as a result 54 * of user input or simulated user input. 55 */ 56 public static final int STATE_DRAGGING = 1; 57 58 /** 59 * A view is currently settling into place as a result of a fling or 60 * predefined non-interactive motion. 61 */ 62 public static final int STATE_SETTLING = 2; 63 64 /** 65 * Edge flag indicating that the left edge should be affected. 66 */ 67 public static final int EDGE_LEFT = 1 << 0; 68 69 /** 70 * Edge flag indicating that the right edge should be affected. 71 */ 72 public static final int EDGE_RIGHT = 1 << 1; 73 74 /** 75 * Edge flag indicating that the top edge should be affected. 76 */ 77 public static final int EDGE_TOP = 1 << 2; 78 79 /** 80 * Edge flag indicating that the bottom edge should be affected. 81 */ 82 public static final int EDGE_BOTTOM = 1 << 3; 83 84 /** 85 * Edge flag set indicating all edges should be affected. 86 */ 87 public static final int EDGE_ALL = EDGE_LEFT | EDGE_TOP | EDGE_RIGHT | EDGE_BOTTOM; 88 89 /** 90 * Indicates that a check should occur along the horizontal axis 91 */ 92 public static final int DIRECTION_HORIZONTAL = 1 << 0; 93 94 /** 95 * Indicates that a check should occur along the vertical axis 96 */ 97 public static final int DIRECTION_VERTICAL = 1 << 1; 98 99 /** 100 * Indicates that a check should occur along all axes 101 */ 102 public static final int DIRECTION_ALL = DIRECTION_HORIZONTAL | DIRECTION_VERTICAL; 103 104 private static final int EDGE_SIZE = 20; // dp 105 106 private static final int BASE_SETTLE_DURATION = 256; // ms 107 private static final int MAX_SETTLE_DURATION = 600; // ms 108 109 // Current drag state; idle, dragging or settling 110 private int mDragState; 111 112 // Distance to travel before a drag may begin 113 private int mTouchSlop; 114 115 // Last known position/pointer tracking 116 private int mActivePointerId = INVALID_POINTER; 117 private float[] mInitialMotionX; 118 private float[] mInitialMotionY; 119 private float[] mLastMotionX; 120 private float[] mLastMotionY; 121 private int[] mInitialEdgesTouched; 122 private int[] mEdgeDragsInProgress; 123 private int[] mEdgeDragsLocked; 124 private int mPointersDown; 125 126 private VelocityTracker mVelocityTracker; 127 private float mMaxVelocity; 128 private float mMinVelocity; 129 130 private int mEdgeSize; 131 private int mTrackingEdges; 132 133 private ScrollerCompat mScroller; 134 135 private final Callback mCallback; 136 137 private View mCapturedView; 138 private boolean mReleaseInProgress; 139 140 private final ViewGroup mParentView; 141 142 /** 143 * A Callback is used as a communication channel with the ViewDragHelper back to the 144 * parent view using it. <code>on*</code>methods are invoked on siginficant events and several 145 * accessor methods are expected to provide the ViewDragHelper with more information 146 * about the state of the parent view upon request. The callback also makes decisions 147 * governing the range and draggability of child views. 148 */ 149 public static abstract class Callback { 150 /** 151 * Called when the drag state changes. See the <code>STATE_*</code> constants 152 * for more information. 153 * 154 * @param state The new drag state 155 * 156 * @see #STATE_IDLE 157 * @see #STATE_DRAGGING 158 * @see #STATE_SETTLING 159 */ 160 public void onViewDragStateChanged(int state) {} 161 162 /** 163 * Called when the captured view's position changes as the result of a drag or settle. 164 * 165 * @param changedView View whose position changed 166 * @param left New X coordinate of the left edge of the view 167 * @param top New Y coordinate of the top edge of the view 168 * @param dx Change in X position from the last call 169 * @param dy Change in Y position from the last call 170 */ 171 public void onViewPositionChanged(View changedView, int left, int top, int dx, int dy) {} 172 173 /** 174 * Called when a child view is captured for dragging or settling. The ID of the pointer 175 * currently dragging the captured view is supplied. If activePointerId is 176 * identified as {@link #INVALID_POINTER} the capture is programmatic instead of 177 * pointer-initiated. 178 * 179 * @param capturedChild Child view that was captured 180 * @param activePointerId Pointer id tracking the child capture 181 */ 182 public void onViewCaptured(View capturedChild, int activePointerId) {} 183 184 /** 185 * Called when the child view is no longer being actively dragged. 186 * The fling velocity is also supplied, if relevant. The velocity values may 187 * be clamped to system minimums or maximums. 188 * 189 * <p>Calling code may decide to fling or otherwise release the view to let it 190 * settle into place. It should do so using {@link #settleCapturedViewAt(int, int)} 191 * or {@link #flingCapturedView(int, int, int, int)}. If the Callback invokes 192 * one of these methods, the ViewDragHelper will enter {@link #STATE_SETTLING} 193 * and the view capture will not fully end until it comes to a complete stop. 194 * If neither of these methods is invoked before <code>onViewReleased</code> returns, 195 * the view will stop in place and the ViewDragHelper will return to 196 * {@link #STATE_IDLE}.</p> 197 * 198 * @param releasedChild The captured child view now being released 199 * @param xvel X velocity of the pointer as it left the screen in pixels per second. 200 * @param yvel Y velocity of the pointer as it left the screen in pixels per second. 201 */ 202 public void onViewReleased(View releasedChild, float xvel, float yvel) {} 203 204 /** 205 * Called when one of the subscribed edges in the parent view has been touched 206 * by the user while no child view is currently captured. 207 * 208 * @param edgeFlags A combination of edge flags describing the edge(s) currently touched 209 * @param pointerId ID of the pointer touching the described edge(s) 210 * @see #EDGE_LEFT 211 * @see #EDGE_TOP 212 * @see #EDGE_RIGHT 213 * @see #EDGE_BOTTOM 214 */ 215 public void onEdgeTouched(int edgeFlags, int pointerId) {} 216 217 /** 218 * Called when the given edge may become locked. This can happen if an edge drag 219 * was preliminarily rejected before beginning, but after {@link #onEdgeTouched(int, int)} 220 * was called. This method should return true to lock this edge or false to leave it 221 * unlocked. The default behavior is to leave edges unlocked. 222 * 223 * @param edgeFlags A combination of edge flags describing the edge(s) locked 224 * @return true to lock the edge, false to leave it unlocked 225 */ 226 public boolean onEdgeLock(int edgeFlags) { 227 return false; 228 } 229 230 /** 231 * Called when the user has started a deliberate drag away from one 232 * of the subscribed edges in the parent view while no child view is currently captured. 233 * 234 * @param edgeFlags A combination of edge flags describing the edge(s) dragged 235 * @param pointerId ID of the pointer touching the described edge(s) 236 * @see #EDGE_LEFT 237 * @see #EDGE_TOP 238 * @see #EDGE_RIGHT 239 * @see #EDGE_BOTTOM 240 */ 241 public void onEdgeDragStarted(int edgeFlags, int pointerId) {} 242 243 /** 244 * Called to determine the Z-order of child views. 245 * 246 * @param index the ordered position to query for 247 * @return index of the view that should be ordered at position <code>index</code> 248 */ 249 public int getOrderedChildIndex(int index) { 250 return index; 251 } 252 253 /** 254 * Return the magnitude of a draggable child view's horizontal range of motion in pixels. 255 * This method should return 0 for views that cannot move horizontally. 256 * 257 * @param child Child view to check 258 * @return range of horizontal motion in pixels 259 */ 260 public int getViewHorizontalDragRange(View child) { 261 return 0; 262 } 263 264 /** 265 * Return the magnitude of a draggable child view's vertical range of motion in pixels. 266 * This method should return 0 for views that cannot move vertically. 267 * 268 * @param child Child view to check 269 * @return range of vertical motion in pixels 270 */ 271 public int getViewVerticalDragRange(View child) { 272 return 0; 273 } 274 275 /** 276 * Called when the user's input indicates that they want to capture the given child view 277 * with the pointer indicated by pointerId. The callback should return true if the user 278 * is permitted to drag the given view with the indicated pointer. 279 * 280 * <p>ViewDragHelper may call this method multiple times for the same view even if 281 * the view is already captured; this indicates that a new pointer is trying to take 282 * control of the view.</p> 283 * 284 * <p>If this method returns true, a call to {@link #onViewCaptured(android.view.View, int)} 285 * will follow if the capture is successful.</p> 286 * 287 * @param child Child the user is attempting to capture 288 * @param pointerId ID of the pointer attempting the capture 289 * @return true if capture should be allowed, false otherwise 290 */ 291 public abstract boolean tryCaptureView(View child, int pointerId); 292 293 /** 294 * Restrict the motion of the dragged child view along the horizontal axis. 295 * The default implementation does not allow horizontal motion; the extending 296 * class must override this method and provide the desired clamping. 297 * 298 * 299 * @param child Child view being dragged 300 * @param left Attempted motion along the X axis 301 * @param dx Proposed change in position for left 302 * @return The new clamped position for left 303 */ 304 public int clampViewPositionHorizontal(View child, int left, int dx) { 305 return 0; 306 } 307 308 /** 309 * Restrict the motion of the dragged child view along the vertical axis. 310 * The default implementation does not allow vertical motion; the extending 311 * class must override this method and provide the desired clamping. 312 * 313 * 314 * @param child Child view being dragged 315 * @param top Attempted motion along the Y axis 316 * @param dy Proposed change in position for top 317 * @return The new clamped position for top 318 */ 319 public int clampViewPositionVertical(View child, int top, int dy) { 320 return 0; 321 } 322 } 323 324 /** 325 * Interpolator defining the animation curve for mScroller 326 */ 327 private static final Interpolator sInterpolator = new Interpolator() { 328 public float getInterpolation(float t) { 329 t -= 1.0f; 330 return t * t * t * t * t + 1.0f; 331 } 332 }; 333 334 private final Runnable mSetIdleRunnable = new Runnable() { 335 public void run() { 336 setDragState(STATE_IDLE); 337 } 338 }; 339 340 /** 341 * Factory method to create a new ViewDragHelper. 342 * 343 * @param forParent Parent view to monitor 344 * @param cb Callback to provide information and receive events 345 * @return a new ViewDragHelper instance 346 */ 347 public static ViewDragHelper create(ViewGroup forParent, Callback cb) { 348 return new ViewDragHelper(forParent.getContext(), forParent, cb); 349 } 350 351 /** 352 * Factory method to create a new ViewDragHelper. 353 * 354 * @param forParent Parent view to monitor 355 * @param sensitivity Multiplier for how sensitive the helper should be about detecting 356 * the start of a drag. Larger values are more sensitive. 1.0f is normal. 357 * @param cb Callback to provide information and receive events 358 * @return a new ViewDragHelper instance 359 */ 360 public static ViewDragHelper create(ViewGroup forParent, float sensitivity, Callback cb) { 361 final ViewDragHelper helper = create(forParent, cb); 362 helper.mTouchSlop = (int) (helper.mTouchSlop * (1 / sensitivity)); 363 return helper; 364 } 365 366 /** 367 * Apps should use ViewDragHelper.create() to get a new instance. 368 * This will allow VDH to use internal compatibility implementations for different 369 * platform versions. 370 * 371 * @param context Context to initialize config-dependent params from 372 * @param forParent Parent view to monitor 373 */ 374 private ViewDragHelper(Context context, ViewGroup forParent, Callback cb) { 375 if (forParent == null) { 376 throw new IllegalArgumentException("Parent view may not be null"); 377 } 378 if (cb == null) { 379 throw new IllegalArgumentException("Callback may not be null"); 380 } 381 382 mParentView = forParent; 383 mCallback = cb; 384 385 final ViewConfiguration vc = ViewConfiguration.get(context); 386 final float density = context.getResources().getDisplayMetrics().density; 387 mEdgeSize = (int) (EDGE_SIZE * density + 0.5f); 388 389 mTouchSlop = vc.getScaledTouchSlop(); 390 mMaxVelocity = vc.getScaledMaximumFlingVelocity(); 391 mMinVelocity = vc.getScaledMinimumFlingVelocity(); 392 mScroller = ScrollerCompat.create(context, sInterpolator); 393 } 394 395 /** 396 * Set the minimum velocity that will be detected as having a magnitude greater than zero 397 * in pixels per second. Callback methods accepting a velocity will be clamped appropriately. 398 * 399 * @param minVel Minimum velocity to detect 400 */ 401 public void setMinVelocity(float minVel) { 402 mMinVelocity = minVel; 403 } 404 405 /** 406 * Return the currently configured minimum velocity. Any flings with a magnitude less 407 * than this value in pixels per second. Callback methods accepting a velocity will receive 408 * zero as a velocity value if the real detected velocity was below this threshold. 409 * 410 * @return the minimum velocity that will be detected 411 */ 412 public float getMinVelocity() { 413 return mMinVelocity; 414 } 415 416 /** 417 * Retrieve the current drag state of this helper. This will return one of 418 * {@link #STATE_IDLE}, {@link #STATE_DRAGGING} or {@link #STATE_SETTLING}. 419 * @return The current drag state 420 */ 421 public int getViewDragState() { 422 return mDragState; 423 } 424 425 /** 426 * Enable edge tracking for the selected edges of the parent view. 427 * The callback's {@link Callback#onEdgeTouched(int, int)} and 428 * {@link Callback#onEdgeDragStarted(int, int)} methods will only be invoked 429 * for edges for which edge tracking has been enabled. 430 * 431 * @param edgeFlags Combination of edge flags describing the edges to watch 432 * @see #EDGE_LEFT 433 * @see #EDGE_TOP 434 * @see #EDGE_RIGHT 435 * @see #EDGE_BOTTOM 436 */ 437 public void setEdgeTrackingEnabled(int edgeFlags) { 438 mTrackingEdges = edgeFlags; 439 } 440 441 /** 442 * Return the size of an edge. This is the range in pixels along the edges of this view 443 * that will actively detect edge touches or drags if edge tracking is enabled. 444 * 445 * @return The size of an edge in pixels 446 * @see #setEdgeTrackingEnabled(int) 447 */ 448 public int getEdgeSize() { 449 return mEdgeSize; 450 } 451 452 /** 453 * Capture a specific child view for dragging within the parent. The callback will be notified 454 * but {@link Callback#tryCaptureView(android.view.View, int)} will not be asked permission to 455 * capture this view. 456 * 457 * @param childView Child view to capture 458 * @param activePointerId ID of the pointer that is dragging the captured child view 459 */ 460 public void captureChildView(View childView, int activePointerId) { 461 if (childView.getParent() != mParentView) { 462 throw new IllegalArgumentException("captureChildView: parameter must be a descendant " + 463 "of the ViewDragHelper's tracked parent view (" + mParentView + ")"); 464 } 465 466 mCapturedView = childView; 467 mActivePointerId = activePointerId; 468 mCallback.onViewCaptured(childView, activePointerId); 469 setDragState(STATE_DRAGGING); 470 } 471 472 /** 473 * @return The currently captured view, or null if no view has been captured. 474 */ 475 public View getCapturedView() { 476 return mCapturedView; 477 } 478 479 /** 480 * @return The ID of the pointer currently dragging the captured view, 481 * or {@link #INVALID_POINTER}. 482 */ 483 public int getActivePointerId() { 484 return mActivePointerId; 485 } 486 487 /** 488 * @return The minimum distance in pixels that the user must travel to initiate a drag 489 */ 490 public int getTouchSlop() { 491 return mTouchSlop; 492 } 493 494 /** 495 * The result of a call to this method is equivalent to 496 * {@link #processTouchEvent(android.view.MotionEvent)} receiving an ACTION_CANCEL event. 497 */ 498 public void cancel() { 499 mActivePointerId = INVALID_POINTER; 500 clearMotionHistory(); 501 502 if (mVelocityTracker != null) { 503 mVelocityTracker.recycle(); 504 mVelocityTracker = null; 505 } 506 } 507 508 /** 509 * {@link #cancel()}, but also abort all motion in progress and snap to the end of any 510 * animation. 511 */ 512 public void abort() { 513 cancel(); 514 if (mDragState == STATE_SETTLING) { 515 final int oldX = mScroller.getCurrX(); 516 final int oldY = mScroller.getCurrY(); 517 mScroller.abortAnimation(); 518 final int newX = mScroller.getCurrX(); 519 final int newY = mScroller.getCurrY(); 520 mCallback.onViewPositionChanged(mCapturedView, newX, newY, newX - oldX, newY - oldY); 521 } 522 setDragState(STATE_IDLE); 523 } 524 525 /** 526 * Animate the view <code>child</code> to the given (left, top) position. 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 * <p>This operation does not count as a capture event, though {@link #getCapturedView()} 532 * will still report the sliding view while the slide is in progress.</p> 533 * 534 * @param child Child view to capture and animate 535 * @param finalLeft Final left position of child 536 * @param finalTop Final top position of child 537 * @return true if animation should continue through {@link #continueSettling(boolean)} calls 538 */ 539 public boolean smoothSlideViewTo(View child, int finalLeft, int finalTop) { 540 mCapturedView = child; 541 mActivePointerId = INVALID_POINTER; 542 543 boolean continueSliding = forceSettleCapturedViewAt(finalLeft, finalTop, 0, 0); 544 if (!continueSliding && mDragState == STATE_IDLE && mCapturedView != null) { 545 // If we're in an IDLE state to begin with and aren't moving anywhere, we 546 // end up having a non-null capturedView with an IDLE dragState 547 mCapturedView = null; 548 } 549 550 return continueSliding; 551 } 552 553 /** 554 * Settle the captured view at the given (left, top) position. 555 * The appropriate velocity from prior motion will be taken into account. 556 * If this method returns true, the caller should invoke {@link #continueSettling(boolean)} 557 * on each subsequent frame to continue the motion until it returns false. If this method 558 * returns false there is no further work to do to complete the movement. 559 * 560 * @param finalLeft Settled left edge position for the captured view 561 * @param finalTop Settled top edge position for the captured view 562 * @return true if animation should continue through {@link #continueSettling(boolean)} calls 563 */ 564 public boolean settleCapturedViewAt(int finalLeft, int finalTop) { 565 if (!mReleaseInProgress) { 566 throw new IllegalStateException("Cannot settleCapturedViewAt outside of a call to " + 567 "Callback#onViewReleased"); 568 } 569 570 return forceSettleCapturedViewAt(finalLeft, finalTop, 571 (int) VelocityTrackerCompat.getXVelocity(mVelocityTracker, mActivePointerId), 572 (int) VelocityTrackerCompat.getYVelocity(mVelocityTracker, mActivePointerId)); 573 } 574 575 /** 576 * Settle the captured view at the given (left, top) position. 577 * 578 * @param finalLeft Target left position for the captured view 579 * @param finalTop Target top position for the captured view 580 * @param xvel Horizontal velocity 581 * @param yvel Vertical velocity 582 * @return true if animation should continue through {@link #continueSettling(boolean)} calls 583 */ 584 private boolean forceSettleCapturedViewAt(int finalLeft, int finalTop, int xvel, int yvel) { 585 final int startLeft = mCapturedView.getLeft(); 586 final int startTop = mCapturedView.getTop(); 587 final int dx = finalLeft - startLeft; 588 final int dy = finalTop - startTop; 589 590 if (dx == 0 && dy == 0) { 591 // Nothing to do. Send callbacks, be done. 592 mScroller.abortAnimation(); 593 setDragState(STATE_IDLE); 594 return false; 595 } 596 597 final int duration = computeSettleDuration(mCapturedView, dx, dy, xvel, yvel); 598 mScroller.startScroll(startLeft, startTop, dx, dy, duration); 599 600 setDragState(STATE_SETTLING); 601 return true; 602 } 603 604 private int computeSettleDuration(View child, int dx, int dy, int xvel, int yvel) { 605 xvel = clampMag(xvel, (int) mMinVelocity, (int) mMaxVelocity); 606 yvel = clampMag(yvel, (int) mMinVelocity, (int) mMaxVelocity); 607 final int absDx = Math.abs(dx); 608 final int absDy = Math.abs(dy); 609 final int absXVel = Math.abs(xvel); 610 final int absYVel = Math.abs(yvel); 611 final int addedVel = absXVel + absYVel; 612 final int addedDistance = absDx + absDy; 613 614 final float xweight = xvel != 0 ? (float) absXVel / addedVel : 615 (float) absDx / addedDistance; 616 final float yweight = yvel != 0 ? (float) absYVel / addedVel : 617 (float) absDy / addedDistance; 618 619 int xduration = computeAxisDuration(dx, xvel, mCallback.getViewHorizontalDragRange(child)); 620 int yduration = computeAxisDuration(dy, yvel, mCallback.getViewVerticalDragRange(child)); 621 622 return (int) (xduration * xweight + yduration * yweight); 623 } 624 625 private int computeAxisDuration(int delta, int velocity, int motionRange) { 626 if (delta == 0) { 627 return 0; 628 } 629 630 final int width = mParentView.getWidth(); 631 final int halfWidth = width / 2; 632 final float distanceRatio = Math.min(1f, (float) Math.abs(delta) / width); 633 final float distance = halfWidth + halfWidth * 634 distanceInfluenceForSnapDuration(distanceRatio); 635 636 int duration; 637 velocity = Math.abs(velocity); 638 if (velocity > 0) { 639 duration = 4 * Math.round(1000 * Math.abs(distance / velocity)); 640 } else { 641 final float range = (float) Math.abs(delta) / motionRange; 642 duration = (int) ((range + 1) * BASE_SETTLE_DURATION); 643 } 644 return Math.min(duration, MAX_SETTLE_DURATION); 645 } 646 647 /** 648 * Clamp the magnitude of value for absMin and absMax. 649 * If the value is below the minimum, it will be clamped to zero. 650 * If the value is above the maximum, it will be clamped to the maximum. 651 * 652 * @param value Value to clamp 653 * @param absMin Absolute value of the minimum significant value to return 654 * @param absMax Absolute value of the maximum value to return 655 * @return The clamped value with the same sign as <code>value</code> 656 */ 657 private int clampMag(int value, int absMin, int absMax) { 658 final int absValue = Math.abs(value); 659 if (absValue < absMin) return 0; 660 if (absValue > absMax) return value > 0 ? absMax : -absMax; 661 return value; 662 } 663 664 /** 665 * Clamp the magnitude of value for absMin and absMax. 666 * If the value is below the minimum, it will be clamped to zero. 667 * If the value is above the maximum, it will be clamped to the maximum. 668 * 669 * @param value Value to clamp 670 * @param absMin Absolute value of the minimum significant value to return 671 * @param absMax Absolute value of the maximum value to return 672 * @return The clamped value with the same sign as <code>value</code> 673 */ 674 private float clampMag(float value, float absMin, float absMax) { 675 final float absValue = Math.abs(value); 676 if (absValue < absMin) return 0; 677 if (absValue > absMax) return value > 0 ? absMax : -absMax; 678 return value; 679 } 680 681 private float distanceInfluenceForSnapDuration(float f) { 682 f -= 0.5f; // center the values about 0. 683 f *= 0.3f * Math.PI / 2.0f; 684 return (float) Math.sin(f); 685 } 686 687 /** 688 * Settle the captured view based on standard free-moving fling behavior. 689 * The caller should invoke {@link #continueSettling(boolean)} on each subsequent frame 690 * to continue the motion until it returns false. 691 * 692 * @param minLeft Minimum X position for the view's left edge 693 * @param minTop Minimum Y position for the view's top edge 694 * @param maxLeft Maximum X position for the view's left edge 695 * @param maxTop Maximum Y position for the view's top edge 696 */ 697 public void flingCapturedView(int minLeft, int minTop, int maxLeft, int maxTop) { 698 if (!mReleaseInProgress) { 699 throw new IllegalStateException("Cannot flingCapturedView outside of a call to " + 700 "Callback#onViewReleased"); 701 } 702 703 mScroller.fling(mCapturedView.getLeft(), mCapturedView.getTop(), 704 (int) VelocityTrackerCompat.getXVelocity(mVelocityTracker, mActivePointerId), 705 (int) VelocityTrackerCompat.getYVelocity(mVelocityTracker, mActivePointerId), 706 minLeft, maxLeft, minTop, maxTop); 707 708 setDragState(STATE_SETTLING); 709 } 710 711 /** 712 * Move the captured settling view by the appropriate amount for the current time. 713 * If <code>continueSettling</code> returns true, the caller should call it again 714 * on the next frame to continue. 715 * 716 * @param deferCallbacks true if state callbacks should be deferred via posted message. 717 * Set this to true if you are calling this method from 718 * {@link android.view.View#computeScroll()} or similar methods 719 * invoked as part of layout or drawing. 720 * @return true if settle is still in progress 721 */ 722 public boolean continueSettling(boolean deferCallbacks) { 723 if (mDragState == STATE_SETTLING) { 724 boolean keepGoing = mScroller.computeScrollOffset(); 725 final int x = mScroller.getCurrX(); 726 final int y = mScroller.getCurrY(); 727 final int dx = x - mCapturedView.getLeft(); 728 final int dy = y - mCapturedView.getTop(); 729 730 if (dx != 0) { 731 ViewCompat.offsetLeftAndRight(mCapturedView, dx); 732 } 733 if (dy != 0) { 734 ViewCompat.offsetTopAndBottom(mCapturedView, dy); 735 } 736 737 if (dx != 0 || dy != 0) { 738 mCallback.onViewPositionChanged(mCapturedView, x, y, dx, dy); 739 } 740 741 if (keepGoing && x == mScroller.getFinalX() && y == mScroller.getFinalY()) { 742 // Close enough. The interpolator/scroller might think we're still moving 743 // but the user sure doesn't. 744 mScroller.abortAnimation(); 745 keepGoing = false; 746 } 747 748 if (!keepGoing) { 749 if (deferCallbacks) { 750 mParentView.post(mSetIdleRunnable); 751 } else { 752 setDragState(STATE_IDLE); 753 } 754 } 755 } 756 757 return mDragState == STATE_SETTLING; 758 } 759 760 /** 761 * Like all callback events this must happen on the UI thread, but release 762 * involves some extra semantics. During a release (mReleaseInProgress) 763 * is the only time it is valid to call {@link #settleCapturedViewAt(int, int)} 764 * or {@link #flingCapturedView(int, int, int, int)}. 765 */ 766 private void dispatchViewReleased(float xvel, float yvel) { 767 mReleaseInProgress = true; 768 mCallback.onViewReleased(mCapturedView, xvel, yvel); 769 mReleaseInProgress = false; 770 771 if (mDragState == STATE_DRAGGING) { 772 // onViewReleased didn't call a method that would have changed this. Go idle. 773 setDragState(STATE_IDLE); 774 } 775 } 776 777 private void clearMotionHistory() { 778 if (mInitialMotionX == null) { 779 return; 780 } 781 Arrays.fill(mInitialMotionX, 0); 782 Arrays.fill(mInitialMotionY, 0); 783 Arrays.fill(mLastMotionX, 0); 784 Arrays.fill(mLastMotionY, 0); 785 Arrays.fill(mInitialEdgesTouched, 0); 786 Arrays.fill(mEdgeDragsInProgress, 0); 787 Arrays.fill(mEdgeDragsLocked, 0); 788 mPointersDown = 0; 789 } 790 791 private void clearMotionHistory(int pointerId) { 792 if (mInitialMotionX == null || !isPointerDown(pointerId)) { 793 return; 794 } 795 mInitialMotionX[pointerId] = 0; 796 mInitialMotionY[pointerId] = 0; 797 mLastMotionX[pointerId] = 0; 798 mLastMotionY[pointerId] = 0; 799 mInitialEdgesTouched[pointerId] = 0; 800 mEdgeDragsInProgress[pointerId] = 0; 801 mEdgeDragsLocked[pointerId] = 0; 802 mPointersDown &= ~(1 << pointerId); 803 } 804 805 private void ensureMotionHistorySizeForId(int pointerId) { 806 if (mInitialMotionX == null || mInitialMotionX.length <= pointerId) { 807 float[] imx = new float[pointerId + 1]; 808 float[] imy = new float[pointerId + 1]; 809 float[] lmx = new float[pointerId + 1]; 810 float[] lmy = new float[pointerId + 1]; 811 int[] iit = new int[pointerId + 1]; 812 int[] edip = new int[pointerId + 1]; 813 int[] edl = new int[pointerId + 1]; 814 815 if (mInitialMotionX != null) { 816 System.arraycopy(mInitialMotionX, 0, imx, 0, mInitialMotionX.length); 817 System.arraycopy(mInitialMotionY, 0, imy, 0, mInitialMotionY.length); 818 System.arraycopy(mLastMotionX, 0, lmx, 0, mLastMotionX.length); 819 System.arraycopy(mLastMotionY, 0, lmy, 0, mLastMotionY.length); 820 System.arraycopy(mInitialEdgesTouched, 0, iit, 0, mInitialEdgesTouched.length); 821 System.arraycopy(mEdgeDragsInProgress, 0, edip, 0, mEdgeDragsInProgress.length); 822 System.arraycopy(mEdgeDragsLocked, 0, edl, 0, mEdgeDragsLocked.length); 823 } 824 825 mInitialMotionX = imx; 826 mInitialMotionY = imy; 827 mLastMotionX = lmx; 828 mLastMotionY = lmy; 829 mInitialEdgesTouched = iit; 830 mEdgeDragsInProgress = edip; 831 mEdgeDragsLocked = edl; 832 } 833 } 834 835 private void saveInitialMotion(float x, float y, int pointerId) { 836 ensureMotionHistorySizeForId(pointerId); 837 mInitialMotionX[pointerId] = mLastMotionX[pointerId] = x; 838 mInitialMotionY[pointerId] = mLastMotionY[pointerId] = y; 839 mInitialEdgesTouched[pointerId] = getEdgesTouched((int) x, (int) y); 840 mPointersDown |= 1 << pointerId; 841 } 842 843 private void saveLastMotion(MotionEvent ev) { 844 final int pointerCount = MotionEventCompat.getPointerCount(ev); 845 for (int i = 0; i < pointerCount; i++) { 846 final int pointerId = MotionEventCompat.getPointerId(ev, i); 847 // If pointer is invalid then skip saving on ACTION_MOVE. 848 if (!isValidPointerForActionMove(pointerId)) { 849 continue; 850 } 851 final float x = MotionEventCompat.getX(ev, i); 852 final float y = MotionEventCompat.getY(ev, i); 853 mLastMotionX[pointerId] = x; 854 mLastMotionY[pointerId] = y; 855 } 856 } 857 858 /** 859 * Check if the given pointer ID represents a pointer that is currently down (to the best 860 * of the ViewDragHelper's knowledge). 861 * 862 * <p>The state used to report this information is populated by the methods 863 * {@link #shouldInterceptTouchEvent(android.view.MotionEvent)} or 864 * {@link #processTouchEvent(android.view.MotionEvent)}. If one of these methods has not 865 * been called for all relevant MotionEvents to track, the information reported 866 * by this method may be stale or incorrect.</p> 867 * 868 * @param pointerId pointer ID to check; corresponds to IDs provided by MotionEvent 869 * @return true if the pointer with the given ID is still down 870 */ 871 public boolean isPointerDown(int pointerId) { 872 return (mPointersDown & 1 << pointerId) != 0; 873 } 874 875 void setDragState(int state) { 876 mParentView.removeCallbacks(mSetIdleRunnable); 877 if (mDragState != state) { 878 mDragState = state; 879 mCallback.onViewDragStateChanged(state); 880 if (mDragState == STATE_IDLE) { 881 mCapturedView = null; 882 } 883 } 884 } 885 886 /** 887 * Attempt to capture the view with the given pointer ID. The callback will be involved. 888 * This will put us into the "dragging" state. If we've already captured this view with 889 * this pointer this method will immediately return true without consulting the callback. 890 * 891 * @param toCapture View to capture 892 * @param pointerId Pointer to capture with 893 * @return true if capture was successful 894 */ 895 boolean tryCaptureViewForDrag(View toCapture, int pointerId) { 896 if (toCapture == mCapturedView && mActivePointerId == pointerId) { 897 // Already done! 898 return true; 899 } 900 if (toCapture != null && mCallback.tryCaptureView(toCapture, pointerId)) { 901 mActivePointerId = pointerId; 902 captureChildView(toCapture, pointerId); 903 return true; 904 } 905 return false; 906 } 907 908 /** 909 * Tests scrollability within child views of v given a delta of dx. 910 * 911 * @param v View to test for horizontal scrollability 912 * @param checkV Whether the view v passed should itself be checked for scrollability (true), 913 * or just its children (false). 914 * @param dx Delta scrolled in pixels along the X axis 915 * @param dy Delta scrolled in pixels along the Y axis 916 * @param x X coordinate of the active touch point 917 * @param y Y coordinate of the active touch point 918 * @return true if child views of v can be scrolled by delta of dx. 919 */ 920 protected boolean canScroll(View v, boolean checkV, int dx, int dy, int x, int y) { 921 if (v instanceof ViewGroup) { 922 final ViewGroup group = (ViewGroup) v; 923 final int scrollX = v.getScrollX(); 924 final int scrollY = v.getScrollY(); 925 final int count = group.getChildCount(); 926 // Count backwards - let topmost views consume scroll distance first. 927 for (int i = count - 1; i >= 0; i--) { 928 // TODO: Add versioned support here for transformed views. 929 // This will not work for transformed views in Honeycomb+ 930 final View child = group.getChildAt(i); 931 if (x + scrollX >= child.getLeft() && x + scrollX < child.getRight() && 932 y + scrollY >= child.getTop() && y + scrollY < child.getBottom() && 933 canScroll(child, true, dx, dy, x + scrollX - child.getLeft(), 934 y + scrollY - child.getTop())) { 935 return true; 936 } 937 } 938 } 939 940 return checkV && (ViewCompat.canScrollHorizontally(v, -dx) || 941 ViewCompat.canScrollVertically(v, -dy)); 942 } 943 944 /** 945 * Check if this event as provided to the parent view's onInterceptTouchEvent should 946 * cause the parent to intercept the touch event stream. 947 * 948 * @param ev MotionEvent provided to onInterceptTouchEvent 949 * @return true if the parent view should return true from onInterceptTouchEvent 950 */ 951 public boolean shouldInterceptTouchEvent(MotionEvent ev) { 952 final int action = MotionEventCompat.getActionMasked(ev); 953 final int actionIndex = MotionEventCompat.getActionIndex(ev); 954 955 if (action == MotionEvent.ACTION_DOWN) { 956 // Reset things for a new event stream, just in case we didn't get 957 // the whole previous stream. 958 cancel(); 959 } 960 961 if (mVelocityTracker == null) { 962 mVelocityTracker = VelocityTracker.obtain(); 963 } 964 mVelocityTracker.addMovement(ev); 965 966 switch (action) { 967 case MotionEvent.ACTION_DOWN: { 968 final float x = ev.getX(); 969 final float y = ev.getY(); 970 final int pointerId = MotionEventCompat.getPointerId(ev, 0); 971 saveInitialMotion(x, y, pointerId); 972 973 final View toCapture = findTopChildUnder((int) x, (int) y); 974 975 // Catch a settling view if possible. 976 if (toCapture == mCapturedView && mDragState == STATE_SETTLING) { 977 tryCaptureViewForDrag(toCapture, pointerId); 978 } 979 980 final int edgesTouched = mInitialEdgesTouched[pointerId]; 981 if ((edgesTouched & mTrackingEdges) != 0) { 982 mCallback.onEdgeTouched(edgesTouched & mTrackingEdges, pointerId); 983 } 984 break; 985 } 986 987 case MotionEventCompat.ACTION_POINTER_DOWN: { 988 final int pointerId = MotionEventCompat.getPointerId(ev, actionIndex); 989 final float x = MotionEventCompat.getX(ev, actionIndex); 990 final float y = MotionEventCompat.getY(ev, actionIndex); 991 992 saveInitialMotion(x, y, pointerId); 993 994 // A ViewDragHelper can only manipulate one view at a time. 995 if (mDragState == STATE_IDLE) { 996 final int edgesTouched = mInitialEdgesTouched[pointerId]; 997 if ((edgesTouched & mTrackingEdges) != 0) { 998 mCallback.onEdgeTouched(edgesTouched & mTrackingEdges, pointerId); 999 } 1000 } else if (mDragState == STATE_SETTLING) { 1001 // Catch a settling view if possible. 1002 final View toCapture = findTopChildUnder((int) x, (int) y); 1003 if (toCapture == mCapturedView) { 1004 tryCaptureViewForDrag(toCapture, pointerId); 1005 } 1006 } 1007 break; 1008 } 1009 1010 case MotionEvent.ACTION_MOVE: { 1011 if (mInitialMotionX == null || mInitialMotionY == null) break; 1012 1013 // First to cross a touch slop over a draggable view wins. Also report edge drags. 1014 final int pointerCount = MotionEventCompat.getPointerCount(ev); 1015 for (int i = 0; i < pointerCount; i++) { 1016 final int pointerId = MotionEventCompat.getPointerId(ev, i); 1017 1018 // If pointer is invalid then skip the ACTION_MOVE. 1019 if (!isValidPointerForActionMove(pointerId)) continue; 1020 1021 final float x = MotionEventCompat.getX(ev, i); 1022 final float y = MotionEventCompat.getY(ev, i); 1023 final float dx = x - mInitialMotionX[pointerId]; 1024 final float dy = y - mInitialMotionY[pointerId]; 1025 1026 final View toCapture = findTopChildUnder((int) x, (int) y); 1027 final boolean pastSlop = toCapture != null && checkTouchSlop(toCapture, dx, dy); 1028 if (pastSlop) { 1029 // check the callback's 1030 // getView[Horizontal|Vertical]DragRange methods to know 1031 // if you can move at all along an axis, then see if it 1032 // would clamp to the same value. If you can't move at 1033 // all in every dimension with a nonzero range, bail. 1034 final int oldLeft = toCapture.getLeft(); 1035 final int targetLeft = oldLeft + (int) dx; 1036 final int newLeft = mCallback.clampViewPositionHorizontal(toCapture, 1037 targetLeft, (int) dx); 1038 final int oldTop = toCapture.getTop(); 1039 final int targetTop = oldTop + (int) dy; 1040 final int newTop = mCallback.clampViewPositionVertical(toCapture, targetTop, 1041 (int) dy); 1042 final int horizontalDragRange = mCallback.getViewHorizontalDragRange( 1043 toCapture); 1044 final int verticalDragRange = mCallback.getViewVerticalDragRange(toCapture); 1045 if ((horizontalDragRange == 0 || horizontalDragRange > 0 1046 && newLeft == oldLeft) && (verticalDragRange == 0 1047 || verticalDragRange > 0 && newTop == oldTop)) { 1048 break; 1049 } 1050 } 1051 reportNewEdgeDrags(dx, dy, pointerId); 1052 if (mDragState == STATE_DRAGGING) { 1053 // Callback might have started an edge drag 1054 break; 1055 } 1056 1057 if (pastSlop && tryCaptureViewForDrag(toCapture, pointerId)) { 1058 break; 1059 } 1060 } 1061 saveLastMotion(ev); 1062 break; 1063 } 1064 1065 case MotionEventCompat.ACTION_POINTER_UP: { 1066 final int pointerId = MotionEventCompat.getPointerId(ev, actionIndex); 1067 clearMotionHistory(pointerId); 1068 break; 1069 } 1070 1071 case MotionEvent.ACTION_UP: 1072 case MotionEvent.ACTION_CANCEL: { 1073 cancel(); 1074 break; 1075 } 1076 } 1077 1078 return mDragState == STATE_DRAGGING; 1079 } 1080 1081 /** 1082 * Process a touch event received by the parent view. This method will dispatch callback events 1083 * as needed before returning. The parent view's onTouchEvent implementation should call this. 1084 * 1085 * @param ev The touch event received by the parent view 1086 */ 1087 public void processTouchEvent(MotionEvent ev) { 1088 final int action = MotionEventCompat.getActionMasked(ev); 1089 final int actionIndex = MotionEventCompat.getActionIndex(ev); 1090 1091 if (action == MotionEvent.ACTION_DOWN) { 1092 // Reset things for a new event stream, just in case we didn't get 1093 // the whole previous stream. 1094 cancel(); 1095 } 1096 1097 if (mVelocityTracker == null) { 1098 mVelocityTracker = VelocityTracker.obtain(); 1099 } 1100 mVelocityTracker.addMovement(ev); 1101 1102 switch (action) { 1103 case MotionEvent.ACTION_DOWN: { 1104 final float x = ev.getX(); 1105 final float y = ev.getY(); 1106 final int pointerId = MotionEventCompat.getPointerId(ev, 0); 1107 final View toCapture = findTopChildUnder((int) x, (int) y); 1108 1109 saveInitialMotion(x, y, pointerId); 1110 1111 // Since the parent is already directly processing this touch event, 1112 // there is no reason to delay for a slop before dragging. 1113 // Start immediately if possible. 1114 tryCaptureViewForDrag(toCapture, pointerId); 1115 1116 final int edgesTouched = mInitialEdgesTouched[pointerId]; 1117 if ((edgesTouched & mTrackingEdges) != 0) { 1118 mCallback.onEdgeTouched(edgesTouched & mTrackingEdges, pointerId); 1119 } 1120 break; 1121 } 1122 1123 case MotionEventCompat.ACTION_POINTER_DOWN: { 1124 final int pointerId = MotionEventCompat.getPointerId(ev, actionIndex); 1125 final float x = MotionEventCompat.getX(ev, actionIndex); 1126 final float y = MotionEventCompat.getY(ev, actionIndex); 1127 1128 saveInitialMotion(x, y, pointerId); 1129 1130 // A ViewDragHelper can only manipulate one view at a time. 1131 if (mDragState == STATE_IDLE) { 1132 // If we're idle we can do anything! Treat it like a normal down event. 1133 1134 final View toCapture = findTopChildUnder((int) x, (int) y); 1135 tryCaptureViewForDrag(toCapture, pointerId); 1136 1137 final int edgesTouched = mInitialEdgesTouched[pointerId]; 1138 if ((edgesTouched & mTrackingEdges) != 0) { 1139 mCallback.onEdgeTouched(edgesTouched & mTrackingEdges, pointerId); 1140 } 1141 } else if (isCapturedViewUnder((int) x, (int) y)) { 1142 // We're still tracking a captured view. If the same view is under this 1143 // point, we'll swap to controlling it with this pointer instead. 1144 // (This will still work if we're "catching" a settling view.) 1145 1146 tryCaptureViewForDrag(mCapturedView, pointerId); 1147 } 1148 break; 1149 } 1150 1151 case MotionEvent.ACTION_MOVE: { 1152 if (mDragState == STATE_DRAGGING) { 1153 // If pointer is invalid then skip the ACTION_MOVE. 1154 if (!isValidPointerForActionMove(mActivePointerId)) break; 1155 1156 final int index = MotionEventCompat.findPointerIndex(ev, mActivePointerId); 1157 final float x = MotionEventCompat.getX(ev, index); 1158 final float y = MotionEventCompat.getY(ev, index); 1159 final int idx = (int) (x - mLastMotionX[mActivePointerId]); 1160 final int idy = (int) (y - mLastMotionY[mActivePointerId]); 1161 1162 dragTo(mCapturedView.getLeft() + idx, mCapturedView.getTop() + idy, idx, idy); 1163 1164 saveLastMotion(ev); 1165 } else { 1166 // Check to see if any pointer is now over a draggable view. 1167 final int pointerCount = MotionEventCompat.getPointerCount(ev); 1168 for (int i = 0; i < pointerCount; i++) { 1169 final int pointerId = MotionEventCompat.getPointerId(ev, i); 1170 1171 // If pointer is invalid then skip the ACTION_MOVE. 1172 if (!isValidPointerForActionMove(pointerId)) continue; 1173 1174 final float x = MotionEventCompat.getX(ev, i); 1175 final float y = MotionEventCompat.getY(ev, i); 1176 final float dx = x - mInitialMotionX[pointerId]; 1177 final float dy = y - mInitialMotionY[pointerId]; 1178 1179 reportNewEdgeDrags(dx, dy, pointerId); 1180 if (mDragState == STATE_DRAGGING) { 1181 // Callback might have started an edge drag. 1182 break; 1183 } 1184 1185 final View toCapture = findTopChildUnder((int) x, (int) y); 1186 if (checkTouchSlop(toCapture, dx, dy) && 1187 tryCaptureViewForDrag(toCapture, pointerId)) { 1188 break; 1189 } 1190 } 1191 saveLastMotion(ev); 1192 } 1193 break; 1194 } 1195 1196 case MotionEventCompat.ACTION_POINTER_UP: { 1197 final int pointerId = MotionEventCompat.getPointerId(ev, actionIndex); 1198 if (mDragState == STATE_DRAGGING && pointerId == mActivePointerId) { 1199 // Try to find another pointer that's still holding on to the captured view. 1200 int newActivePointer = INVALID_POINTER; 1201 final int pointerCount = MotionEventCompat.getPointerCount(ev); 1202 for (int i = 0; i < pointerCount; i++) { 1203 final int id = MotionEventCompat.getPointerId(ev, i); 1204 if (id == mActivePointerId) { 1205 // This one's going away, skip. 1206 continue; 1207 } 1208 1209 final float x = MotionEventCompat.getX(ev, i); 1210 final float y = MotionEventCompat.getY(ev, i); 1211 if (findTopChildUnder((int) x, (int) y) == mCapturedView && 1212 tryCaptureViewForDrag(mCapturedView, id)) { 1213 newActivePointer = mActivePointerId; 1214 break; 1215 } 1216 } 1217 1218 if (newActivePointer == INVALID_POINTER) { 1219 // We didn't find another pointer still touching the view, release it. 1220 releaseViewForPointerUp(); 1221 } 1222 } 1223 clearMotionHistory(pointerId); 1224 break; 1225 } 1226 1227 case MotionEvent.ACTION_UP: { 1228 if (mDragState == STATE_DRAGGING) { 1229 releaseViewForPointerUp(); 1230 } 1231 cancel(); 1232 break; 1233 } 1234 1235 case MotionEvent.ACTION_CANCEL: { 1236 if (mDragState == STATE_DRAGGING) { 1237 dispatchViewReleased(0, 0); 1238 } 1239 cancel(); 1240 break; 1241 } 1242 } 1243 } 1244 1245 private void reportNewEdgeDrags(float dx, float dy, int pointerId) { 1246 int dragsStarted = 0; 1247 if (checkNewEdgeDrag(dx, dy, pointerId, EDGE_LEFT)) { 1248 dragsStarted |= EDGE_LEFT; 1249 } 1250 if (checkNewEdgeDrag(dy, dx, pointerId, EDGE_TOP)) { 1251 dragsStarted |= EDGE_TOP; 1252 } 1253 if (checkNewEdgeDrag(dx, dy, pointerId, EDGE_RIGHT)) { 1254 dragsStarted |= EDGE_RIGHT; 1255 } 1256 if (checkNewEdgeDrag(dy, dx, pointerId, EDGE_BOTTOM)) { 1257 dragsStarted |= EDGE_BOTTOM; 1258 } 1259 1260 if (dragsStarted != 0) { 1261 mEdgeDragsInProgress[pointerId] |= dragsStarted; 1262 mCallback.onEdgeDragStarted(dragsStarted, pointerId); 1263 } 1264 } 1265 1266 private boolean checkNewEdgeDrag(float delta, float odelta, int pointerId, int edge) { 1267 final float absDelta = Math.abs(delta); 1268 final float absODelta = Math.abs(odelta); 1269 1270 if ((mInitialEdgesTouched[pointerId] & edge) != edge || (mTrackingEdges & edge) == 0 || 1271 (mEdgeDragsLocked[pointerId] & edge) == edge || 1272 (mEdgeDragsInProgress[pointerId] & edge) == edge || 1273 (absDelta <= mTouchSlop && absODelta <= mTouchSlop)) { 1274 return false; 1275 } 1276 if (absDelta < absODelta * 0.5f && mCallback.onEdgeLock(edge)) { 1277 mEdgeDragsLocked[pointerId] |= edge; 1278 return false; 1279 } 1280 return (mEdgeDragsInProgress[pointerId] & edge) == 0 && absDelta > mTouchSlop; 1281 } 1282 1283 /** 1284 * Check if we've crossed a reasonable touch slop for the given child view. 1285 * If the child cannot be dragged along the horizontal or vertical axis, motion 1286 * along that axis will not count toward the slop check. 1287 * 1288 * @param child Child to check 1289 * @param dx Motion since initial position along X axis 1290 * @param dy Motion since initial position along Y axis 1291 * @return true if the touch slop has been crossed 1292 */ 1293 private boolean checkTouchSlop(View child, float dx, float dy) { 1294 if (child == null) { 1295 return false; 1296 } 1297 final boolean checkHorizontal = mCallback.getViewHorizontalDragRange(child) > 0; 1298 final boolean checkVertical = mCallback.getViewVerticalDragRange(child) > 0; 1299 1300 if (checkHorizontal && checkVertical) { 1301 return dx * dx + dy * dy > mTouchSlop * mTouchSlop; 1302 } else if (checkHorizontal) { 1303 return Math.abs(dx) > mTouchSlop; 1304 } else if (checkVertical) { 1305 return Math.abs(dy) > mTouchSlop; 1306 } 1307 return false; 1308 } 1309 1310 /** 1311 * Check if any pointer tracked in the current gesture has crossed 1312 * the required slop threshold. 1313 * 1314 * <p>This depends on internal state populated by 1315 * {@link #shouldInterceptTouchEvent(android.view.MotionEvent)} or 1316 * {@link #processTouchEvent(android.view.MotionEvent)}. You should only rely on 1317 * the results of this method after all currently available touch data 1318 * has been provided to one of these two methods.</p> 1319 * 1320 * @param directions Combination of direction flags, see {@link #DIRECTION_HORIZONTAL}, 1321 * {@link #DIRECTION_VERTICAL}, {@link #DIRECTION_ALL} 1322 * @return true if the slop threshold has been crossed, false otherwise 1323 */ 1324 public boolean checkTouchSlop(int directions) { 1325 final int count = mInitialMotionX.length; 1326 for (int i = 0; i < count; i++) { 1327 if (checkTouchSlop(directions, i)) { 1328 return true; 1329 } 1330 } 1331 return false; 1332 } 1333 1334 /** 1335 * Check if the specified pointer tracked in the current gesture has crossed 1336 * the required slop threshold. 1337 * 1338 * <p>This depends on internal state populated by 1339 * {@link #shouldInterceptTouchEvent(android.view.MotionEvent)} or 1340 * {@link #processTouchEvent(android.view.MotionEvent)}. You should only rely on 1341 * the results of this method after all currently available touch data 1342 * has been provided to one of these two methods.</p> 1343 * 1344 * @param directions Combination of direction flags, see {@link #DIRECTION_HORIZONTAL}, 1345 * {@link #DIRECTION_VERTICAL}, {@link #DIRECTION_ALL} 1346 * @param pointerId ID of the pointer to slop check as specified by MotionEvent 1347 * @return true if the slop threshold has been crossed, false otherwise 1348 */ 1349 public boolean checkTouchSlop(int directions, int pointerId) { 1350 if (!isPointerDown(pointerId)) { 1351 return false; 1352 } 1353 1354 final boolean checkHorizontal = (directions & DIRECTION_HORIZONTAL) == DIRECTION_HORIZONTAL; 1355 final boolean checkVertical = (directions & DIRECTION_VERTICAL) == DIRECTION_VERTICAL; 1356 1357 final float dx = mLastMotionX[pointerId] - mInitialMotionX[pointerId]; 1358 final float dy = mLastMotionY[pointerId] - mInitialMotionY[pointerId]; 1359 1360 if (checkHorizontal && checkVertical) { 1361 return dx * dx + dy * dy > mTouchSlop * mTouchSlop; 1362 } else if (checkHorizontal) { 1363 return Math.abs(dx) > mTouchSlop; 1364 } else if (checkVertical) { 1365 return Math.abs(dy) > mTouchSlop; 1366 } 1367 return false; 1368 } 1369 1370 /** 1371 * Check if any of the edges specified were initially touched in the currently active gesture. 1372 * If there is no currently active gesture this method will return false. 1373 * 1374 * @param edges Edges to check for an initial edge touch. See {@link #EDGE_LEFT}, 1375 * {@link #EDGE_TOP}, {@link #EDGE_RIGHT}, {@link #EDGE_BOTTOM} and 1376 * {@link #EDGE_ALL} 1377 * @return true if any of the edges specified were initially touched in the current gesture 1378 */ 1379 public boolean isEdgeTouched(int edges) { 1380 final int count = mInitialEdgesTouched.length; 1381 for (int i = 0; i < count; i++) { 1382 if (isEdgeTouched(edges, i)) { 1383 return true; 1384 } 1385 } 1386 return false; 1387 } 1388 1389 /** 1390 * Check if any of the edges specified were initially touched by the pointer with 1391 * the specified ID. If there is no currently active gesture or if there is no pointer with 1392 * the given ID currently down this method will return false. 1393 * 1394 * @param edges Edges to check for an initial edge touch. See {@link #EDGE_LEFT}, 1395 * {@link #EDGE_TOP}, {@link #EDGE_RIGHT}, {@link #EDGE_BOTTOM} and 1396 * {@link #EDGE_ALL} 1397 * @return true if any of the edges specified were initially touched in the current gesture 1398 */ 1399 public boolean isEdgeTouched(int edges, int pointerId) { 1400 return isPointerDown(pointerId) && (mInitialEdgesTouched[pointerId] & edges) != 0; 1401 } 1402 1403 private void releaseViewForPointerUp() { 1404 mVelocityTracker.computeCurrentVelocity(1000, mMaxVelocity); 1405 final float xvel = clampMag( 1406 VelocityTrackerCompat.getXVelocity(mVelocityTracker, mActivePointerId), 1407 mMinVelocity, mMaxVelocity); 1408 final float yvel = clampMag( 1409 VelocityTrackerCompat.getYVelocity(mVelocityTracker, mActivePointerId), 1410 mMinVelocity, mMaxVelocity); 1411 dispatchViewReleased(xvel, yvel); 1412 } 1413 1414 private void dragTo(int left, int top, int dx, int dy) { 1415 int clampedX = left; 1416 int clampedY = top; 1417 final int oldLeft = mCapturedView.getLeft(); 1418 final int oldTop = mCapturedView.getTop(); 1419 if (dx != 0) { 1420 clampedX = mCallback.clampViewPositionHorizontal(mCapturedView, left, dx); 1421 ViewCompat.offsetLeftAndRight(mCapturedView, clampedX - oldLeft); 1422 } 1423 if (dy != 0) { 1424 clampedY = mCallback.clampViewPositionVertical(mCapturedView, top, dy); 1425 ViewCompat.offsetTopAndBottom(mCapturedView, clampedY - oldTop); 1426 } 1427 1428 if (dx != 0 || dy != 0) { 1429 final int clampedDx = clampedX - oldLeft; 1430 final int clampedDy = clampedY - oldTop; 1431 mCallback.onViewPositionChanged(mCapturedView, clampedX, clampedY, 1432 clampedDx, clampedDy); 1433 } 1434 } 1435 1436 /** 1437 * Determine if the currently captured view is under the given point in the 1438 * parent view's coordinate system. If there is no captured view this method 1439 * will return false. 1440 * 1441 * @param x X position to test in the parent's coordinate system 1442 * @param y Y position to test in the parent's coordinate system 1443 * @return true if the captured view is under the given point, false otherwise 1444 */ 1445 public boolean isCapturedViewUnder(int x, int y) { 1446 return isViewUnder(mCapturedView, x, y); 1447 } 1448 1449 /** 1450 * Determine if the supplied view is under the given point in the 1451 * parent view's coordinate system. 1452 * 1453 * @param view Child view of the parent to hit test 1454 * @param x X position to test in the parent's coordinate system 1455 * @param y Y position to test in the parent's coordinate system 1456 * @return true if the supplied view is under the given point, false otherwise 1457 */ 1458 public boolean isViewUnder(View view, int x, int y) { 1459 if (view == null) { 1460 return false; 1461 } 1462 return x >= view.getLeft() && 1463 x < view.getRight() && 1464 y >= view.getTop() && 1465 y < view.getBottom(); 1466 } 1467 1468 /** 1469 * Find the topmost child under the given point within the parent view's coordinate system. 1470 * The child order is determined using {@link Callback#getOrderedChildIndex(int)}. 1471 * 1472 * @param x X position to test in the parent's coordinate system 1473 * @param y Y position to test in the parent's coordinate system 1474 * @return The topmost child view under (x, y) or null if none found. 1475 */ 1476 public View findTopChildUnder(int x, int y) { 1477 final int childCount = mParentView.getChildCount(); 1478 for (int i = childCount - 1; i >= 0; i--) { 1479 final View child = mParentView.getChildAt(mCallback.getOrderedChildIndex(i)); 1480 if (x >= child.getLeft() && x < child.getRight() && 1481 y >= child.getTop() && y < child.getBottom()) { 1482 return child; 1483 } 1484 } 1485 return null; 1486 } 1487 1488 private int getEdgesTouched(int x, int y) { 1489 int result = 0; 1490 1491 if (x < mParentView.getLeft() + mEdgeSize) result |= EDGE_LEFT; 1492 if (y < mParentView.getTop() + mEdgeSize) result |= EDGE_TOP; 1493 if (x > mParentView.getRight() - mEdgeSize) result |= EDGE_RIGHT; 1494 if (y > mParentView.getBottom() - mEdgeSize) result |= EDGE_BOTTOM; 1495 1496 return result; 1497 } 1498 1499 private boolean isValidPointerForActionMove(int pointerId) { 1500 if (!isPointerDown(pointerId)) { 1501 Log.e(TAG, "Ignoring pointerId=" + pointerId + " because ACTION_DOWN was not received " 1502 + "for this pointer before ACTION_MOVE. It likely happened because " 1503 + " ViewDragHelper did not receive all the events in the event stream."); 1504 return false; 1505 } 1506 return true; 1507 } 1508}