| /* |
| * Copyright 2018 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 androidx.customview.widget; |
| |
| import android.content.Context; |
| import android.util.Log; |
| 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 android.widget.OverScroller; |
| |
| import androidx.annotation.NonNull; |
| import androidx.annotation.Nullable; |
| import androidx.annotation.Px; |
| import androidx.core.view.ViewCompat; |
| |
| import java.util.Arrays; |
| |
| /** |
| * ViewDragHelper is a utility class for writing custom ViewGroups. It offers a number |
| * of useful operations and state tracking for allowing a user to drag and reposition |
| * views within their parent ViewGroup. |
| */ |
| public class ViewDragHelper { |
| private static final String TAG = "ViewDragHelper"; |
| |
| /** |
| * A null/invalid pointer ID. |
| */ |
| public static final int INVALID_POINTER = -1; |
| |
| /** |
| * A view is not currently being dragged or animating as a result of a fling/snap. |
| */ |
| public static final int STATE_IDLE = 0; |
| |
| /** |
| * A view is currently being dragged. The position is currently changing as a result |
| * of user input or simulated user input. |
| */ |
| public static final int STATE_DRAGGING = 1; |
| |
| /** |
| * A view is currently settling into place as a result of a fling or |
| * predefined non-interactive motion. |
| */ |
| public static final int STATE_SETTLING = 2; |
| |
| /** |
| * Edge flag indicating that the left edge should be affected. |
| */ |
| public static final int EDGE_LEFT = 1 << 0; |
| |
| /** |
| * Edge flag indicating that the right edge should be affected. |
| */ |
| public static final int EDGE_RIGHT = 1 << 1; |
| |
| /** |
| * Edge flag indicating that the top edge should be affected. |
| */ |
| public static final int EDGE_TOP = 1 << 2; |
| |
| /** |
| * Edge flag indicating that the bottom edge should be affected. |
| */ |
| public static final int EDGE_BOTTOM = 1 << 3; |
| |
| /** |
| * Edge flag set indicating all edges should be affected. |
| */ |
| public static final int EDGE_ALL = EDGE_LEFT | EDGE_TOP | EDGE_RIGHT | EDGE_BOTTOM; |
| |
| /** |
| * Indicates that a check should occur along the horizontal axis |
| */ |
| public static final int DIRECTION_HORIZONTAL = 1 << 0; |
| |
| /** |
| * Indicates that a check should occur along the vertical axis |
| */ |
| public static final int DIRECTION_VERTICAL = 1 << 1; |
| |
| /** |
| * Indicates that a check should occur along all axes |
| */ |
| public static final int DIRECTION_ALL = DIRECTION_HORIZONTAL | DIRECTION_VERTICAL; |
| |
| private 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 float mMaxVelocity; |
| private float mMinVelocity; |
| |
| private int mEdgeSize; |
| private int mTrackingEdges; |
| |
| private OverScroller mScroller; |
| |
| private final Callback mCallback; |
| |
| private View mCapturedView; |
| private boolean mReleaseInProgress; |
| |
| private final ViewGroup mParentView; |
| |
| /** |
| * A Callback is used as a communication channel with the ViewDragHelper back to the |
| * parent view using it. <code>on*</code>methods are invoked on siginficant events and several |
| * accessor methods are expected to provide the ViewDragHelper with more information |
| * about the state of the parent view upon request. The callback also makes decisions |
| * governing the range and draggability of child views. |
| */ |
| public abstract static 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(@NonNull View changedView, int left, int top, @Px int dx, |
| @Px 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(@NonNull View capturedChild, int activePointerId) {} |
| |
| /** |
| * Called when the child view is no longer being actively dragged. |
| * The fling velocity is also supplied, if relevant. The velocity values may |
| * be clamped to system minimums or maximums. |
| * |
| * <p>Calling code may decide to fling or otherwise release the view to let it |
| * settle into place. It should do so using {@link #settleCapturedViewAt(int, int)} |
| * or {@link #flingCapturedView(int, int, int, int)}. If the Callback invokes |
| * one of these methods, the ViewDragHelper will enter {@link #STATE_SETTLING} |
| * and the view capture will not fully end until it comes to a complete stop. |
| * If neither of these methods is invoked before <code>onViewReleased</code> returns, |
| * the view will stop in place and the ViewDragHelper will return to |
| * {@link #STATE_IDLE}.</p> |
| * |
| * @param releasedChild The captured child view now being released |
| * @param xvel X velocity of the pointer as it left the screen in pixels per second. |
| * @param yvel Y velocity of the pointer as it left the screen in pixels per second. |
| */ |
| public void onViewReleased(@NonNull 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(@NonNull 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(@NonNull View child) { |
| return 0; |
| } |
| |
| /** |
| * Called when the user's input indicates that they want to capture the given child view |
| * with the pointer indicated by pointerId. The callback should return true if the user |
| * is permitted to drag the given view with the indicated pointer. |
| * |
| * <p>ViewDragHelper may call this method multiple times for the same view even if |
| * the view is already captured; this indicates that a new pointer is trying to take |
| * control of the view.</p> |
| * |
| * <p>If this method returns true, a call to {@link #onViewCaptured(android.view.View, int)} |
| * will follow if the capture is successful.</p> |
| * |
| * @param child Child the user is attempting to capture |
| * @param pointerId ID of the pointer attempting the capture |
| * @return true if capture should be allowed, false otherwise |
| */ |
| public abstract boolean tryCaptureView(@NonNull 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(@NonNull 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(@NonNull View child, int top, int dy) { |
| return 0; |
| } |
| } |
| |
| /** |
| * 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); |
| } |
| }; |
| |
| /** |
| * 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(@NonNull ViewGroup forParent, @NonNull 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(@NonNull ViewGroup forParent, float sensitivity, |
| @NonNull Callback cb) { |
| final ViewDragHelper helper = create(forParent, cb); |
| helper.mTouchSlop = (int) (helper.mTouchSlop * (1 / sensitivity)); |
| return helper; |
| } |
| |
| /** |
| * Apps should use ViewDragHelper.create() to get a new instance. |
| * This will allow VDH to use internal compatibility implementations for different |
| * platform versions. |
| * |
| * @param context Context to initialize config-dependent params from |
| * @param forParent Parent view to monitor |
| */ |
| private ViewDragHelper(@NonNull Context context, @NonNull ViewGroup forParent, |
| @NonNull 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 = new OverScroller(context, sInterpolator); |
| } |
| |
| /** |
| * 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; |
| } |
| |
| /** |
| * 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 Callback#onEdgeTouched(int, int)} and |
| * {@link 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) |
| */ |
| @Px |
| public int getEdgeSize() { |
| return mEdgeSize; |
| } |
| |
| /** |
| * Capture a specific child view for dragging within the parent. The callback will be notified |
| * but {@link 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(@NonNull View childView, int activePointerId) { |
| if (childView.getParent() != mParentView) { |
| throw new IllegalArgumentException("captureChildView: parameter must be a descendant " |
| + "of the ViewDragHelper's tracked parent view (" + mParentView + ")"); |
| } |
| |
| mCapturedView = childView; |
| mActivePointerId = activePointerId; |
| mCallback.onViewCaptured(childView, activePointerId); |
| setDragState(STATE_DRAGGING); |
| } |
| |
| /** |
| * @return The currently captured view, or null if no view has been captured. |
| */ |
| @Nullable |
| 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 |
| */ |
| @Px |
| 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(@NonNull View child, int finalLeft, int finalTop) { |
| mCapturedView = child; |
| mActivePointerId = INVALID_POINTER; |
| |
| boolean continueSliding = forceSettleCapturedViewAt(finalLeft, finalTop, 0, 0); |
| if (!continueSliding && mDragState == STATE_IDLE && mCapturedView != null) { |
| // If we're in an IDLE state to begin with and aren't moving anywhere, we |
| // end up having a non-null capturedView with an IDLE dragState |
| mCapturedView = null; |
| } |
| |
| return continueSliding; |
| } |
| |
| /** |
| * 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) mVelocityTracker.getXVelocity(mActivePointerId), |
| (int) mVelocityTracker.getYVelocity(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 * (float) 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) mVelocityTracker.getXVelocity(mActivePointerId), |
| (int) mVelocityTracker.getYVelocity(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) { |
| ViewCompat.offsetLeftAndRight(mCapturedView, dx); |
| } |
| if (dy != 0) { |
| ViewCompat.offsetTopAndBottom(mCapturedView, 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 = false; |
| } |
| |
| 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(mInitialEdgesTouched, 0); |
| Arrays.fill(mEdgeDragsInProgress, 0); |
| Arrays.fill(mEdgeDragsLocked, 0); |
| mPointersDown = 0; |
| } |
| |
| private void clearMotionHistory(int pointerId) { |
| if (mInitialMotionX == null || !isPointerDown(pointerId)) { |
| 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 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(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; |
| } |
| } |
| |
| private void saveInitialMotion(float x, float y, 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(MotionEvent ev) { |
| final int pointerCount = ev.getPointerCount(); |
| for (int i = 0; i < pointerCount; i++) { |
| final int pointerId = ev.getPointerId(i); |
| // If pointer is invalid then skip saving on ACTION_MOVE. |
| if (!isValidPointerForActionMove(pointerId)) { |
| continue; |
| } |
| final float x = ev.getX(i); |
| final float y = ev.getY(i); |
| mLastMotionX[pointerId] = x; |
| mLastMotionY[pointerId] = y; |
| } |
| } |
| |
| /** |
| * Check if the given pointer ID represents a pointer that is currently down (to the best |
| * of the ViewDragHelper's knowledge). |
| * |
| * <p>The state used to report this information is populated by the methods |
| * {@link #shouldInterceptTouchEvent(android.view.MotionEvent)} or |
| * {@link #processTouchEvent(android.view.MotionEvent)}. If one of these methods has not |
| * been called for all relevant MotionEvents to track, the information reported |
| * by this method may be stale or incorrect.</p> |
| * |
| * @param pointerId pointer ID to check; corresponds to IDs provided by MotionEvent |
| * @return true if the pointer with the given ID is still down |
| */ |
| public boolean isPointerDown(int pointerId) { |
| return (mPointersDown & 1 << pointerId) != 0; |
| } |
| |
| void setDragState(int state) { |
| mParentView.removeCallbacks(mSetIdleRunnable); |
| if (mDragState != state) { |
| mDragState = state; |
| mCallback.onViewDragStateChanged(state); |
| if (mDragState == 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(@NonNull 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 && (v.canScrollHorizontally(-dx) || v.canScrollVertically(-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(@NonNull MotionEvent ev) { |
| final int action = ev.getActionMasked(); |
| final int actionIndex = ev.getActionIndex(); |
| |
| 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 = ev.getPointerId(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 MotionEvent.ACTION_POINTER_DOWN: { |
| final int pointerId = ev.getPointerId(actionIndex); |
| final float x = ev.getX(actionIndex); |
| final float y = ev.getY(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: { |
| if (mInitialMotionX == null || mInitialMotionY == null) break; |
| |
| // First to cross a touch slop over a draggable view wins. Also report edge drags. |
| final int pointerCount = ev.getPointerCount(); |
| for (int i = 0; i < pointerCount; i++) { |
| final int pointerId = ev.getPointerId(i); |
| |
| // If pointer is invalid then skip the ACTION_MOVE. |
| if (!isValidPointerForActionMove(pointerId)) continue; |
| |
| final float x = ev.getX(i); |
| final float y = ev.getY(i); |
| final float dx = x - mInitialMotionX[pointerId]; |
| final float dy = y - mInitialMotionY[pointerId]; |
| |
| final View toCapture = findTopChildUnder((int) x, (int) y); |
| final boolean pastSlop = toCapture != null && checkTouchSlop(toCapture, dx, dy); |
| if (pastSlop) { |
| // check the callback's |
| // getView[Horizontal|Vertical]DragRange methods to know |
| // if you can move at all along an axis, then see if it |
| // would clamp to the same value. If you can't move at |
| // all in every dimension with a nonzero range, bail. |
| final int oldLeft = toCapture.getLeft(); |
| final int targetLeft = oldLeft + (int) dx; |
| final int newLeft = mCallback.clampViewPositionHorizontal(toCapture, |
| targetLeft, (int) dx); |
| final int oldTop = toCapture.getTop(); |
| final int targetTop = oldTop + (int) dy; |
| final int newTop = mCallback.clampViewPositionVertical(toCapture, targetTop, |
| (int) dy); |
| final int hDragRange = mCallback.getViewHorizontalDragRange(toCapture); |
| final int vDragRange = mCallback.getViewVerticalDragRange(toCapture); |
| if ((hDragRange == 0 || (hDragRange > 0 && newLeft == oldLeft)) |
| && (vDragRange == 0 || (vDragRange > 0 && newTop == oldTop))) { |
| break; |
| } |
| } |
| reportNewEdgeDrags(dx, dy, pointerId); |
| if (mDragState == STATE_DRAGGING) { |
| // Callback might have started an edge drag |
| break; |
| } |
| |
| if (pastSlop && tryCaptureViewForDrag(toCapture, pointerId)) { |
| break; |
| } |
| } |
| saveLastMotion(ev); |
| break; |
| } |
| |
| case MotionEvent.ACTION_POINTER_UP: { |
| final int pointerId = ev.getPointerId(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(@NonNull MotionEvent ev) { |
| final int action = ev.getActionMasked(); |
| final int actionIndex = ev.getActionIndex(); |
| |
| 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 = ev.getPointerId(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 MotionEvent.ACTION_POINTER_DOWN: { |
| final int pointerId = ev.getPointerId(actionIndex); |
| final float x = ev.getX(actionIndex); |
| final float y = ev.getY(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) { |
| // If pointer is invalid then skip the ACTION_MOVE. |
| if (!isValidPointerForActionMove(mActivePointerId)) break; |
| |
| final int index = ev.findPointerIndex(mActivePointerId); |
| final float x = ev.getX(index); |
| final float y = ev.getY(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 = ev.getPointerCount(); |
| for (int i = 0; i < pointerCount; i++) { |
| final int pointerId = ev.getPointerId(i); |
| |
| // If pointer is invalid then skip the ACTION_MOVE. |
| if (!isValidPointerForActionMove(pointerId)) continue; |
| |
| final float x = ev.getX(i); |
| final float y = ev.getY(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 MotionEvent.ACTION_POINTER_UP: { |
| final int pointerId = ev.getPointerId(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 = ev.getPointerCount(); |
| for (int i = 0; i < pointerCount; i++) { |
| final int id = ev.getPointerId(i); |
| if (id == mActivePointerId) { |
| // This one's going away, skip. |
| continue; |
| } |
| |
| final float x = ev.getX(i); |
| final float y = ev.getY(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 ((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(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 = 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(int edges, int pointerId) { |
| return isPointerDown(pointerId) && (mInitialEdgesTouched[pointerId] & edges) != 0; |
| } |
| |
| private void releaseViewForPointerUp() { |
| mVelocityTracker.computeCurrentVelocity(1000, mMaxVelocity); |
| final float xvel = clampMag( |
| mVelocityTracker.getXVelocity(mActivePointerId), |
| mMinVelocity, mMaxVelocity); |
| final float yvel = clampMag( |
| mVelocityTracker.getYVelocity(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); |
| ViewCompat.offsetLeftAndRight(mCapturedView, clampedX - oldLeft); |
| } |
| if (dy != 0) { |
| clampedY = mCallback.clampViewPositionVertical(mCapturedView, top, dy); |
| ViewCompat.offsetTopAndBottom(mCapturedView, 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(@Nullable 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 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. |
| */ |
| @Nullable |
| 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 getEdgesTouched(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; |
| } |
| |
| private boolean isValidPointerForActionMove(int pointerId) { |
| if (!isPointerDown(pointerId)) { |
| Log.e(TAG, "Ignoring pointerId=" + pointerId + " because ACTION_DOWN was not received " |
| + "for this pointer before ACTION_MOVE. It likely happened because " |
| + " ViewDragHelper did not receive all the events in the event stream."); |
| return false; |
| } |
| return true; |
| } |
| } |
