Java tutorial
package com.cmbb.smartmarket.widget; /** * ??LovelyBaby * ?? * N.Sun * 16/3/4 ?11:58 */ /* * Copyright (C) 2015 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. */ import android.content.Context; import android.content.res.TypedArray; import android.graphics.Canvas; import android.graphics.Rect; import android.os.Bundle; import android.os.Parcel; import android.os.Parcelable; import android.support.v4.view.AccessibilityDelegateCompat; import android.support.v4.view.InputDeviceCompat; import android.support.v4.view.MotionEventCompat; import android.support.v4.view.NestedScrollingChild; import android.support.v4.view.NestedScrollingChildHelper; import android.support.v4.view.NestedScrollingParent; import android.support.v4.view.NestedScrollingParentHelper; import android.support.v4.view.ScrollingView; import android.support.v4.view.VelocityTrackerCompat; import android.support.v4.view.ViewCompat; import android.support.v4.view.accessibility.AccessibilityEventCompat; import android.support.v4.view.accessibility.AccessibilityNodeInfoCompat; import android.support.v4.view.accessibility.AccessibilityRecordCompat; import android.support.v4.widget.EdgeEffectCompat; import android.support.v4.widget.ScrollerCompat; import android.util.AttributeSet; import android.util.Log; import android.util.TypedValue; import android.view.FocusFinder; import android.view.KeyEvent; import android.view.MotionEvent; import android.view.VelocityTracker; import android.view.View; import android.view.ViewConfiguration; import android.view.ViewGroup; import android.view.ViewParent; import android.view.accessibility.AccessibilityEvent; import android.view.animation.AnimationUtils; import android.widget.FrameLayout; import android.widget.ScrollView; import java.util.List; /** * NestedScrollView is just like {@link ScrollView}, but it supports acting * as both a nested scrolling parent and child on both new and old versions of Android. * Nested scrolling is enabled by default. */ public class NestedScrollView extends FrameLayout implements NestedScrollingParent, NestedScrollingChild, ScrollingView { static final int ANIMATED_SCROLL_GAP = 250; static final float MAX_SCROLL_FACTOR = 0.5f; private static final String TAG = "NestedScrollView"; /** * Interface definition for a callback to be invoked when the scroll * X or Y positions of a view change. * <p/> * <p>This version of the interface works on all versions of Android, back to API v4.</p> * * @see #setOnScrollChangeListener(OnScrollChangeListener) */ public interface OnScrollChangeListener { /** * Called when the scroll position of a view changes. * * @param v The view whose scroll position has changed. * @param scrollX Current horizontal scroll origin. * @param scrollY Current vertical scroll origin. * @param oldScrollX Previous horizontal scroll origin. * @param oldScrollY Previous vertical scroll origin. */ void onScrollChange(NestedScrollView v, int scrollX, int scrollY, int oldScrollX, int oldScrollY); } private long mLastScroll; private final Rect mTempRect = new Rect(); private ScrollerCompat mScroller; private EdgeEffectCompat mEdgeGlowTop; private EdgeEffectCompat mEdgeGlowBottom; /** * Position of the last motion event. */ private int mLastMotionY; /** * True when the layout has changed but the traversal has not come through yet. * Ideally the view hierarchy would keep track of this for us. */ private boolean mIsLayoutDirty = true; private boolean mIsLaidOut = false; /** * The child to give focus to in the event that a child has requested focus while the * layout is dirty. This prevents the scroll from being wrong if the child has not been * laid out before requesting focus. */ private View mChildToScrollTo = null; /** * True if the user is currently dragging this ScrollView around. This is * not the same as 'is being flinged', which can be checked by * mScroller.isFinished() (flinging begins when the user lifts his finger). */ private boolean mIsBeingDragged = false; /** * Determines speed during touch scrolling */ private VelocityTracker mVelocityTracker; /** * When set to true, the scroll view measure its child to make it fill the currently * visible area. */ private boolean mFillViewport; /** * Whether arrow scrolling is animated. */ private boolean mSmoothScrollingEnabled = true; private int mTouchSlop; private int mMinimumVelocity; private int mMaximumVelocity; /** * ID of the active pointer. This is used to retain consistency during * drags/flings if multiple pointers are used. */ private int mActivePointerId = INVALID_POINTER; /** * Used during scrolling to retrieve the new offset within the window. */ private final int[] mScrollOffset = new int[2]; private final int[] mScrollConsumed = new int[2]; private int mNestedYOffset; /** * Sentinel value for no current active pointer. * Used by {@link #mActivePointerId}. */ private static final int INVALID_POINTER = -1; private SavedState mSavedState; private static final AccessibilityDelegate ACCESSIBILITY_DELEGATE = new AccessibilityDelegate(); private static final int[] SCROLLVIEW_STYLEABLE = new int[] { android.R.attr.fillViewport }; private final NestedScrollingParentHelper mParentHelper; private final NestedScrollingChildHelper mChildHelper; private float mVerticalScrollFactor; private OnScrollChangeListener mOnScrollChangeListener; public NestedScrollView(Context context) { this(context, null); } public NestedScrollView(Context context, AttributeSet attrs) { this(context, attrs, 0); } public NestedScrollView(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); initScrollView(); final TypedArray a = context.obtainStyledAttributes(attrs, SCROLLVIEW_STYLEABLE, defStyleAttr, 0); setFillViewport(a.getBoolean(0, false)); a.recycle(); mParentHelper = new NestedScrollingParentHelper(this); mChildHelper = new NestedScrollingChildHelper(this); // ...because why else would you be using this widget? setNestedScrollingEnabled(true); ViewCompat.setAccessibilityDelegate(this, ACCESSIBILITY_DELEGATE); } // NestedScrollingChild @Override public void setNestedScrollingEnabled(boolean enabled) { mChildHelper.setNestedScrollingEnabled(enabled); } @Override public boolean isNestedScrollingEnabled() { return mChildHelper.isNestedScrollingEnabled(); } @Override public boolean startNestedScroll(int axes) { return mChildHelper.startNestedScroll(axes); } @Override public void stopNestedScroll() { mChildHelper.stopNestedScroll(); } @Override public boolean hasNestedScrollingParent() { return mChildHelper.hasNestedScrollingParent(); } @Override public boolean dispatchNestedScroll(int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed, int[] offsetInWindow) { return mChildHelper.dispatchNestedScroll(dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed, offsetInWindow); } @Override public boolean dispatchNestedPreScroll(int dx, int dy, int[] consumed, int[] offsetInWindow) { return mChildHelper.dispatchNestedPreScroll(dx, dy, consumed, offsetInWindow); } @Override public boolean dispatchNestedFling(float velocityX, float velocityY, boolean consumed) { return mChildHelper.dispatchNestedFling(velocityX, velocityY, consumed); } @Override public boolean dispatchNestedPreFling(float velocityX, float velocityY) { return mChildHelper.dispatchNestedPreFling(velocityX, velocityY); } // NestedScrollingParent @Override public boolean onStartNestedScroll(View child, View target, int nestedScrollAxes) { return (nestedScrollAxes & ViewCompat.SCROLL_AXIS_VERTICAL) != 0; } @Override public void onNestedScrollAccepted(View child, View target, int nestedScrollAxes) { mParentHelper.onNestedScrollAccepted(child, target, nestedScrollAxes); startNestedScroll(ViewCompat.SCROLL_AXIS_VERTICAL); } @Override public void onStopNestedScroll(View target) { mParentHelper.onStopNestedScroll(target); stopNestedScroll(); } @Override public void onNestedScroll(View target, int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed) { final int oldScrollY = getScrollY(); scrollBy(0, dyUnconsumed); final int myConsumed = getScrollY() - oldScrollY; final int myUnconsumed = dyUnconsumed - myConsumed; dispatchNestedScroll(0, myConsumed, 0, myUnconsumed, null); } @Override public void onNestedPreScroll(View target, int dx, int dy, int[] consumed) { // Do nothing } @Override public boolean onNestedFling(View target, float velocityX, float velocityY, boolean consumed) { if (!consumed) { flingWithNestedDispatch((int) velocityY); return true; } return false; } @Override public boolean onNestedPreFling(View target, float velocityX, float velocityY) { // Do nothing return false; } @Override public int getNestedScrollAxes() { return mParentHelper.getNestedScrollAxes(); } // ScrollView import public boolean shouldDelayChildPressedState() { return true; } @Override protected float getTopFadingEdgeStrength() { if (getChildCount() == 0) { return 0.0f; } final int length = getVerticalFadingEdgeLength(); final int scrollY = getScrollY(); if (scrollY < length) { return scrollY / (float) length; } return 1.0f; } @Override protected float getBottomFadingEdgeStrength() { if (getChildCount() == 0) { return 0.0f; } final int length = getVerticalFadingEdgeLength(); final int bottomEdge = getHeight() - getPaddingBottom(); final int span = getChildAt(0).getBottom() - getScrollY() - bottomEdge; if (span < length) { return span / (float) length; } return 1.0f; } /** * @return The maximum amount this scroll view will scroll in response to * an arrow event. */ public int getMaxScrollAmount() { return (int) (MAX_SCROLL_FACTOR * getHeight()); } private void initScrollView() { mScroller = ScrollerCompat.create(getContext(), null); setFocusable(true); setDescendantFocusability(FOCUS_AFTER_DESCENDANTS); setWillNotDraw(false); final ViewConfiguration configuration = ViewConfiguration.get(getContext()); mTouchSlop = configuration.getScaledTouchSlop(); mMinimumVelocity = configuration.getScaledMinimumFlingVelocity(); mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); } @Override public void addView(View child) { if (getChildCount() > 0) { throw new IllegalStateException("ScrollView can host only one direct child"); } super.addView(child); } @Override public void addView(View child, int index) { if (getChildCount() > 0) { throw new IllegalStateException("ScrollView can host only one direct child"); } super.addView(child, index); } @Override public void addView(View child, ViewGroup.LayoutParams params) { if (getChildCount() > 0) { throw new IllegalStateException("ScrollView can host only one direct child"); } super.addView(child, params); } @Override public void addView(View child, int index, ViewGroup.LayoutParams params) { if (getChildCount() > 0) { throw new IllegalStateException("ScrollView can host only one direct child"); } super.addView(child, index, params); } /** * Register a callback to be invoked when the scroll X or Y positions of * this view change. * <p>This version of the method works on all versions of Android, back to API v4.</p> * * @param l The listener to notify when the scroll X or Y position changes. * @see View#getScrollX() * @see View#getScrollY() */ public void setOnScrollChangeListener(OnScrollChangeListener l) { mOnScrollChangeListener = l; } /** * @return Returns true this ScrollView can be scrolled */ private boolean canScroll() { View child = getChildAt(0); if (child != null) { int childHeight = child.getHeight(); return getHeight() < childHeight + getPaddingTop() + getPaddingBottom(); } return false; } /** * Indicates whether this ScrollView's content is stretched to fill the viewport. * * @return True if the content fills the viewport, false otherwise. * @attr ref android.R.styleable#ScrollView_fillViewport */ public boolean isFillViewport() { return mFillViewport; } /** * Indicates this ScrollView whether it should stretch its content height to fill * the viewport or not. * * @param fillViewport True to stretch the content's height to the viewport's * boundaries, false otherwise. * @attr ref android.R.styleable#ScrollView_fillViewport */ public void setFillViewport(boolean fillViewport) { if (fillViewport != mFillViewport) { mFillViewport = fillViewport; requestLayout(); } } /** * @return Whether arrow scrolling will animate its transition. */ public boolean isSmoothScrollingEnabled() { return mSmoothScrollingEnabled; } /** * Set whether arrow scrolling will animate its transition. * * @param smoothScrollingEnabled whether arrow scrolling will animate its transition */ public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) { mSmoothScrollingEnabled = smoothScrollingEnabled; } @Override protected void onScrollChanged(int l, int t, int oldl, int oldt) { super.onScrollChanged(l, t, oldl, oldt); if (mOnScrollChangeListener != null) { mOnScrollChangeListener.onScrollChange(this, l, t, oldl, oldt); } } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); if (!mFillViewport) { return; } final int heightMode = MeasureSpec.getMode(heightMeasureSpec); if (heightMode == MeasureSpec.UNSPECIFIED) { return; } if (getChildCount() > 0) { final View child = getChildAt(0); int height = getMeasuredHeight(); if (child.getMeasuredHeight() < height) { final LayoutParams lp = (LayoutParams) child.getLayoutParams(); int childWidthMeasureSpec = getChildMeasureSpec(widthMeasureSpec, getPaddingLeft() + getPaddingRight(), lp.width); height -= getPaddingTop(); height -= getPaddingBottom(); int childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY); child.measure(childWidthMeasureSpec, childHeightMeasureSpec); } } } @Override public boolean dispatchKeyEvent(KeyEvent event) { // Let the focused view and/or our descendants get the key first return super.dispatchKeyEvent(event) || executeKeyEvent(event); } /** * You can call this function yourself to have the scroll view perform * scrolling from a key event, just as if the event had been dispatched to * it by the view hierarchy. * * @param event The key event to execute. * @return Return true if the event was handled, else false. */ public boolean executeKeyEvent(KeyEvent event) { mTempRect.setEmpty(); if (!canScroll()) { if (isFocused() && event.getKeyCode() != KeyEvent.KEYCODE_BACK) { View currentFocused = findFocus(); if (currentFocused == this) currentFocused = null; View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, View.FOCUS_DOWN); return nextFocused != null && nextFocused != this && nextFocused.requestFocus(View.FOCUS_DOWN); } return false; } boolean handled = false; if (event.getAction() == KeyEvent.ACTION_DOWN) { switch (event.getKeyCode()) { case KeyEvent.KEYCODE_DPAD_UP: if (!event.isAltPressed()) { handled = arrowScroll(View.FOCUS_UP); } else { handled = fullScroll(View.FOCUS_UP); } break; case KeyEvent.KEYCODE_DPAD_DOWN: if (!event.isAltPressed()) { handled = arrowScroll(View.FOCUS_DOWN); } else { handled = fullScroll(View.FOCUS_DOWN); } break; case KeyEvent.KEYCODE_SPACE: pageScroll(event.isShiftPressed() ? View.FOCUS_UP : View.FOCUS_DOWN); break; } } return handled; } private boolean inChild(int x, int y) { if (getChildCount() > 0) { final int scrollY = getScrollY(); final View child = getChildAt(0); return !(y < child.getTop() - scrollY || y >= child.getBottom() - scrollY || x < child.getLeft() || x >= child.getRight()); } return false; } private void initOrResetVelocityTracker() { if (mVelocityTracker == null) { mVelocityTracker = VelocityTracker.obtain(); } else { mVelocityTracker.clear(); } } private void initVelocityTrackerIfNotExists() { if (mVelocityTracker == null) { mVelocityTracker = VelocityTracker.obtain(); } } private void recycleVelocityTracker() { if (mVelocityTracker != null) { mVelocityTracker.recycle(); mVelocityTracker = null; } } @Override public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) { if (disallowIntercept) { recycleVelocityTracker(); } super.requestDisallowInterceptTouchEvent(disallowIntercept); } @Override public boolean onInterceptTouchEvent(MotionEvent ev) { /* * This method JUST determines whether we want to intercept the motion. * If we return true, onMotionEvent will be called and we do the actual * scrolling there. */ /* * Shortcut the most recurring case: the user is in the dragging * state and he is moving his finger. We want to intercept this * motion. */ final int action = ev.getAction(); if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) { return true; } switch (action & MotionEventCompat.ACTION_MASK) { case MotionEvent.ACTION_MOVE: { /* * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check * whether the user has moved far enough from his original down touch. */ /* * Locally do absolute value. mLastMotionY is set to the y value * of the down event. */ final int activePointerId = mActivePointerId; if (activePointerId == INVALID_POINTER) { // If we don't have a valid id, the touch down wasn't on content. break; } final int pointerIndex = MotionEventCompat.findPointerIndex(ev, activePointerId); if (pointerIndex == -1) { Log.e(TAG, "Invalid pointerId=" + activePointerId + " in onInterceptTouchEvent"); break; } final int y = (int) MotionEventCompat.getY(ev, pointerIndex); final int yDiff = Math.abs(y - mLastMotionY); if (yDiff > mTouchSlop && (getNestedScrollAxes() & ViewCompat.SCROLL_AXIS_VERTICAL) == 0) { mIsBeingDragged = true; mLastMotionY = y; initVelocityTrackerIfNotExists(); mVelocityTracker.addMovement(ev); mNestedYOffset = 0; final ViewParent parent = getParent(); if (parent != null) { parent.requestDisallowInterceptTouchEvent(true); } } break; } case MotionEvent.ACTION_DOWN: { final int y = (int) ev.getY(); if (!inChild((int) ev.getX(), (int) y)) { // mIsBeingDragged = !mScroller.isFinished(); mIsBeingDragged = false; recycleVelocityTracker(); break; } /* * Remember location of down touch. * ACTION_DOWN always refers to pointer index 0. */ mLastMotionY = y; mActivePointerId = MotionEventCompat.getPointerId(ev, 0); initOrResetVelocityTracker(); mVelocityTracker.addMovement(ev); /* * If being flinged and user touches the screen, initiate drag; * otherwise don't. mScroller.isFinished should be false when * being flinged. */ // mIsBeingDragged = !mScroller.isFinished(); mIsBeingDragged = false; startNestedScroll(ViewCompat.SCROLL_AXIS_VERTICAL); break; } case MotionEvent.ACTION_CANCEL: case MotionEvent.ACTION_UP: /* Release the drag */ mIsBeingDragged = false; mActivePointerId = INVALID_POINTER; recycleVelocityTracker(); if (mScroller.springBack(getScrollX(), getScrollY(), 0, 0, 0, getScrollRange())) { ViewCompat.postInvalidateOnAnimation(this); } stopNestedScroll(); break; case MotionEventCompat.ACTION_POINTER_UP: onSecondaryPointerUp(ev); break; } /* * The only time we want to intercept motion events is if we are in the * drag mode. */ return mIsBeingDragged; } @Override public boolean onTouchEvent(MotionEvent ev) { initVelocityTrackerIfNotExists(); MotionEvent vtev = MotionEvent.obtain(ev); final int actionMasked = MotionEventCompat.getActionMasked(ev); if (actionMasked == MotionEvent.ACTION_DOWN) { mNestedYOffset = 0; } vtev.offsetLocation(0, mNestedYOffset); switch (actionMasked) { case MotionEvent.ACTION_DOWN: { if (getChildCount() == 0) { return false; } if ((mIsBeingDragged = !mScroller.isFinished())) { final ViewParent parent = getParent(); if (parent != null) { parent.requestDisallowInterceptTouchEvent(true); } } /* * If being flinged and user touches, stop the fling. isFinished * will be false if being flinged. */ if (!mScroller.isFinished()) { mScroller.abortAnimation(); } // Remember where the motion event started mLastMotionY = (int) ev.getY(); mActivePointerId = MotionEventCompat.getPointerId(ev, 0); startNestedScroll(ViewCompat.SCROLL_AXIS_VERTICAL); break; } case MotionEvent.ACTION_MOVE: final int activePointerIndex = MotionEventCompat.findPointerIndex(ev, mActivePointerId); if (activePointerIndex == -1) { Log.e(TAG, "Invalid pointerId=" + mActivePointerId + " in onTouchEvent"); break; } final int y = (int) MotionEventCompat.getY(ev, activePointerIndex); int deltaY = mLastMotionY - y; if (dispatchNestedPreScroll(0, deltaY, mScrollConsumed, mScrollOffset)) { deltaY -= mScrollConsumed[1]; vtev.offsetLocation(0, mScrollOffset[1]); mNestedYOffset += mScrollOffset[1]; } if (!mIsBeingDragged && Math.abs(deltaY) > mTouchSlop) { final ViewParent parent = getParent(); if (parent != null) { parent.requestDisallowInterceptTouchEvent(true); } mIsBeingDragged = true; if (deltaY > 0) { deltaY -= mTouchSlop; } else { deltaY += mTouchSlop; } } if (mIsBeingDragged) { // Scroll to follow the motion event mLastMotionY = y - mScrollOffset[1]; final int oldY = getScrollY(); final int range = getScrollRange(); final int overscrollMode = ViewCompat.getOverScrollMode(this); boolean canOverscroll = overscrollMode == ViewCompat.OVER_SCROLL_ALWAYS || (overscrollMode == ViewCompat.OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); // Calling overScrollByCompat will call onOverScrolled, which // calls onScrollChanged if applicable. if (overScrollByCompat(0, deltaY, 0, getScrollY(), 0, range, 0, 0, true) && !hasNestedScrollingParent()) { // Break our velocity if we hit a scroll barrier. mVelocityTracker.clear(); } final int scrolledDeltaY = getScrollY() - oldY; final int unconsumedY = deltaY - scrolledDeltaY; if (dispatchNestedScroll(0, scrolledDeltaY, 0, unconsumedY, mScrollOffset)) { mLastMotionY -= mScrollOffset[1]; vtev.offsetLocation(0, mScrollOffset[1]); mNestedYOffset += mScrollOffset[1]; } else if (canOverscroll) { ensureGlows(); final int pulledToY = oldY + deltaY; if (pulledToY < 0) { mEdgeGlowTop.onPull((float) deltaY / getHeight(), MotionEventCompat.getX(ev, activePointerIndex) / getWidth()); if (!mEdgeGlowBottom.isFinished()) { mEdgeGlowBottom.onRelease(); } } else if (pulledToY > range) { mEdgeGlowBottom.onPull((float) deltaY / getHeight(), 1.f - MotionEventCompat.getX(ev, activePointerIndex) / getWidth()); if (!mEdgeGlowTop.isFinished()) { mEdgeGlowTop.onRelease(); } } if (mEdgeGlowTop != null && (!mEdgeGlowTop.isFinished() || !mEdgeGlowBottom.isFinished())) { ViewCompat.postInvalidateOnAnimation(this); } } } break; case MotionEvent.ACTION_UP: if (mIsBeingDragged) { final VelocityTracker velocityTracker = mVelocityTracker; velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); int initialVelocity = (int) VelocityTrackerCompat.getYVelocity(velocityTracker, mActivePointerId); if ((Math.abs(initialVelocity) > mMinimumVelocity)) { flingWithNestedDispatch(-initialVelocity); } else if (mScroller.springBack(getScrollX(), getScrollY(), 0, 0, 0, getScrollRange())) { ViewCompat.postInvalidateOnAnimation(this); } } mActivePointerId = INVALID_POINTER; endDrag(); break; case MotionEvent.ACTION_CANCEL: if (mIsBeingDragged && getChildCount() > 0) { if (mScroller.springBack(getScrollX(), getScrollY(), 0, 0, 0, getScrollRange())) { ViewCompat.postInvalidateOnAnimation(this); } } mActivePointerId = INVALID_POINTER; endDrag(); break; case MotionEventCompat.ACTION_POINTER_DOWN: { final int index = MotionEventCompat.getActionIndex(ev); mLastMotionY = (int) MotionEventCompat.getY(ev, index); mActivePointerId = MotionEventCompat.getPointerId(ev, index); break; } case MotionEventCompat.ACTION_POINTER_UP: onSecondaryPointerUp(ev); mLastMotionY = (int) MotionEventCompat.getY(ev, MotionEventCompat.findPointerIndex(ev, mActivePointerId)); break; } if (mVelocityTracker != null) { mVelocityTracker.addMovement(vtev); } vtev.recycle(); return true; } private void onSecondaryPointerUp(MotionEvent ev) { final int pointerIndex = (ev.getAction() & MotionEventCompat.ACTION_POINTER_INDEX_MASK) >> MotionEventCompat.ACTION_POINTER_INDEX_SHIFT; final int pointerId = MotionEventCompat.getPointerId(ev, pointerIndex); if (pointerId == mActivePointerId) { // This was our active pointer going up. Choose a new // active pointer and adjust accordingly. // TODO: Make this decision more intelligent. final int newPointerIndex = pointerIndex == 0 ? 1 : 0; mLastMotionY = (int) MotionEventCompat.getY(ev, newPointerIndex); mActivePointerId = MotionEventCompat.getPointerId(ev, newPointerIndex); if (mVelocityTracker != null) { mVelocityTracker.clear(); } } } public boolean onGenericMotionEvent(MotionEvent event) { if ((MotionEventCompat.getSource(event) & InputDeviceCompat.SOURCE_CLASS_POINTER) != 0) { switch (event.getAction()) { case MotionEventCompat.ACTION_SCROLL: { if (!mIsBeingDragged) { final float vscroll = MotionEventCompat.getAxisValue(event, MotionEventCompat.AXIS_VSCROLL); if (vscroll != 0) { final int delta = (int) (vscroll * getVerticalScrollFactorCompat()); final int range = getScrollRange(); int oldScrollY = getScrollY(); int newScrollY = oldScrollY - delta; if (newScrollY < 0) { newScrollY = 0; } else if (newScrollY > range) { newScrollY = range; } if (newScrollY != oldScrollY) { super.scrollTo(getScrollX(), newScrollY); return true; } } } } } } return false; } private float getVerticalScrollFactorCompat() { if (mVerticalScrollFactor == 0) { TypedValue outValue = new TypedValue(); final Context context = getContext(); if (!context.getTheme().resolveAttribute(android.R.attr.listPreferredItemHeight, outValue, true)) { throw new IllegalStateException("Expected theme to define listPreferredItemHeight."); } mVerticalScrollFactor = outValue.getDimension(context.getResources().getDisplayMetrics()); } return mVerticalScrollFactor; } protected void onOverScrolled(int scrollX, int scrollY, boolean clampedX, boolean clampedY) { super.scrollTo(scrollX, scrollY); } boolean overScrollByCompat(int deltaX, int deltaY, int scrollX, int scrollY, int scrollRangeX, int scrollRangeY, int maxOverScrollX, int maxOverScrollY, boolean isTouchEvent) { final int overScrollMode = ViewCompat.getOverScrollMode(this); final boolean canScrollHorizontal = computeHorizontalScrollRange() > computeHorizontalScrollExtent(); final boolean canScrollVertical = computeVerticalScrollRange() > computeVerticalScrollExtent(); final boolean overScrollHorizontal = overScrollMode == ViewCompat.OVER_SCROLL_ALWAYS || (overScrollMode == ViewCompat.OVER_SCROLL_IF_CONTENT_SCROLLS && canScrollHorizontal); final boolean overScrollVertical = overScrollMode == ViewCompat.OVER_SCROLL_ALWAYS || (overScrollMode == ViewCompat.OVER_SCROLL_IF_CONTENT_SCROLLS && canScrollVertical); int newScrollX = scrollX + deltaX; if (!overScrollHorizontal) { maxOverScrollX = 0; } int newScrollY = scrollY + deltaY; if (!overScrollVertical) { maxOverScrollY = 0; } // Clamp values if at the limits and record final int left = -maxOverScrollX; final int right = maxOverScrollX + scrollRangeX; final int top = -maxOverScrollY; final int bottom = maxOverScrollY + scrollRangeY; boolean clampedX = false; if (newScrollX > right) { newScrollX = right; clampedX = true; } else if (newScrollX < left) { newScrollX = left; clampedX = true; } boolean clampedY = false; if (newScrollY > bottom) { newScrollY = bottom; clampedY = true; } else if (newScrollY < top) { newScrollY = top; clampedY = true; } if (clampedY) { mScroller.springBack(newScrollX, newScrollY, 0, 0, 0, getScrollRange()); } onOverScrolled(newScrollX, newScrollY, clampedX, clampedY); return clampedX || clampedY; } private int getScrollRange() { int scrollRange = 0; if (getChildCount() > 0) { View child = getChildAt(0); scrollRange = Math.max(0, child.getHeight() - (getHeight() - getPaddingBottom() - getPaddingTop())); } return scrollRange; } /** * <p> * Finds the next focusable component that fits in the specified bounds. * </p> * * @param topFocus look for a candidate is the one at the top of the bounds * if topFocus is true, or at the bottom of the bounds if topFocus is * false * @param top the top offset of the bounds in which a focusable must be * found * @param bottom the bottom offset of the bounds in which a focusable must * be found * @return the next focusable component in the bounds or null if none can * be found */ private View findFocusableViewInBounds(boolean topFocus, int top, int bottom) { List<View> focusables = getFocusables(View.FOCUS_FORWARD); View focusCandidate = null; /* * A fully contained focusable is one where its top is below the bound's * top, and its bottom is above the bound's bottom. A partially * contained focusable is one where some part of it is within the * bounds, but it also has some part that is not within bounds. A fully contained * focusable is preferred to a partially contained focusable. */ boolean foundFullyContainedFocusable = false; int count = focusables.size(); for (int i = 0; i < count; i++) { View view = focusables.get(i); int viewTop = view.getTop(); int viewBottom = view.getBottom(); if (top < viewBottom && viewTop < bottom) { /* * the focusable is in the target area, it is a candidate for * focusing */ final boolean viewIsFullyContained = (top < viewTop) && (viewBottom < bottom); if (focusCandidate == null) { /* No candidate, take this one */ focusCandidate = view; foundFullyContainedFocusable = viewIsFullyContained; } else { final boolean viewIsCloserToBoundary = (topFocus && viewTop < focusCandidate.getTop()) || (!topFocus && viewBottom > focusCandidate.getBottom()); if (foundFullyContainedFocusable) { if (viewIsFullyContained && viewIsCloserToBoundary) { /* * We're dealing with only fully contained views, so * it has to be closer to the boundary to beat our * candidate */ focusCandidate = view; } } else { if (viewIsFullyContained) { /* Any fully contained view beats a partially contained view */ focusCandidate = view; foundFullyContainedFocusable = true; } else if (viewIsCloserToBoundary) { /* * Partially contained view beats another partially * contained view if it's closer */ focusCandidate = view; } } } } } return focusCandidate; } /** * <p>Handles scrolling in response to a "page up/down" shortcut press. This * method will scroll the view by one page up or down and give the focus * to the topmost/bottommost component in the new visible area. If no * component is a good candidate for focus, this scrollview reclaims the * focus.</p> * * @param direction the scroll direction: {@link View#FOCUS_UP} * to go one page up or * {@link View#FOCUS_DOWN} to go one page down * @return true if the key event is consumed by this method, false otherwise */ public boolean pageScroll(int direction) { boolean down = direction == View.FOCUS_DOWN; int height = getHeight(); if (down) { mTempRect.top = getScrollY() + height; int count = getChildCount(); if (count > 0) { View view = getChildAt(count - 1); if (mTempRect.top + height > view.getBottom()) { mTempRect.top = view.getBottom() - height; } } } else { mTempRect.top = getScrollY() - height; if (mTempRect.top < 0) { mTempRect.top = 0; } } mTempRect.bottom = mTempRect.top + height; return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom); } /** * <p>Handles scrolling in response to a "home/end" shortcut press. This * method will scroll the view to the top or bottom and give the focus * to the topmost/bottommost component in the new visible area. If no * component is a good candidate for focus, this scrollview reclaims the * focus.</p> * * @param direction the scroll direction: {@link View#FOCUS_UP} * to go the top of the view or * {@link View#FOCUS_DOWN} to go the bottom * @return true if the key event is consumed by this method, false otherwise */ public boolean fullScroll(int direction) { boolean down = direction == View.FOCUS_DOWN; int height = getHeight(); mTempRect.top = 0; mTempRect.bottom = height; if (down) { int count = getChildCount(); if (count > 0) { View view = getChildAt(count - 1); mTempRect.bottom = view.getBottom() + getPaddingBottom(); mTempRect.top = mTempRect.bottom - height; } } return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom); } /** * <p>Scrolls the view to make the area defined by <code>top</code> and * <code>bottom</code> visible. This method attempts to give the focus * to a component visible in this area. If no component can be focused in * the new visible area, the focus is reclaimed by this ScrollView.</p> * * @param direction the scroll direction: {@link View#FOCUS_UP} * to go upward, {@link View#FOCUS_DOWN} to downward * @param top the top offset of the new area to be made visible * @param bottom the bottom offset of the new area to be made visible * @return true if the key event is consumed by this method, false otherwise */ private boolean scrollAndFocus(int direction, int top, int bottom) { boolean handled = true; int height = getHeight(); int containerTop = getScrollY(); int containerBottom = containerTop + height; boolean up = direction == View.FOCUS_UP; View newFocused = findFocusableViewInBounds(up, top, bottom); if (newFocused == null) { newFocused = this; } if (top >= containerTop && bottom <= containerBottom) { handled = false; } else { int delta = up ? (top - containerTop) : (bottom - containerBottom); doScrollY(delta); } if (newFocused != findFocus()) newFocused.requestFocus(direction); return handled; } /** * Handle scrolling in response to an up or down arrow click. * * @param direction The direction corresponding to the arrow key that was * pressed * @return True if we consumed the event, false otherwise */ public boolean arrowScroll(int direction) { View currentFocused = findFocus(); if (currentFocused == this) currentFocused = null; View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); final int maxJump = getMaxScrollAmount(); if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump, getHeight())) { nextFocused.getDrawingRect(mTempRect); offsetDescendantRectToMyCoords(nextFocused, mTempRect); int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); doScrollY(scrollDelta); nextFocused.requestFocus(direction); } else { // no new focus int scrollDelta = maxJump; if (direction == View.FOCUS_UP && getScrollY() < scrollDelta) { scrollDelta = getScrollY(); } else if (direction == View.FOCUS_DOWN) { if (getChildCount() > 0) { int daBottom = getChildAt(0).getBottom(); int screenBottom = getScrollY() + getHeight() - getPaddingBottom(); if (daBottom - screenBottom < maxJump) { scrollDelta = daBottom - screenBottom; } } } if (scrollDelta == 0) { return false; } doScrollY(direction == View.FOCUS_DOWN ? scrollDelta : -scrollDelta); } if (currentFocused != null && currentFocused.isFocused() && isOffScreen(currentFocused)) { // previously focused item still has focus and is off screen, give // it up (take it back to ourselves) // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are // sure to // get it) final int descendantFocusability = getDescendantFocusability(); // save setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); requestFocus(); setDescendantFocusability(descendantFocusability); // restore } return true; } /** * @return whether the descendant of this scroll view is scrolled off * screen. */ private boolean isOffScreen(View descendant) { return !isWithinDeltaOfScreen(descendant, 0, getHeight()); } /** * @return whether the descendant of this scroll view is within delta * pixels of being on the screen. */ private boolean isWithinDeltaOfScreen(View descendant, int delta, int height) { descendant.getDrawingRect(mTempRect); offsetDescendantRectToMyCoords(descendant, mTempRect); return (mTempRect.bottom + delta) >= getScrollY() && (mTempRect.top - delta) <= (getScrollY() + height); } /** * Smooth scroll by a Y delta * * @param delta the number of pixels to scroll by on the Y axis */ private void doScrollY(int delta) { if (delta != 0) { if (mSmoothScrollingEnabled) { smoothScrollBy(0, delta); } else { scrollBy(0, delta); } } } /** * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. * * @param dx the number of pixels to scroll by on the X axis * @param dy the number of pixels to scroll by on the Y axis */ public final void smoothScrollBy(int dx, int dy) { if (getChildCount() == 0) { // Nothing to do. return; } long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; if (duration > ANIMATED_SCROLL_GAP) { final int height = getHeight() - getPaddingBottom() - getPaddingTop(); final int bottom = getChildAt(0).getHeight(); final int maxY = Math.max(0, bottom - height); final int scrollY = getScrollY(); dy = Math.max(0, Math.min(scrollY + dy, maxY)) - scrollY; mScroller.startScroll(getScrollX(), scrollY, 0, dy); ViewCompat.postInvalidateOnAnimation(this); } else { if (!mScroller.isFinished()) { mScroller.abortAnimation(); } scrollBy(dx, dy); } mLastScroll = AnimationUtils.currentAnimationTimeMillis(); } /** * Like {@link #scrollTo}, but scroll smoothly instead of immediately. * * @param x the position where to scroll on the X axis * @param y the position where to scroll on the Y axis */ public final void smoothScrollTo(int x, int y) { smoothScrollBy(x - getScrollX(), y - getScrollY()); } /** * <p>The scroll range of a scroll view is the overall height of all of its * children.</p> * * @hide */ @Override public int computeVerticalScrollRange() { final int count = getChildCount(); final int contentHeight = getHeight() - getPaddingBottom() - getPaddingTop(); if (count == 0) { return contentHeight; } int scrollRange = getChildAt(0).getBottom(); final int scrollY = getScrollY(); final int overscrollBottom = Math.max(0, scrollRange - contentHeight); if (scrollY < 0) { scrollRange -= scrollY; } else if (scrollY > overscrollBottom) { scrollRange += scrollY - overscrollBottom; } return scrollRange; } /** * @hide */ @Override public int computeVerticalScrollOffset() { return Math.max(0, super.computeVerticalScrollOffset()); } /** * @hide */ @Override public int computeVerticalScrollExtent() { return super.computeVerticalScrollExtent(); } /** * @hide */ @Override public int computeHorizontalScrollRange() { return super.computeHorizontalScrollRange(); } /** * @hide */ @Override public int computeHorizontalScrollOffset() { return super.computeHorizontalScrollOffset(); } /** * @hide */ @Override public int computeHorizontalScrollExtent() { return super.computeHorizontalScrollExtent(); } @Override protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) { ViewGroup.LayoutParams lp = child.getLayoutParams(); int childWidthMeasureSpec; int childHeightMeasureSpec; childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, getPaddingLeft() + getPaddingRight(), lp.width); childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); child.measure(childWidthMeasureSpec, childHeightMeasureSpec); } @Override protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, int parentHeightMeasureSpec, int heightUsed) { final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams(); final int childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, getPaddingLeft() + getPaddingRight() + lp.leftMargin + lp.rightMargin + widthUsed, lp.width); final int childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(lp.topMargin + lp.bottomMargin, MeasureSpec.UNSPECIFIED); child.measure(childWidthMeasureSpec, childHeightMeasureSpec); } @Override public void computeScroll() { if (mScroller.computeScrollOffset()) { int oldX = getScrollX(); int oldY = getScrollY(); int x = mScroller.getCurrX(); int y = mScroller.getCurrY(); if (oldX != x || oldY != y) { final int range = getScrollRange(); final int overscrollMode = ViewCompat.getOverScrollMode(this); final boolean canOverscroll = overscrollMode == ViewCompat.OVER_SCROLL_ALWAYS || (overscrollMode == ViewCompat.OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0); overScrollByCompat(x - oldX, y - oldY, oldX, oldY, 0, range, 0, 0, false); if (canOverscroll) { ensureGlows(); if (y <= 0 && oldY > 0) { mEdgeGlowTop.onAbsorb((int) mScroller.getCurrVelocity()); } else if (y >= range && oldY < range) { mEdgeGlowBottom.onAbsorb((int) mScroller.getCurrVelocity()); } } } } } /** * Scrolls the view to the given child. * * @param child the View to scroll to */ private void scrollToChild(View child) { child.getDrawingRect(mTempRect); /* Offset from child's local coordinates to ScrollView coordinates */ offsetDescendantRectToMyCoords(child, mTempRect); int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); if (scrollDelta != 0) { scrollBy(0, scrollDelta); } } /** * If rect is off screen, scroll just enough to get it (or at least the * first screen size chunk of it) on screen. * * @param rect The rectangle. * @param immediate True to scroll immediately without animation * @return true if scrolling was performed */ private boolean scrollToChildRect(Rect rect, boolean immediate) { final int delta = computeScrollDeltaToGetChildRectOnScreen(rect); final boolean scroll = delta != 0; if (scroll) { if (immediate) { scrollBy(0, delta); } else { smoothScrollBy(0, delta); } } return scroll; } /** * Compute the amount to scroll in the Y direction in order to get * a rectangle completely on the screen (or, if taller than the screen, * at least the first screen size chunk of it). * * @param rect The rect. * @return The scroll delta. */ protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) { if (getChildCount() == 0) return 0; int height = getHeight(); int screenTop = getScrollY(); int screenBottom = screenTop + height; int fadingEdge = getVerticalFadingEdgeLength(); // leave room for top fading edge as long as rect isn't at very top if (rect.top > 0) { screenTop += fadingEdge; } // leave room for bottom fading edge as long as rect isn't at very bottom if (rect.bottom < getChildAt(0).getHeight()) { screenBottom -= fadingEdge; } int scrollYDelta = 0; if (rect.bottom > screenBottom && rect.top > screenTop) { // need to move down to get it in view: move down just enough so // that the entire rectangle is in view (or at least the first // screen size chunk). if (rect.height() > height) { // just enough to get screen size chunk on scrollYDelta += (rect.top - screenTop); } else { // get entire rect at bottom of screen scrollYDelta += (rect.bottom - screenBottom); } // make sure we aren't scrolling beyond the end of our content int bottom = getChildAt(0).getBottom(); int distanceToBottom = bottom - screenBottom; scrollYDelta = Math.min(scrollYDelta, distanceToBottom); } else if (rect.top < screenTop && rect.bottom < screenBottom) { // need to move up to get it in view: move up just enough so that // entire rectangle is in view (or at least the first screen // size chunk of it). if (rect.height() > height) { // screen size chunk scrollYDelta -= (screenBottom - rect.bottom); } else { // entire rect at top scrollYDelta -= (screenTop - rect.top); } // make sure we aren't scrolling any further than the top our content scrollYDelta = Math.max(scrollYDelta, -getScrollY()); } return scrollYDelta; } @Override public void requestChildFocus(View child, View focused) { if (!mIsLayoutDirty) { scrollToChild(focused); } else { // The child may not be laid out yet, we can't compute the scroll yet mChildToScrollTo = focused; } super.requestChildFocus(child, focused); } /** * When looking for focus in children of a scroll view, need to be a little * more careful not to give focus to something that is scrolled off screen. * <p/> * This is more expensive than the default {@link ViewGroup} * implementation, otherwise this behavior might have been made the default. */ @Override protected boolean onRequestFocusInDescendants(int direction, Rect previouslyFocusedRect) { // convert from forward / backward notation to up / down / left / right // (ugh). if (direction == View.FOCUS_FORWARD) { direction = View.FOCUS_DOWN; } else if (direction == View.FOCUS_BACKWARD) { direction = View.FOCUS_UP; } final View nextFocus = previouslyFocusedRect == null ? FocusFinder.getInstance().findNextFocus(this, null, direction) : FocusFinder.getInstance().findNextFocusFromRect(this, previouslyFocusedRect, direction); if (nextFocus == null) { return false; } if (isOffScreen(nextFocus)) { return false; } return nextFocus.requestFocus(direction, previouslyFocusedRect); } @Override public boolean requestChildRectangleOnScreen(View child, Rect rectangle, boolean immediate) { // offset into coordinate space of this scroll view rectangle.offset(child.getLeft() - child.getScrollX(), child.getTop() - child.getScrollY()); return scrollToChildRect(rectangle, immediate); } @Override public void requestLayout() { mIsLayoutDirty = true; super.requestLayout(); } @Override protected void onLayout(boolean changed, int l, int t, int r, int b) { super.onLayout(changed, l, t, r, b); mIsLayoutDirty = false; // Give a child focus if it needs it if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) { scrollToChild(mChildToScrollTo); } mChildToScrollTo = null; if (!mIsLaidOut) { if (mSavedState != null) { scrollTo(getScrollX(), mSavedState.scrollPosition); mSavedState = null; } // mScrollY default value is "0" final int childHeight = (getChildCount() > 0) ? getChildAt(0).getMeasuredHeight() : 0; final int scrollRange = Math.max(0, childHeight - (b - t - getPaddingBottom() - getPaddingTop())); // Don't forget to clamp if (getScrollY() > scrollRange) { scrollTo(getScrollX(), scrollRange); } else if (getScrollY() < 0) { scrollTo(getScrollX(), 0); } } // Calling this with the present values causes it to re-claim them scrollTo(getScrollX(), getScrollY()); mIsLaidOut = true; } @Override protected void onAttachedToWindow() { super.onAttachedToWindow(); mIsLaidOut = false; } @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { super.onSizeChanged(w, h, oldw, oldh); View currentFocused = findFocus(); if (null == currentFocused || this == currentFocused) return; // If the currently-focused view was visible on the screen when the // screen was at the old height, then scroll the screen to make that // view visible with the new screen height. if (isWithinDeltaOfScreen(currentFocused, 0, oldh)) { currentFocused.getDrawingRect(mTempRect); offsetDescendantRectToMyCoords(currentFocused, mTempRect); int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); doScrollY(scrollDelta); } } /** * Return true if child is a descendant of parent, (or equal to the parent). */ private static boolean isViewDescendantOf(View child, View parent) { if (child == parent) { return true; } final ViewParent theParent = child.getParent(); return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent); } /** * Fling the scroll view * * @param velocityY The initial velocity in the Y direction. Positive * numbers mean that the finger/cursor is moving down the screen, * which means we want to scroll towards the top. */ public void fling(int velocityY) { if (getChildCount() > 0) { int height = getHeight() - getPaddingBottom() - getPaddingTop(); int bottom = getChildAt(0).getHeight(); mScroller.fling(getScrollX(), getScrollY(), 0, velocityY, 0, 0, 0, Math.max(0, bottom - height), 0, height / 2); ViewCompat.postInvalidateOnAnimation(this); } } private void flingWithNestedDispatch(int velocityY) { final int scrollY = getScrollY(); final boolean canFling = (scrollY > 0 || velocityY > 0) && (scrollY < getScrollRange() || velocityY < 0); if (!dispatchNestedPreFling(0, velocityY)) { dispatchNestedFling(0, velocityY, canFling); if (canFling) { fling(velocityY); } } } private void endDrag() { mIsBeingDragged = false; recycleVelocityTracker(); stopNestedScroll(); if (mEdgeGlowTop != null) { mEdgeGlowTop.onRelease(); mEdgeGlowBottom.onRelease(); } } /** * {@inheritDoc} * <p/> * <p>This version also clamps the scrolling to the bounds of our child. */ @Override public void scrollTo(int x, int y) { // we rely on the fact the View.scrollBy calls scrollTo. if (getChildCount() > 0) { View child = getChildAt(0); x = clamp(x, getWidth() - getPaddingRight() - getPaddingLeft(), child.getWidth()); y = clamp(y, getHeight() - getPaddingBottom() - getPaddingTop(), child.getHeight()); if (x != getScrollX() || y != getScrollY()) { super.scrollTo(x, y); } } } private void ensureGlows() { if (ViewCompat.getOverScrollMode(this) != ViewCompat.OVER_SCROLL_NEVER) { if (mEdgeGlowTop == null) { Context context = getContext(); mEdgeGlowTop = new EdgeEffectCompat(context); mEdgeGlowBottom = new EdgeEffectCompat(context); } } else { mEdgeGlowTop = null; mEdgeGlowBottom = null; } } @Override public void draw(Canvas canvas) { super.draw(canvas); if (mEdgeGlowTop != null) { final int scrollY = getScrollY(); if (!mEdgeGlowTop.isFinished()) { final int restoreCount = canvas.save(); final int width = getWidth() - getPaddingLeft() - getPaddingRight(); canvas.translate(getPaddingLeft(), Math.min(0, scrollY)); mEdgeGlowTop.setSize(width, getHeight()); if (mEdgeGlowTop.draw(canvas)) { ViewCompat.postInvalidateOnAnimation(this); } canvas.restoreToCount(restoreCount); } if (!mEdgeGlowBottom.isFinished()) { final int restoreCount = canvas.save(); final int width = getWidth() - getPaddingLeft() - getPaddingRight(); final int height = getHeight(); canvas.translate(-width + getPaddingLeft(), Math.max(getScrollRange(), scrollY) + height); canvas.rotate(180, width, 0); mEdgeGlowBottom.setSize(width, height); if (mEdgeGlowBottom.draw(canvas)) { ViewCompat.postInvalidateOnAnimation(this); } canvas.restoreToCount(restoreCount); } } } private static int clamp(int n, int my, int child) { if (my >= child || n < 0) { /* my >= child is this case: * |--------------- me ---------------| * |------ child ------| * or * |--------------- me ---------------| * |------ child ------| * or * |--------------- me ---------------| * |------ child ------| * * n < 0 is this case: * |------ me ------| * |-------- child --------| * |-- mScrollX --| */ return 0; } if ((my + n) > child) { /* this case: * |------ me ------| * |------ child ------| * |-- mScrollX --| */ return child - my; } return n; } @Override protected void onRestoreInstanceState(Parcelable state) { SavedState ss = (SavedState) state; super.onRestoreInstanceState(ss.getSuperState()); mSavedState = ss; requestLayout(); } @Override protected Parcelable onSaveInstanceState() { Parcelable superState = super.onSaveInstanceState(); SavedState ss = new SavedState(superState); ss.scrollPosition = getScrollY(); return ss; } static class SavedState extends BaseSavedState { public int scrollPosition; SavedState(Parcelable superState) { super(superState); } public SavedState(Parcel source) { super(source); scrollPosition = source.readInt(); } @Override public void writeToParcel(Parcel dest, int flags) { super.writeToParcel(dest, flags); dest.writeInt(scrollPosition); } @Override public String toString() { return "HorizontalScrollView.SavedState{" + Integer.toHexString(System.identityHashCode(this)) + " scrollPosition=" + scrollPosition + "}"; } public static final Creator<SavedState> CREATOR = new Creator<SavedState>() { public SavedState createFromParcel(Parcel in) { return new SavedState(in); } public SavedState[] newArray(int size) { return new SavedState[size]; } }; } static class AccessibilityDelegate extends AccessibilityDelegateCompat { @Override public boolean performAccessibilityAction(View host, int action, Bundle arguments) { if (super.performAccessibilityAction(host, action, arguments)) { return true; } final NestedScrollView nsvHost = (NestedScrollView) host; if (!nsvHost.isEnabled()) { return false; } switch (action) { case AccessibilityNodeInfoCompat.ACTION_SCROLL_FORWARD: { final int viewportHeight = nsvHost.getHeight() - nsvHost.getPaddingBottom() - nsvHost.getPaddingTop(); final int targetScrollY = Math.min(nsvHost.getScrollY() + viewportHeight, nsvHost.getScrollRange()); if (targetScrollY != nsvHost.getScrollY()) { nsvHost.smoothScrollTo(0, targetScrollY); return true; } } return false; case AccessibilityNodeInfoCompat.ACTION_SCROLL_BACKWARD: { final int viewportHeight = nsvHost.getHeight() - nsvHost.getPaddingBottom() - nsvHost.getPaddingTop(); final int targetScrollY = Math.max(nsvHost.getScrollY() - viewportHeight, 0); if (targetScrollY != nsvHost.getScrollY()) { nsvHost.smoothScrollTo(0, targetScrollY); return true; } } return false; } return false; } @Override public void onInitializeAccessibilityNodeInfo(View host, AccessibilityNodeInfoCompat info) { super.onInitializeAccessibilityNodeInfo(host, info); final NestedScrollView nsvHost = (NestedScrollView) host; info.setClassName(ScrollView.class.getName()); if (nsvHost.isEnabled()) { final int scrollRange = nsvHost.getScrollRange(); if (scrollRange > 0) { info.setScrollable(true); if (nsvHost.getScrollY() > 0) { info.addAction(AccessibilityNodeInfoCompat.ACTION_SCROLL_BACKWARD); } if (nsvHost.getScrollY() < scrollRange) { info.addAction(AccessibilityNodeInfoCompat.ACTION_SCROLL_FORWARD); } } } } @Override public void onInitializeAccessibilityEvent(View host, AccessibilityEvent event) { super.onInitializeAccessibilityEvent(host, event); final NestedScrollView nsvHost = (NestedScrollView) host; event.setClassName(ScrollView.class.getName()); final AccessibilityRecordCompat record = AccessibilityEventCompat.asRecord(event); final boolean scrollable = nsvHost.getScrollRange() > 0; record.setScrollable(scrollable); record.setScrollX(nsvHost.getScrollX()); record.setScrollY(nsvHost.getScrollY()); record.setMaxScrollX(nsvHost.getScrollX()); record.setMaxScrollY(nsvHost.getScrollRange()); } } }