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 18 package com.android.dialer.widget; 19 20 import android.content.Context; 21 import android.support.v4.view.MotionEventCompat; 22 import android.support.v4.view.VelocityTrackerCompat; 23 import android.support.v4.view.ViewCompat; 24 import android.util.Log; 25 import android.view.MotionEvent; 26 import android.view.VelocityTracker; 27 import android.view.View; 28 import android.view.ViewConfiguration; 29 import android.view.ViewGroup; 30 import android.widget.Scroller; 31 32 import 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 */ 39 public 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 // We need to use a Scroller instead of an OverScroller (b/17700698) and as a result, we need 134 // to keep track of the final scroll position ourselves in mFinalScrollY (b/17704016) whenever 135 // we programmatically scroll or fling mScroller. 136 private Scroller mScroller; 137 private int mFinalScrollY; 138 139 private final Callback mCallback; 140 141 private View mCapturedView; 142 private boolean mReleaseInProgress; 143 144 private final ViewGroup mParentView; 145 146 /** 147 * A Callback is used as a communication channel with the ViewDragHelper back to the 148 * parent view using it. <code>on*</code>methods are invoked on siginficant events and several 149 * accessor methods are expected to provide the ViewDragHelper with more information 150 * about the state of the parent view upon request. The callback also makes decisions 151 * governing the range and draggability of child views. 152 */ 153 public static abstract class Callback { 154 /** 155 * Called when the drag state changes. See the <code>STATE_*</code> constants 156 * for more information. 157 * 158 * @param state The new drag state 159 * 160 * @see #STATE_IDLE 161 * @see #STATE_DRAGGING 162 * @see #STATE_SETTLING 163 */ onViewDragStateChanged(int state)164 public void onViewDragStateChanged(int state) {} 165 166 /** 167 * Called when the captured view's position changes as the result of a drag or settle. 168 * 169 * @param changedView View whose position changed 170 * @param left New X coordinate of the left edge of the view 171 * @param top New Y coordinate of the top edge of the view 172 * @param dx Change in X position from the last call 173 * @param dy Change in Y position from the last call 174 */ onViewPositionChanged(View changedView, int left, int top, int dx, int dy)175 public void onViewPositionChanged(View changedView, int left, int top, int dx, int dy) {} 176 177 /** 178 * Called when a child view is captured for dragging or settling. The ID of the pointer 179 * currently dragging the captured view is supplied. If activePointerId is 180 * identified as {@link #INVALID_POINTER} the capture is programmatic instead of 181 * pointer-initiated. 182 * 183 * @param capturedChild Child view that was captured 184 * @param activePointerId Pointer id tracking the child capture 185 */ onViewCaptured(View capturedChild, int activePointerId)186 public void onViewCaptured(View capturedChild, int activePointerId) {} 187 188 /** 189 * Called when the child view is no longer being actively dragged. 190 * The fling velocity is also supplied, if relevant. The velocity values may 191 * be clamped to system minimums or maximums. 192 * 193 * <p>Calling code may decide to fling or otherwise release the view to let it 194 * settle into place. It should do so using {@link #settleCapturedViewAt(int, int)} 195 * or {@link #flingCapturedView(int, int, int, int)}. If the Callback invokes 196 * one of these methods, the ViewDragHelper will enter {@link #STATE_SETTLING} 197 * and the view capture will not fully end until it comes to a complete stop. 198 * If neither of these methods is invoked before <code>onViewReleased</code> returns, 199 * the view will stop in place and the ViewDragHelper will return to 200 * {@link #STATE_IDLE}.</p> 201 * 202 * @param releasedChild The captured child view now being released 203 * @param xvel X velocity of the pointer as it left the screen in pixels per second. 204 * @param yvel Y velocity of the pointer as it left the screen in pixels per second. 205 */ onViewReleased(View releasedChild, float xvel, float yvel)206 public void onViewReleased(View releasedChild, float xvel, float yvel) {} 207 208 /** 209 * Called when the child view has been released with a fling. 210 * 211 * <p>Calling code may decide to fling or otherwise release the view to let it 212 * settle into place.</p> 213 * 214 * @param releasedChild The captured child view now being released 215 * @param xvel X velocity of the fling. 216 * @param yvel Y velocity of the fling. 217 */ onViewFling(View releasedChild, float xvel, float yvel)218 public void onViewFling(View releasedChild, float xvel, float yvel) {} 219 220 /** 221 * Called when one of the subscribed edges in the parent view has been touched 222 * by the user while no child view is currently captured. 223 * 224 * @param edgeFlags A combination of edge flags describing the edge(s) currently touched 225 * @param pointerId ID of the pointer touching the described edge(s) 226 * @see #EDGE_LEFT 227 * @see #EDGE_TOP 228 * @see #EDGE_RIGHT 229 * @see #EDGE_BOTTOM 230 */ onEdgeTouched(int edgeFlags, int pointerId)231 public void onEdgeTouched(int edgeFlags, int pointerId) {} 232 233 /** 234 * Called when the given edge may become locked. This can happen if an edge drag 235 * was preliminarily rejected before beginning, but after {@link #onEdgeTouched(int, int)} 236 * was called. This method should return true to lock this edge or false to leave it 237 * unlocked. The default behavior is to leave edges unlocked. 238 * 239 * @param edgeFlags A combination of edge flags describing the edge(s) locked 240 * @return true to lock the edge, false to leave it unlocked 241 */ onEdgeLock(int edgeFlags)242 public boolean onEdgeLock(int edgeFlags) { 243 return false; 244 } 245 246 /** 247 * Called when the user has started a deliberate drag away from one 248 * of the subscribed edges in the parent view while no child view is currently captured. 249 * 250 * @param edgeFlags A combination of edge flags describing the edge(s) dragged 251 * @param pointerId ID of the pointer touching the described edge(s) 252 * @see #EDGE_LEFT 253 * @see #EDGE_TOP 254 * @see #EDGE_RIGHT 255 * @see #EDGE_BOTTOM 256 */ onEdgeDragStarted(int edgeFlags, int pointerId)257 public void onEdgeDragStarted(int edgeFlags, int pointerId) {} 258 259 /** 260 * Called to determine the Z-order of child views. 261 * 262 * @param index the ordered position to query for 263 * @return index of the view that should be ordered at position <code>index</code> 264 */ getOrderedChildIndex(int index)265 public int getOrderedChildIndex(int index) { 266 return index; 267 } 268 269 /** 270 * Return the magnitude of a draggable child view's horizontal range of motion in pixels. 271 * This method should return 0 for views that cannot move horizontally. 272 * 273 * @param child Child view to check 274 * @return range of horizontal motion in pixels 275 */ getViewHorizontalDragRange(View child)276 public int getViewHorizontalDragRange(View child) { 277 return 0; 278 } 279 280 /** 281 * Return the magnitude of a draggable child view's vertical range of motion in pixels. 282 * This method should return 0 for views that cannot move vertically. 283 * 284 * @param child Child view to check 285 * @return range of vertical motion in pixels 286 */ getViewVerticalDragRange(View child)287 public int getViewVerticalDragRange(View child) { 288 return 0; 289 } 290 291 /** 292 * Called when the user's input indicates that they want to capture the given child view 293 * with the pointer indicated by pointerId. The callback should return true if the user 294 * is permitted to drag the given view with the indicated pointer. 295 * 296 * <p>ViewDragHelper may call this method multiple times for the same view even if 297 * the view is already captured; this indicates that a new pointer is trying to take 298 * control of the view.</p> 299 * 300 * <p>If this method returns true, a call to {@link #onViewCaptured(android.view.View, int)} 301 * will follow if the capture is successful.</p> 302 * 303 * @param child Child the user is attempting to capture 304 * @param pointerId ID of the pointer attempting the capture 305 * @return true if capture should be allowed, false otherwise 306 */ tryCaptureView(View child, int pointerId)307 public abstract boolean tryCaptureView(View child, int pointerId); 308 309 /** 310 * Restrict the motion of the dragged child view along the horizontal axis. 311 * The default implementation does not allow horizontal motion; the extending 312 * class must override this method and provide the desired clamping. 313 * 314 * 315 * @param child Child view being dragged 316 * @param left Attempted motion along the X axis 317 * @param dx Proposed change in position for left 318 * @return The new clamped position for left 319 */ clampViewPositionHorizontal(View child, int left, int dx)320 public int clampViewPositionHorizontal(View child, int left, int dx) { 321 return 0; 322 } 323 324 /** 325 * Restrict the motion of the dragged child view along the vertical axis. 326 * The default implementation does not allow vertical motion; the extending 327 * class must override this method and provide the desired clamping. 328 * 329 * 330 * @param child Child view being dragged 331 * @param top Attempted motion along the Y axis 332 * @param dy Proposed change in position for top 333 * @return The new clamped position for top 334 */ clampViewPositionVertical(View child, int top, int dy)335 public int clampViewPositionVertical(View child, int top, int dy) { 336 return 0; 337 } 338 } 339 340 private final Runnable mSetIdleRunnable = new Runnable() { 341 public void run() { 342 setDragState(STATE_IDLE); 343 } 344 }; 345 346 /** 347 * Factory method to create a new ViewDragHelper. 348 * 349 * @param forParent Parent view to monitor 350 * @param cb Callback to provide information and receive events 351 * @return a new ViewDragHelper instance 352 */ create(ViewGroup forParent, Callback cb)353 public static ViewDragHelper create(ViewGroup forParent, Callback cb) { 354 return new ViewDragHelper(forParent.getContext(), forParent, cb); 355 } 356 357 /** 358 * Factory method to create a new ViewDragHelper. 359 * 360 * @param forParent Parent view to monitor 361 * @param sensitivity Multiplier for how sensitive the helper should be about detecting 362 * the start of a drag. Larger values are more sensitive. 1.0f is normal. 363 * @param cb Callback to provide information and receive events 364 * @return a new ViewDragHelper instance 365 */ create(ViewGroup forParent, float sensitivity, Callback cb)366 public static ViewDragHelper create(ViewGroup forParent, float sensitivity, Callback cb) { 367 final ViewDragHelper helper = create(forParent, cb); 368 helper.mTouchSlop = (int) (helper.mTouchSlop * (1 / sensitivity)); 369 return helper; 370 } 371 372 /** 373 * Apps should use ViewDragHelper.create() to get a new instance. 374 * This will allow VDH to use internal compatibility implementations for different 375 * platform versions. 376 * 377 * @param context Context to initialize config-dependent params from 378 * @param forParent Parent view to monitor 379 */ ViewDragHelper(Context context, ViewGroup forParent, Callback cb)380 private ViewDragHelper(Context context, ViewGroup forParent, Callback cb) { 381 if (forParent == null) { 382 throw new IllegalArgumentException("Parent view may not be null"); 383 } 384 if (cb == null) { 385 throw new IllegalArgumentException("Callback may not be null"); 386 } 387 388 mParentView = forParent; 389 mCallback = cb; 390 391 final ViewConfiguration vc = ViewConfiguration.get(context); 392 final float density = context.getResources().getDisplayMetrics().density; 393 mEdgeSize = (int) (EDGE_SIZE * density + 0.5f); 394 395 mTouchSlop = vc.getScaledTouchSlop(); 396 mMaxVelocity = vc.getScaledMaximumFlingVelocity(); 397 mMinVelocity = vc.getScaledMinimumFlingVelocity(); 398 mScroller = new Scroller(context); 399 } 400 401 /** 402 * Set the minimum velocity that will be detected as having a magnitude greater than zero 403 * in pixels per second. Callback methods accepting a velocity will be clamped appropriately. 404 * 405 * @param minVel Minimum velocity to detect 406 */ setMinVelocity(float minVel)407 public void setMinVelocity(float minVel) { 408 mMinVelocity = minVel; 409 } 410 411 /** 412 * Return the currently configured minimum velocity. Any flings with a magnitude less 413 * than this value in pixels per second. Callback methods accepting a velocity will receive 414 * zero as a velocity value if the real detected velocity was below this threshold. 415 * 416 * @return the minimum velocity that will be detected 417 */ getMinVelocity()418 public float getMinVelocity() { 419 return mMinVelocity; 420 } 421 422 /** 423 * Retrieve the current drag state of this helper. This will return one of 424 * {@link #STATE_IDLE}, {@link #STATE_DRAGGING} or {@link #STATE_SETTLING}. 425 * @return The current drag state 426 */ getViewDragState()427 public int getViewDragState() { 428 return mDragState; 429 } 430 431 /** 432 * Enable edge tracking for the selected edges of the parent view. 433 * The callback's {@link Callback#onEdgeTouched(int, int)} and 434 * {@link Callback#onEdgeDragStarted(int, int)} methods will only be invoked 435 * for edges for which edge tracking has been enabled. 436 * 437 * @param edgeFlags Combination of edge flags describing the edges to watch 438 * @see #EDGE_LEFT 439 * @see #EDGE_TOP 440 * @see #EDGE_RIGHT 441 * @see #EDGE_BOTTOM 442 */ setEdgeTrackingEnabled(int edgeFlags)443 public void setEdgeTrackingEnabled(int edgeFlags) { 444 mTrackingEdges = edgeFlags; 445 } 446 447 /** 448 * Return the size of an edge. This is the range in pixels along the edges of this view 449 * that will actively detect edge touches or drags if edge tracking is enabled. 450 * 451 * @return The size of an edge in pixels 452 * @see #setEdgeTrackingEnabled(int) 453 */ getEdgeSize()454 public int getEdgeSize() { 455 return mEdgeSize; 456 } 457 458 /** 459 * Capture a specific child view for dragging within the parent. The callback will be notified 460 * but {@link Callback#tryCaptureView(android.view.View, int)} will not be asked permission to 461 * capture this view. 462 * 463 * @param childView Child view to capture 464 * @param activePointerId ID of the pointer that is dragging the captured child view 465 */ captureChildView(View childView, int activePointerId)466 public void captureChildView(View childView, int activePointerId) { 467 if (childView.getParent() != mParentView) { 468 throw new IllegalArgumentException("captureChildView: parameter must be a descendant " + 469 "of the ViewDragHelper's tracked parent view (" + mParentView + ")"); 470 } 471 472 mCapturedView = childView; 473 mActivePointerId = activePointerId; 474 mCallback.onViewCaptured(childView, activePointerId); 475 setDragState(STATE_DRAGGING); 476 } 477 478 /** 479 * @return The currently captured view, or null if no view has been captured. 480 */ getCapturedView()481 public View getCapturedView() { 482 return mCapturedView; 483 } 484 485 /** 486 * @return The ID of the pointer currently dragging the captured view, 487 * or {@link #INVALID_POINTER}. 488 */ getActivePointerId()489 public int getActivePointerId() { 490 return mActivePointerId; 491 } 492 493 /** 494 * @return The minimum distance in pixels that the user must travel to initiate a drag 495 */ getTouchSlop()496 public int getTouchSlop() { 497 return mTouchSlop; 498 } 499 500 /** 501 * The result of a call to this method is equivalent to 502 * {@link #processTouchEvent(android.view.MotionEvent)} receiving an ACTION_CANCEL event. 503 */ cancel()504 public void cancel() { 505 mActivePointerId = INVALID_POINTER; 506 clearMotionHistory(); 507 508 if (mVelocityTracker != null) { 509 mVelocityTracker.recycle(); 510 mVelocityTracker = null; 511 } 512 } 513 514 /** 515 * {@link #cancel()}, but also abort all motion in progress and snap to the end of any 516 * animation. 517 */ abort()518 public void abort() { 519 cancel(); 520 if (mDragState == STATE_SETTLING) { 521 final int oldX = mScroller.getCurrX(); 522 final int oldY = mScroller.getCurrY(); 523 mScroller.abortAnimation(); 524 final int newX = mScroller.getCurrX(); 525 final int newY = mScroller.getCurrY(); 526 mCallback.onViewPositionChanged(mCapturedView, newX, newY, newX - oldX, newY - oldY); 527 } 528 setDragState(STATE_IDLE); 529 } 530 531 /** 532 * Animate the view <code>child</code> to the given (left, top) position. 533 * If this method returns true, the caller should invoke {@link #continueSettling(boolean)} 534 * on each subsequent frame to continue the motion until it returns false. If this method 535 * returns false there is no further work to do to complete the movement. 536 * 537 * <p>This operation does not count as a capture event, though {@link #getCapturedView()} 538 * will still report the sliding view while the slide is in progress.</p> 539 * 540 * @param child Child view to capture and animate 541 * @param finalLeft Final left position of child 542 * @param finalTop Final top position of child 543 * @return true if animation should continue through {@link #continueSettling(boolean)} calls 544 */ smoothSlideViewTo(View child, int finalLeft, int finalTop)545 public boolean smoothSlideViewTo(View child, int finalLeft, int finalTop) { 546 mCapturedView = child; 547 mActivePointerId = INVALID_POINTER; 548 549 return forceSettleCapturedViewAt(finalLeft, finalTop, 0, 0); 550 } 551 552 /** 553 * Settle the captured view at the given (left, top) position. 554 * The appropriate velocity from prior motion will be taken into account. 555 * If this method returns true, the caller should invoke {@link #continueSettling(boolean)} 556 * on each subsequent frame to continue the motion until it returns false. If this method 557 * returns false there is no further work to do to complete the movement. 558 * 559 * @param finalLeft Settled left edge position for the captured view 560 * @param finalTop Settled top edge position for the captured view 561 * @return true if animation should continue through {@link #continueSettling(boolean)} calls 562 */ settleCapturedViewAt(int finalLeft, int finalTop)563 public boolean settleCapturedViewAt(int finalLeft, int finalTop) { 564 if (!mReleaseInProgress) { 565 throw new IllegalStateException("Cannot settleCapturedViewAt outside of a call to " + 566 "Callback#onViewReleased"); 567 } 568 569 return forceSettleCapturedViewAt(finalLeft, finalTop, 570 (int) VelocityTrackerCompat.getXVelocity(mVelocityTracker, mActivePointerId), 571 (int) VelocityTrackerCompat.getYVelocity(mVelocityTracker, mActivePointerId)); 572 } 573 574 /** 575 * Settle the captured view at the given (left, top) position. 576 * 577 * @param finalLeft Target left position for the captured view 578 * @param finalTop Target top position for the captured view 579 * @param xvel Horizontal velocity 580 * @param yvel Vertical velocity 581 * @return true if animation should continue through {@link #continueSettling(boolean)} calls 582 */ forceSettleCapturedViewAt(int finalLeft, int finalTop, int xvel, int yvel)583 private boolean forceSettleCapturedViewAt(int finalLeft, int finalTop, int xvel, int yvel) { 584 final int startLeft = mCapturedView.getLeft(); 585 final int startTop = mCapturedView.getTop(); 586 final int dx = finalLeft - startLeft; 587 final int dy = finalTop - startTop; 588 589 if (dx == 0 && dy == 0) { 590 // Nothing to do. Send callbacks, be done. 591 mScroller.abortAnimation(); 592 setDragState(STATE_IDLE); 593 return false; 594 } 595 596 final int duration = computeSettleDuration(mCapturedView, dx, dy, xvel, yvel); 597 mScroller.startScroll(startLeft, startTop, dx, dy, duration); 598 mFinalScrollY = startTop + dy; 599 600 setDragState(STATE_SETTLING); 601 return true; 602 } 603 computeSettleDuration(View child, int dx, int dy, int xvel, int yvel)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 computeAxisDuration(int delta, int velocity, int motionRange)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 */ clampMag(int value, int absMin, int absMax)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 */ clampMag(float value, float absMin, float absMax)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 distanceInfluenceForSnapDuration(float f)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 */ flingCapturedView(int minLeft, int minTop, int maxLeft, int maxTop)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 final int yVelocity = (int) VelocityTrackerCompat 704 .getYVelocity(mVelocityTracker, mActivePointerId); 705 mScroller.fling(mCapturedView.getLeft(), mCapturedView.getTop(), 706 (int) VelocityTrackerCompat.getXVelocity(mVelocityTracker, mActivePointerId), 707 yVelocity, minLeft, maxLeft, minTop, maxTop); 708 mFinalScrollY = yVelocity < 0 ? minTop : maxTop; 709 710 setDragState(STATE_SETTLING); 711 } 712 713 /** 714 * Settle the captured view based on standard free-moving fling behavior. 715 * The caller should invoke {@link #continueSettling(boolean)} on each subsequent frame 716 * to continue the motion until it returns false. 717 * 718 * @param minLeft Minimum X position for the view's left edge 719 * @param minTop Minimum Y position for the view's top edge 720 * @param maxLeft Maximum X position for the view's left edge 721 * @param maxTop Maximum Y position for the view's top edge 722 * @param yvel the Y velocity to fling with 723 */ 724 public void flingCapturedView(int minLeft, int minTop, int maxLeft, int maxTop, int yvel) { 725 if (!mReleaseInProgress) { 726 throw new IllegalStateException("Cannot flingCapturedView outside of a call to " + 727 "Callback#onViewReleased"); 728 } 729 mScroller.abortAnimation(); 730 mScroller.fling(mCapturedView.getLeft(), mCapturedView.getTop(), 0, yvel, 731 Integer.MIN_VALUE, Integer.MAX_VALUE, Integer.MIN_VALUE, Integer.MAX_VALUE); 732 mFinalScrollY = yvel < 0 ? minTop : maxTop; 733 734 setDragState(STATE_SETTLING); 735 } 736 737 /** 738 * Predict how far a fling with {@param yvel} will cause the view to travel from stand still. 739 * @return predicted y offset 740 */ 741 public int predictFlingYOffset(int yvel) { 742 mScroller.abortAnimation(); 743 mScroller.fling(0, 0, 0, yvel, Integer.MIN_VALUE, Integer.MAX_VALUE, Integer.MIN_VALUE, 744 Integer.MAX_VALUE); 745 final int finalY = mScroller.getFinalY(); 746 mScroller.abortAnimation(); 747 return finalY; 748 } 749 750 /** 751 * Move the captured settling view by the appropriate amount for the current time. 752 * If <code>continueSettling</code> returns true, the caller should call it again 753 * on the next frame to continue. 754 * 755 * @param deferCallbacks true if state callbacks should be deferred via posted message. 756 * Set this to true if you are calling this method from 757 * {@link android.view.View#computeScroll()} or similar methods 758 * invoked as part of layout or drawing. 759 * @return true if settle is still in progress 760 */ 761 public boolean continueSettling(boolean deferCallbacks) { 762 if (mDragState == STATE_SETTLING) { 763 boolean keepGoing = mScroller.computeScrollOffset(); 764 int y = mScroller.getCurrY(); 765 766 // Since Scroller's getFinalY() can't be properly set (b/17704016), we need to 767 // perform clamping of mScroller.getCurrY() here. 768 if (y - mCapturedView.getTop() > 0) { 769 y = Math.min(y, mFinalScrollY); 770 } else { 771 y = Math.max(y, mFinalScrollY); 772 } 773 final int dy = y - mCapturedView.getTop(); 774 775 if (dy != 0) { 776 mCapturedView.offsetTopAndBottom(dy); 777 mCallback.onViewPositionChanged(mCapturedView, 0, y, 0, dy); 778 } 779 780 if (keepGoing && y == mFinalScrollY) { 781 // Close enough. The interpolator/scroller might think we're still moving 782 // but the user sure doesn't. 783 mScroller.abortAnimation(); 784 keepGoing = mScroller.isFinished(); 785 } 786 787 if (!keepGoing) { 788 if (deferCallbacks) { 789 mParentView.post(mSetIdleRunnable); 790 } else { 791 setDragState(STATE_IDLE); 792 } 793 } 794 } 795 796 return mDragState == STATE_SETTLING; 797 } 798 799 public void processNestedFling(View target, int yvel) { 800 mCapturedView = target; 801 dispatchViewFling(0, yvel); 802 } 803 804 public int getVelocityMagnitude() { 805 // Use Math.abs() to ensure this always returns an absolute value, even if the 806 // ScrollerCompat implementation changes. 807 return (int) Math.abs(mScroller.getCurrVelocity()); 808 } 809 810 private void dispatchViewFling(float xvel, float yvel) { 811 mReleaseInProgress = true; 812 mCallback.onViewFling(mCapturedView, xvel, yvel); 813 mReleaseInProgress = false; 814 815 if (mDragState == STATE_DRAGGING) { 816 // onViewReleased didn't call a method that would have changed this. Go idle. 817 setDragState(STATE_IDLE); 818 } 819 } 820 821 /** 822 * Like all callback events this must happen on the UI thread, but release 823 * involves some extra semantics. During a release (mReleaseInProgress) 824 * is the only time it is valid to call {@link #settleCapturedViewAt(int, int)} 825 * or {@link #flingCapturedView(int, int, int, int)}. 826 */ 827 private void dispatchViewReleased(float xvel, float yvel) { 828 mReleaseInProgress = true; 829 mCallback.onViewReleased(mCapturedView, xvel, yvel); 830 mReleaseInProgress = false; 831 832 if (mDragState == STATE_DRAGGING) { 833 // onViewReleased didn't call a method that would have changed this. Go idle. 834 setDragState(STATE_IDLE); 835 } 836 } 837 838 private void clearMotionHistory() { 839 if (mInitialMotionX == null) { 840 return; 841 } 842 Arrays.fill(mInitialMotionX, 0); 843 Arrays.fill(mInitialMotionY, 0); 844 Arrays.fill(mLastMotionX, 0); 845 Arrays.fill(mLastMotionY, 0); 846 Arrays.fill(mInitialEdgesTouched, 0); 847 Arrays.fill(mEdgeDragsInProgress, 0); 848 Arrays.fill(mEdgeDragsLocked, 0); 849 mPointersDown = 0; 850 } 851 852 private void clearMotionHistory(int pointerId) { 853 if (mInitialMotionX == null) { 854 return; 855 } 856 mInitialMotionX[pointerId] = 0; 857 mInitialMotionY[pointerId] = 0; 858 mLastMotionX[pointerId] = 0; 859 mLastMotionY[pointerId] = 0; 860 mInitialEdgesTouched[pointerId] = 0; 861 mEdgeDragsInProgress[pointerId] = 0; 862 mEdgeDragsLocked[pointerId] = 0; 863 mPointersDown &= ~(1 << pointerId); 864 } 865 866 private void ensureMotionHistorySizeForId(int pointerId) { 867 if (mInitialMotionX == null || mInitialMotionX.length <= pointerId) { 868 float[] imx = new float[pointerId + 1]; 869 float[] imy = new float[pointerId + 1]; 870 float[] lmx = new float[pointerId + 1]; 871 float[] lmy = new float[pointerId + 1]; 872 int[] iit = new int[pointerId + 1]; 873 int[] edip = new int[pointerId + 1]; 874 int[] edl = new int[pointerId + 1]; 875 876 if (mInitialMotionX != null) { 877 System.arraycopy(mInitialMotionX, 0, imx, 0, mInitialMotionX.length); 878 System.arraycopy(mInitialMotionY, 0, imy, 0, mInitialMotionY.length); 879 System.arraycopy(mLastMotionX, 0, lmx, 0, mLastMotionX.length); 880 System.arraycopy(mLastMotionY, 0, lmy, 0, mLastMotionY.length); 881 System.arraycopy(mInitialEdgesTouched, 0, iit, 0, mInitialEdgesTouched.length); 882 System.arraycopy(mEdgeDragsInProgress, 0, edip, 0, mEdgeDragsInProgress.length); 883 System.arraycopy(mEdgeDragsLocked, 0, edl, 0, mEdgeDragsLocked.length); 884 } 885 886 mInitialMotionX = imx; 887 mInitialMotionY = imy; 888 mLastMotionX = lmx; 889 mLastMotionY = lmy; 890 mInitialEdgesTouched = iit; 891 mEdgeDragsInProgress = edip; 892 mEdgeDragsLocked = edl; 893 } 894 } 895 896 private void saveInitialMotion(float x, float y, int pointerId) { 897 ensureMotionHistorySizeForId(pointerId); 898 mInitialMotionX[pointerId] = mLastMotionX[pointerId] = x; 899 mInitialMotionY[pointerId] = mLastMotionY[pointerId] = y; 900 mInitialEdgesTouched[pointerId] = getEdgesTouched((int) x, (int) y); 901 mPointersDown |= 1 << pointerId; 902 } 903 904 private void saveLastMotion(MotionEvent ev) { 905 final int pointerCount = MotionEventCompat.getPointerCount(ev); 906 for (int i = 0; i < pointerCount; i++) { 907 final int pointerId = MotionEventCompat.getPointerId(ev, i); 908 final float x = MotionEventCompat.getX(ev, i); 909 final float y = MotionEventCompat.getY(ev, i); 910 mLastMotionX[pointerId] = x; 911 mLastMotionY[pointerId] = y; 912 } 913 } 914 915 /** 916 * Check if the given pointer ID represents a pointer that is currently down (to the best 917 * of the ViewDragHelper's knowledge). 918 * 919 * <p>The state used to report this information is populated by the methods 920 * {@link #shouldInterceptTouchEvent(android.view.MotionEvent)} or 921 * {@link #processTouchEvent(android.view.MotionEvent)}. If one of these methods has not 922 * been called for all relevant MotionEvents to track, the information reported 923 * by this method may be stale or incorrect.</p> 924 * 925 * @param pointerId pointer ID to check; corresponds to IDs provided by MotionEvent 926 * @return true if the pointer with the given ID is still down 927 */ 928 public boolean isPointerDown(int pointerId) { 929 return (mPointersDown & 1 << pointerId) != 0; 930 } 931 932 void setDragState(int state) { 933 if (mDragState != state) { 934 mDragState = state; 935 mCallback.onViewDragStateChanged(state); 936 if (state == STATE_IDLE) { 937 mCapturedView = null; 938 } 939 } 940 } 941 942 /** 943 * Attempt to capture the view with the given pointer ID. The callback will be involved. 944 * This will put us into the "dragging" state. If we've already captured this view with 945 * this pointer this method will immediately return true without consulting the callback. 946 * 947 * @param toCapture View to capture 948 * @param pointerId Pointer to capture with 949 * @return true if capture was successful 950 */ 951 boolean tryCaptureViewForDrag(View toCapture, int pointerId) { 952 if (toCapture == mCapturedView && mActivePointerId == pointerId) { 953 // Already done! 954 return true; 955 } 956 if (toCapture != null && mCallback.tryCaptureView(toCapture, pointerId)) { 957 mActivePointerId = pointerId; 958 captureChildView(toCapture, pointerId); 959 return true; 960 } 961 return false; 962 } 963 964 /** 965 * Tests scrollability within child views of v given a delta of dx. 966 * 967 * @param v View to test for horizontal scrollability 968 * @param checkV Whether the view v passed should itself be checked for scrollability (true), 969 * or just its children (false). 970 * @param dx Delta scrolled in pixels along the X axis 971 * @param dy Delta scrolled in pixels along the Y axis 972 * @param x X coordinate of the active touch point 973 * @param y Y coordinate of the active touch point 974 * @return true if child views of v can be scrolled by delta of dx. 975 */ 976 protected boolean canScroll(View v, boolean checkV, int dx, int dy, int x, int y) { 977 if (v instanceof ViewGroup) { 978 final ViewGroup group = (ViewGroup) v; 979 final int scrollX = v.getScrollX(); 980 final int scrollY = v.getScrollY(); 981 final int count = group.getChildCount(); 982 // Count backwards - let topmost views consume scroll distance first. 983 for (int i = count - 1; i >= 0; i--) { 984 // TODO: Add versioned support here for transformed views. 985 // This will not work for transformed views in Honeycomb+ 986 final View child = group.getChildAt(i); 987 if (x + scrollX >= child.getLeft() && x + scrollX < child.getRight() && 988 y + scrollY >= child.getTop() && y + scrollY < child.getBottom() && 989 canScroll(child, true, dx, dy, x + scrollX - child.getLeft(), 990 y + scrollY - child.getTop())) { 991 return true; 992 } 993 } 994 } 995 996 return checkV && (ViewCompat.canScrollHorizontally(v, -dx) || 997 ViewCompat.canScrollVertically(v, -dy)); 998 } 999 1000 /** 1001 * Check if this event as provided to the parent view's onInterceptTouchEvent should 1002 * cause the parent to intercept the touch event stream. 1003 * 1004 * @param ev MotionEvent provided to onInterceptTouchEvent 1005 * @return true if the parent view should return true from onInterceptTouchEvent 1006 */ 1007 public boolean shouldInterceptTouchEvent(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 saveInitialMotion(x, y, pointerId); 1028 1029 final View toCapture = findTopChildUnder((int) x, (int) y); 1030 1031 // Catch a settling view if possible. 1032 if (toCapture == mCapturedView && mDragState == STATE_SETTLING) { 1033 tryCaptureViewForDrag(toCapture, pointerId); 1034 } 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 final int edgesTouched = mInitialEdgesTouched[pointerId]; 1053 if ((edgesTouched & mTrackingEdges) != 0) { 1054 mCallback.onEdgeTouched(edgesTouched & mTrackingEdges, pointerId); 1055 } 1056 } else if (mDragState == STATE_SETTLING) { 1057 // Catch a settling view if possible. 1058 final View toCapture = findTopChildUnder((int) x, (int) y); 1059 if (toCapture == mCapturedView) { 1060 tryCaptureViewForDrag(toCapture, pointerId); 1061 } 1062 } 1063 break; 1064 } 1065 1066 case MotionEvent.ACTION_MOVE: { 1067 // First to cross a touch slop over a draggable view wins. Also report edge drags. 1068 final int pointerCount = MotionEventCompat.getPointerCount(ev); 1069 for (int i = 0; i < pointerCount; i++) { 1070 final int pointerId = MotionEventCompat.getPointerId(ev, i); 1071 final float x = MotionEventCompat.getX(ev, i); 1072 final float y = MotionEventCompat.getY(ev, i); 1073 final float dx = x - mInitialMotionX[pointerId]; 1074 final float dy = y - mInitialMotionY[pointerId]; 1075 1076 reportNewEdgeDrags(dx, dy, pointerId); 1077 if (mDragState == STATE_DRAGGING) { 1078 // Callback might have started an edge drag 1079 break; 1080 } 1081 1082 final View toCapture = findTopChildUnder((int) x, (int) y); 1083 if (toCapture != null && checkTouchSlop(toCapture, dx, dy) && 1084 tryCaptureViewForDrag(toCapture, pointerId)) { 1085 break; 1086 } 1087 } 1088 saveLastMotion(ev); 1089 break; 1090 } 1091 1092 case MotionEventCompat.ACTION_POINTER_UP: { 1093 final int pointerId = MotionEventCompat.getPointerId(ev, actionIndex); 1094 clearMotionHistory(pointerId); 1095 break; 1096 } 1097 1098 case MotionEvent.ACTION_UP: 1099 case MotionEvent.ACTION_CANCEL: { 1100 cancel(); 1101 break; 1102 } 1103 } 1104 1105 return mDragState == STATE_DRAGGING; 1106 } 1107 1108 /** 1109 * Process a touch event received by the parent view. This method will dispatch callback events 1110 * as needed before returning. The parent view's onTouchEvent implementation should call this. 1111 * 1112 * @param ev The touch event received by the parent view 1113 */ 1114 public void processTouchEvent(MotionEvent ev) { 1115 final int action = MotionEventCompat.getActionMasked(ev); 1116 final int actionIndex = MotionEventCompat.getActionIndex(ev); 1117 1118 if (action == MotionEvent.ACTION_DOWN) { 1119 // Reset things for a new event stream, just in case we didn't get 1120 // the whole previous stream. 1121 cancel(); 1122 } 1123 1124 if (mVelocityTracker == null) { 1125 mVelocityTracker = VelocityTracker.obtain(); 1126 } 1127 mVelocityTracker.addMovement(ev); 1128 1129 switch (action) { 1130 case MotionEvent.ACTION_DOWN: { 1131 final float x = ev.getX(); 1132 final float y = ev.getY(); 1133 final int pointerId = MotionEventCompat.getPointerId(ev, 0); 1134 final View toCapture = findTopChildUnder((int) x, (int) y); 1135 1136 saveInitialMotion(x, y, pointerId); 1137 1138 // Since the parent is already directly processing this touch event, 1139 // there is no reason to delay for a slop before dragging. 1140 // Start immediately if possible. 1141 tryCaptureViewForDrag(toCapture, pointerId); 1142 1143 final int edgesTouched = mInitialEdgesTouched[pointerId]; 1144 if ((edgesTouched & mTrackingEdges) != 0) { 1145 mCallback.onEdgeTouched(edgesTouched & mTrackingEdges, pointerId); 1146 } 1147 break; 1148 } 1149 1150 case MotionEventCompat.ACTION_POINTER_DOWN: { 1151 final int pointerId = MotionEventCompat.getPointerId(ev, actionIndex); 1152 final float x = MotionEventCompat.getX(ev, actionIndex); 1153 final float y = MotionEventCompat.getY(ev, actionIndex); 1154 1155 saveInitialMotion(x, y, pointerId); 1156 1157 // A ViewDragHelper can only manipulate one view at a time. 1158 if (mDragState == STATE_IDLE) { 1159 // If we're idle we can do anything! Treat it like a normal down event. 1160 1161 final View toCapture = findTopChildUnder((int) x, (int) y); 1162 tryCaptureViewForDrag(toCapture, pointerId); 1163 1164 final int edgesTouched = mInitialEdgesTouched[pointerId]; 1165 if ((edgesTouched & mTrackingEdges) != 0) { 1166 mCallback.onEdgeTouched(edgesTouched & mTrackingEdges, pointerId); 1167 } 1168 } else if (isCapturedViewUnder((int) x, (int) y)) { 1169 // We're still tracking a captured view. If the same view is under this 1170 // point, we'll swap to controlling it with this pointer instead. 1171 // (This will still work if we're "catching" a settling view.) 1172 1173 tryCaptureViewForDrag(mCapturedView, pointerId); 1174 } 1175 break; 1176 } 1177 1178 case MotionEvent.ACTION_MOVE: { 1179 if (mDragState == STATE_DRAGGING) { 1180 int index = MotionEventCompat.findPointerIndex(ev, mActivePointerId); 1181 if (index < 0) { 1182 Log.e(TAG, "Pointer index for id " + mActivePointerId + " not found." 1183 + " Skipping MotionEvent"); 1184 return; 1185 } 1186 final float x = MotionEventCompat.getX(ev, index); 1187 final float y = MotionEventCompat.getY(ev, index); 1188 final int idx = (int) (x - mLastMotionX[mActivePointerId]); 1189 final int idy = (int) (y - mLastMotionY[mActivePointerId]); 1190 1191 dragTo(mCapturedView.getLeft() + idx, mCapturedView.getTop() + idy, idx, idy); 1192 1193 saveLastMotion(ev); 1194 } else { 1195 // Check to see if any pointer is now over a draggable view. 1196 final int pointerCount = MotionEventCompat.getPointerCount(ev); 1197 for (int i = 0; i < pointerCount; i++) { 1198 final int pointerId = MotionEventCompat.getPointerId(ev, i); 1199 final float x = MotionEventCompat.getX(ev, i); 1200 final float y = MotionEventCompat.getY(ev, i); 1201 final float dx = x - mInitialMotionX[pointerId]; 1202 final float dy = y - mInitialMotionY[pointerId]; 1203 1204 reportNewEdgeDrags(dx, dy, pointerId); 1205 if (mDragState == STATE_DRAGGING) { 1206 // Callback might have started an edge drag. 1207 break; 1208 } 1209 1210 final View toCapture = findTopChildUnder((int) x, (int) y); 1211 if (checkTouchSlop(toCapture, dx, dy) && 1212 tryCaptureViewForDrag(toCapture, pointerId)) { 1213 break; 1214 } 1215 } 1216 saveLastMotion(ev); 1217 } 1218 break; 1219 } 1220 1221 case MotionEventCompat.ACTION_POINTER_UP: { 1222 final int pointerId = MotionEventCompat.getPointerId(ev, actionIndex); 1223 if (mDragState == STATE_DRAGGING && pointerId == mActivePointerId) { 1224 // Try to find another pointer that's still holding on to the captured view. 1225 int newActivePointer = INVALID_POINTER; 1226 final int pointerCount = MotionEventCompat.getPointerCount(ev); 1227 for (int i = 0; i < pointerCount; i++) { 1228 final int id = MotionEventCompat.getPointerId(ev, i); 1229 if (id == mActivePointerId) { 1230 // This one's going away, skip. 1231 continue; 1232 } 1233 1234 final float x = MotionEventCompat.getX(ev, i); 1235 final float y = MotionEventCompat.getY(ev, i); 1236 if (findTopChildUnder((int) x, (int) y) == mCapturedView && 1237 tryCaptureViewForDrag(mCapturedView, id)) { 1238 newActivePointer = mActivePointerId; 1239 break; 1240 } 1241 } 1242 1243 if (newActivePointer == INVALID_POINTER) { 1244 // We didn't find another pointer still touching the view, release it. 1245 releaseViewForPointerUp(); 1246 } 1247 } 1248 clearMotionHistory(pointerId); 1249 break; 1250 } 1251 1252 case MotionEvent.ACTION_UP: { 1253 if (mDragState == STATE_DRAGGING) { 1254 releaseViewForPointerUp(); 1255 } 1256 cancel(); 1257 break; 1258 } 1259 1260 case MotionEvent.ACTION_CANCEL: { 1261 if (mDragState == STATE_DRAGGING) { 1262 dispatchViewReleased(0, 0); 1263 } 1264 cancel(); 1265 break; 1266 } 1267 } 1268 } 1269 1270 private void reportNewEdgeDrags(float dx, float dy, int pointerId) { 1271 int dragsStarted = 0; 1272 if (checkNewEdgeDrag(dx, dy, pointerId, EDGE_LEFT)) { 1273 dragsStarted |= EDGE_LEFT; 1274 } 1275 if (checkNewEdgeDrag(dy, dx, pointerId, EDGE_TOP)) { 1276 dragsStarted |= EDGE_TOP; 1277 } 1278 if (checkNewEdgeDrag(dx, dy, pointerId, EDGE_RIGHT)) { 1279 dragsStarted |= EDGE_RIGHT; 1280 } 1281 if (checkNewEdgeDrag(dy, dx, pointerId, EDGE_BOTTOM)) { 1282 dragsStarted |= EDGE_BOTTOM; 1283 } 1284 1285 if (dragsStarted != 0) { 1286 mEdgeDragsInProgress[pointerId] |= dragsStarted; 1287 mCallback.onEdgeDragStarted(dragsStarted, pointerId); 1288 } 1289 } 1290 1291 private boolean checkNewEdgeDrag(float delta, float odelta, int pointerId, int edge) { 1292 final float absDelta = Math.abs(delta); 1293 final float absODelta = Math.abs(odelta); 1294 1295 if ((mInitialEdgesTouched[pointerId] & edge) != edge || (mTrackingEdges & edge) == 0 || 1296 (mEdgeDragsLocked[pointerId] & edge) == edge || 1297 (mEdgeDragsInProgress[pointerId] & edge) == edge || 1298 (absDelta <= mTouchSlop && absODelta <= mTouchSlop)) { 1299 return false; 1300 } 1301 if (absDelta < absODelta * 0.5f && mCallback.onEdgeLock(edge)) { 1302 mEdgeDragsLocked[pointerId] |= edge; 1303 return false; 1304 } 1305 return (mEdgeDragsInProgress[pointerId] & edge) == 0 && absDelta > mTouchSlop; 1306 } 1307 1308 /** 1309 * Check if we've crossed a reasonable touch slop for the given child view. 1310 * If the child cannot be dragged along the horizontal or vertical axis, motion 1311 * along that axis will not count toward the slop check. 1312 * 1313 * @param child Child to check 1314 * @param dx Motion since initial position along X axis 1315 * @param dy Motion since initial position along Y axis 1316 * @return true if the touch slop has been crossed 1317 */ 1318 private boolean checkTouchSlop(View child, float dx, float dy) { 1319 if (child == null) { 1320 return false; 1321 } 1322 final boolean checkHorizontal = mCallback.getViewHorizontalDragRange(child) > 0; 1323 final boolean checkVertical = mCallback.getViewVerticalDragRange(child) > 0; 1324 1325 if (checkHorizontal && checkVertical) { 1326 return dx * dx + dy * dy > mTouchSlop * mTouchSlop; 1327 } else if (checkHorizontal) { 1328 return Math.abs(dx) > mTouchSlop; 1329 } else if (checkVertical) { 1330 return Math.abs(dy) > mTouchSlop; 1331 } 1332 return false; 1333 } 1334 1335 /** 1336 * Check if any pointer tracked in the current gesture has crossed 1337 * the required slop threshold. 1338 * 1339 * <p>This depends on internal state populated by 1340 * {@link #shouldInterceptTouchEvent(android.view.MotionEvent)} or 1341 * {@link #processTouchEvent(android.view.MotionEvent)}. You should only rely on 1342 * the results of this method after all currently available touch data 1343 * has been provided to one of these two methods.</p> 1344 * 1345 * @param directions Combination of direction flags, see {@link #DIRECTION_HORIZONTAL}, 1346 * {@link #DIRECTION_VERTICAL}, {@link #DIRECTION_ALL} 1347 * @return true if the slop threshold has been crossed, false otherwise 1348 */ 1349 public boolean checkTouchSlop(int directions) { 1350 final int count = mInitialMotionX.length; 1351 for (int i = 0; i < count; i++) { 1352 if (checkTouchSlop(directions, i)) { 1353 return true; 1354 } 1355 } 1356 return false; 1357 } 1358 1359 /** 1360 * Check if the specified pointer tracked in the current gesture has crossed 1361 * the required slop threshold. 1362 * 1363 * <p>This depends on internal state populated by 1364 * {@link #shouldInterceptTouchEvent(android.view.MotionEvent)} or 1365 * {@link #processTouchEvent(android.view.MotionEvent)}. You should only rely on 1366 * the results of this method after all currently available touch data 1367 * has been provided to one of these two methods.</p> 1368 * 1369 * @param directions Combination of direction flags, see {@link #DIRECTION_HORIZONTAL}, 1370 * {@link #DIRECTION_VERTICAL}, {@link #DIRECTION_ALL} 1371 * @param pointerId ID of the pointer to slop check as specified by MotionEvent 1372 * @return true if the slop threshold has been crossed, false otherwise 1373 */ 1374 public boolean checkTouchSlop(int directions, int pointerId) { 1375 if (!isPointerDown(pointerId)) { 1376 return false; 1377 } 1378 1379 final boolean checkHorizontal = (directions & DIRECTION_HORIZONTAL) == DIRECTION_HORIZONTAL; 1380 final boolean checkVertical = (directions & DIRECTION_VERTICAL) == DIRECTION_VERTICAL; 1381 1382 final float dx = mLastMotionX[pointerId] - mInitialMotionX[pointerId]; 1383 final float dy = mLastMotionY[pointerId] - mInitialMotionY[pointerId]; 1384 1385 if (checkHorizontal && checkVertical) { 1386 return dx * dx + dy * dy > mTouchSlop * mTouchSlop; 1387 } else if (checkHorizontal) { 1388 return Math.abs(dx) > mTouchSlop; 1389 } else if (checkVertical) { 1390 return Math.abs(dy) > mTouchSlop; 1391 } 1392 return false; 1393 } 1394 1395 /** 1396 * Check if any of the edges specified were initially touched in the currently active gesture. 1397 * If there is no currently active gesture this method will return false. 1398 * 1399 * @param edges Edges to check for an initial edge touch. See {@link #EDGE_LEFT}, 1400 * {@link #EDGE_TOP}, {@link #EDGE_RIGHT}, {@link #EDGE_BOTTOM} and 1401 * {@link #EDGE_ALL} 1402 * @return true if any of the edges specified were initially touched in the current gesture 1403 */ 1404 public boolean isEdgeTouched(int edges) { 1405 final int count = mInitialEdgesTouched.length; 1406 for (int i = 0; i < count; i++) { 1407 if (isEdgeTouched(edges, i)) { 1408 return true; 1409 } 1410 } 1411 return false; 1412 } 1413 1414 /** 1415 * Check if any of the edges specified were initially touched by the pointer with 1416 * the specified ID. If there is no currently active gesture or if there is no pointer with 1417 * the given ID currently down this method will return false. 1418 * 1419 * @param edges Edges to check for an initial edge touch. See {@link #EDGE_LEFT}, 1420 * {@link #EDGE_TOP}, {@link #EDGE_RIGHT}, {@link #EDGE_BOTTOM} and 1421 * {@link #EDGE_ALL} 1422 * @return true if any of the edges specified were initially touched in the current gesture 1423 */ 1424 public boolean isEdgeTouched(int edges, int pointerId) { 1425 return isPointerDown(pointerId) && (mInitialEdgesTouched[pointerId] & edges) != 0; 1426 } 1427 1428 private void releaseViewForPointerUp() { 1429 mVelocityTracker.computeCurrentVelocity(1000, mMaxVelocity); 1430 final float xvel = clampMag( 1431 VelocityTrackerCompat.getXVelocity(mVelocityTracker, mActivePointerId), 1432 mMinVelocity, mMaxVelocity); 1433 final float yvel = clampMag( 1434 VelocityTrackerCompat.getYVelocity(mVelocityTracker, mActivePointerId), 1435 mMinVelocity, mMaxVelocity); 1436 dispatchViewReleased(xvel, yvel); 1437 } 1438 1439 private void dragTo(int left, int top, int dx, int dy) { 1440 int clampedX = left; 1441 int clampedY = top; 1442 final int oldLeft = mCapturedView.getLeft(); 1443 final int oldTop = mCapturedView.getTop(); 1444 if (dx != 0) { 1445 clampedX = mCallback.clampViewPositionHorizontal(mCapturedView, left, dx); 1446 mCapturedView.offsetLeftAndRight(clampedX - oldLeft); 1447 } 1448 if (dy != 0) { 1449 clampedY = mCallback.clampViewPositionVertical(mCapturedView, top, dy); 1450 mCapturedView.offsetTopAndBottom(clampedY - oldTop); 1451 } 1452 1453 if (dx != 0 || dy != 0) { 1454 final int clampedDx = clampedX - oldLeft; 1455 final int clampedDy = clampedY - oldTop; 1456 mCallback.onViewPositionChanged(mCapturedView, clampedX, clampedY, 1457 clampedDx, clampedDy); 1458 } 1459 } 1460 1461 /** 1462 * Determine if the currently captured view is under the given point in the 1463 * parent view's coordinate system. If there is no captured view this method 1464 * will return false. 1465 * 1466 * @param x X position to test in the parent's coordinate system 1467 * @param y Y position to test in the parent's coordinate system 1468 * @return true if the captured view is under the given point, false otherwise 1469 */ 1470 public boolean isCapturedViewUnder(int x, int y) { 1471 return isViewUnder(mCapturedView, x, y); 1472 } 1473 1474 /** 1475 * Determine if the supplied view is under the given point in the 1476 * parent view's coordinate system. 1477 * 1478 * @param view Child view of the parent to hit test 1479 * @param x X position to test in the parent's coordinate system 1480 * @param y Y position to test in the parent's coordinate system 1481 * @return true if the supplied view is under the given point, false otherwise 1482 */ 1483 public boolean isViewUnder(View view, int x, int y) { 1484 if (view == null) { 1485 return false; 1486 } 1487 return x >= view.getLeft() && 1488 x < view.getRight() && 1489 y >= view.getTop() && 1490 y < view.getBottom(); 1491 } 1492 1493 /** 1494 * Find the topmost child under the given point within the parent view's coordinate system. 1495 * The child order is determined using {@link Callback#getOrderedChildIndex(int)}. 1496 * 1497 * @param x X position to test in the parent's coordinate system 1498 * @param y Y position to test in the parent's coordinate system 1499 * @return The topmost child view under (x, y) or null if none found. 1500 */ 1501 public View findTopChildUnder(int x, int y) { 1502 final int childCount = mParentView.getChildCount(); 1503 for (int i = childCount - 1; i >= 0; i--) { 1504 final View child = mParentView.getChildAt(mCallback.getOrderedChildIndex(i)); 1505 if (x >= child.getLeft() && x < child.getRight() && 1506 y >= child.getTop() && y < child.getBottom()) { 1507 return child; 1508 } 1509 } 1510 return null; 1511 } 1512 1513 private int getEdgesTouched(int x, int y) { 1514 int result = 0; 1515 1516 if (x < mParentView.getLeft() + mEdgeSize) result |= EDGE_LEFT; 1517 if (y < mParentView.getTop() + mEdgeSize) result |= EDGE_TOP; 1518 if (x > mParentView.getRight() - mEdgeSize) result |= EDGE_RIGHT; 1519 if (y > mParentView.getBottom() - mEdgeSize) result |= EDGE_BOTTOM; 1520 1521 return result; 1522 } 1523 1524 /** 1525 * Prepares the {@link ViewDragHelper} for the beginning of a nested scroll. 1526 * 1527 * @param target The child view that is dispatching the nested scroll. 1528 */ 1529 public void startNestedScroll(View target) { 1530 if (mVelocityTracker == null) { 1531 mVelocityTracker = VelocityTracker.obtain(); 1532 } 1533 setDragState(STATE_DRAGGING); 1534 mCapturedView = target; 1535 } 1536 1537 /** 1538 * Informs the {@link ViewDragHelper} that a nested scroll has ended. 1539 * 1540 * @param target The child view that is dispatching the nested scroll. 1541 */ 1542 public void stopNestedScroll(View target) { 1543 mCapturedView = target; 1544 dispatchViewReleased(0, 0); 1545 } 1546 1547 /** 1548 * Update the {@link ViewDragHelper} with a new nested scrolling event. 1549 * 1550 * @param target The child view that is dispatching the nested scroll. 1551 * @param dx The x distance scrolled on the child, in pixels. 1552 * @param dy The y distance scroll on the child, in pixels. 1553 * @param consumed An int array for the {@link ViewDragHelper} to report back the scroll 1554 * deltas that it consumed. 1555 */ 1556 public void processNestedScroll(View target, int dx, int dy, int[] consumed) { 1557 if (mCapturedView == null) { 1558 // This is safe because consumed array is null when called from 1559 // onNestedScroll, and pre-initialized to {0, 0} when called from 1560 // onNestedPreScroll. 1561 return; 1562 } 1563 final int targetX = mCapturedView.getLeft() + dx; 1564 final int targetY = mCapturedView.getTop() + dy; 1565 dragTo(targetX, targetY, dx, dy); 1566 if (consumed != null) { 1567 final int unconsumedX = targetX - mCapturedView.getLeft(); 1568 final int unconsumedY = targetY - mCapturedView.getTop(); 1569 consumed[0] = unconsumedX - dx; 1570 consumed[1] = unconsumedY - dy; 1571 } 1572 } 1573 1574 } 1575