Java tutorial
package gaobq.android.easyslidingmenu; import gaobq.android.easyslidingmenu.SlidingMenu.OnClosedListener; import gaobq.android.easyslidingmenu.SlidingMenu.OnOpenedListener; import java.util.ArrayList; import java.util.List; import android.content.Context; import android.graphics.Canvas; import android.graphics.Rect; import android.os.Build; import android.support.v4.view.KeyEventCompat; import android.support.v4.view.MotionEventCompat; import android.support.v4.view.VelocityTrackerCompat; import android.support.v4.view.ViewCompat; import android.support.v4.view.ViewConfigurationCompat; import android.util.AttributeSet; import android.util.FloatMath; import android.util.Log; import android.view.FocusFinder; import android.view.KeyEvent; import android.view.MotionEvent; import android.view.SoundEffectConstants; import android.view.VelocityTracker; import android.view.View; import android.view.ViewConfiguration; import android.view.ViewGroup; import android.view.animation.Interpolator; import android.widget.Scroller; //import com.slidingmenu.lib.SlidingMenu.OnCloseListener; //import com.slidingmenu.lib.SlidingMenu.OnOpenListener; /** * * Copyright 2012 Jeremy Feinstein 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. * */ public class CustomViewAbove extends ViewGroup { private static final String TAG = "CustomViewAbove"; private static final boolean DEBUG = false; private static final boolean USE_CACHE = false; private static final int MAX_SETTLE_DURATION = 600; // ms private static final int MIN_DISTANCE_FOR_FLING = 25; // dips private static final Interpolator sInterpolator = new Interpolator() { public float getInterpolation(float t) { t -= 1.0f; return t * t * t * t * t + 1.0f; } }; private View mContent; private int mCurItem; private Scroller mScroller; private boolean mScrollingCacheEnabled; private boolean mScrolling; private boolean mIsBeingDragged; private boolean mIsUnableToDrag; private int mTouchSlop; private float mInitialMotionX; /** * Position of the last motion event. */ private float mLastMotionX; private float mLastMotionY; /** * ID of the active pointer. This is used to retain consistency during * drags/flings if multiple pointers are used. */ protected int mActivePointerId = INVALID_POINTER; /** * Sentinel value for no current active pointer. * Used by {@link #mActivePointerId}. */ private static final int INVALID_POINTER = -1; /** * Determines speed during touch scrolling */ protected VelocityTracker mVelocityTracker; private int mMinimumVelocity; protected int mMaximumVelocity; private int mFlingDistance; private CustomViewBehind mViewBehind; // private int mMode; private boolean mEnabled = true; private OnPageChangeListener mOnPageChangeListener; private OnPageChangeListener mInternalPageChangeListener; // private OnCloseListener mCloseListener; // private OnOpenListener mOpenListener; private OnClosedListener mClosedListener; private OnOpenedListener mOpenedListener; private List<View> mIgnoredViews = new ArrayList<View>(); // private int mScrollState = SCROLL_STATE_IDLE; /** * Callback interface for responding to changing state of the selected page. */ public interface OnPageChangeListener { /** * This method will be invoked when the current page is scrolled, either as part * of a programmatically initiated smooth scroll or a user initiated touch scroll. * * @param position Position index of the first page currently being displayed. * Page position+1 will be visible if positionOffset is nonzero. * @param positionOffset Value from [0, 1) indicating the offset from the page at position. * @param positionOffsetPixels Value in pixels indicating the offset from position. */ public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels); /** * This method will be invoked when a new page becomes selected. Animation is not * necessarily complete. * * @param position Position index of the new selected page. */ public void onPageSelected(int position); } /** * Simple implementation of the {@link OnPageChangeListener} interface with stub * implementations of each method. Extend this if you do not intend to override * every method of {@link OnPageChangeListener}. */ public static class SimpleOnPageChangeListener implements OnPageChangeListener { public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { // This space for rent } public void onPageSelected(int position) { // This space for rent } public void onPageScrollStateChanged(int state) { // This space for rent } } public CustomViewAbove(Context context) { this(context, null); } public CustomViewAbove(Context context, AttributeSet attrs) { super(context, attrs); initCustomViewAbove(); } void initCustomViewAbove() { setWillNotDraw(false); setDescendantFocusability(FOCUS_AFTER_DESCENDANTS); setFocusable(true); final Context context = getContext(); mScroller = new Scroller(context, sInterpolator); final ViewConfiguration configuration = ViewConfiguration.get(context); mTouchSlop = ViewConfigurationCompat.getScaledPagingTouchSlop(configuration); mMinimumVelocity = configuration.getScaledMinimumFlingVelocity(); mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); setInternalPageChangeListener(new SimpleOnPageChangeListener() { public void onPageSelected(int position) { if (mViewBehind != null) { switch (position) { case 0: case 2: mViewBehind.setChildrenEnabled(true); break; case 1: mViewBehind.setChildrenEnabled(false); break; } } } }); final float density = context.getResources().getDisplayMetrics().density; mFlingDistance = (int) (MIN_DISTANCE_FOR_FLING * density); } /** * Set the currently selected page. If the CustomViewPager has already been through its first * layout there will be a smooth animated transition between the current item and the * specified item. * * @param item Item index to select */ public void setCurrentItem(int item) { setCurrentItemInternal(item, true, false); } /** * Set the currently selected page. * * @param item Item index to select * @param smoothScroll True to smoothly scroll to the new item, false to transition immediately */ public void setCurrentItem(int item, boolean smoothScroll) { setCurrentItemInternal(item, smoothScroll, false); } public int getCurrentItem() { return mCurItem; } void setCurrentItemInternal(int item, boolean smoothScroll, boolean always) { setCurrentItemInternal(item, smoothScroll, always, 0); } void setCurrentItemInternal(int item, boolean smoothScroll, boolean always, int velocity) { if (!always && mCurItem == item) { setScrollingCacheEnabled(false); return; } item = mViewBehind.getMenuPage(item); final boolean dispatchSelected = mCurItem != item; mCurItem = item; final int destX = getDestScrollX(mCurItem); if (dispatchSelected && mOnPageChangeListener != null) { mOnPageChangeListener.onPageSelected(item); } if (dispatchSelected && mInternalPageChangeListener != null) { mInternalPageChangeListener.onPageSelected(item); } if (smoothScroll) { smoothScrollTo(destX, 0, velocity); } else { completeScroll(); scrollTo(destX, 0); } } /** * Set a listener that will be invoked whenever the page changes or is incrementally * scrolled. See {@link OnPageChangeListener}. * * @param listener Listener to set */ public void setOnPageChangeListener(OnPageChangeListener listener) { mOnPageChangeListener = listener; } /* public void setOnOpenListener(OnOpenListener l) { mOpenListener = l; } public void setOnCloseListener(OnCloseListener l) { mCloseListener = l; } */ public void setOnOpenedListener(OnOpenedListener l) { mOpenedListener = l; } public void setOnClosedListener(OnClosedListener l) { mClosedListener = l; } /** * Set a separate OnPageChangeListener for internal use by the support library. * * @param listener Listener to set * @return The old listener that was set, if any. */ OnPageChangeListener setInternalPageChangeListener(OnPageChangeListener listener) { OnPageChangeListener oldListener = mInternalPageChangeListener; mInternalPageChangeListener = listener; return oldListener; } public void addIgnoredView(View v) { if (!mIgnoredViews.contains(v)) { mIgnoredViews.add(v); } } public void removeIgnoredView(View v) { mIgnoredViews.remove(v); } public void clearIgnoredViews() { mIgnoredViews.clear(); } // 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) FloatMath.sin(f); } public int getDestScrollX(int page) { switch (page) { case 0: case 2: return mViewBehind.getMenuLeft(mContent, page); case 1: return mContent.getLeft(); } return 0; } private int getLeftBound() { return mViewBehind.getAbsLeftBound(mContent); } private int getRightBound() { return mViewBehind.getAbsRightBound(mContent); } public int getContentLeft() { return mContent.getLeft() + mContent.getPaddingLeft(); } public boolean isMenuOpen() { return mCurItem == 0 || mCurItem == 2; } private boolean isInIgnoredView(MotionEvent ev) { Rect rect = new Rect(); for (View v : mIgnoredViews) { v.getHitRect(rect); if (rect.contains((int) ev.getX(), (int) ev.getY())) return true; } return false; } public int getBehindWidth() { if (mViewBehind == null) { return 0; } else { return mViewBehind.getBehindWidth(); } } public int getChildWidth(int i) { switch (i) { case 0: return getBehindWidth(); case 1: return mContent.getWidth(); default: return 0; } } public boolean isSlidingEnabled() { return mEnabled; } public void setSlidingEnabled(boolean b) { mEnabled = b; } /** * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. * * @param x the number of pixels to scroll by on the X axis * @param y the number of pixels to scroll by on the Y axis */ void smoothScrollTo(int x, int y) { smoothScrollTo(x, y, 0); } /** * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. * * @param x the number of pixels to scroll by on the X axis * @param y the number of pixels to scroll by on the Y axis * @param velocity the velocity associated with a fling, if applicable. (0 otherwise) */ void smoothScrollTo(int x, int y, int velocity) { if (getChildCount() == 0) { // Nothing to do. setScrollingCacheEnabled(false); return; } int sx = getScrollX(); int sy = getScrollY(); int dx = x - sx; int dy = y - sy; if (dx == 0 && dy == 0) { completeScroll(); if (isMenuOpen()) { if (mOpenedListener != null) mOpenedListener.onOpened(); } else { if (mClosedListener != null) mClosedListener.onClosed(); } return; } setScrollingCacheEnabled(true); mScrolling = true; final int width = getBehindWidth(); final int halfWidth = width / 2; final float distanceRatio = Math.min(1f, 1.0f * Math.abs(dx) / width); final float distance = halfWidth + halfWidth * distanceInfluenceForSnapDuration(distanceRatio); int duration = 0; velocity = Math.abs(velocity); if (velocity > 0) { duration = 4 * Math.round(1000 * Math.abs(distance / velocity)); } else { final float pageDelta = (float) Math.abs(dx) / width; duration = (int) ((pageDelta + 1) * 100); duration = MAX_SETTLE_DURATION; } duration = Math.min(duration, MAX_SETTLE_DURATION); mScroller.startScroll(sx, sy, dx, dy, duration); invalidate(); } public void setContent(View v) { if (mContent != null) this.removeView(mContent); mContent = v; addView(mContent); } public View getContent() { return mContent; } public void setCustomViewBehind(CustomViewBehind cvb) { mViewBehind = cvb; } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { int width = getDefaultSize(0, widthMeasureSpec); int height = getDefaultSize(0, heightMeasureSpec); setMeasuredDimension(width, height); final int contentWidth = getChildMeasureSpec(widthMeasureSpec, 0, width); final int contentHeight = getChildMeasureSpec(heightMeasureSpec, 0, height); mContent.measure(contentWidth, contentHeight); } @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { super.onSizeChanged(w, h, oldw, oldh); // Make sure scroll position is set correctly. if (w != oldw) { // [ChrisJ] - This fixes the onConfiguration change for orientation issue.. // maybe worth having a look why the recomputeScroll pos is screwing // up? completeScroll(); scrollTo(getDestScrollX(mCurItem), getScrollY()); } } @Override protected void onLayout(boolean changed, int l, int t, int r, int b) { final int width = r - l; final int height = b - t; mContent.layout(0, 0, width, height); } public void setAboveOffset(int i) { // RelativeLayout.LayoutParams params = ((RelativeLayout.LayoutParams)mContent.getLayoutParams()); // params.setMargins(i, params.topMargin, params.rightMargin, params.bottomMargin); mContent.setPadding(i, mContent.getPaddingTop(), mContent.getPaddingRight(), mContent.getPaddingBottom()); } @Override public void computeScroll() { if (!mScroller.isFinished()) { if (mScroller.computeScrollOffset()) { int oldX = getScrollX(); int oldY = getScrollY(); int x = mScroller.getCurrX(); int y = mScroller.getCurrY(); if (oldX != x || oldY != y) { scrollTo(x, y); pageScrolled(x); } // Keep on drawing until the animation has finished. invalidate(); return; } } // Done with scroll, clean up state. completeScroll(); } private void pageScrolled(int xpos) { final int widthWithMargin = getWidth(); final int position = xpos / widthWithMargin; final int offsetPixels = xpos % widthWithMargin; final float offset = (float) offsetPixels / widthWithMargin; onPageScrolled(position, offset, offsetPixels); } /** * This method will be invoked when the current page is scrolled, either as part * of a programmatically initiated smooth scroll or a user initiated touch scroll. * If you override this method you must call through to the superclass implementation * (e.g. super.onPageScrolled(position, offset, offsetPixels)) before onPageScrolled * returns. * * @param position Position index of the first page currently being displayed. * Page position+1 will be visible if positionOffset is nonzero. * @param offset Value from [0, 1) indicating the offset from the page at position. * @param offsetPixels Value in pixels indicating the offset from position. */ protected void onPageScrolled(int position, float offset, int offsetPixels) { if (mOnPageChangeListener != null) { mOnPageChangeListener.onPageScrolled(position, offset, offsetPixels); } if (mInternalPageChangeListener != null) { mInternalPageChangeListener.onPageScrolled(position, offset, offsetPixels); } } private void completeScroll() { boolean needPopulate = mScrolling; if (needPopulate) { // Done with scroll, no longer want to cache view drawing. setScrollingCacheEnabled(false); mScroller.abortAnimation(); int oldX = getScrollX(); int oldY = getScrollY(); int x = mScroller.getCurrX(); int y = mScroller.getCurrY(); if (oldX != x || oldY != y) { scrollTo(x, y); } if (isMenuOpen()) { if (mOpenedListener != null) mOpenedListener.onOpened(); } else { if (mClosedListener != null) mClosedListener.onClosed(); } } mScrolling = false; } protected int mTouchMode = SlidingMenu.TOUCHMODE_MARGIN; public void setTouchMode(int i) { mTouchMode = i; } public int getTouchMode() { return mTouchMode; } private boolean thisTouchAllowed(MotionEvent ev) { int x = (int) (ev.getX() + mScrollX); if (isMenuOpen()) { return mViewBehind.menuOpenTouchAllowed(mContent, mCurItem, x); } else { switch (mTouchMode) { case SlidingMenu.TOUCHMODE_FULLSCREEN: return !isInIgnoredView(ev); case SlidingMenu.TOUCHMODE_NONE: return false; case SlidingMenu.TOUCHMODE_MARGIN: return mViewBehind.marginTouchAllowed(mContent, x); } } return false; } private boolean thisSlideAllowed(float dx) { boolean allowed = false; if (isMenuOpen()) { allowed = mViewBehind.menuOpenSlideAllowed(dx); } else { allowed = mViewBehind.menuClosedSlideAllowed(dx); } if (DEBUG) Log.v(TAG, "this slide allowed " + allowed + " dx: " + dx); return allowed; } private int getPointerIndex(MotionEvent ev, int id) { int activePointerIndex = MotionEventCompat.findPointerIndex(ev, id); if (activePointerIndex == -1) mActivePointerId = INVALID_POINTER; return activePointerIndex; } private boolean mQuickReturn = false; @Override public boolean onInterceptTouchEvent(MotionEvent ev) { if (!mEnabled) return false; final int action = ev.getAction() & MotionEventCompat.ACTION_MASK; if (DEBUG) if (action == MotionEvent.ACTION_DOWN) Log.v(TAG, "Received ACTION_DOWN"); if (action == MotionEvent.ACTION_CANCEL || action == MotionEvent.ACTION_UP || (action != MotionEvent.ACTION_DOWN && mIsUnableToDrag)) { endDrag(); return false; } switch (action) { case MotionEvent.ACTION_MOVE: determineDrag(ev); break; case MotionEvent.ACTION_DOWN: int index = MotionEventCompat.getActionIndex(ev); mActivePointerId = MotionEventCompat.getPointerId(ev, index); if (mActivePointerId == INVALID_POINTER) break; mLastMotionX = mInitialMotionX = MotionEventCompat.getX(ev, index); mLastMotionY = MotionEventCompat.getY(ev, index); if (thisTouchAllowed(ev)) { mIsBeingDragged = false; mIsUnableToDrag = false; if (isMenuOpen() && mViewBehind.menuTouchInQuickReturn(mContent, mCurItem, ev.getX() + mScrollX)) { mQuickReturn = true; } } else { mIsUnableToDrag = true; } break; case MotionEventCompat.ACTION_POINTER_UP: onSecondaryPointerUp(ev); break; } if (!mIsBeingDragged) { if (mVelocityTracker == null) { mVelocityTracker = VelocityTracker.obtain(); } mVelocityTracker.addMovement(ev); } return mIsBeingDragged || mQuickReturn; } @Override public boolean onTouchEvent(MotionEvent ev) { if (!mEnabled) return false; if (!mIsBeingDragged && !thisTouchAllowed(ev)) return false; // if (!mIsBeingDragged && !mQuickReturn) // return false; final int action = ev.getAction(); if (mVelocityTracker == null) { mVelocityTracker = VelocityTracker.obtain(); } mVelocityTracker.addMovement(ev); switch (action & MotionEventCompat.ACTION_MASK) { case MotionEvent.ACTION_DOWN: /* * If being flinged and user touches, stop the fling. isFinished * will be false if being flinged. */ completeScroll(); // Remember where the motion event started int index = MotionEventCompat.getActionIndex(ev); mActivePointerId = MotionEventCompat.getPointerId(ev, index); mLastMotionX = mInitialMotionX = ev.getX(); break; case MotionEvent.ACTION_MOVE: if (!mIsBeingDragged) { determineDrag(ev); if (mIsUnableToDrag) return false; } if (mIsBeingDragged) { // Scroll to follow the motion event final int activePointerIndex = getPointerIndex(ev, mActivePointerId); if (mActivePointerId == INVALID_POINTER) break; final float x = MotionEventCompat.getX(ev, activePointerIndex); final float deltaX = mLastMotionX - x; mLastMotionX = x; float oldScrollX = getScrollX(); float scrollX = oldScrollX + deltaX; final float leftBound = getLeftBound(); final float rightBound = getRightBound(); if (scrollX < leftBound) { scrollX = leftBound; } else if (scrollX > rightBound) { scrollX = rightBound; } // Don't lose the rounded component mLastMotionX += scrollX - (int) scrollX; scrollTo((int) scrollX, getScrollY()); pageScrolled((int) scrollX); } break; case MotionEvent.ACTION_UP: if (mIsBeingDragged) { final VelocityTracker velocityTracker = mVelocityTracker; velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); int initialVelocity = (int) VelocityTrackerCompat.getXVelocity(velocityTracker, mActivePointerId); final int scrollX = getScrollX(); // final int widthWithMargin = getWidth(); // final float pageOffset = (float) (scrollX % widthWithMargin) / widthWithMargin; // TODO test this. should get better flinging behavior final float pageOffset = (float) (scrollX - getDestScrollX(mCurItem)) / getBehindWidth(); final int activePointerIndex = getPointerIndex(ev, mActivePointerId); if (mActivePointerId != INVALID_POINTER) { final float x = MotionEventCompat.getX(ev, activePointerIndex); final int totalDelta = (int) (x - mInitialMotionX); int nextPage = determineTargetPage(pageOffset, initialVelocity, totalDelta); setCurrentItemInternal(nextPage, true, true, initialVelocity); } else { setCurrentItemInternal(mCurItem, true, true, initialVelocity); } mActivePointerId = INVALID_POINTER; endDrag(); } else if (mQuickReturn && mViewBehind.menuTouchInQuickReturn(mContent, mCurItem, ev.getX() + mScrollX)) { // close the menu setCurrentItem(1); endDrag(); } break; case MotionEvent.ACTION_CANCEL: if (mIsBeingDragged) { setCurrentItemInternal(mCurItem, true, true); mActivePointerId = INVALID_POINTER; endDrag(); } break; case MotionEventCompat.ACTION_POINTER_DOWN: { final int indexx = MotionEventCompat.getActionIndex(ev); mLastMotionX = MotionEventCompat.getX(ev, indexx); mActivePointerId = MotionEventCompat.getPointerId(ev, indexx); break; } case MotionEventCompat.ACTION_POINTER_UP: onSecondaryPointerUp(ev); int pointerIndex = getPointerIndex(ev, mActivePointerId); if (mActivePointerId == INVALID_POINTER) break; mLastMotionX = MotionEventCompat.getX(ev, pointerIndex); break; } return true; } private void determineDrag(MotionEvent ev) { final int activePointerId = mActivePointerId; final int pointerIndex = getPointerIndex(ev, activePointerId); if (activePointerId == INVALID_POINTER) return; final float x = MotionEventCompat.getX(ev, pointerIndex); final float dx = x - mLastMotionX; final float xDiff = Math.abs(dx); final float y = MotionEventCompat.getY(ev, pointerIndex); final float dy = y - mLastMotionY; final float yDiff = Math.abs(dy); if (xDiff > (isMenuOpen() ? mTouchSlop / 2 : mTouchSlop) && xDiff > yDiff && thisSlideAllowed(dx)) { startDrag(); mLastMotionX = x; mLastMotionY = y; setScrollingCacheEnabled(true); // TODO add back in touch slop check } else if (xDiff > mTouchSlop) { mIsUnableToDrag = true; } } @Override public void scrollTo(int x, int y) { super.scrollTo(x, y); mScrollX = x; mViewBehind.scrollBehindTo(mContent, x, y); ((SlidingMenu) getParent()).manageLayers(getPercentOpen()); } private int determineTargetPage(float pageOffset, int velocity, int deltaX) { int targetPage = mCurItem; if (Math.abs(deltaX) > mFlingDistance && Math.abs(velocity) > mMinimumVelocity) { if (velocity > 0 && deltaX > 0) { targetPage -= 1; } else if (velocity < 0 && deltaX < 0) { targetPage += 1; } } else { targetPage = (int) Math.round(mCurItem + pageOffset); } return targetPage; } protected float getPercentOpen() { return Math.abs(mScrollX - mContent.getLeft()) / getBehindWidth(); } @Override protected void dispatchDraw(Canvas canvas) { super.dispatchDraw(canvas); // Draw the margin drawable if needed. mViewBehind.drawShadow(mContent, canvas); mViewBehind.drawFade(mContent, canvas, getPercentOpen()); mViewBehind.drawSelector(mContent, canvas, getPercentOpen()); } // variables for drawing private float mScrollX = 0.0f; private void onSecondaryPointerUp(MotionEvent ev) { if (DEBUG) Log.v(TAG, "onSecondaryPointerUp called"); final int pointerIndex = MotionEventCompat.getActionIndex(ev); 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. final int newPointerIndex = pointerIndex == 0 ? 1 : 0; mLastMotionX = MotionEventCompat.getX(ev, newPointerIndex); mActivePointerId = MotionEventCompat.getPointerId(ev, newPointerIndex); if (mVelocityTracker != null) { mVelocityTracker.clear(); } } } private void startDrag() { mIsBeingDragged = true; mQuickReturn = false; } private void endDrag() { mQuickReturn = false; mIsBeingDragged = false; mIsUnableToDrag = false; mActivePointerId = INVALID_POINTER; if (mVelocityTracker != null) { mVelocityTracker.recycle(); mVelocityTracker = null; } } private void setScrollingCacheEnabled(boolean enabled) { if (mScrollingCacheEnabled != enabled) { mScrollingCacheEnabled = enabled; if (USE_CACHE) { final int size = getChildCount(); for (int i = 0; i < size; ++i) { final View child = getChildAt(i); if (child.getVisibility() != GONE) { child.setDrawingCacheEnabled(enabled); } } } } } /** * Tests scrollability within child views of v given a delta of dx. * * @param v View to test for horizontal scrollability * @param checkV Whether the view v passed should itself be checked for scrollability (true), * or just its children (false). * @param dx Delta scrolled in pixels * @param x X coordinate of the active touch point * @param y Y coordinate of the active touch point * @return true if child views of v can be scrolled by delta of dx. */ protected boolean canScroll(View v, boolean checkV, int dx, int x, int y) { if (v instanceof ViewGroup) { final ViewGroup group = (ViewGroup) v; final int scrollX = v.getScrollX(); final int scrollY = v.getScrollY(); final int count = group.getChildCount(); // Count backwards - let topmost views consume scroll distance first. for (int i = count - 1; i >= 0; i--) { final View child = group.getChildAt(i); if (x + scrollX >= child.getLeft() && x + scrollX < child.getRight() && y + scrollY >= child.getTop() && y + scrollY < child.getBottom() && canScroll(child, true, dx, x + scrollX - child.getLeft(), y + scrollY - child.getTop())) { return true; } } } return checkV && ViewCompat.canScrollHorizontally(v, -dx); } @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) { boolean handled = false; if (event.getAction() == KeyEvent.ACTION_DOWN) { switch (event.getKeyCode()) { case KeyEvent.KEYCODE_DPAD_LEFT: handled = arrowScroll(FOCUS_LEFT); break; case KeyEvent.KEYCODE_DPAD_RIGHT: handled = arrowScroll(FOCUS_RIGHT); break; case KeyEvent.KEYCODE_TAB: if (Build.VERSION.SDK_INT >= 11) { // The focus finder had a bug handling FOCUS_FORWARD and FOCUS_BACKWARD // before Android 3.0. Ignore the tab key on those devices. if (KeyEventCompat.hasNoModifiers(event)) { handled = arrowScroll(FOCUS_FORWARD); } else if (KeyEventCompat.hasModifiers(event, KeyEvent.META_SHIFT_ON)) { handled = arrowScroll(FOCUS_BACKWARD); } } break; } } return handled; } public boolean arrowScroll(int direction) { View currentFocused = findFocus(); if (currentFocused == this) currentFocused = null; boolean handled = false; View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); if (nextFocused != null && nextFocused != currentFocused) { if (direction == View.FOCUS_LEFT) { handled = nextFocused.requestFocus(); } else if (direction == View.FOCUS_RIGHT) { // If there is nothing to the right, or this is causing us to // jump to the left, then what we really want to do is page right. if (currentFocused != null && nextFocused.getLeft() <= currentFocused.getLeft()) { handled = pageRight(); } else { handled = nextFocused.requestFocus(); } } } else if (direction == FOCUS_LEFT || direction == FOCUS_BACKWARD) { // Trying to move left and nothing there; try to page. handled = pageLeft(); } else if (direction == FOCUS_RIGHT || direction == FOCUS_FORWARD) { // Trying to move right and nothing there; try to page. handled = pageRight(); } if (handled) { playSoundEffect(SoundEffectConstants.getContantForFocusDirection(direction)); } return handled; } boolean pageLeft() { if (mCurItem > 0) { setCurrentItem(mCurItem - 1, true); return true; } return false; } boolean pageRight() { if (mCurItem < 1) { setCurrentItem(mCurItem + 1, true); return true; } return false; } }