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 android.support.v4.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.view.MotionEvent; 25 import android.view.VelocityTracker; 26 import android.view.View; 27 import android.view.ViewConfiguration; 28 import android.view.ViewGroup; 29 import android.view.animation.Interpolator; 30 31 import 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 */ 38 public 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 */ onViewDragStateChanged(int state)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 */ onViewPositionChanged(View changedView, int left, int top, int dx, int dy)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 */ onViewCaptured(View capturedChild, int activePointerId)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 */ onViewReleased(View releasedChild, float xvel, float yvel)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 */ onEdgeTouched(int edgeFlags, int pointerId)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 */ onEdgeLock(int edgeFlags)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 */ onEdgeDragStarted(int edgeFlags, int pointerId)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 */ getOrderedChildIndex(int index)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 */ getViewHorizontalDragRange(View child)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 */ getViewVerticalDragRange(View child)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 */ tryCaptureView(View child, int pointerId)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 */ clampViewPositionHorizontal(View child, int left, int dx)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 */ clampViewPositionVertical(View child, int top, int dy)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 */ create(ViewGroup forParent, Callback cb)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 */ create(ViewGroup forParent, float sensitivity, Callback cb)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 */ ViewDragHelper(Context context, ViewGroup forParent, Callback cb)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 */ setMinVelocity(float minVel)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 */ getMinVelocity()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 */ getViewDragState()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 */ setEdgeTrackingEnabled(int edgeFlags)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 */ getEdgeSize()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 */ captureChildView(View childView, int activePointerId)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 */ getCapturedView()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 */ getActivePointerId()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 */ getTouchSlop()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 */ cancel()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 */ abort()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 */ smoothSlideViewTo(View child, int finalLeft, int finalTop)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 */ 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); 598 599 setDragState(STATE_SETTLING); 600 return true; 601 } 602 computeSettleDuration(View child, int dx, int dy, int xvel, int yvel)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 computeAxisDuration(int delta, int velocity, int motionRange)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 */ clampMag(int value, int absMin, int absMax)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 */ clampMag(float value, float absMin, float absMax)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 distanceInfluenceForSnapDuration(float f)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 */ flingCapturedView(int minLeft, int minTop, int maxLeft, int maxTop)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 */ continueSettling(boolean deferCallbacks)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 */ dispatchViewReleased(float xvel, float yvel)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 clearMotionHistory()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 clearMotionHistory(int pointerId)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 ensureMotionHistorySizeForId(int pointerId)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 saveInitialMotion(float x, float y, int pointerId)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 saveLastMotion(MotionEvent ev)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 */ isPointerDown(int pointerId)866 public boolean isPointerDown(int pointerId) { 867 return (mPointersDown & 1 << pointerId) != 0; 868 } 869 setDragState(int state)870 void setDragState(int state) { 871 if (mDragState != state) { 872 mDragState = state; 873 mCallback.onViewDragStateChanged(state); 874 if (mDragState == STATE_IDLE) { 875 mCapturedView = null; 876 } 877 } 878 } 879 880 /** 881 * Attempt to capture the view with the given pointer ID. The callback will be involved. 882 * This will put us into the "dragging" state. If we've already captured this view with 883 * this pointer this method will immediately return true without consulting the callback. 884 * 885 * @param toCapture View to capture 886 * @param pointerId Pointer to capture with 887 * @return true if capture was successful 888 */ tryCaptureViewForDrag(View toCapture, int pointerId)889 boolean tryCaptureViewForDrag(View toCapture, int pointerId) { 890 if (toCapture == mCapturedView && mActivePointerId == pointerId) { 891 // Already done! 892 return true; 893 } 894 if (toCapture != null && mCallback.tryCaptureView(toCapture, pointerId)) { 895 mActivePointerId = pointerId; 896 captureChildView(toCapture, pointerId); 897 return true; 898 } 899 return false; 900 } 901 902 /** 903 * Tests scrollability within child views of v given a delta of dx. 904 * 905 * @param v View to test for horizontal scrollability 906 * @param checkV Whether the view v passed should itself be checked for scrollability (true), 907 * or just its children (false). 908 * @param dx Delta scrolled in pixels along the X axis 909 * @param dy Delta scrolled in pixels along the Y axis 910 * @param x X coordinate of the active touch point 911 * @param y Y coordinate of the active touch point 912 * @return true if child views of v can be scrolled by delta of dx. 913 */ canScroll(View v, boolean checkV, int dx, int dy, int x, int y)914 protected boolean canScroll(View v, boolean checkV, int dx, int dy, int x, int y) { 915 if (v instanceof ViewGroup) { 916 final ViewGroup group = (ViewGroup) v; 917 final int scrollX = v.getScrollX(); 918 final int scrollY = v.getScrollY(); 919 final int count = group.getChildCount(); 920 // Count backwards - let topmost views consume scroll distance first. 921 for (int i = count - 1; i >= 0; i--) { 922 // TODO: Add versioned support here for transformed views. 923 // This will not work for transformed views in Honeycomb+ 924 final View child = group.getChildAt(i); 925 if (x + scrollX >= child.getLeft() && x + scrollX < child.getRight() && 926 y + scrollY >= child.getTop() && y + scrollY < child.getBottom() && 927 canScroll(child, true, dx, dy, x + scrollX - child.getLeft(), 928 y + scrollY - child.getTop())) { 929 return true; 930 } 931 } 932 } 933 934 return checkV && (ViewCompat.canScrollHorizontally(v, -dx) || 935 ViewCompat.canScrollVertically(v, -dy)); 936 } 937 938 /** 939 * Check if this event as provided to the parent view's onInterceptTouchEvent should 940 * cause the parent to intercept the touch event stream. 941 * 942 * @param ev MotionEvent provided to onInterceptTouchEvent 943 * @return true if the parent view should return true from onInterceptTouchEvent 944 */ shouldInterceptTouchEvent(MotionEvent ev)945 public boolean shouldInterceptTouchEvent(MotionEvent ev) { 946 final int action = MotionEventCompat.getActionMasked(ev); 947 final int actionIndex = MotionEventCompat.getActionIndex(ev); 948 949 if (action == MotionEvent.ACTION_DOWN) { 950 // Reset things for a new event stream, just in case we didn't get 951 // the whole previous stream. 952 cancel(); 953 } 954 955 if (mVelocityTracker == null) { 956 mVelocityTracker = VelocityTracker.obtain(); 957 } 958 mVelocityTracker.addMovement(ev); 959 960 switch (action) { 961 case MotionEvent.ACTION_DOWN: { 962 final float x = ev.getX(); 963 final float y = ev.getY(); 964 final int pointerId = MotionEventCompat.getPointerId(ev, 0); 965 saveInitialMotion(x, y, pointerId); 966 967 final View toCapture = findTopChildUnder((int) x, (int) y); 968 969 // Catch a settling view if possible. 970 if (toCapture == mCapturedView && mDragState == STATE_SETTLING) { 971 tryCaptureViewForDrag(toCapture, pointerId); 972 } 973 974 final int edgesTouched = mInitialEdgesTouched[pointerId]; 975 if ((edgesTouched & mTrackingEdges) != 0) { 976 mCallback.onEdgeTouched(edgesTouched & mTrackingEdges, pointerId); 977 } 978 break; 979 } 980 981 case MotionEventCompat.ACTION_POINTER_DOWN: { 982 final int pointerId = MotionEventCompat.getPointerId(ev, actionIndex); 983 final float x = MotionEventCompat.getX(ev, actionIndex); 984 final float y = MotionEventCompat.getY(ev, actionIndex); 985 986 saveInitialMotion(x, y, pointerId); 987 988 // A ViewDragHelper can only manipulate one view at a time. 989 if (mDragState == STATE_IDLE) { 990 final int edgesTouched = mInitialEdgesTouched[pointerId]; 991 if ((edgesTouched & mTrackingEdges) != 0) { 992 mCallback.onEdgeTouched(edgesTouched & mTrackingEdges, pointerId); 993 } 994 } else if (mDragState == STATE_SETTLING) { 995 // Catch a settling view if possible. 996 final View toCapture = findTopChildUnder((int) x, (int) y); 997 if (toCapture == mCapturedView) { 998 tryCaptureViewForDrag(toCapture, pointerId); 999 } 1000 } 1001 break; 1002 } 1003 1004 case MotionEvent.ACTION_MOVE: { 1005 // First to cross a touch slop over a draggable view wins. Also report edge drags. 1006 final int pointerCount = MotionEventCompat.getPointerCount(ev); 1007 for (int i = 0; i < pointerCount; i++) { 1008 final int pointerId = MotionEventCompat.getPointerId(ev, i); 1009 final float x = MotionEventCompat.getX(ev, i); 1010 final float y = MotionEventCompat.getY(ev, i); 1011 final float dx = x - mInitialMotionX[pointerId]; 1012 final float dy = y - mInitialMotionY[pointerId]; 1013 1014 final View toCapture = findTopChildUnder((int) x, (int) y); 1015 final boolean pastSlop = toCapture != null && checkTouchSlop(toCapture, dx, dy); 1016 if (pastSlop) { 1017 // check the callback's 1018 // getView[Horizontal|Vertical]DragRange methods to know 1019 // if you can move at all along an axis, then see if it 1020 // would clamp to the same value. If you can't move at 1021 // all in every dimension with a nonzero range, bail. 1022 final int oldLeft = toCapture.getLeft(); 1023 final int targetLeft = oldLeft + (int) dx; 1024 final int newLeft = mCallback.clampViewPositionHorizontal(toCapture, 1025 targetLeft, (int) dx); 1026 final int oldTop = toCapture.getTop(); 1027 final int targetTop = oldTop + (int) dy; 1028 final int newTop = mCallback.clampViewPositionVertical(toCapture, targetTop, 1029 (int) dy); 1030 final int horizontalDragRange = mCallback.getViewHorizontalDragRange( 1031 toCapture); 1032 final int verticalDragRange = mCallback.getViewVerticalDragRange(toCapture); 1033 if ((horizontalDragRange == 0 || horizontalDragRange > 0 1034 && newLeft == oldLeft) && (verticalDragRange == 0 1035 || verticalDragRange > 0 && newTop == oldTop)) { 1036 break; 1037 } 1038 } 1039 reportNewEdgeDrags(dx, dy, pointerId); 1040 if (mDragState == STATE_DRAGGING) { 1041 // Callback might have started an edge drag 1042 break; 1043 } 1044 1045 if (pastSlop && tryCaptureViewForDrag(toCapture, pointerId)) { 1046 break; 1047 } 1048 } 1049 saveLastMotion(ev); 1050 break; 1051 } 1052 1053 case MotionEventCompat.ACTION_POINTER_UP: { 1054 final int pointerId = MotionEventCompat.getPointerId(ev, actionIndex); 1055 clearMotionHistory(pointerId); 1056 break; 1057 } 1058 1059 case MotionEvent.ACTION_UP: 1060 case MotionEvent.ACTION_CANCEL: { 1061 cancel(); 1062 break; 1063 } 1064 } 1065 1066 return mDragState == STATE_DRAGGING; 1067 } 1068 1069 /** 1070 * Process a touch event received by the parent view. This method will dispatch callback events 1071 * as needed before returning. The parent view's onTouchEvent implementation should call this. 1072 * 1073 * @param ev The touch event received by the parent view 1074 */ processTouchEvent(MotionEvent ev)1075 public void processTouchEvent(MotionEvent ev) { 1076 final int action = MotionEventCompat.getActionMasked(ev); 1077 final int actionIndex = MotionEventCompat.getActionIndex(ev); 1078 1079 if (action == MotionEvent.ACTION_DOWN) { 1080 // Reset things for a new event stream, just in case we didn't get 1081 // the whole previous stream. 1082 cancel(); 1083 } 1084 1085 if (mVelocityTracker == null) { 1086 mVelocityTracker = VelocityTracker.obtain(); 1087 } 1088 mVelocityTracker.addMovement(ev); 1089 1090 switch (action) { 1091 case MotionEvent.ACTION_DOWN: { 1092 final float x = ev.getX(); 1093 final float y = ev.getY(); 1094 final int pointerId = MotionEventCompat.getPointerId(ev, 0); 1095 final View toCapture = findTopChildUnder((int) x, (int) y); 1096 1097 saveInitialMotion(x, y, pointerId); 1098 1099 // Since the parent is already directly processing this touch event, 1100 // there is no reason to delay for a slop before dragging. 1101 // Start immediately if possible. 1102 tryCaptureViewForDrag(toCapture, pointerId); 1103 1104 final int edgesTouched = mInitialEdgesTouched[pointerId]; 1105 if ((edgesTouched & mTrackingEdges) != 0) { 1106 mCallback.onEdgeTouched(edgesTouched & mTrackingEdges, pointerId); 1107 } 1108 break; 1109 } 1110 1111 case MotionEventCompat.ACTION_POINTER_DOWN: { 1112 final int pointerId = MotionEventCompat.getPointerId(ev, actionIndex); 1113 final float x = MotionEventCompat.getX(ev, actionIndex); 1114 final float y = MotionEventCompat.getY(ev, actionIndex); 1115 1116 saveInitialMotion(x, y, pointerId); 1117 1118 // A ViewDragHelper can only manipulate one view at a time. 1119 if (mDragState == STATE_IDLE) { 1120 // If we're idle we can do anything! Treat it like a normal down event. 1121 1122 final View toCapture = findTopChildUnder((int) x, (int) y); 1123 tryCaptureViewForDrag(toCapture, pointerId); 1124 1125 final int edgesTouched = mInitialEdgesTouched[pointerId]; 1126 if ((edgesTouched & mTrackingEdges) != 0) { 1127 mCallback.onEdgeTouched(edgesTouched & mTrackingEdges, pointerId); 1128 } 1129 } else if (isCapturedViewUnder((int) x, (int) y)) { 1130 // We're still tracking a captured view. If the same view is under this 1131 // point, we'll swap to controlling it with this pointer instead. 1132 // (This will still work if we're "catching" a settling view.) 1133 1134 tryCaptureViewForDrag(mCapturedView, pointerId); 1135 } 1136 break; 1137 } 1138 1139 case MotionEvent.ACTION_MOVE: { 1140 if (mDragState == STATE_DRAGGING) { 1141 final int index = MotionEventCompat.findPointerIndex(ev, mActivePointerId); 1142 final float x = MotionEventCompat.getX(ev, index); 1143 final float y = MotionEventCompat.getY(ev, index); 1144 final int idx = (int) (x - mLastMotionX[mActivePointerId]); 1145 final int idy = (int) (y - mLastMotionY[mActivePointerId]); 1146 1147 dragTo(mCapturedView.getLeft() + idx, mCapturedView.getTop() + idy, idx, idy); 1148 1149 saveLastMotion(ev); 1150 } else { 1151 // Check to see if any pointer is now over a draggable view. 1152 final int pointerCount = MotionEventCompat.getPointerCount(ev); 1153 for (int i = 0; i < pointerCount; i++) { 1154 final int pointerId = MotionEventCompat.getPointerId(ev, i); 1155 final float x = MotionEventCompat.getX(ev, i); 1156 final float y = MotionEventCompat.getY(ev, i); 1157 final float dx = x - mInitialMotionX[pointerId]; 1158 final float dy = y - mInitialMotionY[pointerId]; 1159 1160 reportNewEdgeDrags(dx, dy, pointerId); 1161 if (mDragState == STATE_DRAGGING) { 1162 // Callback might have started an edge drag. 1163 break; 1164 } 1165 1166 final View toCapture = findTopChildUnder((int) x, (int) y); 1167 if (checkTouchSlop(toCapture, dx, dy) && 1168 tryCaptureViewForDrag(toCapture, pointerId)) { 1169 break; 1170 } 1171 } 1172 saveLastMotion(ev); 1173 } 1174 break; 1175 } 1176 1177 case MotionEventCompat.ACTION_POINTER_UP: { 1178 final int pointerId = MotionEventCompat.getPointerId(ev, actionIndex); 1179 if (mDragState == STATE_DRAGGING && pointerId == mActivePointerId) { 1180 // Try to find another pointer that's still holding on to the captured view. 1181 int newActivePointer = INVALID_POINTER; 1182 final int pointerCount = MotionEventCompat.getPointerCount(ev); 1183 for (int i = 0; i < pointerCount; i++) { 1184 final int id = MotionEventCompat.getPointerId(ev, i); 1185 if (id == mActivePointerId) { 1186 // This one's going away, skip. 1187 continue; 1188 } 1189 1190 final float x = MotionEventCompat.getX(ev, i); 1191 final float y = MotionEventCompat.getY(ev, i); 1192 if (findTopChildUnder((int) x, (int) y) == mCapturedView && 1193 tryCaptureViewForDrag(mCapturedView, id)) { 1194 newActivePointer = mActivePointerId; 1195 break; 1196 } 1197 } 1198 1199 if (newActivePointer == INVALID_POINTER) { 1200 // We didn't find another pointer still touching the view, release it. 1201 releaseViewForPointerUp(); 1202 } 1203 } 1204 clearMotionHistory(pointerId); 1205 break; 1206 } 1207 1208 case MotionEvent.ACTION_UP: { 1209 if (mDragState == STATE_DRAGGING) { 1210 releaseViewForPointerUp(); 1211 } 1212 cancel(); 1213 break; 1214 } 1215 1216 case MotionEvent.ACTION_CANCEL: { 1217 if (mDragState == STATE_DRAGGING) { 1218 dispatchViewReleased(0, 0); 1219 } 1220 cancel(); 1221 break; 1222 } 1223 } 1224 } 1225 reportNewEdgeDrags(float dx, float dy, int pointerId)1226 private void reportNewEdgeDrags(float dx, float dy, int pointerId) { 1227 int dragsStarted = 0; 1228 if (checkNewEdgeDrag(dx, dy, pointerId, EDGE_LEFT)) { 1229 dragsStarted |= EDGE_LEFT; 1230 } 1231 if (checkNewEdgeDrag(dy, dx, pointerId, EDGE_TOP)) { 1232 dragsStarted |= EDGE_TOP; 1233 } 1234 if (checkNewEdgeDrag(dx, dy, pointerId, EDGE_RIGHT)) { 1235 dragsStarted |= EDGE_RIGHT; 1236 } 1237 if (checkNewEdgeDrag(dy, dx, pointerId, EDGE_BOTTOM)) { 1238 dragsStarted |= EDGE_BOTTOM; 1239 } 1240 1241 if (dragsStarted != 0) { 1242 mEdgeDragsInProgress[pointerId] |= dragsStarted; 1243 mCallback.onEdgeDragStarted(dragsStarted, pointerId); 1244 } 1245 } 1246 checkNewEdgeDrag(float delta, float odelta, int pointerId, int edge)1247 private boolean checkNewEdgeDrag(float delta, float odelta, int pointerId, int edge) { 1248 final float absDelta = Math.abs(delta); 1249 final float absODelta = Math.abs(odelta); 1250 1251 if ((mInitialEdgesTouched[pointerId] & edge) != edge || (mTrackingEdges & edge) == 0 || 1252 (mEdgeDragsLocked[pointerId] & edge) == edge || 1253 (mEdgeDragsInProgress[pointerId] & edge) == edge || 1254 (absDelta <= mTouchSlop && absODelta <= mTouchSlop)) { 1255 return false; 1256 } 1257 if (absDelta < absODelta * 0.5f && mCallback.onEdgeLock(edge)) { 1258 mEdgeDragsLocked[pointerId] |= edge; 1259 return false; 1260 } 1261 return (mEdgeDragsInProgress[pointerId] & edge) == 0 && absDelta > mTouchSlop; 1262 } 1263 1264 /** 1265 * Check if we've crossed a reasonable touch slop for the given child view. 1266 * If the child cannot be dragged along the horizontal or vertical axis, motion 1267 * along that axis will not count toward the slop check. 1268 * 1269 * @param child Child to check 1270 * @param dx Motion since initial position along X axis 1271 * @param dy Motion since initial position along Y axis 1272 * @return true if the touch slop has been crossed 1273 */ checkTouchSlop(View child, float dx, float dy)1274 private boolean checkTouchSlop(View child, float dx, float dy) { 1275 if (child == null) { 1276 return false; 1277 } 1278 final boolean checkHorizontal = mCallback.getViewHorizontalDragRange(child) > 0; 1279 final boolean checkVertical = mCallback.getViewVerticalDragRange(child) > 0; 1280 1281 if (checkHorizontal && checkVertical) { 1282 return dx * dx + dy * dy > mTouchSlop * mTouchSlop; 1283 } else if (checkHorizontal) { 1284 return Math.abs(dx) > mTouchSlop; 1285 } else if (checkVertical) { 1286 return Math.abs(dy) > mTouchSlop; 1287 } 1288 return false; 1289 } 1290 1291 /** 1292 * Check if any pointer tracked in the current gesture has crossed 1293 * the required slop threshold. 1294 * 1295 * <p>This depends on internal state populated by 1296 * {@link #shouldInterceptTouchEvent(android.view.MotionEvent)} or 1297 * {@link #processTouchEvent(android.view.MotionEvent)}. You should only rely on 1298 * the results of this method after all currently available touch data 1299 * has been provided to one of these two methods.</p> 1300 * 1301 * @param directions Combination of direction flags, see {@link #DIRECTION_HORIZONTAL}, 1302 * {@link #DIRECTION_VERTICAL}, {@link #DIRECTION_ALL} 1303 * @return true if the slop threshold has been crossed, false otherwise 1304 */ checkTouchSlop(int directions)1305 public boolean checkTouchSlop(int directions) { 1306 final int count = mInitialMotionX.length; 1307 for (int i = 0; i < count; i++) { 1308 if (checkTouchSlop(directions, i)) { 1309 return true; 1310 } 1311 } 1312 return false; 1313 } 1314 1315 /** 1316 * Check if the specified pointer tracked in the current gesture has crossed 1317 * the required slop threshold. 1318 * 1319 * <p>This depends on internal state populated by 1320 * {@link #shouldInterceptTouchEvent(android.view.MotionEvent)} or 1321 * {@link #processTouchEvent(android.view.MotionEvent)}. You should only rely on 1322 * the results of this method after all currently available touch data 1323 * has been provided to one of these two methods.</p> 1324 * 1325 * @param directions Combination of direction flags, see {@link #DIRECTION_HORIZONTAL}, 1326 * {@link #DIRECTION_VERTICAL}, {@link #DIRECTION_ALL} 1327 * @param pointerId ID of the pointer to slop check as specified by MotionEvent 1328 * @return true if the slop threshold has been crossed, false otherwise 1329 */ checkTouchSlop(int directions, int pointerId)1330 public boolean checkTouchSlop(int directions, int pointerId) { 1331 if (!isPointerDown(pointerId)) { 1332 return false; 1333 } 1334 1335 final boolean checkHorizontal = (directions & DIRECTION_HORIZONTAL) == DIRECTION_HORIZONTAL; 1336 final boolean checkVertical = (directions & DIRECTION_VERTICAL) == DIRECTION_VERTICAL; 1337 1338 final float dx = mLastMotionX[pointerId] - mInitialMotionX[pointerId]; 1339 final float dy = mLastMotionY[pointerId] - mInitialMotionY[pointerId]; 1340 1341 if (checkHorizontal && checkVertical) { 1342 return dx * dx + dy * dy > mTouchSlop * mTouchSlop; 1343 } else if (checkHorizontal) { 1344 return Math.abs(dx) > mTouchSlop; 1345 } else if (checkVertical) { 1346 return Math.abs(dy) > mTouchSlop; 1347 } 1348 return false; 1349 } 1350 1351 /** 1352 * Check if any of the edges specified were initially touched in the currently active gesture. 1353 * If there is no currently active gesture this method will return false. 1354 * 1355 * @param edges Edges to check for an initial edge touch. See {@link #EDGE_LEFT}, 1356 * {@link #EDGE_TOP}, {@link #EDGE_RIGHT}, {@link #EDGE_BOTTOM} and 1357 * {@link #EDGE_ALL} 1358 * @return true if any of the edges specified were initially touched in the current gesture 1359 */ isEdgeTouched(int edges)1360 public boolean isEdgeTouched(int edges) { 1361 final int count = mInitialEdgesTouched.length; 1362 for (int i = 0; i < count; i++) { 1363 if (isEdgeTouched(edges, i)) { 1364 return true; 1365 } 1366 } 1367 return false; 1368 } 1369 1370 /** 1371 * Check if any of the edges specified were initially touched by the pointer with 1372 * the specified ID. If there is no currently active gesture or if there is no pointer with 1373 * the given ID currently down this method will return false. 1374 * 1375 * @param edges Edges to check for an initial edge touch. See {@link #EDGE_LEFT}, 1376 * {@link #EDGE_TOP}, {@link #EDGE_RIGHT}, {@link #EDGE_BOTTOM} and 1377 * {@link #EDGE_ALL} 1378 * @return true if any of the edges specified were initially touched in the current gesture 1379 */ isEdgeTouched(int edges, int pointerId)1380 public boolean isEdgeTouched(int edges, int pointerId) { 1381 return isPointerDown(pointerId) && (mInitialEdgesTouched[pointerId] & edges) != 0; 1382 } 1383 releaseViewForPointerUp()1384 private void releaseViewForPointerUp() { 1385 mVelocityTracker.computeCurrentVelocity(1000, mMaxVelocity); 1386 final float xvel = clampMag( 1387 VelocityTrackerCompat.getXVelocity(mVelocityTracker, mActivePointerId), 1388 mMinVelocity, mMaxVelocity); 1389 final float yvel = clampMag( 1390 VelocityTrackerCompat.getYVelocity(mVelocityTracker, mActivePointerId), 1391 mMinVelocity, mMaxVelocity); 1392 dispatchViewReleased(xvel, yvel); 1393 } 1394 dragTo(int left, int top, int dx, int dy)1395 private void dragTo(int left, int top, int dx, int dy) { 1396 int clampedX = left; 1397 int clampedY = top; 1398 final int oldLeft = mCapturedView.getLeft(); 1399 final int oldTop = mCapturedView.getTop(); 1400 if (dx != 0) { 1401 clampedX = mCallback.clampViewPositionHorizontal(mCapturedView, left, dx); 1402 mCapturedView.offsetLeftAndRight(clampedX - oldLeft); 1403 } 1404 if (dy != 0) { 1405 clampedY = mCallback.clampViewPositionVertical(mCapturedView, top, dy); 1406 mCapturedView.offsetTopAndBottom(clampedY - oldTop); 1407 } 1408 1409 if (dx != 0 || dy != 0) { 1410 final int clampedDx = clampedX - oldLeft; 1411 final int clampedDy = clampedY - oldTop; 1412 mCallback.onViewPositionChanged(mCapturedView, clampedX, clampedY, 1413 clampedDx, clampedDy); 1414 } 1415 } 1416 1417 /** 1418 * Determine if the currently captured view is under the given point in the 1419 * parent view's coordinate system. If there is no captured view this method 1420 * will return false. 1421 * 1422 * @param x X position to test in the parent's coordinate system 1423 * @param y Y position to test in the parent's coordinate system 1424 * @return true if the captured view is under the given point, false otherwise 1425 */ isCapturedViewUnder(int x, int y)1426 public boolean isCapturedViewUnder(int x, int y) { 1427 return isViewUnder(mCapturedView, x, y); 1428 } 1429 1430 /** 1431 * Determine if the supplied view is under the given point in the 1432 * parent view's coordinate system. 1433 * 1434 * @param view Child view of the parent to hit test 1435 * @param x X position to test in the parent's coordinate system 1436 * @param y Y position to test in the parent's coordinate system 1437 * @return true if the supplied view is under the given point, false otherwise 1438 */ isViewUnder(View view, int x, int y)1439 public boolean isViewUnder(View view, int x, int y) { 1440 if (view == null) { 1441 return false; 1442 } 1443 return x >= view.getLeft() && 1444 x < view.getRight() && 1445 y >= view.getTop() && 1446 y < view.getBottom(); 1447 } 1448 1449 /** 1450 * Find the topmost child under the given point within the parent view's coordinate system. 1451 * The child order is determined using {@link Callback#getOrderedChildIndex(int)}. 1452 * 1453 * @param x X position to test in the parent's coordinate system 1454 * @param y Y position to test in the parent's coordinate system 1455 * @return The topmost child view under (x, y) or null if none found. 1456 */ findTopChildUnder(int x, int y)1457 public View findTopChildUnder(int x, int y) { 1458 final int childCount = mParentView.getChildCount(); 1459 for (int i = childCount - 1; i >= 0; i--) { 1460 final View child = mParentView.getChildAt(mCallback.getOrderedChildIndex(i)); 1461 if (x >= child.getLeft() && x < child.getRight() && 1462 y >= child.getTop() && y < child.getBottom()) { 1463 return child; 1464 } 1465 } 1466 return null; 1467 } 1468 getEdgesTouched(int x, int y)1469 private int getEdgesTouched(int x, int y) { 1470 int result = 0; 1471 1472 if (x < mParentView.getLeft() + mEdgeSize) result |= EDGE_LEFT; 1473 if (y < mParentView.getTop() + mEdgeSize) result |= EDGE_TOP; 1474 if (x > mParentView.getRight() - mEdgeSize) result |= EDGE_RIGHT; 1475 if (y > mParentView.getBottom() - mEdgeSize) result |= EDGE_BOTTOM; 1476 1477 return result; 1478 } 1479 }