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/*
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.launcher2;
import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.animation.ValueAnimator;
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.util.AttributeSet;
import android.util.Log;
import android.view.InputDevice;
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.accessibility.AccessibilityManager;
import android.view.accessibility.AccessibilityNodeInfo;
import android.view.animation.Interpolator;
import android.widget.Scroller;
import com.android.launcher.R;
import java.util.ArrayList;
/**
* An abstraction of the original Workspace which supports browsing through a
* sequential list of "pages"
*/
public abstract class PagedView extends ViewGroup implements ViewGroup.OnHierarchyChangeListener {
private static final String TAG = "PagedView";
private static final boolean DEBUG = false;
protected static final int INVALID_PAGE = -1;
// the min drag distance for a fling to register, to prevent random page shifts
private static final int MIN_LENGTH_FOR_FLING = 25;
protected static final int PAGE_SNAP_ANIMATION_DURATION = 550;
protected static final int MAX_PAGE_SNAP_DURATION = 750;
protected static final int SLOW_PAGE_SNAP_ANIMATION_DURATION = 950;
protected static final float NANOTIME_DIV = 1000000000.0f;
private static final float OVERSCROLL_ACCELERATE_FACTOR = 2;
private static final float OVERSCROLL_DAMP_FACTOR = 0.14f;
private static final float RETURN_TO_ORIGINAL_PAGE_THRESHOLD = 0.33f;
// The page is moved more than halfway, automatically move to the next page on touch up.
private static final float SIGNIFICANT_MOVE_THRESHOLD = 0.4f;
// The following constants need to be scaled based on density. The scaled versions will be
// assigned to the corresponding member variables below.
private static final int FLING_THRESHOLD_VELOCITY = 500;
private static final int MIN_SNAP_VELOCITY = 1500;
private static final int MIN_FLING_VELOCITY = 250;
static final int AUTOMATIC_PAGE_SPACING = -1;
protected int mFlingThresholdVelocity;
protected int mMinFlingVelocity;
protected int mMinSnapVelocity;
protected float mDensity;
protected float mSmoothingTime;
protected float mTouchX;
protected boolean mFirstLayout = true;
protected int mCurrentPage;
protected int mNextPage = INVALID_PAGE;
protected int mMaxScrollX;
protected Scroller mScroller;
private VelocityTracker mVelocityTracker;
private float mDownMotionX;
protected float mLastMotionX;
protected float mLastMotionXRemainder;
protected float mLastMotionY;
protected float mTotalMotionX;
private int mLastScreenCenter = -1;
private int[] mChildOffsets;
private int[] mChildRelativeOffsets;
private int[] mChildOffsetsWithLayoutScale;
protected final static int TOUCH_STATE_REST = 0;
protected final static int TOUCH_STATE_SCROLLING = 1;
protected final static int TOUCH_STATE_PREV_PAGE = 2;
protected final static int TOUCH_STATE_NEXT_PAGE = 3;
protected final static float ALPHA_QUANTIZE_LEVEL = 0.0001f;
protected int mTouchState = TOUCH_STATE_REST;
protected boolean mForceScreenScrolled = false;
protected OnLongClickListener mLongClickListener;
protected boolean mAllowLongPress = true;
protected int mTouchSlop;
private int mPagingTouchSlop;
private int mMaximumVelocity;
private int mMinimumWidth;
protected int mPageSpacing;
protected int mPageLayoutPaddingTop;
protected int mPageLayoutPaddingBottom;
protected int mPageLayoutPaddingLeft;
protected int mPageLayoutPaddingRight;
protected int mPageLayoutWidthGap;
protected int mPageLayoutHeightGap;
protected int mCellCountX = 0;
protected int mCellCountY = 0;
protected boolean mCenterPagesVertically;
protected boolean mAllowOverScroll = true;
protected int mUnboundedScrollX;
protected int[] mTempVisiblePagesRange = new int[2];
protected boolean mForceDrawAllChildrenNextFrame;
// mOverScrollX is equal to getScrollX() when we're within the normal scroll range. Otherwise
// it is equal to the scaled overscroll position. We use a separate value so as to prevent
// the screens from continuing to translate beyond the normal bounds.
protected int mOverScrollX;
// parameter that adjusts the layout to be optimized for pages with that scale factor
protected float mLayoutScale = 1.0f;
protected static final int INVALID_POINTER = -1;
protected int mActivePointerId = INVALID_POINTER;
private PageSwitchListener mPageSwitchListener;
protected ArrayList<Boolean> mDirtyPageContent;
// If true, syncPages and syncPageItems will be called to refresh pages
protected boolean mContentIsRefreshable = true;
// If true, modify alpha of neighboring pages as user scrolls left/right
protected boolean mFadeInAdjacentScreens = true;
// It true, use a different slop parameter (pagingTouchSlop = 2 * touchSlop) for deciding
// to switch to a new page
protected boolean mUsePagingTouchSlop = true;
// If true, the subclass should directly update scrollX itself in its computeScroll method
// (SmoothPagedView does this)
protected boolean mDeferScrollUpdate = false;
protected boolean mIsPageMoving = false;
// All syncs and layout passes are deferred until data is ready.
protected boolean mIsDataReady = false;
// Scrolling indicator
private ValueAnimator mScrollIndicatorAnimator;
private View mScrollIndicator;
private int mScrollIndicatorPaddingLeft;
private int mScrollIndicatorPaddingRight;
private boolean mHasScrollIndicator = true;
private boolean mShouldShowScrollIndicator = false;
private boolean mShouldShowScrollIndicatorImmediately = false;
protected static final int sScrollIndicatorFadeInDuration = 150;
protected static final int sScrollIndicatorFadeOutDuration = 650;
protected static final int sScrollIndicatorFlashDuration = 650;
private boolean mScrollingPaused = false;
// If set, will defer loading associated pages until the scrolling settles
private boolean mDeferLoadAssociatedPagesUntilScrollCompletes;
public interface PageSwitchListener {
void onPageSwitch(View newPage, int newPageIndex);
}
public PagedView(Context context) {
this(context, null);
}
public PagedView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public PagedView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
TypedArray a = context.obtainStyledAttributes(attrs,
R.styleable.PagedView, defStyle, 0);
setPageSpacing(a.getDimensionPixelSize(R.styleable.PagedView_pageSpacing, 0));
mPageLayoutPaddingTop = a.getDimensionPixelSize(
R.styleable.PagedView_pageLayoutPaddingTop, 0);
mPageLayoutPaddingBottom = a.getDimensionPixelSize(
R.styleable.PagedView_pageLayoutPaddingBottom, 0);
mPageLayoutPaddingLeft = a.getDimensionPixelSize(
R.styleable.PagedView_pageLayoutPaddingLeft, 0);
mPageLayoutPaddingRight = a.getDimensionPixelSize(
R.styleable.PagedView_pageLayoutPaddingRight, 0);
mPageLayoutWidthGap = a.getDimensionPixelSize(
R.styleable.PagedView_pageLayoutWidthGap, 0);
mPageLayoutHeightGap = a.getDimensionPixelSize(
R.styleable.PagedView_pageLayoutHeightGap, 0);
mScrollIndicatorPaddingLeft =
a.getDimensionPixelSize(R.styleable.PagedView_scrollIndicatorPaddingLeft, 0);
mScrollIndicatorPaddingRight =
a.getDimensionPixelSize(R.styleable.PagedView_scrollIndicatorPaddingRight, 0);
a.recycle();
setHapticFeedbackEnabled(false);
init();
}
/**
* Initializes various states for this workspace.
*/
protected void init() {
mDirtyPageContent = new ArrayList<Boolean>();
mDirtyPageContent.ensureCapacity(32);
mScroller = new Scroller(getContext(), new ScrollInterpolator());
mCurrentPage = 0;
mCenterPagesVertically = true;
final ViewConfiguration configuration = ViewConfiguration.get(getContext());
mTouchSlop = configuration.getScaledTouchSlop();
mPagingTouchSlop = configuration.getScaledPagingTouchSlop();
mMaximumVelocity = configuration.getScaledMaximumFlingVelocity();
mDensity = getResources().getDisplayMetrics().density;
mFlingThresholdVelocity = (int) (FLING_THRESHOLD_VELOCITY * mDensity);
mMinFlingVelocity = (int) (MIN_FLING_VELOCITY * mDensity);
mMinSnapVelocity = (int) (MIN_SNAP_VELOCITY * mDensity);
setOnHierarchyChangeListener(this);
}
public void setPageSwitchListener(PageSwitchListener pageSwitchListener) {
mPageSwitchListener = pageSwitchListener;
if (mPageSwitchListener != null) {
mPageSwitchListener.onPageSwitch(getPageAt(mCurrentPage), mCurrentPage);
}
}
/**
* Note: this is a reimplementation of View.isLayoutRtl() since that is currently hidden api.
*/
public boolean isLayoutRtl() {
return (getLayoutDirection() == LAYOUT_DIRECTION_RTL);
}
/**
* Called by subclasses to mark that data is ready, and that we can begin loading and laying
* out pages.
*/
protected void setDataIsReady() {
mIsDataReady = true;
}
protected boolean isDataReady() {
return mIsDataReady;
}
/**
* Returns the index of the currently displayed page.
*
* @return The index of the currently displayed page.
*/
int getCurrentPage() {
return mCurrentPage;
}
int getNextPage() {
return (mNextPage != INVALID_PAGE) ? mNextPage : mCurrentPage;
}
int getPageCount() {
return getChildCount();
}
View getPageAt(int index) {
return getChildAt(index);
}
protected int indexToPage(int index) {
return index;
}
/**
* Updates the scroll of the current page immediately to its final scroll position. We use this
* in CustomizePagedView to allow tabs to share the same PagedView while resetting the scroll of
* the previous tab page.
*/
protected void updateCurrentPageScroll() {
// If the current page is invalid, just reset the scroll position to zero
int newX = 0;
if (0 <= mCurrentPage && mCurrentPage < getPageCount()) {
int offset = getChildOffset(mCurrentPage);
int relOffset = getRelativeChildOffset(mCurrentPage);
newX = offset - relOffset;
}
scrollTo(newX, 0);
mScroller.setFinalX(newX);
mScroller.forceFinished(true);
}
/**
* Called during AllApps/Home transitions to avoid unnecessary work. When that other animation
* ends, {@link #resumeScrolling()} should be called, along with
* {@link #updateCurrentPageScroll()} to correctly set the final state and re-enable scrolling.
*/
void pauseScrolling() {
mScroller.forceFinished(true);
cancelScrollingIndicatorAnimations();
mScrollingPaused = true;
}
/**
* Enables scrolling again.
* @see #pauseScrolling()
*/
void resumeScrolling() {
mScrollingPaused = false;
}
/**
* Sets the current page.
*/
void setCurrentPage(int currentPage) {
if (!mScroller.isFinished()) {
mScroller.abortAnimation();
}
// don't introduce any checks like mCurrentPage == currentPage here-- if we change the
// the default
if (getChildCount() == 0) {
return;
}
mCurrentPage = Math.max(0, Math.min(currentPage, getPageCount() - 1));
updateCurrentPageScroll();
updateScrollingIndicator();
notifyPageSwitchListener();
invalidate();
}
protected void notifyPageSwitchListener() {
if (mPageSwitchListener != null) {
mPageSwitchListener.onPageSwitch(getPageAt(mCurrentPage), mCurrentPage);
}
}
protected void pageBeginMoving() {
if (!mIsPageMoving) {
mIsPageMoving = true;
onPageBeginMoving();
}
}
protected void pageEndMoving() {
if (mIsPageMoving) {
mIsPageMoving = false;
onPageEndMoving();
}
}
protected boolean isPageMoving() {
return mIsPageMoving;
}
// a method that subclasses can override to add behavior
protected void onPageBeginMoving() {
}
// a method that subclasses can override to add behavior
protected void onPageEndMoving() {
}
/**
* Registers the specified listener on each page contained in this workspace.
*
* @param l The listener used to respond to long clicks.
*/
@Override
public void setOnLongClickListener(OnLongClickListener l) {
mLongClickListener = l;
final int count = getPageCount();
for (int i = 0; i < count; i++) {
getPageAt(i).setOnLongClickListener(l);
}
}
@Override
public void scrollBy(int x, int y) {
scrollTo(mUnboundedScrollX + x, getScrollY() + y);
}
@Override
public void scrollTo(int x, int y) {
final boolean isRtl = isLayoutRtl();
mUnboundedScrollX = x;
boolean isXBeforeFirstPage = isRtl ? (x > mMaxScrollX) : (x < 0);
boolean isXAfterLastPage = isRtl ? (x < 0) : (x > mMaxScrollX);
if (isXBeforeFirstPage) {
super.scrollTo(0, y);
if (mAllowOverScroll) {
if (isRtl) {
overScroll(x - mMaxScrollX);
} else {
overScroll(x);
}
}
} else if (isXAfterLastPage) {
super.scrollTo(mMaxScrollX, y);
if (mAllowOverScroll) {
if (isRtl) {
overScroll(x);
} else {
overScroll(x - mMaxScrollX);
}
}
} else {
mOverScrollX = x;
super.scrollTo(x, y);
}
mTouchX = x;
mSmoothingTime = System.nanoTime() / NANOTIME_DIV;
}
// we moved this functionality to a helper function so SmoothPagedView can reuse it
protected boolean computeScrollHelper() {
if (mScroller.computeScrollOffset()) {
// Don't bother scrolling if the page does not need to be moved
if (getScrollX() != mScroller.getCurrX()
|| getScrollY() != mScroller.getCurrY()
|| mOverScrollX != mScroller.getCurrX()) {
scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
}
invalidate();
return true;
} else if (mNextPage != INVALID_PAGE) {
mCurrentPage = Math.max(0, Math.min(mNextPage, getPageCount() - 1));
mNextPage = INVALID_PAGE;
notifyPageSwitchListener();
// Load the associated pages if necessary
if (mDeferLoadAssociatedPagesUntilScrollCompletes) {
loadAssociatedPages(mCurrentPage);
mDeferLoadAssociatedPagesUntilScrollCompletes = false;
}
// We don't want to trigger a page end moving unless the page has settled
// and the user has stopped scrolling
if (mTouchState == TOUCH_STATE_REST) {
pageEndMoving();
}
// Notify the user when the page changes
AccessibilityManager accessibilityManager = (AccessibilityManager)
getContext().getSystemService(Context.ACCESSIBILITY_SERVICE);
if (accessibilityManager.isEnabled()) {
AccessibilityEvent ev =
AccessibilityEvent.obtain(AccessibilityEvent.TYPE_VIEW_SCROLLED);
ev.getText().add(getCurrentPageDescription());
sendAccessibilityEventUnchecked(ev);
}
return true;
}
return false;
}
@Override
public void computeScroll() {
computeScrollHelper();
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
if (!mIsDataReady) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
return;
}
final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
final int widthSize = MeasureSpec.getSize(widthMeasureSpec);
final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
int heightSize = MeasureSpec.getSize(heightMeasureSpec);
if (widthMode != MeasureSpec.EXACTLY) {
throw new IllegalStateException("Workspace can only be used in EXACTLY mode.");
}
// Return early if we aren't given a proper dimension
if (widthSize <= 0 || heightSize <= 0) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
return;
}
/* Allow the height to be set as WRAP_CONTENT. This allows the particular case
* of the All apps view on XLarge displays to not take up more space then it needs. Width
* is still not allowed to be set as WRAP_CONTENT since many parts of the code expect
* each page to have the same width.
*/
int maxChildHeight = 0;
final int verticalPadding = getPaddingTop() + getPaddingBottom();
final int horizontalPadding = getPaddingLeft() + getPaddingRight();
// The children are given the same width and height as the workspace
// unless they were set to WRAP_CONTENT
if (DEBUG) Log.d(TAG, "PagedView.onMeasure(): " + widthSize + ", " + heightSize);
final int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
// disallowing padding in paged view (just pass 0)
final View child = getPageAt(i);
final LayoutParams lp = (LayoutParams) child.getLayoutParams();
int childWidthMode;
if (lp.width == LayoutParams.WRAP_CONTENT) {
childWidthMode = MeasureSpec.AT_MOST;
} else {
childWidthMode = MeasureSpec.EXACTLY;
}
int childHeightMode;
if (lp.height == LayoutParams.WRAP_CONTENT) {
childHeightMode = MeasureSpec.AT_MOST;
} else {
childHeightMode = MeasureSpec.EXACTLY;
}
final int childWidthMeasureSpec =
MeasureSpec.makeMeasureSpec(widthSize - horizontalPadding, childWidthMode);
final int childHeightMeasureSpec =
MeasureSpec.makeMeasureSpec(heightSize - verticalPadding, childHeightMode);
child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
maxChildHeight = Math.max(maxChildHeight, child.getMeasuredHeight());
if (DEBUG) Log.d(TAG, "\tmeasure-child" + i + ": " + child.getMeasuredWidth() + ", "
+ child.getMeasuredHeight());
}
if (heightMode == MeasureSpec.AT_MOST) {
heightSize = maxChildHeight + verticalPadding;
}
setMeasuredDimension(widthSize, heightSize);
// We can't call getChildOffset/getRelativeChildOffset until we set the measured dimensions.
// We also wait until we set the measured dimensions before flushing the cache as well, to
// ensure that the cache is filled with good values.
invalidateCachedOffsets();
if (childCount > 0) {
if (DEBUG) Log.d(TAG, "getRelativeChildOffset(): " + getMeasuredWidth() + ", "
+ getChildWidth(0));
// Calculate the variable page spacing if necessary
if (mPageSpacing == AUTOMATIC_PAGE_SPACING) {
// The gap between pages in the PagedView should be equal to the gap from the page
// to the edge of the screen (so it is not visible in the current screen). To
// account for unequal padding on each side of the paged view, we take the maximum
// of the left/right gap and use that as the gap between each page.
int offset = getRelativeChildOffset(0);
int spacing = Math.max(offset, widthSize - offset -
getChildAt(0).getMeasuredWidth());
setPageSpacing(spacing);
}
}
updateScrollingIndicatorPosition();
if (childCount > 0) {
final int index = isLayoutRtl() ? 0 : childCount - 1;
mMaxScrollX = getChildOffset(index) - getRelativeChildOffset(index);
} else {
mMaxScrollX = 0;
}
}
protected void scrollToNewPageWithoutMovingPages(int newCurrentPage) {
int newX = getChildOffset(newCurrentPage) - getRelativeChildOffset(newCurrentPage);
int delta = newX - getScrollX();
final int pageCount = getChildCount();
for (int i = 0; i < pageCount; i++) {
View page = (View) getPageAt(i);
page.setX(page.getX() + delta);
}
setCurrentPage(newCurrentPage);
}
// A layout scale of 1.0f assumes that the pages, in their unshrunken state, have a
// scale of 1.0f. A layout scale of 0.8f assumes the pages have a scale of 0.8f, and
// tightens the layout accordingly
public void setLayoutScale(float childrenScale) {
mLayoutScale = childrenScale;
invalidateCachedOffsets();
// Now we need to do a re-layout, but preserving absolute X and Y coordinates
int childCount = getChildCount();
float childrenX[] = new float[childCount];
float childrenY[] = new float[childCount];
for (int i = 0; i < childCount; i++) {
final View child = getPageAt(i);
childrenX[i] = child.getX();
childrenY[i] = child.getY();
}
// Trigger a full re-layout (never just call onLayout directly!)
int widthSpec = MeasureSpec.makeMeasureSpec(getMeasuredWidth(), MeasureSpec.EXACTLY);
int heightSpec = MeasureSpec.makeMeasureSpec(getMeasuredHeight(), MeasureSpec.EXACTLY);
requestLayout();
measure(widthSpec, heightSpec);
layout(getLeft(), getTop(), getRight(), getBottom());
for (int i = 0; i < childCount; i++) {
final View child = getPageAt(i);
child.setX(childrenX[i]);
child.setY(childrenY[i]);
}
// Also, the page offset has changed (since the pages are now smaller);
// update the page offset, but again preserving absolute X and Y coordinates
scrollToNewPageWithoutMovingPages(mCurrentPage);
}
public void setPageSpacing(int pageSpacing) {
mPageSpacing = pageSpacing;
invalidateCachedOffsets();
}
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
if (!mIsDataReady) {
return;
}
if (DEBUG) Log.d(TAG, "PagedView.onLayout()");
final int verticalPadding = getPaddingTop() + getPaddingBottom();
final int childCount = getChildCount();
final boolean isRtl = isLayoutRtl();
final int startIndex = isRtl ? childCount - 1 : 0;
final int endIndex = isRtl ? -1 : childCount;
final int delta = isRtl ? -1 : 1;
int childLeft = getRelativeChildOffset(startIndex);
for (int i = startIndex; i != endIndex; i += delta) {
final View child = getPageAt(i);
if (child.getVisibility() != View.GONE) {
final int childWidth = getScaledMeasuredWidth(child);
final int childHeight = child.getMeasuredHeight();
int childTop = getPaddingTop();
if (mCenterPagesVertically) {
childTop += ((getMeasuredHeight() - verticalPadding) - childHeight) / 2;
}
if (DEBUG) Log.d(TAG, "\tlayout-child" + i + ": " + childLeft + ", " + childTop);
child.layout(childLeft, childTop,
childLeft + child.getMeasuredWidth(), childTop + childHeight);
childLeft += childWidth + mPageSpacing;
}
}
if (mFirstLayout && mCurrentPage >= 0 && mCurrentPage < getChildCount()) {
setHorizontalScrollBarEnabled(false);
updateCurrentPageScroll();
setHorizontalScrollBarEnabled(true);
mFirstLayout = false;
}
}
protected void screenScrolled(int screenCenter) {
if (isScrollingIndicatorEnabled()) {
updateScrollingIndicator();
}
boolean isInOverscroll = mOverScrollX < 0 || mOverScrollX > mMaxScrollX;
if (mFadeInAdjacentScreens && !isInOverscroll) {
for (int i = 0; i < getChildCount(); i++) {
View child = getChildAt(i);
if (child != null) {
float scrollProgress = getScrollProgress(screenCenter, child, i);
float alpha = 1 - Math.abs(scrollProgress);
child.setAlpha(alpha);
}
}
invalidate();
}
}
@Override
public void onChildViewAdded(View parent, View child) {
// This ensures that when children are added, they get the correct transforms / alphas
// in accordance with any scroll effects.
mForceScreenScrolled = true;
invalidate();
invalidateCachedOffsets();
}
@Override
public void onChildViewRemoved(View parent, View child) {
}
protected void invalidateCachedOffsets() {
int count = getChildCount();
if (count == 0) {
mChildOffsets = null;
mChildRelativeOffsets = null;
mChildOffsetsWithLayoutScale = null;
return;
}
mChildOffsets = new int[count];
mChildRelativeOffsets = new int[count];
mChildOffsetsWithLayoutScale = new int[count];
for (int i = 0; i < count; i++) {
mChildOffsets[i] = -1;
mChildRelativeOffsets[i] = -1;
mChildOffsetsWithLayoutScale[i] = -1;
}
}
protected int getChildOffset(int index) {
final boolean isRtl = isLayoutRtl();
int[] childOffsets = Float.compare(mLayoutScale, 1f) == 0 ?
mChildOffsets : mChildOffsetsWithLayoutScale;
if (childOffsets != null && childOffsets[index] != -1) {
return childOffsets[index];
} else {
if (getChildCount() == 0)
return 0;
final int startIndex = isRtl ? getChildCount() - 1 : 0;
final int endIndex = isRtl ? index : index;
final int delta = isRtl ? -1 : 1;
int offset = getRelativeChildOffset(startIndex);
for (int i = startIndex; i != endIndex; i += delta) {
offset += getScaledMeasuredWidth(getPageAt(i)) + mPageSpacing;
}
if (childOffsets != null) {
childOffsets[index] = offset;
}
return offset;
}
}
protected int getRelativeChildOffset(int index) {
if (mChildRelativeOffsets != null && mChildRelativeOffsets[index] != -1) {
return mChildRelativeOffsets[index];
} else {
final int padding = getPaddingLeft() + getPaddingRight();
final int offset = getPaddingLeft() +
(getMeasuredWidth() - padding - getChildWidth(index)) / 2;
if (mChildRelativeOffsets != null) {
mChildRelativeOffsets[index] = offset;
}
return offset;
}
}
protected int getScaledMeasuredWidth(View child) {
// This functions are called enough times that it actually makes a difference in the
// profiler -- so just inline the max() here
final int measuredWidth = child.getMeasuredWidth();
final int minWidth = mMinimumWidth;
final int maxWidth = (minWidth > measuredWidth) ? minWidth : measuredWidth;
return (int) (maxWidth * mLayoutScale + 0.5f);
}
protected void getVisiblePages(int[] range) {
final boolean isRtl = isLayoutRtl();
final int pageCount = getChildCount();
if (pageCount > 0) {
final int screenWidth = getMeasuredWidth();
int leftScreen = isRtl ? pageCount - 1 : 0;
int rightScreen = 0;
int endIndex = isRtl ? 0 : pageCount - 1;
int delta = isRtl ? -1 : 1;
View currPage = getPageAt(leftScreen);
while (leftScreen != endIndex &&
currPage.getX() + currPage.getWidth() -
currPage.getPaddingRight() < getScrollX()) {
leftScreen += delta;
currPage = getPageAt(leftScreen);
}
rightScreen = leftScreen;
currPage = getPageAt(rightScreen + delta);
while (rightScreen != endIndex &&
currPage.getX() - currPage.getPaddingLeft() < getScrollX() + screenWidth) {
rightScreen += delta;
currPage = getPageAt(rightScreen + delta);
}
range[0] = Math.min(leftScreen, rightScreen);
range[1] = Math.max(leftScreen, rightScreen);
} else {
range[0] = -1;
range[1] = -1;
}
}
protected boolean shouldDrawChild(View child) {
return child.getAlpha() > 0;
}
@Override
protected void dispatchDraw(Canvas canvas) {
int halfScreenSize = getMeasuredWidth() / 2;
// mOverScrollX is equal to getScrollX() when we're within the normal scroll range.
// Otherwise it is equal to the scaled overscroll position.
int screenCenter = mOverScrollX + halfScreenSize;
if (screenCenter != mLastScreenCenter || mForceScreenScrolled) {
// set mForceScreenScrolled before calling screenScrolled so that screenScrolled can
// set it for the next frame
mForceScreenScrolled = false;
screenScrolled(screenCenter);
mLastScreenCenter = screenCenter;
}
// Find out which screens are visible; as an optimization we only call draw on them
final int pageCount = getChildCount();
if (pageCount > 0) {
getVisiblePages(mTempVisiblePagesRange);
final int leftScreen = mTempVisiblePagesRange[0];
final int rightScreen = mTempVisiblePagesRange[1];
if (leftScreen != -1 && rightScreen != -1) {
final long drawingTime = getDrawingTime();
// Clip to the bounds
canvas.save();
canvas.clipRect(getScrollX(), getScrollY(), getScrollX() + getRight() - getLeft(),
getScrollY() + getBottom() - getTop());
for (int i = getChildCount() - 1; i >= 0; i--) {
final View v = getPageAt(i);
if (mForceDrawAllChildrenNextFrame ||
(leftScreen <= i && i <= rightScreen && shouldDrawChild(v))) {
drawChild(canvas, v, drawingTime);
}
}
mForceDrawAllChildrenNextFrame = false;
canvas.restore();
}
}
}
@Override
public boolean requestChildRectangleOnScreen(View child, Rect rectangle, boolean immediate) {
int page = indexToPage(indexOfChild(child));
if (page != mCurrentPage || !mScroller.isFinished()) {
snapToPage(page);
return true;
}
return false;
}
@Override
protected boolean onRequestFocusInDescendants(int direction, Rect previouslyFocusedRect) {
int focusablePage;
if (mNextPage != INVALID_PAGE) {
focusablePage = mNextPage;
} else {
focusablePage = mCurrentPage;
}
View v = getPageAt(focusablePage);
if (v != null) {
return v.requestFocus(direction, previouslyFocusedRect);
}
return false;
}
@Override
public boolean dispatchUnhandledMove(View focused, int direction) {
// XXX-RTL: This will be fixed in a future CL
if (direction == View.FOCUS_LEFT) {
if (getCurrentPage() > 0) {
snapToPage(getCurrentPage() - 1);
return true;
}
} else if (direction == View.FOCUS_RIGHT) {
if (getCurrentPage() < getPageCount() - 1) {
snapToPage(getCurrentPage() + 1);
return true;
}
}
return super.dispatchUnhandledMove(focused, direction);
}
@Override
public void addFocusables(ArrayList<View> views, int direction, int focusableMode) {
// XXX-RTL: This will be fixed in a future CL
if (mCurrentPage >= 0 && mCurrentPage < getPageCount()) {
getPageAt(mCurrentPage).addFocusables(views, direction, focusableMode);
}
if (direction == View.FOCUS_LEFT) {
if (mCurrentPage > 0) {
getPageAt(mCurrentPage - 1).addFocusables(views, direction, focusableMode);
}
} else if (direction == View.FOCUS_RIGHT){
if (mCurrentPage < getPageCount() - 1) {
getPageAt(mCurrentPage + 1).addFocusables(views, direction, focusableMode);
}
}
}
/**
* If one of our descendant views decides that it could be focused now, only
* pass that along if it's on the current page.
*
* This happens when live folders requery, and if they're off page, they
* end up calling requestFocus, which pulls it on page.
*/
@Override
public void focusableViewAvailable(View focused) {
View current = getPageAt(mCurrentPage);
View v = focused;
while (true) {
if (v == current) {
super.focusableViewAvailable(focused);
return;
}
if (v == this) {
return;
}
ViewParent parent = v.getParent();
if (parent instanceof View) {
v = (View)v.getParent();
} else {
return;
}
}
}
/**
* {@inheritDoc}
*/
@Override
public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) {
if (disallowIntercept) {
// We need to make sure to cancel our long press if
// a scrollable widget takes over touch events
final View currentPage = getPageAt(mCurrentPage);
currentPage.cancelLongPress();
}
super.requestDisallowInterceptTouchEvent(disallowIntercept);
}
/**
* Return true if a tap at (x, y) should trigger a flip to the previous page.
*/
protected boolean hitsPreviousPage(float x, float y) {
if (isLayoutRtl()) {
return (x > (getMeasuredWidth() - getRelativeChildOffset(mCurrentPage) + mPageSpacing));
} else {
return (x < getRelativeChildOffset(mCurrentPage) - mPageSpacing);
}
}
/**
* Return true if a tap at (x, y) should trigger a flip to the next page.
*/
protected boolean hitsNextPage(float x, float y) {
if (isLayoutRtl()) {
return (x < getRelativeChildOffset(mCurrentPage) - mPageSpacing);
} else {
return (x > (getMeasuredWidth() - getRelativeChildOffset(mCurrentPage) + mPageSpacing));
}
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
/*
* This method JUST determines whether we want to intercept the motion.
* If we return true, onTouchEvent will be called and we do the actual
* scrolling there.
*/
acquireVelocityTrackerAndAddMovement(ev);
// Skip touch handling if there are no pages to swipe
if (getChildCount() <= 0) return super.onInterceptTouchEvent(ev);
/*
* 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) &&
(mTouchState == TOUCH_STATE_SCROLLING)) {
return true;
}
switch (action & MotionEvent.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.
*/
if (mActivePointerId != INVALID_POINTER) {
determineScrollingStart(ev);
break;
}
// if mActivePointerId is INVALID_POINTER, then we must have missed an ACTION_DOWN
// event. in that case, treat the first occurence of a move event as a ACTION_DOWN
// i.e. fall through to the next case (don't break)
// (We sometimes miss ACTION_DOWN events in Workspace because it ignores all events
// while it's small- this was causing a crash before we checked for INVALID_POINTER)
}
case MotionEvent.ACTION_DOWN: {
final float x = ev.getX();
final float y = ev.getY();
// Remember location of down touch
mDownMotionX = x;
mLastMotionX = x;
mLastMotionY = y;
mLastMotionXRemainder = 0;
mTotalMotionX = 0;
mActivePointerId = ev.getPointerId(0);
mAllowLongPress = true;
/*
* If being flinged and user touches the screen, initiate drag;
* otherwise don't. mScroller.isFinished should be false when
* being flinged.
*/
final int xDist = Math.abs(mScroller.getFinalX() - mScroller.getCurrX());
final boolean finishedScrolling = (mScroller.isFinished() || xDist < mTouchSlop);
if (finishedScrolling) {
mTouchState = TOUCH_STATE_REST;
mScroller.abortAnimation();
} else {
mTouchState = TOUCH_STATE_SCROLLING;
}
// check if this can be the beginning of a tap on the side of the pages
// to scroll the current page
if (mTouchState != TOUCH_STATE_PREV_PAGE && mTouchState != TOUCH_STATE_NEXT_PAGE) {
if (getChildCount() > 0) {
if (hitsPreviousPage(x, y)) {
mTouchState = TOUCH_STATE_PREV_PAGE;
} else if (hitsNextPage(x, y)) {
mTouchState = TOUCH_STATE_NEXT_PAGE;
}
}
}
break;
}
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_CANCEL:
mTouchState = TOUCH_STATE_REST;
mAllowLongPress = false;
mActivePointerId = INVALID_POINTER;
releaseVelocityTracker();
break;
case MotionEvent.ACTION_POINTER_UP:
onSecondaryPointerUp(ev);
releaseVelocityTracker();
break;
}
/*
* The only time we want to intercept motion events is if we are in the
* drag mode.
*/
return mTouchState != TOUCH_STATE_REST;
}
protected void determineScrollingStart(MotionEvent ev) {
determineScrollingStart(ev, 1.0f);
}
/*
* Determines if we should change the touch state to start scrolling after the
* user moves their touch point too far.
*/
protected void determineScrollingStart(MotionEvent ev, float touchSlopScale) {
/*
* Locally do absolute value. mLastMotionX is set to the y value
* of the down event.
*/
final int pointerIndex = ev.findPointerIndex(mActivePointerId);
if (pointerIndex == -1) {
return;
}
final float x = ev.getX(pointerIndex);
final float y = ev.getY(pointerIndex);
final int xDiff = (int) Math.abs(x - mLastMotionX);
final int yDiff = (int) Math.abs(y - mLastMotionY);
final int touchSlop = Math.round(touchSlopScale * mTouchSlop);
boolean xPaged = xDiff > mPagingTouchSlop;
boolean xMoved = xDiff > touchSlop;
boolean yMoved = yDiff > touchSlop;
if (xMoved || xPaged || yMoved) {
if (mUsePagingTouchSlop ? xPaged : xMoved) {
// Scroll if the user moved far enough along the X axis
mTouchState = TOUCH_STATE_SCROLLING;
mTotalMotionX += Math.abs(mLastMotionX - x);
mLastMotionX = x;
mLastMotionXRemainder = 0;
mTouchX = getScrollX();
mSmoothingTime = System.nanoTime() / NANOTIME_DIV;
pageBeginMoving();
}
// Either way, cancel any pending longpress
cancelCurrentPageLongPress();
}
}
protected void cancelCurrentPageLongPress() {
if (mAllowLongPress) {
mAllowLongPress = false;
// Try canceling the long press. It could also have been scheduled
// by a distant descendant, so use the mAllowLongPress flag to block
// everything
final View currentPage = getPageAt(mCurrentPage);
if (currentPage != null) {
currentPage.cancelLongPress();
}
}
}
protected float getScrollProgress(int screenCenter, View v, int page) {
final int halfScreenSize = getMeasuredWidth() / 2;
int totalDistance = getScaledMeasuredWidth(v) + mPageSpacing;
int delta = screenCenter - (getChildOffset(page) -
getRelativeChildOffset(page) + halfScreenSize);
float scrollProgress = delta / (totalDistance * 1.0f);
scrollProgress = Math.min(scrollProgress, 1.0f);
scrollProgress = Math.max(scrollProgress, -1.0f);
return scrollProgress;
}
// This curve determines how the effect of scrolling over the limits of the page dimishes
// as the user pulls further and further from the bounds
private float overScrollInfluenceCurve(float f) {
f -= 1.0f;
return f * f * f + 1.0f;
}
protected void acceleratedOverScroll(float amount) {
int screenSize = getMeasuredWidth();
// We want to reach the max over scroll effect when the user has
// over scrolled half the size of the screen
float f = OVERSCROLL_ACCELERATE_FACTOR * (amount / screenSize);
if (f == 0) return;
// Clamp this factor, f, to -1 < f < 1
if (Math.abs(f) >= 1) {
f /= Math.abs(f);
}
int overScrollAmount = (int) Math.round(f * screenSize);
if (amount < 0) {
mOverScrollX = overScrollAmount;
super.scrollTo(0, getScrollY());
} else {
mOverScrollX = mMaxScrollX + overScrollAmount;
super.scrollTo(mMaxScrollX, getScrollY());
}
invalidate();
}
protected void dampedOverScroll(float amount) {
int screenSize = getMeasuredWidth();
float f = (amount / screenSize);
if (f == 0) return;
f = f / (Math.abs(f)) * (overScrollInfluenceCurve(Math.abs(f)));
// Clamp this factor, f, to -1 < f < 1
if (Math.abs(f) >= 1) {
f /= Math.abs(f);
}
int overScrollAmount = (int) Math.round(OVERSCROLL_DAMP_FACTOR * f * screenSize);
if (amount < 0) {
mOverScrollX = overScrollAmount;
super.scrollTo(0, getScrollY());
} else {
mOverScrollX = mMaxScrollX + overScrollAmount;
super.scrollTo(mMaxScrollX, getScrollY());
}
invalidate();
}
protected void overScroll(float amount) {
dampedOverScroll(amount);
}
protected float maxOverScroll() {
// Using the formula in overScroll, assuming that f = 1.0 (which it should generally not
// exceed). Used to find out how much extra wallpaper we need for the over scroll effect
float f = 1.0f;
f = f / (Math.abs(f)) * (overScrollInfluenceCurve(Math.abs(f)));
return OVERSCROLL_DAMP_FACTOR * f;
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
// Skip touch handling if there are no pages to swipe
if (getChildCount() <= 0) return super.onTouchEvent(ev);
acquireVelocityTrackerAndAddMovement(ev);
final int action = ev.getAction();
switch (action & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
/*
* 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
mDownMotionX = mLastMotionX = ev.getX();
mLastMotionXRemainder = 0;
mTotalMotionX = 0;
mActivePointerId = ev.getPointerId(0);
if (mTouchState == TOUCH_STATE_SCROLLING) {
pageBeginMoving();
}
break;
case MotionEvent.ACTION_MOVE:
if (mTouchState == TOUCH_STATE_SCROLLING) {
// Scroll to follow the motion event
final int pointerIndex = ev.findPointerIndex(mActivePointerId);
final float x = ev.getX(pointerIndex);
final float deltaX = mLastMotionX + mLastMotionXRemainder - x;
mTotalMotionX += Math.abs(deltaX);
// Only scroll and update mLastMotionX if we have moved some discrete amount. We
// keep the remainder because we are actually testing if we've moved from the last
// scrolled position (which is discrete).
if (Math.abs(deltaX) >= 1.0f) {
mTouchX += deltaX;
mSmoothingTime = System.nanoTime() / NANOTIME_DIV;
if (!mDeferScrollUpdate) {
scrollBy((int) deltaX, 0);
if (DEBUG) Log.d(TAG, "onTouchEvent().Scrolling: " + deltaX);
} else {
invalidate();
}
mLastMotionX = x;
mLastMotionXRemainder = deltaX - (int) deltaX;
} else {
awakenScrollBars();
}
} else {
determineScrollingStart(ev);
}
break;
case MotionEvent.ACTION_UP:
if (mTouchState == TOUCH_STATE_SCROLLING) {
final int activePointerId = mActivePointerId;
final int pointerIndex = ev.findPointerIndex(activePointerId);
final float x = ev.getX(pointerIndex);
final VelocityTracker velocityTracker = mVelocityTracker;
velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);
int velocityX = (int) velocityTracker.getXVelocity(activePointerId);
final int deltaX = (int) (x - mDownMotionX);
final int pageWidth = getScaledMeasuredWidth(getPageAt(mCurrentPage));
boolean isSignificantMove = Math.abs(deltaX) > pageWidth *
SIGNIFICANT_MOVE_THRESHOLD;
mTotalMotionX += Math.abs(mLastMotionX + mLastMotionXRemainder - x);
boolean isFling = mTotalMotionX > MIN_LENGTH_FOR_FLING &&
Math.abs(velocityX) > mFlingThresholdVelocity;
// In the case that the page is moved far to one direction and then is flung
// in the opposite direction, we use a threshold to determine whether we should
// just return to the starting page, or if we should skip one further.
boolean returnToOriginalPage = false;
if (Math.abs(deltaX) > pageWidth * RETURN_TO_ORIGINAL_PAGE_THRESHOLD &&
Math.signum(velocityX) != Math.signum(deltaX) && isFling) {
returnToOriginalPage = true;
}
int finalPage;
// We give flings precedence over large moves, which is why we short-circuit our
// test for a large move if a fling has been registered. That is, a large
// move to the left and fling to the right will register as a fling to the right.
final boolean isRtl = isLayoutRtl();
boolean isDeltaXLeft = isRtl ? deltaX > 0 : deltaX < 0;
boolean isVelocityXLeft = isRtl ? velocityX > 0 : velocityX < 0;
if (((isSignificantMove && !isDeltaXLeft && !isFling) ||
(isFling && !isVelocityXLeft)) && mCurrentPage > 0) {
finalPage = returnToOriginalPage ? mCurrentPage : mCurrentPage - 1;
snapToPageWithVelocity(finalPage, velocityX);
} else if (((isSignificantMove && isDeltaXLeft && !isFling) ||
(isFling && isVelocityXLeft)) &&
mCurrentPage < getChildCount() - 1) {
finalPage = returnToOriginalPage ? mCurrentPage : mCurrentPage + 1;
snapToPageWithVelocity(finalPage, velocityX);
} else {
snapToDestination();
}
} else if (mTouchState == TOUCH_STATE_PREV_PAGE) {
// at this point we have not moved beyond the touch slop
// (otherwise mTouchState would be TOUCH_STATE_SCROLLING), so
// we can just page
int nextPage = Math.max(0, mCurrentPage - 1);
if (nextPage != mCurrentPage) {
snapToPage(nextPage);
} else {
snapToDestination();
}
} else if (mTouchState == TOUCH_STATE_NEXT_PAGE) {
// at this point we have not moved beyond the touch slop
// (otherwise mTouchState would be TOUCH_STATE_SCROLLING), so
// we can just page
int nextPage = Math.min(getChildCount() - 1, mCurrentPage + 1);
if (nextPage != mCurrentPage) {
snapToPage(nextPage);
} else {
snapToDestination();
}
} else {
onUnhandledTap(ev);
}
mTouchState = TOUCH_STATE_REST;
mActivePointerId = INVALID_POINTER;
releaseVelocityTracker();
break;
case MotionEvent.ACTION_CANCEL:
if (mTouchState == TOUCH_STATE_SCROLLING) {
snapToDestination();
}
mTouchState = TOUCH_STATE_REST;
mActivePointerId = INVALID_POINTER;
releaseVelocityTracker();
break;
case MotionEvent.ACTION_POINTER_UP:
onSecondaryPointerUp(ev);
break;
}
return true;
}
@Override
public boolean onGenericMotionEvent(MotionEvent event) {
if ((event.getSource() & InputDevice.SOURCE_CLASS_POINTER) != 0) {
switch (event.getAction()) {
case MotionEvent.ACTION_SCROLL: {
// Handle mouse (or ext. device) by shifting the page depending on the scroll
final float vscroll;
final float hscroll;
if ((event.getMetaState() & KeyEvent.META_SHIFT_ON) != 0) {
vscroll = 0;
hscroll = event.getAxisValue(MotionEvent.AXIS_VSCROLL);
} else {
vscroll = -event.getAxisValue(MotionEvent.AXIS_VSCROLL);
hscroll = event.getAxisValue(MotionEvent.AXIS_HSCROLL);
}
if (hscroll != 0 || vscroll != 0) {
boolean isForwardScroll = isLayoutRtl() ? (hscroll < 0 || vscroll < 0)
: (hscroll > 0 || vscroll > 0);
if (isForwardScroll) {
scrollRight();
} else {
scrollLeft();
}
return true;
}
}
}
}
return super.onGenericMotionEvent(event);
}
private void acquireVelocityTrackerAndAddMovement(MotionEvent ev) {
if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
}
mVelocityTracker.addMovement(ev);
}
private void releaseVelocityTracker() {
if (mVelocityTracker != null) {
mVelocityTracker.recycle();
mVelocityTracker = null;
}
}
private void onSecondaryPointerUp(MotionEvent ev) {
final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >>
MotionEvent.ACTION_POINTER_INDEX_SHIFT;
final int pointerId = ev.getPointerId(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;
mLastMotionX = mDownMotionX = ev.getX(newPointerIndex);
mLastMotionY = ev.getY(newPointerIndex);
mLastMotionXRemainder = 0;
mActivePointerId = ev.getPointerId(newPointerIndex);
if (mVelocityTracker != null) {
mVelocityTracker.clear();
}
}
}
protected void onUnhandledTap(MotionEvent ev) {}
@Override
public void requestChildFocus(View child, View focused) {
super.requestChildFocus(child, focused);
int page = indexToPage(indexOfChild(child));
if (page >= 0 && page != getCurrentPage() && !isInTouchMode()) {
snapToPage(page);
}
}
protected int getChildIndexForRelativeOffset(int relativeOffset) {
final boolean isRtl = isLayoutRtl();
final int childCount = getChildCount();
int left;
int right;
final int startIndex = isRtl ? childCount - 1 : 0;
final int endIndex = isRtl ? -1 : childCount;
final int delta = isRtl ? -1 : 1;
for (int i = startIndex; i != endIndex; i += delta) {
left = getRelativeChildOffset(i);
right = (left + getScaledMeasuredWidth(getPageAt(i)));
if (left <= relativeOffset && relativeOffset <= right) {
return i;
}
}
return -1;
}
protected int getChildWidth(int index) {
// This functions are called enough times that it actually makes a difference in the
// profiler -- so just inline the max() here
final int measuredWidth = getPageAt(index).getMeasuredWidth();
final int minWidth = mMinimumWidth;
return (minWidth > measuredWidth) ? minWidth : measuredWidth;
}
int getPageNearestToCenterOfScreen() {
int minDistanceFromScreenCenter = Integer.MAX_VALUE;
int minDistanceFromScreenCenterIndex = -1;
int screenCenter = getScrollX() + (getMeasuredWidth() / 2);
final int childCount = getChildCount();
for (int i = 0; i < childCount; ++i) {
View layout = (View) getPageAt(i);
int childWidth = getScaledMeasuredWidth(layout);
int halfChildWidth = (childWidth / 2);
int childCenter = getChildOffset(i) + halfChildWidth;
int distanceFromScreenCenter = Math.abs(childCenter - screenCenter);
if (distanceFromScreenCenter < minDistanceFromScreenCenter) {
minDistanceFromScreenCenter = distanceFromScreenCenter;
minDistanceFromScreenCenterIndex = i;
}
}
return minDistanceFromScreenCenterIndex;
}
protected void snapToDestination() {
snapToPage(getPageNearestToCenterOfScreen(), PAGE_SNAP_ANIMATION_DURATION);
}
private static class ScrollInterpolator implements Interpolator {
public ScrollInterpolator() {
}
public float getInterpolation(float t) {
t -= 1.0f;
return t*t*t*t*t + 1;
}
}
// We want the duration of the page snap animation to be influenced by the distance that
// the screen has to travel, however, we don't want this duration to be effected in a
// purely linear fashion. Instead, we use this method to moderate the effect that the distance
// of travel has on the overall snap duration.
float distanceInfluenceForSnapDuration(float f) {
f -= 0.5f; // center the values about 0.
f *= 0.3f * Math.PI / 2.0f;
return (float) Math.sin(f);
}
protected void snapToPageWithVelocity(int whichPage, int velocity) {
whichPage = Math.max(0, Math.min(whichPage, getChildCount() - 1));
int halfScreenSize = getMeasuredWidth() / 2;
if (DEBUG) Log.d(TAG, "snapToPage.getChildOffset(): " + getChildOffset(whichPage));
if (DEBUG) Log.d(TAG, "snapToPageWithVelocity.getRelativeChildOffset(): "
+ getMeasuredWidth() + ", " + getChildWidth(whichPage));
final int newX = getChildOffset(whichPage) - getRelativeChildOffset(whichPage);
int delta = newX - mUnboundedScrollX;
int duration = 0;
if (Math.abs(velocity) < mMinFlingVelocity) {
// If the velocity is low enough, then treat this more as an automatic page advance
// as opposed to an apparent physical response to flinging
snapToPage(whichPage, PAGE_SNAP_ANIMATION_DURATION);
return;
}
// Here we compute a "distance" that will be used in the computation of the overall
// snap duration. This is a function of the actual distance that needs to be traveled;
// we keep this value close to half screen size in order to reduce the variance in snap
// duration as a function of the distance the page needs to travel.
float distanceRatio = Math.min(1f, 1.0f * Math.abs(delta) / (2 * halfScreenSize));
float distance = halfScreenSize + halfScreenSize *
distanceInfluenceForSnapDuration(distanceRatio);
velocity = Math.abs(velocity);
velocity = Math.max(mMinSnapVelocity, velocity);
// we want the page's snap velocity to approximately match the velocity at which the
// user flings, so we scale the duration by a value near to the derivative of the scroll
// interpolator at zero, ie. 5. We use 4 to make it a little slower.
duration = 4 * Math.round(1000 * Math.abs(distance / velocity));
duration = Math.min(duration, MAX_PAGE_SNAP_DURATION);
snapToPage(whichPage, delta, duration);
}
protected void snapToPage(int whichPage) {
snapToPage(whichPage, PAGE_SNAP_ANIMATION_DURATION);
}
protected void snapToPage(int whichPage, int duration) {
whichPage = Math.max(0, Math.min(whichPage, getPageCount() - 1));
if (DEBUG) Log.d(TAG, "snapToPage.getChildOffset(): " + getChildOffset(whichPage));
if (DEBUG) Log.d(TAG, "snapToPage.getRelativeChildOffset(): " + getMeasuredWidth() + ", "
+ getChildWidth(whichPage));
int newX = getChildOffset(whichPage) - getRelativeChildOffset(whichPage);
final int sX = mUnboundedScrollX;
final int delta = newX - sX;
snapToPage(whichPage, delta, duration);
}
protected void snapToPage(int whichPage, int delta, int duration) {
mNextPage = whichPage;
View focusedChild = getFocusedChild();
if (focusedChild != null && whichPage != mCurrentPage &&
focusedChild == getPageAt(mCurrentPage)) {
focusedChild.clearFocus();
}
pageBeginMoving();
awakenScrollBars(duration);
if (duration == 0) {
duration = Math.abs(delta);
}
if (!mScroller.isFinished()) mScroller.abortAnimation();
mScroller.startScroll(mUnboundedScrollX, 0, delta, 0, duration);
// Load associated pages immediately if someone else is handling the scroll, otherwise defer
// loading associated pages until the scroll settles
if (mDeferScrollUpdate) {
loadAssociatedPages(mNextPage);
} else {
mDeferLoadAssociatedPagesUntilScrollCompletes = true;
}
notifyPageSwitchListener();
invalidate();
}
public void scrollLeft() {
if (mScroller.isFinished()) {
if (mCurrentPage > 0) snapToPage(mCurrentPage - 1);
} else {
if (mNextPage > 0) snapToPage(mNextPage - 1);
}
}
public void scrollRight() {
if (mScroller.isFinished()) {
if (mCurrentPage < getChildCount() -1) snapToPage(mCurrentPage + 1);
} else {
if (mNextPage < getChildCount() -1) snapToPage(mNextPage + 1);
}
}
public int getPageForView(View v) {
int result = -1;
if (v != null) {
ViewParent vp = v.getParent();
int count = getChildCount();
for (int i = 0; i < count; i++) {
if (vp == getPageAt(i)) {
return i;
}
}
}
return result;
}
/**
* @return True is long presses are still allowed for the current touch
*/
public boolean allowLongPress() {
return mAllowLongPress;
}
/**
* Set true to allow long-press events to be triggered, usually checked by
* {@link Launcher} to accept or block dpad-initiated long-presses.
*/
public void setAllowLongPress(boolean allowLongPress) {
mAllowLongPress = allowLongPress;
}
public static class SavedState extends BaseSavedState {
int currentPage = -1;
SavedState(Parcelable superState) {
super(superState);
}
private SavedState(Parcel in) {
super(in);
currentPage = in.readInt();
}
@Override
public void writeToParcel(Parcel out, int flags) {
super.writeToParcel(out, flags);
out.writeInt(currentPage);
}
public static final Parcelable.Creator<SavedState> CREATOR =
new Parcelable.Creator<SavedState>() {
public SavedState createFromParcel(Parcel in) {
return new SavedState(in);
}
public SavedState[] newArray(int size) {
return new SavedState[size];
}
};
}
protected void loadAssociatedPages(int page) {
loadAssociatedPages(page, false);
}
protected void loadAssociatedPages(int page, boolean immediateAndOnly) {
if (mContentIsRefreshable) {
final int count = getChildCount();
if (page < count) {
int lowerPageBound = getAssociatedLowerPageBound(page);
int upperPageBound = getAssociatedUpperPageBound(page);
if (DEBUG) Log.d(TAG, "loadAssociatedPages: " + lowerPageBound + "/"
+ upperPageBound);
// First, clear any pages that should no longer be loaded
for (int i = 0; i < count; ++i) {
Page layout = (Page) getPageAt(i);
if ((i < lowerPageBound) || (i > upperPageBound)) {
if (layout.getPageChildCount() > 0) {
layout.removeAllViewsOnPage();
}
mDirtyPageContent.set(i, true);
}
}
// Next, load any new pages
for (int i = 0; i < count; ++i) {
if ((i != page) && immediateAndOnly) {
continue;
}
if (lowerPageBound <= i && i <= upperPageBound) {
if (mDirtyPageContent.get(i)) {
syncPageItems(i, (i == page) && immediateAndOnly);
mDirtyPageContent.set(i, false);
}
}
}
}
}
}
protected int getAssociatedLowerPageBound(int page) {
return Math.max(0, page - 1);
}
protected int getAssociatedUpperPageBound(int page) {
final int count = getChildCount();
return Math.min(page + 1, count - 1);
}
/**
* This method is called ONLY to synchronize the number of pages that the paged view has.
* To actually fill the pages with information, implement syncPageItems() below. It is
* guaranteed that syncPageItems() will be called for a particular page before it is shown,
* and therefore, individual page items do not need to be updated in this method.
*/
public abstract void syncPages();
/**
* This method is called to synchronize the items that are on a particular page. If views on
* the page can be reused, then they should be updated within this method.
*/
public abstract void syncPageItems(int page, boolean immediate);
protected void invalidatePageData() {
invalidatePageData(-1, false);
}
protected void invalidatePageData(int currentPage) {
invalidatePageData(currentPage, false);
}
protected void invalidatePageData(int currentPage, boolean immediateAndOnly) {
if (!mIsDataReady) {
return;
}
if (mContentIsRefreshable) {
// Force all scrolling-related behavior to end
mScroller.forceFinished(true);
mNextPage = INVALID_PAGE;
// Update all the pages
syncPages();
// We must force a measure after we've loaded the pages to update the content width and
// to determine the full scroll width
measure(MeasureSpec.makeMeasureSpec(getMeasuredWidth(), MeasureSpec.EXACTLY),
MeasureSpec.makeMeasureSpec(getMeasuredHeight(), MeasureSpec.EXACTLY));
// Set a new page as the current page if necessary
if (currentPage > -1) {
setCurrentPage(Math.min(getPageCount() - 1, currentPage));
}
// Mark each of the pages as dirty
final int count = getChildCount();
mDirtyPageContent.clear();
for (int i = 0; i < count; ++i) {
mDirtyPageContent.add(true);
}
// Load any pages that are necessary for the current window of views
loadAssociatedPages(mCurrentPage, immediateAndOnly);
requestLayout();
}
}
protected View getScrollingIndicator() {
// We use mHasScrollIndicator to prevent future lookups if there is no sibling indicator
// found
if (mHasScrollIndicator && mScrollIndicator == null) {
ViewGroup parent = (ViewGroup) getParent();
if (parent != null) {
mScrollIndicator = (View) (parent.findViewById(R.id.paged_view_indicator));
mHasScrollIndicator = mScrollIndicator != null;
if (mHasScrollIndicator) {
mScrollIndicator.setVisibility(View.VISIBLE);
}
}
}
return mScrollIndicator;
}
protected boolean isScrollingIndicatorEnabled() {
return true;
}
Runnable hideScrollingIndicatorRunnable = new Runnable() {
@Override
public void run() {
hideScrollingIndicator(false);
}
};
protected void flashScrollingIndicator(boolean animated) {
removeCallbacks(hideScrollingIndicatorRunnable);
showScrollingIndicator(!animated);
postDelayed(hideScrollingIndicatorRunnable, sScrollIndicatorFlashDuration);
}
protected void showScrollingIndicator(boolean immediately) {
mShouldShowScrollIndicator = true;
mShouldShowScrollIndicatorImmediately = true;
if (getChildCount() <= 1) return;
if (!isScrollingIndicatorEnabled()) return;
mShouldShowScrollIndicator = false;
getScrollingIndicator();
if (mScrollIndicator != null) {
// Fade the indicator in
updateScrollingIndicatorPosition();
mScrollIndicator.setVisibility(View.VISIBLE);
cancelScrollingIndicatorAnimations();
if (immediately || mScrollingPaused) {
mScrollIndicator.setAlpha(1f);
} else {
mScrollIndicatorAnimator = LauncherAnimUtils.ofFloat(mScrollIndicator, "alpha", 1f);
mScrollIndicatorAnimator.setDuration(sScrollIndicatorFadeInDuration);
mScrollIndicatorAnimator.start();
}
}
}
protected void cancelScrollingIndicatorAnimations() {
if (mScrollIndicatorAnimator != null) {
mScrollIndicatorAnimator.cancel();
}
}
protected void hideScrollingIndicator(boolean immediately) {
if (getChildCount() <= 1) return;
if (!isScrollingIndicatorEnabled()) return;
getScrollingIndicator();
if (mScrollIndicator != null) {
// Fade the indicator out
updateScrollingIndicatorPosition();
cancelScrollingIndicatorAnimations();
if (immediately || mScrollingPaused) {
mScrollIndicator.setVisibility(View.INVISIBLE);
mScrollIndicator.setAlpha(0f);
} else {
mScrollIndicatorAnimator = LauncherAnimUtils.ofFloat(mScrollIndicator, "alpha", 0f);
mScrollIndicatorAnimator.setDuration(sScrollIndicatorFadeOutDuration);
mScrollIndicatorAnimator.addListener(new AnimatorListenerAdapter() {
private boolean cancelled = false;
@Override
public void onAnimationCancel(android.animation.Animator animation) {
cancelled = true;
}
@Override
public void onAnimationEnd(Animator animation) {
if (!cancelled) {
mScrollIndicator.setVisibility(View.INVISIBLE);
}
}
});
mScrollIndicatorAnimator.start();
}
}
}
/**
* To be overridden by subclasses to determine whether the scroll indicator should stretch to
* fill its space on the track or not.
*/
protected boolean hasElasticScrollIndicator() {
return true;
}
private void updateScrollingIndicator() {
if (getChildCount() <= 1) return;
if (!isScrollingIndicatorEnabled()) return;
getScrollingIndicator();
if (mScrollIndicator != null) {
updateScrollingIndicatorPosition();
}
if (mShouldShowScrollIndicator) {
showScrollingIndicator(mShouldShowScrollIndicatorImmediately);
}
}
private void updateScrollingIndicatorPosition() {
final boolean isRtl = isLayoutRtl();
if (!isScrollingIndicatorEnabled()) return;
if (mScrollIndicator == null) return;
int numPages = getChildCount();
int pageWidth = getMeasuredWidth();
int trackWidth = pageWidth - mScrollIndicatorPaddingLeft - mScrollIndicatorPaddingRight;
int indicatorWidth = mScrollIndicator.getMeasuredWidth() -
mScrollIndicator.getPaddingLeft() - mScrollIndicator.getPaddingRight();
float scrollPos = isRtl ? mMaxScrollX - getScrollX() : getScrollX();
float offset = Math.max(0f, Math.min(1f, (float) scrollPos / mMaxScrollX));
if (isRtl) {
offset = 1f - offset;
}
int indicatorSpace = trackWidth / numPages;
int indicatorPos = (int) (offset * (trackWidth - indicatorSpace)) + mScrollIndicatorPaddingLeft;
if (hasElasticScrollIndicator()) {
if (mScrollIndicator.getMeasuredWidth() != indicatorSpace) {
mScrollIndicator.getLayoutParams().width = indicatorSpace;
mScrollIndicator.requestLayout();
}
} else {
int indicatorCenterOffset = indicatorSpace / 2 - indicatorWidth / 2;
indicatorPos += indicatorCenterOffset;
}
mScrollIndicator.setTranslationX(indicatorPos);
}
public void showScrollIndicatorTrack() {
}
public void hideScrollIndicatorTrack() {
}
/* Accessibility */
@Override
public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
super.onInitializeAccessibilityNodeInfo(info);
info.setScrollable(getPageCount() > 1);
if (getCurrentPage() < getPageCount() - 1) {
info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_FORWARD);
}
if (getCurrentPage() > 0) {
info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD);
}
}
@Override
public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
super.onInitializeAccessibilityEvent(event);
event.setScrollable(true);
if (event.getEventType() == AccessibilityEvent.TYPE_VIEW_SCROLLED) {
event.setFromIndex(mCurrentPage);
event.setToIndex(mCurrentPage);
event.setItemCount(getChildCount());
}
}
@Override
public boolean performAccessibilityAction(int action, Bundle arguments) {
if (super.performAccessibilityAction(action, arguments)) {
return true;
}
switch (action) {
case AccessibilityNodeInfo.ACTION_SCROLL_FORWARD: {
if (getCurrentPage() < getPageCount() - 1) {
scrollRight();
return true;
}
} break;
case AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD: {
if (getCurrentPage() > 0) {
scrollLeft();
return true;
}
} break;
}
return false;
}
protected String getCurrentPageDescription() {
return String.format(getContext().getString(R.string.default_scroll_format),
getNextPage() + 1, getChildCount());
}
@Override
public boolean onHoverEvent(android.view.MotionEvent event) {
return true;
}
}