Java tutorial
/* * 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 com.ysy.classpower_utils.swipe_back; 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; /** * OwnViewDragHelper 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 OwnViewDragHelper { private static final String TAG = "OwnViewDragHelper"; /** * 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 OwnViewDragHelper * 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 OwnViewDragHelper 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 OwnViewDragHelper 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 OwnViewDragHelper 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> * OwnViewDragHelper 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 OwnViewDragHelper. * * @param forParent Parent view to monitor * @param cb Callback to provide information and receive events * @return a new OwnViewDragHelper instance */ public static OwnViewDragHelper create(ViewGroup forParent, Callback cb) { return new OwnViewDragHelper(forParent.getContext(), forParent, cb); } /** * Factory method to create a new OwnViewDragHelper. * * @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 OwnViewDragHelper instance */ public static OwnViewDragHelper create(ViewGroup forParent, float sensitivity, Callback cb) { final OwnViewDragHelper helper = create(forParent, cb); helper.mTouchSlop = (int) (helper.mTouchSlop * (1 / sensitivity)); return helper; } /** * Apps should use OwnViewDragHelper.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 OwnViewDragHelper(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 OwnViewDragHelper.Callback#onEdgeTouched(int, int)} * and * {@link OwnViewDragHelper.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 OwnViewDragHelper.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 OwnViewDragHelper'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 OwnViewDragHelper'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 OwnViewDragHelper 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 OwnViewDragHelper 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 OwnViewDragHelper.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; } }