/*
* Copyright (C) 2013 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package me.imid.swipebacklayout.lib;
import android.content.Context;
import android.support.v4.view.MotionEventCompat;
import android.support.v4.view.VelocityTrackerCompat;
import android.support.v4.view.ViewCompat;
import android.support.v4.widget.ScrollerCompat;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.view.animation.Interpolator;
import java.util.Arrays;
/**
* ViewDragHelper is a utility class for writing custom ViewGroups. It offers a
* number of useful operations and state tracking for allowing a user to drag
* and reposition views within their parent ViewGroup.
*/
public class ViewDragHelper {
private static final String TAG = "ViewDragHelper";
/**
* A null/invalid pointer ID.
*/
public static final int INVALID_POINTER = -1;
/**
* A view is not currently being dragged or animating as a result of a
* fling/snap.
*/
public static final int STATE_IDLE = 0;
/**
* A view is currently being dragged. The position is currently changing as
* a result of user input or simulated user input.
*/
public static final int STATE_DRAGGING = 1;
/**
* A view is currently settling into place as a result of a fling or
* predefined non-interactive motion.
*/
public static final int STATE_SETTLING = 2;
/**
* Edge flag indicating that the left edge should be affected.
*/
public static final int EDGE_LEFT = 1 << 0;
/**
* Edge flag indicating that the right edge should be affected.
*/
public static final int EDGE_RIGHT = 1 << 1;
/**
* Edge flag indicating that the top edge should be affected.
*/
public static final int EDGE_TOP = 1 << 2;
/**
* Edge flag indicating that the bottom edge should be affected.
*/
public static final int EDGE_BOTTOM = 1 << 3;
/**
* Edge flag set indicating all edges should be affected.
*/
public static final int EDGE_ALL = EDGE_LEFT | EDGE_TOP | EDGE_RIGHT | EDGE_BOTTOM;
/**
* Indicates that a check should occur along the horizontal axis
*/
public static final int DIRECTION_HORIZONTAL = 1 << 0;
/**
* Indicates that a check should occur along the vertical axis
*/
public static final int DIRECTION_VERTICAL = 1 << 1;
/**
* Indicates that a check should occur along all axes
*/
public static final int DIRECTION_ALL = DIRECTION_HORIZONTAL | DIRECTION_VERTICAL;
public static final int EDGE_SIZE = 20; // dp
private static final int BASE_SETTLE_DURATION = 256; // ms
private static final int MAX_SETTLE_DURATION = 600; // ms
// Current drag state; idle, dragging or settling
private int mDragState;
// Distance to travel before a drag may begin
private int mTouchSlop;
// Last known position/pointer tracking
private int mActivePointerId = INVALID_POINTER;
private float[] mInitialMotionX;
private float[] mInitialMotionY;
private float[] mLastMotionX;
private float[] mLastMotionY;
private int[] mInitialEdgeTouched;
private int[] mEdgeDragsInProgress;
private int[] mEdgeDragsLocked;
private int mPointersDown;
private VelocityTracker mVelocityTracker;
private float mMaxVelocity;
private float mMinVelocity;
private int mEdgeSize;
private int mTrackingEdges;
private ScrollerCompat mScroller;
private final Callback mCallback;
private View mCapturedView;
private boolean mReleaseInProgress;
private final ViewGroup mParentView;
/**
* A Callback is used as a communication channel with the ViewDragHelper
* back to the parent view using it. <code>on*</code>methods are invoked on
* siginficant events and several accessor methods are expected to provide
* the ViewDragHelper with more information about the state of the parent
* view upon request. The callback also makes decisions governing the range
* and draggability of child views.
*/
public static abstract class Callback {
/**
* Called when the drag state changes. See the <code>STATE_*</code>
* constants for more information.
*
* @param state The new drag state
* @see #STATE_IDLE
* @see #STATE_DRAGGING
* @see #STATE_SETTLING
*/
public void onViewDragStateChanged(int state) {
}
/**
* Called when the captured view's position changes as the result of a
* drag or settle.
*
* @param changedView View whose position changed
* @param left New X coordinate of the left edge of the view
* @param top New Y coordinate of the top edge of the view
* @param dx Change in X position from the last call
* @param dy Change in Y position from the last call
*/
public void onViewPositionChanged(View changedView, int left, int top, int dx, int dy) {
}
/**
* Called when a child view is captured for dragging or settling. The ID
* of the pointer currently dragging the captured view is supplied. If
* activePointerId is identified as {@link #INVALID_POINTER} the capture
* is programmatic instead of pointer-initiated.
*
* @param capturedChild Child view that was captured
* @param activePointerId Pointer id tracking the child capture
*/
public void onViewCaptured(View capturedChild, int activePointerId) {
}
/**
* Called when the child view is no longer being actively dragged. The
* fling velocity is also supplied, if relevant. The velocity values may
* be clamped to system minimums or maximums.
* <p>
* Calling code may decide to fling or otherwise release the view to let
* it settle into place. It should do so using
* {@link #settleCapturedViewAt(int, int)} or
* {@link #flingCapturedView(int, int, int, int)}. If the Callback
* invokes one of these methods, the ViewDragHelper will enter
* {@link #STATE_SETTLING} and the view capture will not fully end until
* it comes to a complete stop. If neither of these methods is invoked
* before <code>onViewReleased</code> returns, the view will stop in
* place and the ViewDragHelper will return to {@link #STATE_IDLE}.
* </p>
*
* @param releasedChild The captured child view now being released
* @param xvel X velocity of the pointer as it left the screen in pixels
* per second.
* @param yvel Y velocity of the pointer as it left the screen in pixels
* per second.
*/
public void onViewReleased(View releasedChild, float xvel, float yvel) {
}
/**
* Called when one of the subscribed edges in the parent view has been
* touched by the user while no child view is currently captured.
*
* @param edgeFlags A combination of edge flags describing the edge(s)
* currently touched
* @param pointerId ID of the pointer touching the described edge(s)
* @see #EDGE_LEFT
* @see #EDGE_TOP
* @see #EDGE_RIGHT
* @see #EDGE_BOTTOM
*/
public void onEdgeTouched(int edgeFlags, int pointerId) {
}
/**
* Called when the given edge may become locked. This can happen if an
* edge drag was preliminarily rejected before beginning, but after
* {@link #onEdgeTouched(int, int)} was called. This method should
* return true to lock this edge or false to leave it unlocked. The
* default behavior is to leave edges unlocked.
*
* @param edgeFlags A combination of edge flags describing the edge(s)
* locked
* @return true to lock the edge, false to leave it unlocked
*/
public boolean onEdgeLock(int edgeFlags) {
return false;
}
/**
* Called when the user has started a deliberate drag away from one of
* the subscribed edges in the parent view while no child view is
* currently captured.
*
* @param edgeFlags A combination of edge flags describing the edge(s)
* dragged
* @param pointerId ID of the pointer touching the described edge(s)
* @see #EDGE_LEFT
* @see #EDGE_TOP
* @see #EDGE_RIGHT
* @see #EDGE_BOTTOM
*/
public void onEdgeDragStarted(int edgeFlags, int pointerId) {
}
/**
* Called to determine the Z-order of child views.
*
* @param index the ordered position to query for
* @return index of the view that should be ordered at position
* <code>index</code>
*/
public int getOrderedChildIndex(int index) {
return index;
}
/**
* Return the magnitude of a draggable child view's horizontal range of
* motion in pixels. This method should return 0 for views that cannot
* move horizontally.
*
* @param child Child view to check
* @return range of horizontal motion in pixels
*/
public int getViewHorizontalDragRange(View child) {
return 0;
}
/**
* Return the magnitude of a draggable child view's vertical range of
* motion in pixels. This method should return 0 for views that cannot
* move vertically.
*
* @param child Child view to check
* @return range of vertical motion in pixels
*/
public int getViewVerticalDragRange(View child) {
return 0;
}
/**
* Called when the user's input indicates that they want to capture the
* given child view with the pointer indicated by pointerId. The
* callback should return true if the user is permitted to drag the
* given view with the indicated pointer.
* <p>
* ViewDragHelper may call this method multiple times for the same view
* even if the view is already captured; this indicates that a new
* pointer is trying to take control of the view.
* </p>
* <p>
* If this method returns true, a call to
* {@link #onViewCaptured(android.view.View, int)} will follow if the
* capture is successful.
* </p>
*
* @param child Child the user is attempting to capture
* @param pointerId ID of the pointer attempting the capture
* @return true if capture should be allowed, false otherwise
*/
public abstract boolean tryCaptureView(View child, int pointerId);
/**
* Restrict the motion of the dragged child view along the horizontal
* axis. The default implementation does not allow horizontal motion;
* the extending class must override this method and provide the desired
* clamping.
*
* @param child Child view being dragged
* @param left Attempted motion along the X axis
* @param dx Proposed change in position for left
* @return The new clamped position for left
*/
public int clampViewPositionHorizontal(View child, int left, int dx) {
return 0;
}
/**
* Restrict the motion of the dragged child view along the vertical
* axis. The default implementation does not allow vertical motion; the
* extending class must override this method and provide the desired
* clamping.
*
* @param child Child view being dragged
* @param top Attempted motion along the Y axis
* @param dy Proposed change in position for top
* @return The new clamped position for top
*/
public int clampViewPositionVertical(View child, int top, int dy) {
return 0;
}
}
/**
* Interpolator defining the animation curve for mScroller
*/
private static final Interpolator sInterpolator = new Interpolator() {
public float getInterpolation(float t) {
t -= 1.0f;
return t * t * t * t * t + 1.0f;
}
};
private final Runnable mSetIdleRunnable = new Runnable() {
public void run() {
setDragState(STATE_IDLE);
}
};
/**
* Factory method to create a new ViewDragHelper.
*
* @param forParent Parent view to monitor
* @param cb Callback to provide information and receive events
* @return a new ViewDragHelper instance
*/
public static ViewDragHelper create(ViewGroup forParent, Callback cb) {
return new ViewDragHelper(forParent.getContext(), forParent, cb);
}
/**
* Factory method to create a new ViewDragHelper.
*
* @param forParent Parent view to monitor
* @param sensitivity Multiplier for how sensitive the helper should be
* about detecting the start of a drag. Larger values are more
* sensitive. 1.0f is normal.
* @param cb Callback to provide information and receive events
* @return a new ViewDragHelper instance
*/
public static ViewDragHelper create(ViewGroup forParent, float sensitivity, Callback cb) {
final ViewDragHelper helper = create(forParent, cb);
helper.mTouchSlop = (int) (helper.mTouchSlop * (1 / sensitivity));
return helper;
}
/**
* Apps should use ViewDragHelper.create() to get a new instance. This will
* allow VDH to use internal compatibility implementations for different
* platform versions.
*
* @param context Context to initialize config-dependent params from
* @param forParent Parent view to monitor
*/
private ViewDragHelper(Context context, ViewGroup forParent, Callback cb) {
if (forParent == null) {
throw new IllegalArgumentException("Parent view may not be null");
}
if (cb == null) {
throw new IllegalArgumentException("Callback may not be null");
}
mParentView = forParent;
mCallback = cb;
final ViewConfiguration vc = ViewConfiguration.get(context);
final float density = context.getResources().getDisplayMetrics().density;
mEdgeSize = (int) (EDGE_SIZE * density + 0.5f);
mTouchSlop = vc.getScaledTouchSlop();
mMaxVelocity = vc.getScaledMaximumFlingVelocity();
mMinVelocity = vc.getScaledMinimumFlingVelocity();
mScroller = ScrollerCompat.create(context, sInterpolator);
}
/**
* Sets the sensitivity of the dragger.
*
* @param context The application context.
* @param sensitivity value between 0 and 1, the final value for touchSlop =
* ViewConfiguration.getScaledTouchSlop * (1 / s);
*/
public void setSensitivity(Context context, float sensitivity) {
float s = Math.max(0f, Math.min(1.0f, sensitivity));
ViewConfiguration viewConfiguration = ViewConfiguration.get(context);
mTouchSlop = (int) (viewConfiguration.getScaledTouchSlop() * (1 / s));
}
/**
* Set the minimum velocity that will be detected as having a magnitude
* greater than zero in pixels per second. Callback methods accepting a
* velocity will be clamped appropriately.
*
* @param minVel minimum velocity to detect
*/
public void setMinVelocity(float minVel) {
mMinVelocity = minVel;
}
/**
* Set the max velocity that will be detected as having a magnitude
* greater than zero in pixels per second. Callback methods accepting a
* velocity will be clamped appropriately.
*
* @param maxVel max velocity to detect
*/
public void setMaxVelocity(float maxVel) {
mMaxVelocity = maxVel;
}
/**
* Return the currently configured minimum velocity. Any flings with a
* magnitude less than this value in pixels per second. Callback methods
* accepting a velocity will receive zero as a velocity value if the real
* detected velocity was below this threshold.
*
* @return the minimum velocity that will be detected
*/
public float getMinVelocity() {
return mMinVelocity;
}
/**
* Retrieve the current drag state of this helper. This will return one of
* {@link #STATE_IDLE}, {@link #STATE_DRAGGING} or {@link #STATE_SETTLING}.
*
* @return The current drag state
*/
public int getViewDragState() {
return mDragState;
}
/**
* Enable edge tracking for the selected edges of the parent view. The
* callback's
* {@link me.imid.swipebacklayout.lib.ViewDragHelper.Callback#onEdgeTouched(int, int)}
* and
* {@link me.imid.swipebacklayout.lib.ViewDragHelper.Callback#onEdgeDragStarted(int, int)}
* methods will only be invoked for edges for which edge tracking has been
* enabled.
*
* @param edgeFlags Combination of edge flags describing the edges to watch
* @see #EDGE_LEFT
* @see #EDGE_TOP
* @see #EDGE_RIGHT
* @see #EDGE_BOTTOM
*/
public void setEdgeTrackingEnabled(int edgeFlags) {
mTrackingEdges = edgeFlags;
}
/**
* Return the size of an edge. This is the range in pixels along the edges
* of this view that will actively detect edge touches or drags if edge
* tracking is enabled.
*
* @return The size of an edge in pixels
* @see #setEdgeTrackingEnabled(int)
*/
public int getEdgeSize() {
return mEdgeSize;
}
/**
* Set the size of an edge. This is the range in pixels along the edges of
* this view that will actively detect edge touches or drags if edge
* tracking is enabled.
*
* @param size The size of an edge in pixels
*/
public void setEdgeSize(int size) {
mEdgeSize = size;
}
/**
* Capture a specific child view for dragging within the parent. The
* callback will be notified but
* {@link me.imid.swipebacklayout.lib.ViewDragHelper.Callback#tryCaptureView(android.view.View, int)}
* will not be asked permission to capture this view.
*
* @param childView Child view to capture
* @param activePointerId ID of the pointer that is dragging the captured
* child view
*/
public void captureChildView(View childView, int activePointerId) {
if (childView.getParent() != mParentView) {
throw new IllegalArgumentException("captureChildView: parameter must be a descendant "
+ "of the ViewDragHelper's tracked parent view (" + mParentView + ")");
}
mCapturedView = childView;
mActivePointerId = activePointerId;
mCallback.onViewCaptured(childView, activePointerId);
setDragState(STATE_DRAGGING);
}
/**
* @return The currently captured view, or null if no view has been
* captured.
*/
public View getCapturedView() {
return mCapturedView;
}
/**
* @return The ID of the pointer currently dragging the captured view, or
* {@link #INVALID_POINTER}.
*/
public int getActivePointerId() {
return mActivePointerId;
}
/**
* @return The minimum distance in pixels that the user must travel to
* initiate a drag
*/
public int getTouchSlop() {
return mTouchSlop;
}
/**
* The result of a call to this method is equivalent to
* {@link #processTouchEvent(android.view.MotionEvent)} receiving an
* ACTION_CANCEL event.
*/
public void cancel() {
mActivePointerId = INVALID_POINTER;
clearMotionHistory();
if (mVelocityTracker != null) {
mVelocityTracker.recycle();
mVelocityTracker = null;
}
}
/**
* {@link #cancel()}, but also abort all motion in progress and snap to the
* end of any animation.
*/
public void abort() {
cancel();
if (mDragState == STATE_SETTLING) {
final int oldX = mScroller.getCurrX();
final int oldY = mScroller.getCurrY();
mScroller.abortAnimation();
final int newX = mScroller.getCurrX();
final int newY = mScroller.getCurrY();
mCallback.onViewPositionChanged(mCapturedView, newX, newY, newX - oldX, newY - oldY);
}
setDragState(STATE_IDLE);
}
/**
* Animate the view <code>child</code> to the given (left, top) position. If
* this method returns true, the caller should invoke
* {@link #continueSettling(boolean)} on each subsequent frame to continue
* the motion until it returns false. If this method returns false there is
* no further work to do to complete the movement.
* <p>
* This operation does not count as a capture event, though
* {@link #getCapturedView()} will still report the sliding view while the
* slide is in progress.
* </p>
*
* @param child Child view to capture and animate
* @param finalLeft Final left position of child
* @param finalTop Final top position of child
* @return true if animation should continue through
* {@link #continueSettling(boolean)} calls
*/
public boolean smoothSlideViewTo(View child, int finalLeft, int finalTop) {
mCapturedView = child;
mActivePointerId = INVALID_POINTER;
return forceSettleCapturedViewAt(finalLeft, finalTop, 0, 0);
}
/**
* Settle the captured view at the given (left, top) position. The
* appropriate velocity from prior motion will be taken into account. If
* this method returns true, the caller should invoke
* {@link #continueSettling(boolean)} on each subsequent frame to continue
* the motion until it returns false. If this method returns false there is
* no further work to do to complete the movement.
*
* @param finalLeft Settled left edge position for the captured view
* @param finalTop Settled top edge position for the captured view
* @return true if animation should continue through
* {@link #continueSettling(boolean)} calls
*/
public boolean settleCapturedViewAt(int finalLeft, int finalTop) {
if (!mReleaseInProgress) {
throw new IllegalStateException("Cannot settleCapturedViewAt outside of a call to "
+ "Callback#onViewReleased");
}
return forceSettleCapturedViewAt(finalLeft, finalTop,
(int) VelocityTrackerCompat.getXVelocity(mVelocityTracker, mActivePointerId),
(int) VelocityTrackerCompat.getYVelocity(mVelocityTracker, mActivePointerId));
}
/**
* Settle the captured view at the given (left, top) position.
*
* @param finalLeft Target left position for the captured view
* @param finalTop Target top position for the captured view
* @param xvel Horizontal velocity
* @param yvel Vertical velocity
* @return true if animation should continue through
* {@link #continueSettling(boolean)} calls
*/
private boolean forceSettleCapturedViewAt(int finalLeft, int finalTop, int xvel, int yvel) {
final int startLeft = mCapturedView.getLeft();
final int startTop = mCapturedView.getTop();
final int dx = finalLeft - startLeft;
final int dy = finalTop - startTop;
if (dx == 0 && dy == 0) {
// Nothing to do. Send callbacks, be done.
mScroller.abortAnimation();
setDragState(STATE_IDLE);
return false;
}
final int duration = computeSettleDuration(mCapturedView, dx, dy, xvel, yvel);
mScroller.startScroll(startLeft, startTop, dx, dy, duration);
setDragState(STATE_SETTLING);
return true;
}
private int computeSettleDuration(View child, int dx, int dy, int xvel, int yvel) {
xvel = clampMag(xvel, (int) mMinVelocity, (int) mMaxVelocity);
yvel = clampMag(yvel, (int) mMinVelocity, (int) mMaxVelocity);
final int absDx = Math.abs(dx);
final int absDy = Math.abs(dy);
final int absXVel = Math.abs(xvel);
final int absYVel = Math.abs(yvel);
final int addedVel = absXVel + absYVel;
final int addedDistance = absDx + absDy;
final float xweight = xvel != 0 ? (float) absXVel / addedVel : (float) absDx
/ addedDistance;
final float yweight = yvel != 0 ? (float) absYVel / addedVel : (float) absDy
/ addedDistance;
int xduration = computeAxisDuration(dx, xvel, mCallback.getViewHorizontalDragRange(child));
int yduration = computeAxisDuration(dy, yvel, mCallback.getViewVerticalDragRange(child));
return (int) (xduration * xweight + yduration * yweight);
}
private int computeAxisDuration(int delta, int velocity, int motionRange) {
if (delta == 0) {
return 0;
}
final int width = mParentView.getWidth();
final int halfWidth = width / 2;
final float distanceRatio = Math.min(1f, (float) Math.abs(delta) / width);
final float distance = halfWidth + halfWidth
* distanceInfluenceForSnapDuration(distanceRatio);
int duration;
velocity = Math.abs(velocity);
if (velocity > 0) {
duration = 4 * Math.round(1000 * Math.abs(distance / velocity));
} else {
final float range = (float) Math.abs(delta) / motionRange;
duration = (int) ((range + 1) * BASE_SETTLE_DURATION);
}
return Math.min(duration, MAX_SETTLE_DURATION);
}
/**
* Clamp the magnitude of value for absMin and absMax. If the value is below
* the minimum, it will be clamped to zero. If the value is above the
* maximum, it will be clamped to the maximum.
*
* @param value Value to clamp
* @param absMin Absolute value of the minimum significant value to return
* @param absMax Absolute value of the maximum value to return
* @return The clamped value with the same sign as <code>value</code>
*/
private int clampMag(int value, int absMin, int absMax) {
final int absValue = Math.abs(value);
if (absValue < absMin)
return 0;
if (absValue > absMax)
return value > 0 ? absMax : -absMax;
return value;
}
/**
* Clamp the magnitude of value for absMin and absMax. If the value is below
* the minimum, it will be clamped to zero. If the value is above the
* maximum, it will be clamped to the maximum.
*
* @param value Value to clamp
* @param absMin Absolute value of the minimum significant value to return
* @param absMax Absolute value of the maximum value to return
* @return The clamped value with the same sign as <code>value</code>
*/
private float clampMag(float value, float absMin, float absMax) {
final float absValue = Math.abs(value);
if (absValue < absMin)
return 0;
if (absValue > absMax)
return value > 0 ? absMax : -absMax;
return value;
}
private float distanceInfluenceForSnapDuration(float f) {
f -= 0.5f; // center the values about 0.
f *= 0.3f * Math.PI / 2.0f;
return (float) Math.sin(f);
}
/**
* Settle the captured view based on standard free-moving fling behavior.
* The caller should invoke {@link #continueSettling(boolean)} on each
* subsequent frame to continue the motion until it returns false.
*
* @param minLeft Minimum X position for the view's left edge
* @param minTop Minimum Y position for the view's top edge
* @param maxLeft Maximum X position for the view's left edge
* @param maxTop Maximum Y position for the view's top edge
*/
public void flingCapturedView(int minLeft, int minTop, int maxLeft, int maxTop) {
if (!mReleaseInProgress) {
throw new IllegalStateException("Cannot flingCapturedView outside of a call to "
+ "Callback#onViewReleased");
}
mScroller.fling(mCapturedView.getLeft(), mCapturedView.getTop(),
(int) VelocityTrackerCompat.getXVelocity(mVelocityTracker, mActivePointerId),
(int) VelocityTrackerCompat.getYVelocity(mVelocityTracker, mActivePointerId),
minLeft, maxLeft, minTop, maxTop);
setDragState(STATE_SETTLING);
}
/**
* Move the captured settling view by the appropriate amount for the current
* time. If <code>continueSettling</code> returns true, the caller should
* call it again on the next frame to continue.
*
* @param deferCallbacks true if state callbacks should be deferred via
* posted message. Set this to true if you are calling this
* method from {@link android.view.View#computeScroll()} or
* similar methods invoked as part of layout or drawing.
* @return true if settle is still in progress
*/
public boolean continueSettling(boolean deferCallbacks) {
if (mDragState == STATE_SETTLING) {
boolean keepGoing = mScroller.computeScrollOffset();
final int x = mScroller.getCurrX();
final int y = mScroller.getCurrY();
final int dx = x - mCapturedView.getLeft();
final int dy = y - mCapturedView.getTop();
if (dx != 0) {
mCapturedView.offsetLeftAndRight(dx);
}
if (dy != 0) {
mCapturedView.offsetTopAndBottom(dy);
}
if (dx != 0 || dy != 0) {
mCallback.onViewPositionChanged(mCapturedView, x, y, dx, dy);
}
if (keepGoing && x == mScroller.getFinalX() && y == mScroller.getFinalY()) {
// Close enough. The interpolator/scroller might think we're
// still moving
// but the user sure doesn't.
mScroller.abortAnimation();
keepGoing = mScroller.isFinished();
}
if (!keepGoing) {
if (deferCallbacks) {
mParentView.post(mSetIdleRunnable);
} else {
setDragState(STATE_IDLE);
}
}
}
return mDragState == STATE_SETTLING;
}
/**
* Like all callback events this must happen on the UI thread, but release
* involves some extra semantics. During a release (mReleaseInProgress) is
* the only time it is valid to call {@link #settleCapturedViewAt(int, int)}
* or {@link #flingCapturedView(int, int, int, int)}.
*/
private void dispatchViewReleased(float xvel, float yvel) {
mReleaseInProgress = true;
mCallback.onViewReleased(mCapturedView, xvel, yvel);
mReleaseInProgress = false;
if (mDragState == STATE_DRAGGING) {
// onViewReleased didn't call a method that would have changed this.
// Go idle.
setDragState(STATE_IDLE);
}
}
private void clearMotionHistory() {
if (mInitialMotionX == null) {
return;
}
Arrays.fill(mInitialMotionX, 0);
Arrays.fill(mInitialMotionY, 0);
Arrays.fill(mLastMotionX, 0);
Arrays.fill(mLastMotionY, 0);
Arrays.fill(mInitialEdgeTouched, 0);
Arrays.fill(mEdgeDragsInProgress, 0);
Arrays.fill(mEdgeDragsLocked, 0);
mPointersDown = 0;
}
private void clearMotionHistory(int pointerId) {
if (mInitialMotionX == null) {
return;
}
mInitialMotionX[pointerId] = 0;
mInitialMotionY[pointerId] = 0;
mLastMotionX[pointerId] = 0;
mLastMotionY[pointerId] = 0;
mInitialEdgeTouched[pointerId] = 0;
mEdgeDragsInProgress[pointerId] = 0;
mEdgeDragsLocked[pointerId] = 0;
mPointersDown &= ~(1 << pointerId);
}
private void ensureMotionHistorySizeForId(int pointerId) {
if (mInitialMotionX == null || mInitialMotionX.length <= pointerId) {
float[] imx = new float[pointerId + 1];
float[] imy = new float[pointerId + 1];
float[] lmx = new float[pointerId + 1];
float[] lmy = new float[pointerId + 1];
int[] iit = new int[pointerId + 1];
int[] edip = new int[pointerId + 1];
int[] edl = new int[pointerId + 1];
if (mInitialMotionX != null) {
System.arraycopy(mInitialMotionX, 0, imx, 0, mInitialMotionX.length);
System.arraycopy(mInitialMotionY, 0, imy, 0, mInitialMotionY.length);
System.arraycopy(mLastMotionX, 0, lmx, 0, mLastMotionX.length);
System.arraycopy(mLastMotionY, 0, lmy, 0, mLastMotionY.length);
System.arraycopy(mInitialEdgeTouched, 0, iit, 0, mInitialEdgeTouched.length);
System.arraycopy(mEdgeDragsInProgress, 0, edip, 0, mEdgeDragsInProgress.length);
System.arraycopy(mEdgeDragsLocked, 0, edl, 0, mEdgeDragsLocked.length);
}
mInitialMotionX = imx;
mInitialMotionY = imy;
mLastMotionX = lmx;
mLastMotionY = lmy;
mInitialEdgeTouched = iit;
mEdgeDragsInProgress = edip;
mEdgeDragsLocked = edl;
}
}
private void saveInitialMotion(float x, float y, int pointerId) {
ensureMotionHistorySizeForId(pointerId);
mInitialMotionX[pointerId] = mLastMotionX[pointerId] = x;
mInitialMotionY[pointerId] = mLastMotionY[pointerId] = y;
mInitialEdgeTouched[pointerId] = getEdgeTouched((int) x, (int) y);
mPointersDown |= 1 << pointerId;
}
private void saveLastMotion(MotionEvent ev) {
final int pointerCount = MotionEventCompat.getPointerCount(ev);
for (int i = 0; i < pointerCount; i++) {
final int pointerId = MotionEventCompat.getPointerId(ev, i);
final float x = MotionEventCompat.getX(ev, i);
final float y = MotionEventCompat.getY(ev, i);
mLastMotionX[pointerId] = x;
mLastMotionY[pointerId] = y;
}
}
/**
* Check if the given pointer ID represents a pointer that is currently down
* (to the best of the ViewDragHelper's knowledge).
* <p>
* The state used to report this information is populated by the methods
* {@link #shouldInterceptTouchEvent(android.view.MotionEvent)} or
* {@link #processTouchEvent(android.view.MotionEvent)}. If one of these
* methods has not been called for all relevant MotionEvents to track, the
* information reported by this method may be stale or incorrect.
* </p>
*
* @param pointerId pointer ID to check; corresponds to IDs provided by
* MotionEvent
* @return true if the pointer with the given ID is still down
*/
public boolean isPointerDown(int pointerId) {
return (mPointersDown & 1 << pointerId) != 0;
}
void setDragState(int state) {
if (mDragState != state) {
mDragState = state;
mCallback.onViewDragStateChanged(state);
if (state == STATE_IDLE) {
mCapturedView = null;
}
}
}
/**
* Attempt to capture the view with the given pointer ID. The callback will
* be involved. This will put us into the "dragging" state. If we've already
* captured this view with this pointer this method will immediately return
* true without consulting the callback.
*
* @param toCapture View to capture
* @param pointerId Pointer to capture with
* @return true if capture was successful
*/
boolean tryCaptureViewForDrag(View toCapture, int pointerId) {
if (toCapture == mCapturedView && mActivePointerId == pointerId) {
// Already done!
return true;
}
if (toCapture != null && mCallback.tryCaptureView(toCapture, pointerId)) {
mActivePointerId = pointerId;
captureChildView(toCapture, pointerId);
return true;
}
return false;
}
/**
* Tests scrollability within child views of v given a delta of dx.
*
* @param v View to test for horizontal scrollability
* @param checkV Whether the view v passed should itself be checked for
* scrollability (true), or just its children (false).
* @param dx Delta scrolled in pixels along the X axis
* @param dy Delta scrolled in pixels along the Y axis
* @param x X coordinate of the active touch point
* @param y Y coordinate of the active touch point
* @return true if child views of v can be scrolled by delta of dx.
*/
protected boolean canScroll(View v, boolean checkV, int dx, int dy, int x, int y) {
if (v instanceof ViewGroup) {
final ViewGroup group = (ViewGroup) v;
final int scrollX = v.getScrollX();
final int scrollY = v.getScrollY();
final int count = group.getChildCount();
// Count backwards - let topmost views consume scroll distance
// first.
for (int i = count - 1; i >= 0; i--) {
// TODO: Add versioned support here for transformed views.
// This will not work for transformed views in Honeycomb+
final View child = group.getChildAt(i);
if (x + scrollX >= child.getLeft()
&& x + scrollX < child.getRight()
&& y + scrollY >= child.getTop()
&& y + scrollY < child.getBottom()
&& canScroll(child, true, dx, dy, x + scrollX - child.getLeft(), y
+ scrollY - child.getTop())) {
return true;
}
}
}
return checkV
&& (ViewCompat.canScrollHorizontally(v, -dx) || ViewCompat.canScrollVertically(v,
-dy));
}
/**
* Check if this event as provided to the parent view's
* onInterceptTouchEvent should cause the parent to intercept the touch
* event stream.
*
* @param ev MotionEvent provided to onInterceptTouchEvent
* @return true if the parent view should return true from
* onInterceptTouchEvent
*/
public boolean shouldInterceptTouchEvent(MotionEvent ev) {
final int action = MotionEventCompat.getActionMasked(ev);
final int actionIndex = MotionEventCompat.getActionIndex(ev);
if (action == MotionEvent.ACTION_DOWN) {
// Reset things for a new event stream, just in case we didn't get
// the whole previous stream.
cancel();
}
if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
}
mVelocityTracker.addMovement(ev);
switch (action) {
case MotionEvent.ACTION_DOWN: {
final float x = ev.getX();
final float y = ev.getY();
final int pointerId = MotionEventCompat.getPointerId(ev, 0);
saveInitialMotion(x, y, pointerId);
final View toCapture = findTopChildUnder((int) x, (int) y);
// Catch a settling view if possible.
if (toCapture == mCapturedView && mDragState == STATE_SETTLING) {
tryCaptureViewForDrag(toCapture, pointerId);
}
final int edgesTouched = mInitialEdgeTouched[pointerId];
if ((edgesTouched & mTrackingEdges) != 0) {
mCallback.onEdgeTouched(edgesTouched & mTrackingEdges, pointerId);
}
break;
}
case MotionEventCompat.ACTION_POINTER_DOWN: {
final int pointerId = MotionEventCompat.getPointerId(ev, actionIndex);
final float x = MotionEventCompat.getX(ev, actionIndex);
final float y = MotionEventCompat.getY(ev, actionIndex);
saveInitialMotion(x, y, pointerId);
// A ViewDragHelper can only manipulate one view at a time.
if (mDragState == STATE_IDLE) {
final int edgesTouched = mInitialEdgeTouched[pointerId];
if ((edgesTouched & mTrackingEdges) != 0) {
mCallback.onEdgeTouched(edgesTouched & mTrackingEdges, pointerId);
}
} else if (mDragState == STATE_SETTLING) {
// Catch a settling view if possible.
final View toCapture = findTopChildUnder((int) x, (int) y);
if (toCapture == mCapturedView) {
tryCaptureViewForDrag(toCapture, pointerId);
}
}
break;
}
case MotionEvent.ACTION_MOVE: {
// First to cross a touch slop over a draggable view wins. Also
// report edge drags.
final int pointerCount = MotionEventCompat.getPointerCount(ev);
for (int i = 0; i < pointerCount; i++) {
final int pointerId = MotionEventCompat.getPointerId(ev, i);
final float x = MotionEventCompat.getX(ev, i);
final float y = MotionEventCompat.getY(ev, i);
final float dx = x - mInitialMotionX[pointerId];
final float dy = y - mInitialMotionY[pointerId];
reportNewEdgeDrags(dx, dy, pointerId);
if (mDragState == STATE_DRAGGING) {
// Callback might have started an edge drag
break;
}
final View toCapture = findTopChildUnder((int) x, (int) y);
if (toCapture != null && checkTouchSlop(toCapture, dx, dy)
&& tryCaptureViewForDrag(toCapture, pointerId)) {
break;
}
}
saveLastMotion(ev);
break;
}
case MotionEventCompat.ACTION_POINTER_UP: {
final int pointerId = MotionEventCompat.getPointerId(ev, actionIndex);
clearMotionHistory(pointerId);
break;
}
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_CANCEL: {
cancel();
break;
}
}
return mDragState == STATE_DRAGGING;
}
/**
* Process a touch event received by the parent view. This method will
* dispatch callback events as needed before returning. The parent view's
* onTouchEvent implementation should call this.
*
* @param ev The touch event received by the parent view
*/
public void processTouchEvent(MotionEvent ev) {
final int action = MotionEventCompat.getActionMasked(ev);
final int actionIndex = MotionEventCompat.getActionIndex(ev);
if (action == MotionEvent.ACTION_DOWN) {
// Reset things for a new event stream, just in case we didn't get
// the whole previous stream.
cancel();
}
if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
}
mVelocityTracker.addMovement(ev);
switch (action) {
case MotionEvent.ACTION_DOWN: {
final float x = ev.getX();
final float y = ev.getY();
final int pointerId = MotionEventCompat.getPointerId(ev, 0);
final View toCapture = findTopChildUnder((int) x, (int) y);
saveInitialMotion(x, y, pointerId);
// Since the parent is already directly processing this touch
// event,
// there is no reason to delay for a slop before dragging.
// Start immediately if possible.
tryCaptureViewForDrag(toCapture, pointerId);
final int edgesTouched = mInitialEdgeTouched[pointerId];
if ((edgesTouched & mTrackingEdges) != 0) {
mCallback.onEdgeTouched(edgesTouched & mTrackingEdges, pointerId);
}
break;
}
case MotionEventCompat.ACTION_POINTER_DOWN: {
final int pointerId = MotionEventCompat.getPointerId(ev, actionIndex);
final float x = MotionEventCompat.getX(ev, actionIndex);
final float y = MotionEventCompat.getY(ev, actionIndex);
saveInitialMotion(x, y, pointerId);
// A ViewDragHelper can only manipulate one view at a time.
if (mDragState == STATE_IDLE) {
// If we're idle we can do anything! Treat it like a normal
// down event.
final View toCapture = findTopChildUnder((int) x, (int) y);
tryCaptureViewForDrag(toCapture, pointerId);
final int edgesTouched = mInitialEdgeTouched[pointerId];
if ((edgesTouched & mTrackingEdges) != 0) {
mCallback.onEdgeTouched(edgesTouched & mTrackingEdges, pointerId);
}
} else if (isCapturedViewUnder((int) x, (int) y)) {
// We're still tracking a captured view. If the same view is
// under this
// point, we'll swap to controlling it with this pointer
// instead.
// (This will still work if we're "catching" a settling
// view.)
tryCaptureViewForDrag(mCapturedView, pointerId);
}
break;
}
case MotionEvent.ACTION_MOVE: {
if (mDragState == STATE_DRAGGING) {
final int index = MotionEventCompat.findPointerIndex(ev, mActivePointerId);
final float x = MotionEventCompat.getX(ev, index);
final float y = MotionEventCompat.getY(ev, index);
final int idx = (int) (x - mLastMotionX[mActivePointerId]);
final int idy = (int) (y - mLastMotionY[mActivePointerId]);
dragTo(mCapturedView.getLeft() + idx, mCapturedView.getTop() + idy, idx, idy);
saveLastMotion(ev);
} else {
// Check to see if any pointer is now over a draggable view.
final int pointerCount = MotionEventCompat.getPointerCount(ev);
for (int i = 0; i < pointerCount; i++) {
final int pointerId = MotionEventCompat.getPointerId(ev, i);
final float x = MotionEventCompat.getX(ev, i);
final float y = MotionEventCompat.getY(ev, i);
final float dx = x - mInitialMotionX[pointerId];
final float dy = y - mInitialMotionY[pointerId];
reportNewEdgeDrags(dx, dy, pointerId);
if (mDragState == STATE_DRAGGING) {
// Callback might have started an edge drag.
break;
}
final View toCapture = findTopChildUnder((int) x, (int) y);
if (checkTouchSlop(toCapture, dx, dy)
&& tryCaptureViewForDrag(toCapture, pointerId)) {
break;
}
}
saveLastMotion(ev);
}
break;
}
case MotionEventCompat.ACTION_POINTER_UP: {
final int pointerId = MotionEventCompat.getPointerId(ev, actionIndex);
if (mDragState == STATE_DRAGGING && pointerId == mActivePointerId) {
// Try to find another pointer that's still holding on to
// the captured view.
int newActivePointer = INVALID_POINTER;
final int pointerCount = MotionEventCompat.getPointerCount(ev);
for (int i = 0; i < pointerCount; i++) {
final int id = MotionEventCompat.getPointerId(ev, i);
if (id == mActivePointerId) {
// This one's going away, skip.
continue;
}
final float x = MotionEventCompat.getX(ev, i);
final float y = MotionEventCompat.getY(ev, i);
if (findTopChildUnder((int) x, (int) y) == mCapturedView
&& tryCaptureViewForDrag(mCapturedView, id)) {
newActivePointer = mActivePointerId;
break;
}
}
if (newActivePointer == INVALID_POINTER) {
// We didn't find another pointer still touching the
// view, release it.
releaseViewForPointerUp();
}
}
clearMotionHistory(pointerId);
break;
}
case MotionEvent.ACTION_UP: {
if (mDragState == STATE_DRAGGING) {
releaseViewForPointerUp();
}
cancel();
break;
}
case MotionEvent.ACTION_CANCEL: {
if (mDragState == STATE_DRAGGING) {
dispatchViewReleased(0, 0);
}
cancel();
break;
}
}
}
private void reportNewEdgeDrags(float dx, float dy, int pointerId) {
int dragsStarted = 0;
if (checkNewEdgeDrag(dx, dy, pointerId, EDGE_LEFT)) {
dragsStarted |= EDGE_LEFT;
}
if (checkNewEdgeDrag(dy, dx, pointerId, EDGE_TOP)) {
dragsStarted |= EDGE_TOP;
}
if (checkNewEdgeDrag(dx, dy, pointerId, EDGE_RIGHT)) {
dragsStarted |= EDGE_RIGHT;
}
if (checkNewEdgeDrag(dy, dx, pointerId, EDGE_BOTTOM)) {
dragsStarted |= EDGE_BOTTOM;
}
if (dragsStarted != 0) {
mEdgeDragsInProgress[pointerId] |= dragsStarted;
mCallback.onEdgeDragStarted(dragsStarted, pointerId);
}
}
private boolean checkNewEdgeDrag(float delta, float odelta, int pointerId, int edge) {
final float absDelta = Math.abs(delta);
final float absODelta = Math.abs(odelta);
if ((mInitialEdgeTouched[pointerId] & edge) != edge || (mTrackingEdges & edge) == 0
|| (mEdgeDragsLocked[pointerId] & edge) == edge
|| (mEdgeDragsInProgress[pointerId] & edge) == edge
|| (absDelta <= mTouchSlop && absODelta <= mTouchSlop)) {
return false;
}
if (absDelta < absODelta * 0.5f && mCallback.onEdgeLock(edge)) {
mEdgeDragsLocked[pointerId] |= edge;
return false;
}
return (mEdgeDragsInProgress[pointerId] & edge) == 0 && absDelta > mTouchSlop;
}
/**
* Check if we've crossed a reasonable touch slop for the given child view.
* If the child cannot be dragged along the horizontal or vertical axis,
* motion along that axis will not count toward the slop check.
*
* @param child Child to check
* @param dx Motion since initial position along X axis
* @param dy Motion since initial position along Y axis
* @return true if the touch slop has been crossed
*/
private boolean checkTouchSlop(View child, float dx, float dy) {
if (child == null) {
return false;
}
final boolean checkHorizontal = mCallback.getViewHorizontalDragRange(child) > 0;
final boolean checkVertical = mCallback.getViewVerticalDragRange(child) > 0;
if (checkHorizontal && checkVertical) {
return dx * dx + dy * dy > mTouchSlop * mTouchSlop;
} else if (checkHorizontal) {
return Math.abs(dx) > mTouchSlop;
} else if (checkVertical) {
return Math.abs(dy) > mTouchSlop;
}
return false;
}
/**
* Check if any pointer tracked in the current gesture has crossed the
* required slop threshold.
* <p>
* This depends on internal state populated by
* {@link #shouldInterceptTouchEvent(android.view.MotionEvent)} or
* {@link #processTouchEvent(android.view.MotionEvent)}. You should only
* rely on the results of this method after all currently available touch
* data has been provided to one of these two methods.
* </p>
*
* @param directions Combination of direction flags, see
* {@link #DIRECTION_HORIZONTAL}, {@link #DIRECTION_VERTICAL},
* {@link #DIRECTION_ALL}
* @return true if the slop threshold has been crossed, false otherwise
*/
public boolean checkTouchSlop(int directions) {
final int count = mInitialMotionX.length;
for (int i = 0; i < count; i++) {
if (checkTouchSlop(directions, i)) {
return true;
}
}
return false;
}
/**
* Check if the specified pointer tracked in the current gesture has crossed
* the required slop threshold.
* <p>
* This depends on internal state populated by
* {@link #shouldInterceptTouchEvent(android.view.MotionEvent)} or
* {@link #processTouchEvent(android.view.MotionEvent)}. You should only
* rely on the results of this method after all currently available touch
* data has been provided to one of these two methods.
* </p>
*
* @param directions Combination of direction flags, see
* {@link #DIRECTION_HORIZONTAL}, {@link #DIRECTION_VERTICAL},
* {@link #DIRECTION_ALL}
* @param pointerId ID of the pointer to slop check as specified by
* MotionEvent
* @return true if the slop threshold has been crossed, false otherwise
*/
public boolean checkTouchSlop(int directions, int pointerId) {
if (!isPointerDown(pointerId)) {
return false;
}
final boolean checkHorizontal = (directions & DIRECTION_HORIZONTAL) == DIRECTION_HORIZONTAL;
final boolean checkVertical = (directions & DIRECTION_VERTICAL) == DIRECTION_VERTICAL;
final float dx = mLastMotionX[pointerId] - mInitialMotionX[pointerId];
final float dy = mLastMotionY[pointerId] - mInitialMotionY[pointerId];
if (checkHorizontal && checkVertical) {
return dx * dx + dy * dy > mTouchSlop * mTouchSlop;
} else if (checkHorizontal) {
return Math.abs(dx) > mTouchSlop;
} else if (checkVertical) {
return Math.abs(dy) > mTouchSlop;
}
return false;
}
/**
* Check if any of the edges specified were initially touched in the
* currently active gesture. If there is no currently active gesture this
* method will return false.
*
* @param edges Edges to check for an initial edge touch. See
* {@link #EDGE_LEFT}, {@link #EDGE_TOP}, {@link #EDGE_RIGHT},
* {@link #EDGE_BOTTOM} and {@link #EDGE_ALL}
* @return true if any of the edges specified were initially touched in the
* current gesture
*/
public boolean isEdgeTouched(int edges) {
final int count = mInitialEdgeTouched.length;
for (int i = 0; i < count; i++) {
if (isEdgeTouched(edges, i)) {
return true;
}
}
return false;
}
/**
* Check if any of the edges specified were initially touched by the pointer
* with the specified ID. If there is no currently active gesture or if
* there is no pointer with the given ID currently down this method will
* return false.
*
* @param edges Edges to check for an initial edge touch. See
* {@link #EDGE_LEFT}, {@link #EDGE_TOP}, {@link #EDGE_RIGHT},
* {@link #EDGE_BOTTOM} and {@link #EDGE_ALL}
* @return true if any of the edges specified were initially touched in the
* current gesture
*/
public boolean isEdgeTouched(int edges, int pointerId) {
return isPointerDown(pointerId) && (mInitialEdgeTouched[pointerId] & edges) != 0;
}
private void releaseViewForPointerUp() {
mVelocityTracker.computeCurrentVelocity(1000, mMaxVelocity);
final float xvel = clampMag(
VelocityTrackerCompat.getXVelocity(mVelocityTracker, mActivePointerId),
mMinVelocity, mMaxVelocity);
final float yvel = clampMag(
VelocityTrackerCompat.getYVelocity(mVelocityTracker, mActivePointerId),
mMinVelocity, mMaxVelocity);
dispatchViewReleased(xvel, yvel);
}
private void dragTo(int left, int top, int dx, int dy) {
int clampedX = left;
int clampedY = top;
final int oldLeft = mCapturedView.getLeft();
final int oldTop = mCapturedView.getTop();
if (dx != 0) {
clampedX = mCallback.clampViewPositionHorizontal(mCapturedView, left, dx);
mCapturedView.offsetLeftAndRight(clampedX - oldLeft);
}
if (dy != 0) {
clampedY = mCallback.clampViewPositionVertical(mCapturedView, top, dy);
mCapturedView.offsetTopAndBottom(clampedY - oldTop);
}
if (dx != 0 || dy != 0) {
final int clampedDx = clampedX - oldLeft;
final int clampedDy = clampedY - oldTop;
mCallback
.onViewPositionChanged(mCapturedView, clampedX, clampedY, clampedDx, clampedDy);
}
}
/**
* Determine if the currently captured view is under the given point in the
* parent view's coordinate system. If there is no captured view this method
* will return false.
*
* @param x X position to test in the parent's coordinate system
* @param y Y position to test in the parent's coordinate system
* @return true if the captured view is under the given point, false
* otherwise
*/
public boolean isCapturedViewUnder(int x, int y) {
return isViewUnder(mCapturedView, x, y);
}
/**
* Determine if the supplied view is under the given point in the parent
* view's coordinate system.
*
* @param view Child view of the parent to hit test
* @param x X position to test in the parent's coordinate system
* @param y Y position to test in the parent's coordinate system
* @return true if the supplied view is under the given point, false
* otherwise
*/
public boolean isViewUnder(View view, int x, int y) {
if (view == null) {
return false;
}
return x >= view.getLeft() && x < view.getRight() && y >= view.getTop()
&& y < view.getBottom();
}
/**
* Find the topmost child under the given point within the parent view's
* coordinate system. The child order is determined using
* {@link me.imid.swipebacklayout.lib.ViewDragHelper.Callback#getOrderedChildIndex(int)}
* .
*
* @param x X position to test in the parent's coordinate system
* @param y Y position to test in the parent's coordinate system
* @return The topmost child view under (x, y) or null if none found.
*/
public View findTopChildUnder(int x, int y) {
final int childCount = mParentView.getChildCount();
for (int i = childCount - 1; i >= 0; i--) {
final View child = mParentView.getChildAt(mCallback.getOrderedChildIndex(i));
if (x >= child.getLeft() && x < child.getRight() && y >= child.getTop()
&& y < child.getBottom()) {
return child;
}
}
return null;
}
private int getEdgeTouched(int x, int y) {
int result = 0;
if (x < mParentView.getLeft() + mEdgeSize)
result = EDGE_LEFT;
if (y < mParentView.getTop() + mEdgeSize)
result = EDGE_TOP;
if (x > mParentView.getRight() - mEdgeSize)
result = EDGE_RIGHT;
if (y > mParentView.getBottom() - mEdgeSize)
result = EDGE_BOTTOM;
return result;
}
}
public class ViewDragHelper
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