1/* 2 * Copyright (C) 2013 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 18package android.support.v4.widget; 19 20import android.content.Context; 21import android.support.v4.view.MotionEventCompat; 22import android.support.v4.view.VelocityTrackerCompat; 23import android.support.v4.view.ViewCompat; 24import android.view.MotionEvent; 25import android.view.VelocityTracker; 26import android.view.View; 27import android.view.ViewConfiguration; 28import android.view.ViewGroup; 29import android.view.animation.Interpolator; 30 31import java.util.Arrays; 32 33/** 34 * ViewDragHelper is a utility class for writing custom ViewGroups. It offers a number 35 * of useful operations and state tracking for allowing a user to drag and reposition 36 * views within their parent ViewGroup. 37 */ 38public class ViewDragHelper { 39 private static final String TAG = "ViewDragHelper"; 40 41 /** 42 * A null/invalid pointer ID. 43 */ 44 public static final int INVALID_POINTER = -1; 45 46 /** 47 * A view is not currently being dragged or animating as a result of a fling/snap. 48 */ 49 public static final int STATE_IDLE = 0; 50 51 /** 52 * A view is currently being dragged. The position is currently changing as a result 53 * of user input or simulated user input. 54 */ 55 public static final int STATE_DRAGGING = 1; 56 57 /** 58 * A view is currently settling into place as a result of a fling or 59 * predefined non-interactive motion. 60 */ 61 public static final int STATE_SETTLING = 2; 62 63 /** 64 * Edge flag indicating that the left edge should be affected. 65 */ 66 public static final int EDGE_LEFT = 1 << 0; 67 68 /** 69 * Edge flag indicating that the right edge should be affected. 70 */ 71 public static final int EDGE_RIGHT = 1 << 1; 72 73 /** 74 * Edge flag indicating that the top edge should be affected. 75 */ 76 public static final int EDGE_TOP = 1 << 2; 77 78 /** 79 * Edge flag indicating that the bottom edge should be affected. 80 */ 81 public static final int EDGE_BOTTOM = 1 << 3; 82 83 /** 84 * Edge flag set indicating all edges should be affected. 85 */ 86 public static final int EDGE_ALL = EDGE_LEFT | EDGE_TOP | EDGE_RIGHT | EDGE_BOTTOM; 87 88 /** 89 * Indicates that a check should occur along the horizontal axis 90 */ 91 public static final int DIRECTION_HORIZONTAL = 1 << 0; 92 93 /** 94 * Indicates that a check should occur along the vertical axis 95 */ 96 public static final int DIRECTION_VERTICAL = 1 << 1; 97 98 /** 99 * Indicates that a check should occur along all axes 100 */ 101 public static final int DIRECTION_ALL = DIRECTION_HORIZONTAL | DIRECTION_VERTICAL; 102 103 private static final int EDGE_SIZE = 20; // dp 104 105 private static final int BASE_SETTLE_DURATION = 256; // ms 106 private static final int MAX_SETTLE_DURATION = 600; // ms 107 108 // Current drag state; idle, dragging or settling 109 private int mDragState; 110 111 // Distance to travel before a drag may begin 112 private int mTouchSlop; 113 114 // Last known position/pointer tracking 115 private int mActivePointerId = INVALID_POINTER; 116 private float[] mInitialMotionX; 117 private float[] mInitialMotionY; 118 private float[] mLastMotionX; 119 private float[] mLastMotionY; 120 private int[] mInitialEdgesTouched; 121 private int[] mEdgeDragsInProgress; 122 private int[] mEdgeDragsLocked; 123 private int mPointersDown; 124 125 private VelocityTracker mVelocityTracker; 126 private float mMaxVelocity; 127 private float mMinVelocity; 128 129 private int mEdgeSize; 130 private int mTrackingEdges; 131 132 private ScrollerCompat mScroller; 133 134 private final Callback mCallback; 135 136 private View mCapturedView; 137 private boolean mReleaseInProgress; 138 139 private final ViewGroup mParentView; 140 141 /** 142 * A Callback is used as a communication channel with the ViewDragHelper back to the 143 * parent view using it. <code>on*</code>methods are invoked on siginficant events and several 144 * accessor methods are expected to provide the ViewDragHelper with more information 145 * about the state of the parent view upon request. The callback also makes decisions 146 * governing the range and draggability of child views. 147 */ 148 public static abstract class Callback { 149 /** 150 * Called when the drag state changes. See the <code>STATE_*</code> constants 151 * for more information. 152 * 153 * @param state The new drag state 154 * 155 * @see #STATE_IDLE 156 * @see #STATE_DRAGGING 157 * @see #STATE_SETTLING 158 */ 159 public void onViewDragStateChanged(int state) {} 160 161 /** 162 * Called when the captured view's position changes as the result of a drag or settle. 163 * 164 * @param changedView View whose position changed 165 * @param left New X coordinate of the left edge of the view 166 * @param top New Y coordinate of the top edge of the view 167 * @param dx Change in X position from the last call 168 * @param dy Change in Y position from the last call 169 */ 170 public void onViewPositionChanged(View changedView, int left, int top, int dx, int dy) {} 171 172 /** 173 * Called when a child view is captured for dragging or settling. The ID of the pointer 174 * currently dragging the captured view is supplied. If activePointerId is 175 * identified as {@link #INVALID_POINTER} the capture is programmatic instead of 176 * pointer-initiated. 177 * 178 * @param capturedChild Child view that was captured 179 * @param activePointerId Pointer id tracking the child capture 180 */ 181 public void onViewCaptured(View capturedChild, int activePointerId) {} 182 183 /** 184 * Called when the child view is no longer being actively dragged. 185 * The fling velocity is also supplied, if relevant. The velocity values may 186 * be clamped to system minimums or maximums. 187 * 188 * <p>Calling code may decide to fling or otherwise release the view to let it 189 * settle into place. It should do so using {@link #settleCapturedViewAt(int, int)} 190 * or {@link #flingCapturedView(int, int, int, int)}. If the Callback invokes 191 * one of these methods, the ViewDragHelper will enter {@link #STATE_SETTLING} 192 * and the view capture will not fully end until it comes to a complete stop. 193 * If neither of these methods is invoked before <code>onViewReleased</code> returns, 194 * the view will stop in place and the ViewDragHelper will return to 195 * {@link #STATE_IDLE}.</p> 196 * 197 * @param releasedChild The captured child view now being released 198 * @param xvel X velocity of the pointer as it left the screen in pixels per second. 199 * @param yvel Y velocity of the pointer as it left the screen in pixels per second. 200 */ 201 public void onViewReleased(View releasedChild, float xvel, float yvel) {} 202 203 /** 204 * Called when one of the subscribed edges in the parent view has been touched 205 * by the user while no child view is currently captured. 206 * 207 * @param edgeFlags A combination of edge flags describing the edge(s) currently touched 208 * @param pointerId ID of the pointer touching the described edge(s) 209 * @see #EDGE_LEFT 210 * @see #EDGE_TOP 211 * @see #EDGE_RIGHT 212 * @see #EDGE_BOTTOM 213 */ 214 public void onEdgeTouched(int edgeFlags, int pointerId) {} 215 216 /** 217 * Called when the given edge may become locked. This can happen if an edge drag 218 * was preliminarily rejected before beginning, but after {@link #onEdgeTouched(int, int)} 219 * was called. This method should return true to lock this edge or false to leave it 220 * unlocked. The default behavior is to leave edges unlocked. 221 * 222 * @param edgeFlags A combination of edge flags describing the edge(s) locked 223 * @return true to lock the edge, false to leave it unlocked 224 */ 225 public boolean onEdgeLock(int edgeFlags) { 226 return false; 227 } 228 229 /** 230 * Called when the user has started a deliberate drag away from one 231 * of the subscribed edges in the parent view while no child view is currently captured. 232 * 233 * @param edgeFlags A combination of edge flags describing the edge(s) dragged 234 * @param pointerId ID of the pointer touching the described edge(s) 235 * @see #EDGE_LEFT 236 * @see #EDGE_TOP 237 * @see #EDGE_RIGHT 238 * @see #EDGE_BOTTOM 239 */ 240 public void onEdgeDragStarted(int edgeFlags, int pointerId) {} 241 242 /** 243 * Called to determine the Z-order of child views. 244 * 245 * @param index the ordered position to query for 246 * @return index of the view that should be ordered at position <code>index</code> 247 */ 248 public int getOrderedChildIndex(int index) { 249 return index; 250 } 251 252 /** 253 * Return the magnitude of a draggable child view's horizontal range of motion in pixels. 254 * This method should return 0 for views that cannot move horizontally. 255 * 256 * @param child Child view to check 257 * @return range of horizontal motion in pixels 258 */ 259 public int getViewHorizontalDragRange(View child) { 260 return 0; 261 } 262 263 /** 264 * Return the magnitude of a draggable child view's vertical range of motion in pixels. 265 * This method should return 0 for views that cannot move vertically. 266 * 267 * @param child Child view to check 268 * @return range of vertical motion in pixels 269 */ 270 public int getViewVerticalDragRange(View child) { 271 return 0; 272 } 273 274 /** 275 * Called when the user's input indicates that they want to capture the given child view 276 * with the pointer indicated by pointerId. The callback should return true if the user 277 * is permitted to drag the given view with the indicated pointer. 278 * 279 * <p>ViewDragHelper may call this method multiple times for the same view even if 280 * the view is already captured; this indicates that a new pointer is trying to take 281 * control of the view.</p> 282 * 283 * <p>If this method returns true, a call to {@link #onViewCaptured(android.view.View, int)} 284 * will follow if the capture is successful.</p> 285 * 286 * @param child Child the user is attempting to capture 287 * @param pointerId ID of the pointer attempting the capture 288 * @return true if capture should be allowed, false otherwise 289 */ 290 public abstract boolean tryCaptureView(View child, int pointerId); 291 292 /** 293 * Restrict the motion of the dragged child view along the horizontal axis. 294 * The default implementation does not allow horizontal motion; the extending 295 * class must override this method and provide the desired clamping. 296 * 297 * 298 * @param child Child view being dragged 299 * @param left Attempted motion along the X axis 300 * @param dx Proposed change in position for left 301 * @return The new clamped position for left 302 */ 303 public int clampViewPositionHorizontal(View child, int left, int dx) { 304 return 0; 305 } 306 307 /** 308 * Restrict the motion of the dragged child view along the vertical axis. 309 * The default implementation does not allow vertical motion; the extending 310 * class must override this method and provide the desired clamping. 311 * 312 * 313 * @param child Child view being dragged 314 * @param top Attempted motion along the Y axis 315 * @param dy Proposed change in position for top 316 * @return The new clamped position for top 317 */ 318 public int clampViewPositionVertical(View child, int top, int dy) { 319 return 0; 320 } 321 } 322 323 /** 324 * Interpolator defining the animation curve for mScroller 325 */ 326 private static final Interpolator sInterpolator = new Interpolator() { 327 public float getInterpolation(float t) { 328 t -= 1.0f; 329 return t * t * t * t * t + 1.0f; 330 } 331 }; 332 333 private final Runnable mSetIdleRunnable = new Runnable() { 334 public void run() { 335 setDragState(STATE_IDLE); 336 } 337 }; 338 339 /** 340 * Factory method to create a new ViewDragHelper. 341 * 342 * @param forParent Parent view to monitor 343 * @param cb Callback to provide information and receive events 344 * @return a new ViewDragHelper instance 345 */ 346 public static ViewDragHelper create(ViewGroup forParent, Callback cb) { 347 return new ViewDragHelper(forParent.getContext(), forParent, cb); 348 } 349 350 /** 351 * Factory method to create a new ViewDragHelper. 352 * 353 * @param forParent Parent view to monitor 354 * @param sensitivity Multiplier for how sensitive the helper should be about detecting 355 * the start of a drag. Larger values are more sensitive. 1.0f is normal. 356 * @param cb Callback to provide information and receive events 357 * @return a new ViewDragHelper instance 358 */ 359 public static ViewDragHelper create(ViewGroup forParent, float sensitivity, Callback cb) { 360 final ViewDragHelper helper = create(forParent, cb); 361 helper.mTouchSlop = (int) (helper.mTouchSlop * (1 / sensitivity)); 362 return helper; 363 } 364 365 /** 366 * Apps should use ViewDragHelper.create() to get a new instance. 367 * This will allow VDH to use internal compatibility implementations for different 368 * platform versions. 369 * 370 * @param context Context to initialize config-dependent params from 371 * @param forParent Parent view to monitor 372 */ 373 private ViewDragHelper(Context context, ViewGroup forParent, Callback cb) { 374 if (forParent == null) { 375 throw new IllegalArgumentException("Parent view may not be null"); 376 } 377 if (cb == null) { 378 throw new IllegalArgumentException("Callback may not be null"); 379 } 380 381 mParentView = forParent; 382 mCallback = cb; 383 384 final ViewConfiguration vc = ViewConfiguration.get(context); 385 final float density = context.getResources().getDisplayMetrics().density; 386 mEdgeSize = (int) (EDGE_SIZE * density + 0.5f); 387 388 mTouchSlop = vc.getScaledTouchSlop(); 389 mMaxVelocity = vc.getScaledMaximumFlingVelocity(); 390 mMinVelocity = vc.getScaledMinimumFlingVelocity(); 391 mScroller = ScrollerCompat.create(context, sInterpolator); 392 } 393 394 /** 395 * Set the minimum velocity that will be detected as having a magnitude greater than zero 396 * in pixels per second. Callback methods accepting a velocity will be clamped appropriately. 397 * 398 * @param minVel Minimum velocity to detect 399 */ 400 public void setMinVelocity(float minVel) { 401 mMinVelocity = minVel; 402 } 403 404 /** 405 * Return the currently configured minimum velocity. Any flings with a magnitude less 406 * than this value in pixels per second. Callback methods accepting a velocity will receive 407 * zero as a velocity value if the real detected velocity was below this threshold. 408 * 409 * @return the minimum velocity that will be detected 410 */ 411 public float getMinVelocity() { 412 return mMinVelocity; 413 } 414 415 /** 416 * Retrieve the current drag state of this helper. This will return one of 417 * {@link #STATE_IDLE}, {@link #STATE_DRAGGING} or {@link #STATE_SETTLING}. 418 * @return The current drag state 419 */ 420 public int getViewDragState() { 421 return mDragState; 422 } 423 424 /** 425 * Enable edge tracking for the selected edges of the parent view. 426 * The callback's {@link Callback#onEdgeTouched(int, int)} and 427 * {@link Callback#onEdgeDragStarted(int, int)} methods will only be invoked 428 * for edges for which edge tracking has been enabled. 429 * 430 * @param edgeFlags Combination of edge flags describing the edges to watch 431 * @see #EDGE_LEFT 432 * @see #EDGE_TOP 433 * @see #EDGE_RIGHT 434 * @see #EDGE_BOTTOM 435 */ 436 public void setEdgeTrackingEnabled(int edgeFlags) { 437 mTrackingEdges = edgeFlags; 438 } 439 440 /** 441 * Return the size of an edge. This is the range in pixels along the edges of this view 442 * that will actively detect edge touches or drags if edge tracking is enabled. 443 * 444 * @return The size of an edge in pixels 445 * @see #setEdgeTrackingEnabled(int) 446 */ 447 public int getEdgeSize() { 448 return mEdgeSize; 449 } 450 451 /** 452 * Capture a specific child view for dragging within the parent. The callback will be notified 453 * but {@link Callback#tryCaptureView(android.view.View, int)} will not be asked permission to 454 * capture this view. 455 * 456 * @param childView Child view to capture 457 * @param activePointerId ID of the pointer that is dragging the captured child view 458 */ 459 public void captureChildView(View childView, int activePointerId) { 460 if (childView.getParent() != mParentView) { 461 throw new IllegalArgumentException("captureChildView: parameter must be a descendant " + 462 "of the ViewDragHelper's tracked parent view (" + mParentView + ")"); 463 } 464 465 mCapturedView = childView; 466 mActivePointerId = activePointerId; 467 mCallback.onViewCaptured(childView, activePointerId); 468 setDragState(STATE_DRAGGING); 469 } 470 471 /** 472 * @return The currently captured view, or null if no view has been captured. 473 */ 474 public View getCapturedView() { 475 return mCapturedView; 476 } 477 478 /** 479 * @return The ID of the pointer currently dragging the captured view, 480 * or {@link #INVALID_POINTER}. 481 */ 482 public int getActivePointerId() { 483 return mActivePointerId; 484 } 485 486 /** 487 * @return The minimum distance in pixels that the user must travel to initiate a drag 488 */ 489 public int getTouchSlop() { 490 return mTouchSlop; 491 } 492 493 /** 494 * The result of a call to this method is equivalent to 495 * {@link #processTouchEvent(android.view.MotionEvent)} receiving an ACTION_CANCEL event. 496 */ 497 public void cancel() { 498 mActivePointerId = INVALID_POINTER; 499 clearMotionHistory(); 500 501 if (mVelocityTracker != null) { 502 mVelocityTracker.recycle(); 503 mVelocityTracker = null; 504 } 505 } 506 507 /** 508 * {@link #cancel()}, but also abort all motion in progress and snap to the end of any 509 * animation. 510 */ 511 public void abort() { 512 cancel(); 513 if (mDragState == STATE_SETTLING) { 514 final int oldX = mScroller.getCurrX(); 515 final int oldY = mScroller.getCurrY(); 516 mScroller.abortAnimation(); 517 final int newX = mScroller.getCurrX(); 518 final int newY = mScroller.getCurrY(); 519 mCallback.onViewPositionChanged(mCapturedView, newX, newY, newX - oldX, newY - oldY); 520 } 521 setDragState(STATE_IDLE); 522 } 523 524 /** 525 * Animate the view <code>child</code> to the given (left, top) position. 526 * If this method returns true, the caller should invoke {@link #continueSettling(boolean)} 527 * on each subsequent frame to continue the motion until it returns false. If this method 528 * returns false there is no further work to do to complete the movement. 529 * 530 * <p>This operation does not count as a capture event, though {@link #getCapturedView()} 531 * will still report the sliding view while the slide is in progress.</p> 532 * 533 * @param child Child view to capture and animate 534 * @param finalLeft Final left position of child 535 * @param finalTop Final top position of child 536 * @return true if animation should continue through {@link #continueSettling(boolean)} calls 537 */ 538 public boolean smoothSlideViewTo(View child, int finalLeft, int finalTop) { 539 mCapturedView = child; 540 mActivePointerId = INVALID_POINTER; 541 542 boolean continueSliding = forceSettleCapturedViewAt(finalLeft, finalTop, 0, 0); 543 if (!continueSliding && mDragState == STATE_IDLE && mCapturedView != null) { 544 // If we're in an IDLE state to begin with and aren't moving anywhere, we 545 // end up having a non-null capturedView with an IDLE dragState 546 mCapturedView = null; 547 } 548 549 return continueSliding; 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 */ 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 */ 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); 598 599 setDragState(STATE_SETTLING); 600 return true; 601 } 602 603 private int computeSettleDuration(View child, int dx, int dy, int xvel, int yvel) { 604 xvel = clampMag(xvel, (int) mMinVelocity, (int) mMaxVelocity); 605 yvel = clampMag(yvel, (int) mMinVelocity, (int) mMaxVelocity); 606 final int absDx = Math.abs(dx); 607 final int absDy = Math.abs(dy); 608 final int absXVel = Math.abs(xvel); 609 final int absYVel = Math.abs(yvel); 610 final int addedVel = absXVel + absYVel; 611 final int addedDistance = absDx + absDy; 612 613 final float xweight = xvel != 0 ? (float) absXVel / addedVel : 614 (float) absDx / addedDistance; 615 final float yweight = yvel != 0 ? (float) absYVel / addedVel : 616 (float) absDy / addedDistance; 617 618 int xduration = computeAxisDuration(dx, xvel, mCallback.getViewHorizontalDragRange(child)); 619 int yduration = computeAxisDuration(dy, yvel, mCallback.getViewVerticalDragRange(child)); 620 621 return (int) (xduration * xweight + yduration * yweight); 622 } 623 624 private int computeAxisDuration(int delta, int velocity, int motionRange) { 625 if (delta == 0) { 626 return 0; 627 } 628 629 final int width = mParentView.getWidth(); 630 final int halfWidth = width / 2; 631 final float distanceRatio = Math.min(1f, (float) Math.abs(delta) / width); 632 final float distance = halfWidth + halfWidth * 633 distanceInfluenceForSnapDuration(distanceRatio); 634 635 int duration; 636 velocity = Math.abs(velocity); 637 if (velocity > 0) { 638 duration = 4 * Math.round(1000 * Math.abs(distance / velocity)); 639 } else { 640 final float range = (float) Math.abs(delta) / motionRange; 641 duration = (int) ((range + 1) * BASE_SETTLE_DURATION); 642 } 643 return Math.min(duration, MAX_SETTLE_DURATION); 644 } 645 646 /** 647 * Clamp the magnitude of value for absMin and absMax. 648 * If the value is below the minimum, it will be clamped to zero. 649 * If the value is above the maximum, it will be clamped to the maximum. 650 * 651 * @param value Value to clamp 652 * @param absMin Absolute value of the minimum significant value to return 653 * @param absMax Absolute value of the maximum value to return 654 * @return The clamped value with the same sign as <code>value</code> 655 */ 656 private int clampMag(int value, int absMin, int absMax) { 657 final int absValue = Math.abs(value); 658 if (absValue < absMin) return 0; 659 if (absValue > absMax) return value > 0 ? absMax : -absMax; 660 return value; 661 } 662 663 /** 664 * Clamp the magnitude of value for absMin and absMax. 665 * If the value is below the minimum, it will be clamped to zero. 666 * If the value is above the maximum, it will be clamped to the maximum. 667 * 668 * @param value Value to clamp 669 * @param absMin Absolute value of the minimum significant value to return 670 * @param absMax Absolute value of the maximum value to return 671 * @return The clamped value with the same sign as <code>value</code> 672 */ 673 private float clampMag(float value, float absMin, float absMax) { 674 final float absValue = Math.abs(value); 675 if (absValue < absMin) return 0; 676 if (absValue > absMax) return value > 0 ? absMax : -absMax; 677 return value; 678 } 679 680 private float distanceInfluenceForSnapDuration(float f) { 681 f -= 0.5f; // center the values about 0. 682 f *= 0.3f * Math.PI / 2.0f; 683 return (float) Math.sin(f); 684 } 685 686 /** 687 * Settle the captured view based on standard free-moving fling behavior. 688 * The caller should invoke {@link #continueSettling(boolean)} on each subsequent frame 689 * to continue the motion until it returns false. 690 * 691 * @param minLeft Minimum X position for the view's left edge 692 * @param minTop Minimum Y position for the view's top edge 693 * @param maxLeft Maximum X position for the view's left edge 694 * @param maxTop Maximum Y position for the view's top edge 695 */ 696 public void flingCapturedView(int minLeft, int minTop, int maxLeft, int maxTop) { 697 if (!mReleaseInProgress) { 698 throw new IllegalStateException("Cannot flingCapturedView outside of a call to " + 699 "Callback#onViewReleased"); 700 } 701 702 mScroller.fling(mCapturedView.getLeft(), mCapturedView.getTop(), 703 (int) VelocityTrackerCompat.getXVelocity(mVelocityTracker, mActivePointerId), 704 (int) VelocityTrackerCompat.getYVelocity(mVelocityTracker, mActivePointerId), 705 minLeft, maxLeft, minTop, maxTop); 706 707 setDragState(STATE_SETTLING); 708 } 709 710 /** 711 * Move the captured settling view by the appropriate amount for the current time. 712 * If <code>continueSettling</code> returns true, the caller should call it again 713 * on the next frame to continue. 714 * 715 * @param deferCallbacks true if state callbacks should be deferred via posted message. 716 * Set this to true if you are calling this method from 717 * {@link android.view.View#computeScroll()} or similar methods 718 * invoked as part of layout or drawing. 719 * @return true if settle is still in progress 720 */ 721 public boolean continueSettling(boolean deferCallbacks) { 722 if (mDragState == STATE_SETTLING) { 723 boolean keepGoing = mScroller.computeScrollOffset(); 724 final int x = mScroller.getCurrX(); 725 final int y = mScroller.getCurrY(); 726 final int dx = x - mCapturedView.getLeft(); 727 final int dy = y - mCapturedView.getTop(); 728 729 if (dx != 0) { 730 mCapturedView.offsetLeftAndRight(dx); 731 } 732 if (dy != 0) { 733 mCapturedView.offsetTopAndBottom(dy); 734 } 735 736 if (dx != 0 || dy != 0) { 737 mCallback.onViewPositionChanged(mCapturedView, x, y, dx, dy); 738 } 739 740 if (keepGoing && x == mScroller.getFinalX() && y == mScroller.getFinalY()) { 741 // Close enough. The interpolator/scroller might think we're still moving 742 // but the user sure doesn't. 743 mScroller.abortAnimation(); 744 keepGoing = false; 745 } 746 747 if (!keepGoing) { 748 if (deferCallbacks) { 749 mParentView.post(mSetIdleRunnable); 750 } else { 751 setDragState(STATE_IDLE); 752 } 753 } 754 } 755 756 return mDragState == STATE_SETTLING; 757 } 758 759 /** 760 * Like all callback events this must happen on the UI thread, but release 761 * involves some extra semantics. During a release (mReleaseInProgress) 762 * is the only time it is valid to call {@link #settleCapturedViewAt(int, int)} 763 * or {@link #flingCapturedView(int, int, int, int)}. 764 */ 765 private void dispatchViewReleased(float xvel, float yvel) { 766 mReleaseInProgress = true; 767 mCallback.onViewReleased(mCapturedView, xvel, yvel); 768 mReleaseInProgress = false; 769 770 if (mDragState == STATE_DRAGGING) { 771 // onViewReleased didn't call a method that would have changed this. Go idle. 772 setDragState(STATE_IDLE); 773 } 774 } 775 776 private void clearMotionHistory() { 777 if (mInitialMotionX == null) { 778 return; 779 } 780 Arrays.fill(mInitialMotionX, 0); 781 Arrays.fill(mInitialMotionY, 0); 782 Arrays.fill(mLastMotionX, 0); 783 Arrays.fill(mLastMotionY, 0); 784 Arrays.fill(mInitialEdgesTouched, 0); 785 Arrays.fill(mEdgeDragsInProgress, 0); 786 Arrays.fill(mEdgeDragsLocked, 0); 787 mPointersDown = 0; 788 } 789 790 private void clearMotionHistory(int pointerId) { 791 if (mInitialMotionX == null) { 792 return; 793 } 794 mInitialMotionX[pointerId] = 0; 795 mInitialMotionY[pointerId] = 0; 796 mLastMotionX[pointerId] = 0; 797 mLastMotionY[pointerId] = 0; 798 mInitialEdgesTouched[pointerId] = 0; 799 mEdgeDragsInProgress[pointerId] = 0; 800 mEdgeDragsLocked[pointerId] = 0; 801 mPointersDown &= ~(1 << pointerId); 802 } 803 804 private void ensureMotionHistorySizeForId(int pointerId) { 805 if (mInitialMotionX == null || mInitialMotionX.length <= pointerId) { 806 float[] imx = new float[pointerId + 1]; 807 float[] imy = new float[pointerId + 1]; 808 float[] lmx = new float[pointerId + 1]; 809 float[] lmy = new float[pointerId + 1]; 810 int[] iit = new int[pointerId + 1]; 811 int[] edip = new int[pointerId + 1]; 812 int[] edl = new int[pointerId + 1]; 813 814 if (mInitialMotionX != null) { 815 System.arraycopy(mInitialMotionX, 0, imx, 0, mInitialMotionX.length); 816 System.arraycopy(mInitialMotionY, 0, imy, 0, mInitialMotionY.length); 817 System.arraycopy(mLastMotionX, 0, lmx, 0, mLastMotionX.length); 818 System.arraycopy(mLastMotionY, 0, lmy, 0, mLastMotionY.length); 819 System.arraycopy(mInitialEdgesTouched, 0, iit, 0, mInitialEdgesTouched.length); 820 System.arraycopy(mEdgeDragsInProgress, 0, edip, 0, mEdgeDragsInProgress.length); 821 System.arraycopy(mEdgeDragsLocked, 0, edl, 0, mEdgeDragsLocked.length); 822 } 823 824 mInitialMotionX = imx; 825 mInitialMotionY = imy; 826 mLastMotionX = lmx; 827 mLastMotionY = lmy; 828 mInitialEdgesTouched = iit; 829 mEdgeDragsInProgress = edip; 830 mEdgeDragsLocked = edl; 831 } 832 } 833 834 private void saveInitialMotion(float x, float y, int pointerId) { 835 ensureMotionHistorySizeForId(pointerId); 836 mInitialMotionX[pointerId] = mLastMotionX[pointerId] = x; 837 mInitialMotionY[pointerId] = mLastMotionY[pointerId] = y; 838 mInitialEdgesTouched[pointerId] = getEdgesTouched((int) x, (int) y); 839 mPointersDown |= 1 << pointerId; 840 } 841 842 private void saveLastMotion(MotionEvent ev) { 843 final int pointerCount = MotionEventCompat.getPointerCount(ev); 844 for (int i = 0; i < pointerCount; i++) { 845 final int pointerId = MotionEventCompat.getPointerId(ev, i); 846 final float x = MotionEventCompat.getX(ev, i); 847 final float y = MotionEventCompat.getY(ev, i); 848 mLastMotionX[pointerId] = x; 849 mLastMotionY[pointerId] = y; 850 } 851 } 852 853 /** 854 * Check if the given pointer ID represents a pointer that is currently down (to the best 855 * of the ViewDragHelper's knowledge). 856 * 857 * <p>The state used to report this information is populated by the methods 858 * {@link #shouldInterceptTouchEvent(android.view.MotionEvent)} or 859 * {@link #processTouchEvent(android.view.MotionEvent)}. If one of these methods has not 860 * been called for all relevant MotionEvents to track, the information reported 861 * by this method may be stale or incorrect.</p> 862 * 863 * @param pointerId pointer ID to check; corresponds to IDs provided by MotionEvent 864 * @return true if the pointer with the given ID is still down 865 */ 866 public boolean isPointerDown(int pointerId) { 867 return (mPointersDown & 1 << pointerId) != 0; 868 } 869 870 void setDragState(int state) { 871 mParentView.removeCallbacks(mSetIdleRunnable); 872 if (mDragState != state) { 873 mDragState = state; 874 mCallback.onViewDragStateChanged(state); 875 if (mDragState == STATE_IDLE) { 876 mCapturedView = null; 877 } 878 } 879 } 880 881 /** 882 * Attempt to capture the view with the given pointer ID. The callback will be involved. 883 * This will put us into the "dragging" state. If we've already captured this view with 884 * this pointer this method will immediately return true without consulting the callback. 885 * 886 * @param toCapture View to capture 887 * @param pointerId Pointer to capture with 888 * @return true if capture was successful 889 */ 890 boolean tryCaptureViewForDrag(View toCapture, int pointerId) { 891 if (toCapture == mCapturedView && mActivePointerId == pointerId) { 892 // Already done! 893 return true; 894 } 895 if (toCapture != null && mCallback.tryCaptureView(toCapture, pointerId)) { 896 mActivePointerId = pointerId; 897 captureChildView(toCapture, pointerId); 898 return true; 899 } 900 return false; 901 } 902 903 /** 904 * Tests scrollability within child views of v given a delta of dx. 905 * 906 * @param v View to test for horizontal scrollability 907 * @param checkV Whether the view v passed should itself be checked for scrollability (true), 908 * or just its children (false). 909 * @param dx Delta scrolled in pixels along the X axis 910 * @param dy Delta scrolled in pixels along the Y axis 911 * @param x X coordinate of the active touch point 912 * @param y Y coordinate of the active touch point 913 * @return true if child views of v can be scrolled by delta of dx. 914 */ 915 protected boolean canScroll(View v, boolean checkV, int dx, int dy, int x, int y) { 916 if (v instanceof ViewGroup) { 917 final ViewGroup group = (ViewGroup) v; 918 final int scrollX = v.getScrollX(); 919 final int scrollY = v.getScrollY(); 920 final int count = group.getChildCount(); 921 // Count backwards - let topmost views consume scroll distance first. 922 for (int i = count - 1; i >= 0; i--) { 923 // TODO: Add versioned support here for transformed views. 924 // This will not work for transformed views in Honeycomb+ 925 final View child = group.getChildAt(i); 926 if (x + scrollX >= child.getLeft() && x + scrollX < child.getRight() && 927 y + scrollY >= child.getTop() && y + scrollY < child.getBottom() && 928 canScroll(child, true, dx, dy, x + scrollX - child.getLeft(), 929 y + scrollY - child.getTop())) { 930 return true; 931 } 932 } 933 } 934 935 return checkV && (ViewCompat.canScrollHorizontally(v, -dx) || 936 ViewCompat.canScrollVertically(v, -dy)); 937 } 938 939 /** 940 * Check if this event as provided to the parent view's onInterceptTouchEvent should 941 * cause the parent to intercept the touch event stream. 942 * 943 * @param ev MotionEvent provided to onInterceptTouchEvent 944 * @return true if the parent view should return true from onInterceptTouchEvent 945 */ 946 public boolean shouldInterceptTouchEvent(MotionEvent ev) { 947 final int action = MotionEventCompat.getActionMasked(ev); 948 final int actionIndex = MotionEventCompat.getActionIndex(ev); 949 950 if (action == MotionEvent.ACTION_DOWN) { 951 // Reset things for a new event stream, just in case we didn't get 952 // the whole previous stream. 953 cancel(); 954 } 955 956 if (mVelocityTracker == null) { 957 mVelocityTracker = VelocityTracker.obtain(); 958 } 959 mVelocityTracker.addMovement(ev); 960 961 switch (action) { 962 case MotionEvent.ACTION_DOWN: { 963 final float x = ev.getX(); 964 final float y = ev.getY(); 965 final int pointerId = MotionEventCompat.getPointerId(ev, 0); 966 saveInitialMotion(x, y, pointerId); 967 968 final View toCapture = findTopChildUnder((int) x, (int) y); 969 970 // Catch a settling view if possible. 971 if (toCapture == mCapturedView && mDragState == STATE_SETTLING) { 972 tryCaptureViewForDrag(toCapture, pointerId); 973 } 974 975 final int edgesTouched = mInitialEdgesTouched[pointerId]; 976 if ((edgesTouched & mTrackingEdges) != 0) { 977 mCallback.onEdgeTouched(edgesTouched & mTrackingEdges, pointerId); 978 } 979 break; 980 } 981 982 case MotionEventCompat.ACTION_POINTER_DOWN: { 983 final int pointerId = MotionEventCompat.getPointerId(ev, actionIndex); 984 final float x = MotionEventCompat.getX(ev, actionIndex); 985 final float y = MotionEventCompat.getY(ev, actionIndex); 986 987 saveInitialMotion(x, y, pointerId); 988 989 // A ViewDragHelper can only manipulate one view at a time. 990 if (mDragState == STATE_IDLE) { 991 final int edgesTouched = mInitialEdgesTouched[pointerId]; 992 if ((edgesTouched & mTrackingEdges) != 0) { 993 mCallback.onEdgeTouched(edgesTouched & mTrackingEdges, pointerId); 994 } 995 } else if (mDragState == STATE_SETTLING) { 996 // Catch a settling view if possible. 997 final View toCapture = findTopChildUnder((int) x, (int) y); 998 if (toCapture == mCapturedView) { 999 tryCaptureViewForDrag(toCapture, pointerId); 1000 } 1001 } 1002 break; 1003 } 1004 1005 case MotionEvent.ACTION_MOVE: { 1006 // First to cross a touch slop over a draggable view wins. Also report edge drags. 1007 final int pointerCount = MotionEventCompat.getPointerCount(ev); 1008 for (int i = 0; i < pointerCount; i++) { 1009 final int pointerId = MotionEventCompat.getPointerId(ev, i); 1010 final float x = MotionEventCompat.getX(ev, i); 1011 final float y = MotionEventCompat.getY(ev, i); 1012 final float dx = x - mInitialMotionX[pointerId]; 1013 final float dy = y - mInitialMotionY[pointerId]; 1014 1015 final View toCapture = findTopChildUnder((int) x, (int) y); 1016 final boolean pastSlop = toCapture != null && checkTouchSlop(toCapture, dx, dy); 1017 if (pastSlop) { 1018 // check the callback's 1019 // getView[Horizontal|Vertical]DragRange methods to know 1020 // if you can move at all along an axis, then see if it 1021 // would clamp to the same value. If you can't move at 1022 // all in every dimension with a nonzero range, bail. 1023 final int oldLeft = toCapture.getLeft(); 1024 final int targetLeft = oldLeft + (int) dx; 1025 final int newLeft = mCallback.clampViewPositionHorizontal(toCapture, 1026 targetLeft, (int) dx); 1027 final int oldTop = toCapture.getTop(); 1028 final int targetTop = oldTop + (int) dy; 1029 final int newTop = mCallback.clampViewPositionVertical(toCapture, targetTop, 1030 (int) dy); 1031 final int horizontalDragRange = mCallback.getViewHorizontalDragRange( 1032 toCapture); 1033 final int verticalDragRange = mCallback.getViewVerticalDragRange(toCapture); 1034 if ((horizontalDragRange == 0 || horizontalDragRange > 0 1035 && newLeft == oldLeft) && (verticalDragRange == 0 1036 || verticalDragRange > 0 && newTop == oldTop)) { 1037 break; 1038 } 1039 } 1040 reportNewEdgeDrags(dx, dy, pointerId); 1041 if (mDragState == STATE_DRAGGING) { 1042 // Callback might have started an edge drag 1043 break; 1044 } 1045 1046 if (pastSlop && tryCaptureViewForDrag(toCapture, pointerId)) { 1047 break; 1048 } 1049 } 1050 saveLastMotion(ev); 1051 break; 1052 } 1053 1054 case MotionEventCompat.ACTION_POINTER_UP: { 1055 final int pointerId = MotionEventCompat.getPointerId(ev, actionIndex); 1056 clearMotionHistory(pointerId); 1057 break; 1058 } 1059 1060 case MotionEvent.ACTION_UP: 1061 case MotionEvent.ACTION_CANCEL: { 1062 cancel(); 1063 break; 1064 } 1065 } 1066 1067 return mDragState == STATE_DRAGGING; 1068 } 1069 1070 /** 1071 * Process a touch event received by the parent view. This method will dispatch callback events 1072 * as needed before returning. The parent view's onTouchEvent implementation should call this. 1073 * 1074 * @param ev The touch event received by the parent view 1075 */ 1076 public void processTouchEvent(MotionEvent ev) { 1077 final int action = MotionEventCompat.getActionMasked(ev); 1078 final int actionIndex = MotionEventCompat.getActionIndex(ev); 1079 1080 if (action == MotionEvent.ACTION_DOWN) { 1081 // Reset things for a new event stream, just in case we didn't get 1082 // the whole previous stream. 1083 cancel(); 1084 } 1085 1086 if (mVelocityTracker == null) { 1087 mVelocityTracker = VelocityTracker.obtain(); 1088 } 1089 mVelocityTracker.addMovement(ev); 1090 1091 switch (action) { 1092 case MotionEvent.ACTION_DOWN: { 1093 final float x = ev.getX(); 1094 final float y = ev.getY(); 1095 final int pointerId = MotionEventCompat.getPointerId(ev, 0); 1096 final View toCapture = findTopChildUnder((int) x, (int) y); 1097 1098 saveInitialMotion(x, y, pointerId); 1099 1100 // Since the parent is already directly processing this touch event, 1101 // there is no reason to delay for a slop before dragging. 1102 // Start immediately if possible. 1103 tryCaptureViewForDrag(toCapture, pointerId); 1104 1105 final int edgesTouched = mInitialEdgesTouched[pointerId]; 1106 if ((edgesTouched & mTrackingEdges) != 0) { 1107 mCallback.onEdgeTouched(edgesTouched & mTrackingEdges, pointerId); 1108 } 1109 break; 1110 } 1111 1112 case MotionEventCompat.ACTION_POINTER_DOWN: { 1113 final int pointerId = MotionEventCompat.getPointerId(ev, actionIndex); 1114 final float x = MotionEventCompat.getX(ev, actionIndex); 1115 final float y = MotionEventCompat.getY(ev, actionIndex); 1116 1117 saveInitialMotion(x, y, pointerId); 1118 1119 // A ViewDragHelper can only manipulate one view at a time. 1120 if (mDragState == STATE_IDLE) { 1121 // If we're idle we can do anything! Treat it like a normal down event. 1122 1123 final View toCapture = findTopChildUnder((int) x, (int) y); 1124 tryCaptureViewForDrag(toCapture, pointerId); 1125 1126 final int edgesTouched = mInitialEdgesTouched[pointerId]; 1127 if ((edgesTouched & mTrackingEdges) != 0) { 1128 mCallback.onEdgeTouched(edgesTouched & mTrackingEdges, pointerId); 1129 } 1130 } else if (isCapturedViewUnder((int) x, (int) y)) { 1131 // We're still tracking a captured view. If the same view is under this 1132 // point, we'll swap to controlling it with this pointer instead. 1133 // (This will still work if we're "catching" a settling view.) 1134 1135 tryCaptureViewForDrag(mCapturedView, pointerId); 1136 } 1137 break; 1138 } 1139 1140 case MotionEvent.ACTION_MOVE: { 1141 if (mDragState == STATE_DRAGGING) { 1142 final int index = MotionEventCompat.findPointerIndex(ev, mActivePointerId); 1143 final float x = MotionEventCompat.getX(ev, index); 1144 final float y = MotionEventCompat.getY(ev, index); 1145 final int idx = (int) (x - mLastMotionX[mActivePointerId]); 1146 final int idy = (int) (y - mLastMotionY[mActivePointerId]); 1147 1148 dragTo(mCapturedView.getLeft() + idx, mCapturedView.getTop() + idy, idx, idy); 1149 1150 saveLastMotion(ev); 1151 } else { 1152 // Check to see if any pointer is now over a draggable view. 1153 final int pointerCount = MotionEventCompat.getPointerCount(ev); 1154 for (int i = 0; i < pointerCount; i++) { 1155 final int pointerId = MotionEventCompat.getPointerId(ev, i); 1156 final float x = MotionEventCompat.getX(ev, i); 1157 final float y = MotionEventCompat.getY(ev, i); 1158 final float dx = x - mInitialMotionX[pointerId]; 1159 final float dy = y - mInitialMotionY[pointerId]; 1160 1161 reportNewEdgeDrags(dx, dy, pointerId); 1162 if (mDragState == STATE_DRAGGING) { 1163 // Callback might have started an edge drag. 1164 break; 1165 } 1166 1167 final View toCapture = findTopChildUnder((int) x, (int) y); 1168 if (checkTouchSlop(toCapture, dx, dy) && 1169 tryCaptureViewForDrag(toCapture, pointerId)) { 1170 break; 1171 } 1172 } 1173 saveLastMotion(ev); 1174 } 1175 break; 1176 } 1177 1178 case MotionEventCompat.ACTION_POINTER_UP: { 1179 final int pointerId = MotionEventCompat.getPointerId(ev, actionIndex); 1180 if (mDragState == STATE_DRAGGING && pointerId == mActivePointerId) { 1181 // Try to find another pointer that's still holding on to the captured view. 1182 int newActivePointer = INVALID_POINTER; 1183 final int pointerCount = MotionEventCompat.getPointerCount(ev); 1184 for (int i = 0; i < pointerCount; i++) { 1185 final int id = MotionEventCompat.getPointerId(ev, i); 1186 if (id == mActivePointerId) { 1187 // This one's going away, skip. 1188 continue; 1189 } 1190 1191 final float x = MotionEventCompat.getX(ev, i); 1192 final float y = MotionEventCompat.getY(ev, i); 1193 if (findTopChildUnder((int) x, (int) y) == mCapturedView && 1194 tryCaptureViewForDrag(mCapturedView, id)) { 1195 newActivePointer = mActivePointerId; 1196 break; 1197 } 1198 } 1199 1200 if (newActivePointer == INVALID_POINTER) { 1201 // We didn't find another pointer still touching the view, release it. 1202 releaseViewForPointerUp(); 1203 } 1204 } 1205 clearMotionHistory(pointerId); 1206 break; 1207 } 1208 1209 case MotionEvent.ACTION_UP: { 1210 if (mDragState == STATE_DRAGGING) { 1211 releaseViewForPointerUp(); 1212 } 1213 cancel(); 1214 break; 1215 } 1216 1217 case MotionEvent.ACTION_CANCEL: { 1218 if (mDragState == STATE_DRAGGING) { 1219 dispatchViewReleased(0, 0); 1220 } 1221 cancel(); 1222 break; 1223 } 1224 } 1225 } 1226 1227 private void reportNewEdgeDrags(float dx, float dy, int pointerId) { 1228 int dragsStarted = 0; 1229 if (checkNewEdgeDrag(dx, dy, pointerId, EDGE_LEFT)) { 1230 dragsStarted |= EDGE_LEFT; 1231 } 1232 if (checkNewEdgeDrag(dy, dx, pointerId, EDGE_TOP)) { 1233 dragsStarted |= EDGE_TOP; 1234 } 1235 if (checkNewEdgeDrag(dx, dy, pointerId, EDGE_RIGHT)) { 1236 dragsStarted |= EDGE_RIGHT; 1237 } 1238 if (checkNewEdgeDrag(dy, dx, pointerId, EDGE_BOTTOM)) { 1239 dragsStarted |= EDGE_BOTTOM; 1240 } 1241 1242 if (dragsStarted != 0) { 1243 mEdgeDragsInProgress[pointerId] |= dragsStarted; 1244 mCallback.onEdgeDragStarted(dragsStarted, pointerId); 1245 } 1246 } 1247 1248 private boolean checkNewEdgeDrag(float delta, float odelta, int pointerId, int edge) { 1249 final float absDelta = Math.abs(delta); 1250 final float absODelta = Math.abs(odelta); 1251 1252 if ((mInitialEdgesTouched[pointerId] & edge) != edge || (mTrackingEdges & edge) == 0 || 1253 (mEdgeDragsLocked[pointerId] & edge) == edge || 1254 (mEdgeDragsInProgress[pointerId] & edge) == edge || 1255 (absDelta <= mTouchSlop && absODelta <= mTouchSlop)) { 1256 return false; 1257 } 1258 if (absDelta < absODelta * 0.5f && mCallback.onEdgeLock(edge)) { 1259 mEdgeDragsLocked[pointerId] |= edge; 1260 return false; 1261 } 1262 return (mEdgeDragsInProgress[pointerId] & edge) == 0 && absDelta > mTouchSlop; 1263 } 1264 1265 /** 1266 * Check if we've crossed a reasonable touch slop for the given child view. 1267 * If the child cannot be dragged along the horizontal or vertical axis, motion 1268 * along that axis will not count toward the slop check. 1269 * 1270 * @param child Child to check 1271 * @param dx Motion since initial position along X axis 1272 * @param dy Motion since initial position along Y axis 1273 * @return true if the touch slop has been crossed 1274 */ 1275 private boolean checkTouchSlop(View child, float dx, float dy) { 1276 if (child == null) { 1277 return false; 1278 } 1279 final boolean checkHorizontal = mCallback.getViewHorizontalDragRange(child) > 0; 1280 final boolean checkVertical = mCallback.getViewVerticalDragRange(child) > 0; 1281 1282 if (checkHorizontal && checkVertical) { 1283 return dx * dx + dy * dy > mTouchSlop * mTouchSlop; 1284 } else if (checkHorizontal) { 1285 return Math.abs(dx) > mTouchSlop; 1286 } else if (checkVertical) { 1287 return Math.abs(dy) > mTouchSlop; 1288 } 1289 return false; 1290 } 1291 1292 /** 1293 * Check if any pointer tracked in the current gesture has crossed 1294 * the required slop threshold. 1295 * 1296 * <p>This depends on internal state populated by 1297 * {@link #shouldInterceptTouchEvent(android.view.MotionEvent)} or 1298 * {@link #processTouchEvent(android.view.MotionEvent)}. You should only rely on 1299 * the results of this method after all currently available touch data 1300 * has been provided to one of these two methods.</p> 1301 * 1302 * @param directions Combination of direction flags, see {@link #DIRECTION_HORIZONTAL}, 1303 * {@link #DIRECTION_VERTICAL}, {@link #DIRECTION_ALL} 1304 * @return true if the slop threshold has been crossed, false otherwise 1305 */ 1306 public boolean checkTouchSlop(int directions) { 1307 final int count = mInitialMotionX.length; 1308 for (int i = 0; i < count; i++) { 1309 if (checkTouchSlop(directions, i)) { 1310 return true; 1311 } 1312 } 1313 return false; 1314 } 1315 1316 /** 1317 * Check if the specified pointer tracked in the current gesture has crossed 1318 * the required slop threshold. 1319 * 1320 * <p>This depends on internal state populated by 1321 * {@link #shouldInterceptTouchEvent(android.view.MotionEvent)} or 1322 * {@link #processTouchEvent(android.view.MotionEvent)}. You should only rely on 1323 * the results of this method after all currently available touch data 1324 * has been provided to one of these two methods.</p> 1325 * 1326 * @param directions Combination of direction flags, see {@link #DIRECTION_HORIZONTAL}, 1327 * {@link #DIRECTION_VERTICAL}, {@link #DIRECTION_ALL} 1328 * @param pointerId ID of the pointer to slop check as specified by MotionEvent 1329 * @return true if the slop threshold has been crossed, false otherwise 1330 */ 1331 public boolean checkTouchSlop(int directions, int pointerId) { 1332 if (!isPointerDown(pointerId)) { 1333 return false; 1334 } 1335 1336 final boolean checkHorizontal = (directions & DIRECTION_HORIZONTAL) == DIRECTION_HORIZONTAL; 1337 final boolean checkVertical = (directions & DIRECTION_VERTICAL) == DIRECTION_VERTICAL; 1338 1339 final float dx = mLastMotionX[pointerId] - mInitialMotionX[pointerId]; 1340 final float dy = mLastMotionY[pointerId] - mInitialMotionY[pointerId]; 1341 1342 if (checkHorizontal && checkVertical) { 1343 return dx * dx + dy * dy > mTouchSlop * mTouchSlop; 1344 } else if (checkHorizontal) { 1345 return Math.abs(dx) > mTouchSlop; 1346 } else if (checkVertical) { 1347 return Math.abs(dy) > mTouchSlop; 1348 } 1349 return false; 1350 } 1351 1352 /** 1353 * Check if any of the edges specified were initially touched in the currently active gesture. 1354 * If there is no currently active gesture this method will return false. 1355 * 1356 * @param edges Edges to check for an initial edge touch. See {@link #EDGE_LEFT}, 1357 * {@link #EDGE_TOP}, {@link #EDGE_RIGHT}, {@link #EDGE_BOTTOM} and 1358 * {@link #EDGE_ALL} 1359 * @return true if any of the edges specified were initially touched in the current gesture 1360 */ 1361 public boolean isEdgeTouched(int edges) { 1362 final int count = mInitialEdgesTouched.length; 1363 for (int i = 0; i < count; i++) { 1364 if (isEdgeTouched(edges, i)) { 1365 return true; 1366 } 1367 } 1368 return false; 1369 } 1370 1371 /** 1372 * Check if any of the edges specified were initially touched by the pointer with 1373 * the specified ID. If there is no currently active gesture or if there is no pointer with 1374 * the given ID currently down this method will return false. 1375 * 1376 * @param edges Edges to check for an initial edge touch. See {@link #EDGE_LEFT}, 1377 * {@link #EDGE_TOP}, {@link #EDGE_RIGHT}, {@link #EDGE_BOTTOM} and 1378 * {@link #EDGE_ALL} 1379 * @return true if any of the edges specified were initially touched in the current gesture 1380 */ 1381 public boolean isEdgeTouched(int edges, int pointerId) { 1382 return isPointerDown(pointerId) && (mInitialEdgesTouched[pointerId] & edges) != 0; 1383 } 1384 1385 private void releaseViewForPointerUp() { 1386 mVelocityTracker.computeCurrentVelocity(1000, mMaxVelocity); 1387 final float xvel = clampMag( 1388 VelocityTrackerCompat.getXVelocity(mVelocityTracker, mActivePointerId), 1389 mMinVelocity, mMaxVelocity); 1390 final float yvel = clampMag( 1391 VelocityTrackerCompat.getYVelocity(mVelocityTracker, mActivePointerId), 1392 mMinVelocity, mMaxVelocity); 1393 dispatchViewReleased(xvel, yvel); 1394 } 1395 1396 private void dragTo(int left, int top, int dx, int dy) { 1397 int clampedX = left; 1398 int clampedY = top; 1399 final int oldLeft = mCapturedView.getLeft(); 1400 final int oldTop = mCapturedView.getTop(); 1401 if (dx != 0) { 1402 clampedX = mCallback.clampViewPositionHorizontal(mCapturedView, left, dx); 1403 mCapturedView.offsetLeftAndRight(clampedX - oldLeft); 1404 } 1405 if (dy != 0) { 1406 clampedY = mCallback.clampViewPositionVertical(mCapturedView, top, dy); 1407 mCapturedView.offsetTopAndBottom(clampedY - oldTop); 1408 } 1409 1410 if (dx != 0 || dy != 0) { 1411 final int clampedDx = clampedX - oldLeft; 1412 final int clampedDy = clampedY - oldTop; 1413 mCallback.onViewPositionChanged(mCapturedView, clampedX, clampedY, 1414 clampedDx, clampedDy); 1415 } 1416 } 1417 1418 /** 1419 * Determine if the currently captured view is under the given point in the 1420 * parent view's coordinate system. If there is no captured view this method 1421 * will return false. 1422 * 1423 * @param x X position to test in the parent's coordinate system 1424 * @param y Y position to test in the parent's coordinate system 1425 * @return true if the captured view is under the given point, false otherwise 1426 */ 1427 public boolean isCapturedViewUnder(int x, int y) { 1428 return isViewUnder(mCapturedView, x, y); 1429 } 1430 1431 /** 1432 * Determine if the supplied view is under the given point in the 1433 * parent view's coordinate system. 1434 * 1435 * @param view Child view of the parent to hit test 1436 * @param x X position to test in the parent's coordinate system 1437 * @param y Y position to test in the parent's coordinate system 1438 * @return true if the supplied view is under the given point, false otherwise 1439 */ 1440 public boolean isViewUnder(View view, int x, int y) { 1441 if (view == null) { 1442 return false; 1443 } 1444 return x >= view.getLeft() && 1445 x < view.getRight() && 1446 y >= view.getTop() && 1447 y < view.getBottom(); 1448 } 1449 1450 /** 1451 * Find the topmost child under the given point within the parent view's coordinate system. 1452 * The child order is determined using {@link Callback#getOrderedChildIndex(int)}. 1453 * 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 The topmost child view under (x, y) or null if none found. 1457 */ 1458 public View findTopChildUnder(int x, int y) { 1459 final int childCount = mParentView.getChildCount(); 1460 for (int i = childCount - 1; i >= 0; i--) { 1461 final View child = mParentView.getChildAt(mCallback.getOrderedChildIndex(i)); 1462 if (x >= child.getLeft() && x < child.getRight() && 1463 y >= child.getTop() && y < child.getBottom()) { 1464 return child; 1465 } 1466 } 1467 return null; 1468 } 1469 1470 private int getEdgesTouched(int x, int y) { 1471 int result = 0; 1472 1473 if (x < mParentView.getLeft() + mEdgeSize) result |= EDGE_LEFT; 1474 if (y < mParentView.getTop() + mEdgeSize) result |= EDGE_TOP; 1475 if (x > mParentView.getRight() - mEdgeSize) result |= EDGE_RIGHT; 1476 if (y > mParentView.getBottom() - mEdgeSize) result |= EDGE_BOTTOM; 1477 1478 return result; 1479 } 1480}