/* * 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 { /** * 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[] mInitialEdgesTouched; private int[] mEdgeDragsInProgress; private int[] mEdgeDragsLocked; private int mPointersDown; private VelocityTracker mVelocityTracker; private final float mMaxVelocity; private float mMinVelocity; private int mEdgeSize; private int mTrackingEdges; private final ScrollerCompat mScroller; private final Callback mCallback; private View mCapturedView; private boolean mReleaseInProgress; private final ViewGroup mParentView; /** * Interpolator defining the animation curve for mScroller */ private static final Interpolator sInterpolator = new Interpolator() { @Override public float getInterpolation(float t) { t -= 1.0f; return t * t * t * t * t + 1.0f; } }; private final Runnable mSetIdleRunnable = new Runnable() { @Override public void run() { setDragState(STATE_IDLE); } }; /** * 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(final Context context, final ViewGroup forParent, final 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); } /** * {@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); } /** * 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; } } /** * 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(final View childView, final 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); } /** * Check if any pointer tracked in the current gesture has crossed the * required slop threshold. *
* 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. *
* * @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(final 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. ** 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. *
* * @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(final int directions, final 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; } /** * Move the captured settling view by the appropriate amount for the current * time. IfcontinueSettling
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(final 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;
}
/**
* 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(final int x, final 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;
}
/**
* 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(final int minLeft, final int minTop, final int maxLeft, final 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);
}
/**
* @return The ID of the pointer currently dragging the captured view, or
* {@link #INVALID_POINTER}.
*/
public int getActivePointerId() {
return mActivePointerId;
}
/**
* @return The currently captured view, or null if no view has been
* captured.
*/
public View getCapturedView() {
return mCapturedView;
}
/**
* 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;
}
/**
* 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;
}
/**
* @return The minimum distance in pixels that the user must travel to
* initiate a drag
*/
public int getTouchSlop() {
return mTouchSlop;
}
/**
* 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;
}
/**
* 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(final int x, final int y) {
return isViewUnder(mCapturedView, x, y);
}
/**
* 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(final int edges) {
final int count = mInitialEdgesTouched.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(final int edges, final int pointerId) {
return isPointerDown(pointerId) && (mInitialEdgesTouched[pointerId] & edges) != 0;
}
/**
* Check if the given pointer ID represents a pointer that is currently down
* (to the best of the ViewDragHelper's knowledge).
* * 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. *
* * @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(final int pointerId) { return (mPointersDown & 1 << pointerId) != 0; } /** * 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(final View view, final int x, final int y) { if (view == null) return false; return x >= view.getLeft() && x < view.getRight() && y >= view.getTop() && y < view.getBottom(); } /** * 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(final 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 = mInitialEdgesTouched[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 = mInitialEdgesTouched[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; } } } /** * 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(final int size) { mEdgeSize = size; } /** * 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(final int edgeFlags) { mTrackingEdges = edgeFlags; } /** * 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(final float minVel) { mMinVelocity = minVel; } /** * 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(final int finalLeft, final 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)); } /** * 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(final 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 = mInitialEdgesTouched[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 = mInitialEdgesTouched[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; } /** * Animate the viewchild
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.
* * This operation does not count as a capture event, though * {@link #getCapturedView()} will still report the sliding view while the * slide is in progress. *
* * @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(final View child, final int finalLeft, final int finalTop) { mCapturedView = child; mActivePointerId = INVALID_POINTER; return forceSettleCapturedViewAt(finalLeft, finalTop, 0, 0); } /** * 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(final View v, final boolean checkV, final int dx, final int dy, final int x, final 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)); } private boolean checkNewEdgeDrag(final float delta, final float odelta, final int pointerId, final int edge) { final float absDelta = Math.abs(delta); final float absODelta = Math.abs(odelta); if ((mInitialEdgesTouched[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(final View child, final float dx, final 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; } /** * 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 asvalue
*/
private float clampMag(final float value, final float absMin, final float absMax) {
final float 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 value
*/
private int clampMag(final int value, final int absMin, final int absMax) {
final int absValue = Math.abs(value);
if (absValue < absMin) return 0;
if (absValue > absMax) return value > 0 ? absMax : -absMax;
return value;
}
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(mInitialEdgesTouched, 0);
Arrays.fill(mEdgeDragsInProgress, 0);
Arrays.fill(mEdgeDragsLocked, 0);
mPointersDown = 0;
}
private void clearMotionHistory(final int pointerId) {
if (mInitialMotionX == null) return;
mInitialMotionX[pointerId] = 0;
mInitialMotionY[pointerId] = 0;
mLastMotionX[pointerId] = 0;
mLastMotionY[pointerId] = 0;
mInitialEdgesTouched[pointerId] = 0;
mEdgeDragsInProgress[pointerId] = 0;
mEdgeDragsLocked[pointerId] = 0;
mPointersDown &= ~(1 << pointerId);
}
private int computeAxisDuration(final int delta, int velocity, final 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);
}
private int computeSettleDuration(final View child, final int dx, final 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;
final int xduration = computeAxisDuration(dx, xvel, mCallback.getViewHorizontalDragRange(child));
final int yduration = computeAxisDuration(dy, yvel, mCallback.getViewVerticalDragRange(child));
return (int) (xduration * xweight + yduration * yweight);
}
/**
* 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(final float xvel, final 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 float distanceInfluenceForSnapDuration(float f) {
f -= 0.5f; // center the values about 0.
f *= 0.3f * Math.PI / 2.0f;
return (float) Math.sin(f);
}
private void dragTo(final int left, final int top, final int dx, final 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);
}
}
private void ensureMotionHistorySizeForId(final int pointerId) {
if (mInitialMotionX == null || mInitialMotionX.length <= pointerId) {
final float[] imx = new float[pointerId + 1];
final float[] imy = new float[pointerId + 1];
final float[] lmx = new float[pointerId + 1];
final float[] lmy = new float[pointerId + 1];
final int[] iit = new int[pointerId + 1];
final int[] edip = new int[pointerId + 1];
final 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(mInitialEdgesTouched, 0, iit, 0, mInitialEdgesTouched.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;
mInitialEdgesTouched = iit;
mEdgeDragsInProgress = edip;
mEdgeDragsLocked = edl;
}
}
/**
* 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(final int finalLeft, final int finalTop, final int xvel, final 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 getEdgesTouched(final int x, final 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;
}
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 reportNewEdgeDrags(final float dx, final float dy, final 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 void saveInitialMotion(final float x, final float y, final int pointerId) {
ensureMotionHistorySizeForId(pointerId);
mInitialMotionX[pointerId] = mLastMotionX[pointerId] = x;
mInitialMotionY[pointerId] = mLastMotionY[pointerId] = y;
mInitialEdgesTouched[pointerId] = getEdgesTouched((int) x, (int) y);
mPointersDown |= 1 << pointerId;
}
private void saveLastMotion(final 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;
}
}
void setDragState(final 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(final View toCapture, final 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;
}
/**
* 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(final ViewGroup forParent, final 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(final ViewGroup forParent, final float sensitivity, final Callback cb) {
final ViewDragHelper helper = create(forParent, cb);
helper.mTouchSlop = (int) (helper.mTouchSlop * (1 / sensitivity));
return helper;
}
/**
* A Callback is used as a communication channel with the ViewDragHelper
* back to the parent view using it. on*
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 {
/**
* 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(final View child, final int left, final 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(final View child, final int top, final int dy) {
return 0;
}
/**
* 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
* index
*/
public int getOrderedChildIndex(final 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(final 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(final View child) {
return 0;
}
/**
* 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(final int edgeFlags, final 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(final int edgeFlags) {
return false;
}
/**
* 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(final int edgeFlags, final int pointerId) {
}
/**
* 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(final View capturedChild, final int activePointerId) {
}
/**
* Called when the drag state changes. See the STATE_*
* constants for more information.
*
* @param state The new drag state
* @see #STATE_IDLE
* @see #STATE_DRAGGING
* @see #STATE_SETTLING
*/
public void onViewDragStateChanged(final 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(final View changedView, final int left, final int top, final int dx,
final int dy) {
}
/**
* 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.
*
* 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 onViewReleased
returns, the view will stop in
* place and the ViewDragHelper will return to {@link #STATE_IDLE}.
*
* 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. *
** If this method returns true, a call to * {@link #onViewCaptured(android.view.View, int)} will follow if the * capture is successful. *
* * @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); } }