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package net.myegotrip.egotrip.utils; /*from w ww .ja v a 2 s . c o m*/ import java.util.List; import android.content.Context; import android.graphics.Rect; import android.util.AttributeSet; 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.animation.AnimationUtils; import android.widget.FrameLayout; import android.widget.LinearLayout; import android.widget.Scroller; import android.widget.TextView; /** * Layout container for a view hierarchy that can be scrolled by the user, * allowing it to be larger than the physical display. A TwoDScrollView is a * {@link FrameLayout}, meaning you should place one child in it containing the * entire contents to scroll; this child may itself be a layout manager with a * complex hierarchy of objects. A child that is often used is a * {@link LinearLayout} in a vertical orientation, presenting a vertical array * of top-level items that the user can scroll through. * * <p> * The {@link TextView} class also takes care of its own scrolling, so does not * require a TwoDScrollView, but using the two together is possible to achieve * the effect of a text view within a larger container. */ public class TwoDScrollView extends FrameLayout { static final int ANIMATED_SCROLL_GAP = 250; static final float MAX_SCROLL_FACTOR = 0.5f; private long mLastScroll; private final Rect mTempRect = new Rect(); private Scroller mScroller; /** * Flag to indicate that we are moving focus ourselves. This is so the code * that watches for focus changes initiated outside this TwoDScrollView * knows that it does not have to do anything. */ private boolean mTwoDScrollViewMovedFocus; /** * Position of the last motion event. */ private float mLastMotionY; private float mLastMotionX; /** * 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; /** * 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 TwoDScrollView 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; /** * Whether arrow scrolling is animated. */ private int mTouchSlop; private int mMinimumVelocity; private int mMaximumVelocity; public TwoDScrollView(Context context) { super(context); initTwoDScrollView(); } public TwoDScrollView(Context context, AttributeSet attrs) { super(context, attrs); initTwoDScrollView(); } public TwoDScrollView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); initTwoDScrollView(); } @Override protected float getTopFadingEdgeStrength() { if (getChildCount() == 0) { return 0.0f; } final int length = getVerticalFadingEdgeLength(); if (getScrollY() < length) { return getScrollY() / (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; } @Override protected float getLeftFadingEdgeStrength() { if (getChildCount() == 0) { return 0.0f; } final int length = getHorizontalFadingEdgeLength(); if (getScrollX() < length) { return getScrollX() / (float) length; } return 1.0f; } @Override protected float getRightFadingEdgeStrength() { if (getChildCount() == 0) { return 0.0f; } final int length = getHorizontalFadingEdgeLength(); final int rightEdge = getWidth() - getPaddingRight(); final int span = getChildAt(0).getRight() - getScrollX() - rightEdge; 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 getMaxScrollAmountVertical() { return (int) (MAX_SCROLL_FACTOR * getHeight()); } public int getMaxScrollAmountHorizontal() { return (int) (MAX_SCROLL_FACTOR * getWidth()); } private void initTwoDScrollView() { mScroller = new Scroller(getContext()); 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("TwoDScrollView can host only one direct child"); } super.addView(child); } @Override public void addView(View child, int index) { if (getChildCount() > 0) { throw new IllegalStateException("TwoDScrollView 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("TwoDScrollView 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("TwoDScrollView can host only one direct child"); } super.addView(child, index, params); } /** * @return Returns true this TwoDScrollView can be scrolled */ private boolean canScroll() { View child = getChildAt(0); if (child != null) { int childHeight = child.getHeight(); int childWidth = child.getWidth(); return (getHeight() < childHeight + getPaddingTop() + getPaddingBottom()) || (getWidth() < childWidth + getPaddingLeft() + getPaddingRight()); } return false; } @Override public boolean dispatchKeyEvent(KeyEvent event) { // Let the focused view and/or our descendants get the key first boolean handled = super.dispatchKeyEvent(event); if (handled) { return true; } return 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()) { 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, false); } else { handled = fullScroll(View.FOCUS_UP, false); } break; case KeyEvent.KEYCODE_DPAD_DOWN: if (!event.isAltPressed()) { handled = arrowScroll(View.FOCUS_DOWN, false); } else { handled = fullScroll(View.FOCUS_DOWN, false); } break; case KeyEvent.KEYCODE_DPAD_LEFT: if (!event.isAltPressed()) { handled = arrowScroll(View.FOCUS_LEFT, true); } else { handled = fullScroll(View.FOCUS_LEFT, true); } break; case KeyEvent.KEYCODE_DPAD_RIGHT: if (!event.isAltPressed()) { handled = arrowScroll(View.FOCUS_RIGHT, true); } else { handled = fullScroll(View.FOCUS_RIGHT, true); } break; } } return handled; } @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; } if (!canScroll()) { mIsBeingDragged = false; return false; } final float y = ev.getY(); final float x = ev.getX(); switch (action) { 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 yDiff = (int) Math.abs(y - mLastMotionY); final int xDiff = (int) Math.abs(x - mLastMotionX); if (yDiff > mTouchSlop || xDiff > mTouchSlop) { mIsBeingDragged = true; } break; case MotionEvent.ACTION_DOWN: /* Remember location of down touch */ mLastMotionY = y; mLastMotionX = x; /* * If being flinged and user touches the screen, initiate drag; * otherwise don't. mScroller.isFinished should be false when being * flinged. */ mIsBeingDragged = !mScroller.isFinished(); break; case MotionEvent.ACTION_CANCEL: case MotionEvent.ACTION_UP: /* Release the drag */ mIsBeingDragged = false; 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) { if (ev.getAction() == MotionEvent.ACTION_DOWN && ev.getEdgeFlags() != 0) { // Don't handle edge touches immediately -- they may actually belong // to one of our // descendants. return false; } if (!canScroll()) { return false; } if (mVelocityTracker == null) { mVelocityTracker = VelocityTracker.obtain(); } mVelocityTracker.addMovement(ev); final int action = ev.getAction(); final float y = ev.getY(); final float x = ev.getX(); switch (action) { 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 mLastMotionY = y; mLastMotionX = x; break; case MotionEvent.ACTION_MOVE: // Scroll to follow the motion event int deltaX = (int) (mLastMotionX - x); int deltaY = (int) (mLastMotionY - y); mLastMotionX = x; mLastMotionY = y; if (deltaX < 0) { if (getScrollX() < 0) { deltaX = 0; } } else if (deltaX > 0) { final int rightEdge = getWidth() - getPaddingRight(); final int availableToScroll = getChildAt(0).getRight() - getScrollX() - rightEdge; if (availableToScroll > 0) { deltaX = Math.min(availableToScroll, deltaX); } else { deltaX = 0; } } if (deltaY < 0) { if (getScrollY() < 0) { deltaY = 0; } } else if (deltaY > 0) { final int bottomEdge = getHeight() - getPaddingBottom(); final int availableToScroll = getChildAt(0).getBottom() - getScrollY() - bottomEdge; if (availableToScroll > 0) { deltaY = Math.min(availableToScroll, deltaY); } else { deltaY = 0; } } if (deltaY != 0 || deltaX != 0) scrollBy(deltaX, deltaY); break; case MotionEvent.ACTION_UP: final VelocityTracker velocityTracker = mVelocityTracker; velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); int initialXVelocity = (int) velocityTracker.getXVelocity(); int initialYVelocity = (int) velocityTracker.getYVelocity(); if ((Math.abs(initialXVelocity) + Math.abs(initialYVelocity) > mMinimumVelocity) && getChildCount() > 0) { fling(-initialXVelocity, -initialYVelocity); } if (mVelocityTracker != null) { mVelocityTracker.recycle(); mVelocityTracker = null; } } return true; } /** * Finds the next focusable component that fits in this View's bounds * (excluding fading edges) pretending that this View's top is located at * the parameter top. * * @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 (the fading edge is assumed to start at this position) * @param preferredFocusable * the View that has highest priority and will be returned if it * is within my bounds (null is valid) * @return the next focusable component in the bounds or null if none can be * found */ private View findFocusableViewInMyBounds(final boolean topFocus, final int top, final boolean leftFocus, final int left, View preferredFocusable) { /* * The fading edge's transparent side should be considered for focus * since it's mostly visible, so we divide the actual fading edge length * by 2. */ final int verticalFadingEdgeLength = getVerticalFadingEdgeLength() / 2; final int topWithoutFadingEdge = top + verticalFadingEdgeLength; final int bottomWithoutFadingEdge = top + getHeight() - verticalFadingEdgeLength; final int horizontalFadingEdgeLength = getHorizontalFadingEdgeLength() / 2; final int leftWithoutFadingEdge = left + horizontalFadingEdgeLength; final int rightWithoutFadingEdge = left + getWidth() - horizontalFadingEdgeLength; if ((preferredFocusable != null) && (preferredFocusable.getTop() < bottomWithoutFadingEdge) && (preferredFocusable.getBottom() > topWithoutFadingEdge) && (preferredFocusable.getLeft() < rightWithoutFadingEdge) && (preferredFocusable.getRight() > leftWithoutFadingEdge)) { return preferredFocusable; } return findFocusableViewInBounds(topFocus, topWithoutFadingEdge, bottomWithoutFadingEdge, leftFocus, leftWithoutFadingEdge, rightWithoutFadingEdge); } /** * 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, boolean leftFocus, int left, int right) { 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(); int viewLeft = view.getLeft(); int viewRight = view.getRight(); if (top < viewBottom && viewTop < bottom && left < viewRight && viewLeft < right) { /* * the focusable is in the target area, it is a candidate for * focusing */ final boolean viewIsFullyContained = (top < viewTop) && (viewBottom < bottom) && (left < viewLeft) && (viewRight < right); if (focusCandidate == null) { /* No candidate, take this one */ focusCandidate = view; foundFullyContainedFocusable = viewIsFullyContained; } else { final boolean viewIsCloserToVerticalBoundary = (topFocus && viewTop < focusCandidate.getTop()) || (!topFocus && viewBottom > focusCandidate.getBottom()); final boolean viewIsCloserToHorizontalBoundary = (leftFocus && viewLeft < focusCandidate.getLeft()) || (!leftFocus && viewRight > focusCandidate.getRight()); if (foundFullyContainedFocusable) { if (viewIsFullyContained && viewIsCloserToVerticalBoundary && viewIsCloserToHorizontalBoundary) { /* * 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 (viewIsCloserToVerticalBoundary && viewIsCloserToHorizontalBoundary) { /* * Partially contained view beats another partially * contained view if it's closer */ focusCandidate = view; } } } } } return focusCandidate; } /** * <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 android.view.View#FOCUS_UP} to go * the top of the view or {@link android.view.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 horizontal) { if (!horizontal) { 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(); mTempRect.top = mTempRect.bottom - height; } } return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom, 0, 0, 0); } else { boolean right = direction == View.FOCUS_DOWN; int width = getWidth(); mTempRect.left = 0; mTempRect.right = width; if (right) { int count = getChildCount(); if (count > 0) { View view = getChildAt(count - 1); mTempRect.right = view.getBottom(); mTempRect.left = mTempRect.right - width; } } return scrollAndFocus(0, 0, 0, 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 android.view.View#FOCUS_UP} to go * upward {@link android.view.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 directionY, int top, int bottom, int directionX, int left, int right) { boolean handled = true; int height = getHeight(); int containerTop = getScrollY(); int containerBottom = containerTop + height; boolean up = directionY == View.FOCUS_UP; int width = getWidth(); int containerLeft = getScrollX(); int containerRight = containerLeft + width; boolean leftwards = directionX == View.FOCUS_UP; View newFocused = findFocusableViewInBounds(up, top, bottom, leftwards, left, right); if (newFocused == null) { newFocused = this; } if ((top >= containerTop && bottom <= containerBottom) || (left >= containerLeft && right <= containerRight)) { handled = false; } else { int deltaY = up ? (top - containerTop) : (bottom - containerBottom); int deltaX = leftwards ? (left - containerLeft) : (right - containerRight); doScroll(deltaX, deltaY); } if (newFocused != findFocus() && newFocused.requestFocus(directionY)) { mTwoDScrollViewMovedFocus = true; mTwoDScrollViewMovedFocus = false; } 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, boolean horizontal) { View currentFocused = findFocus(); if (currentFocused == this) currentFocused = null; View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); final int maxJump = horizontal ? getMaxScrollAmountHorizontal() : getMaxScrollAmountVertical(); if (!horizontal) { if (nextFocused != null) { nextFocused.getDrawingRect(mTempRect); offsetDescendantRectToMyCoords(nextFocused, mTempRect); int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); doScroll(0, 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(); if (daBottom - screenBottom < maxJump) { scrollDelta = daBottom - screenBottom; } } } if (scrollDelta == 0) { return false; } doScroll(0, direction == View.FOCUS_DOWN ? scrollDelta : -scrollDelta); } } else { if (nextFocused != null) { nextFocused.getDrawingRect(mTempRect); offsetDescendantRectToMyCoords(nextFocused, mTempRect); int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); doScroll(scrollDelta, 0); 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(); if (daBottom - screenBottom < maxJump) { scrollDelta = daBottom - screenBottom; } } } if (scrollDelta == 0) { return false; } doScroll(direction == View.FOCUS_DOWN ? scrollDelta : -scrollDelta, 0); } } return true; } /** * Smooth scroll by a Y delta * * @param delta * the number of pixels to scroll by on the Y axis */ private void doScroll(int deltaX, int deltaY) { if (deltaX != 0 || deltaY != 0) { smoothScrollBy(deltaX, deltaY); } } /** * 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) { long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; if (duration > ANIMATED_SCROLL_GAP) { mScroller.startScroll(getScrollX(), getScrollY(), dx, dy); awakenScrollBars(mScroller.getDuration()); invalidate(); } 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> */ @Override protected int computeVerticalScrollRange() { int count = getChildCount(); return count == 0 ? getHeight() : (getChildAt(0)).getBottom(); } @Override protected int computeHorizontalScrollRange() { int count = getChildCount(); return count == 0 ? getWidth() : (getChildAt(0)).getRight(); } @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()) { // This is called at drawing time by ViewGroup. We don't want to // re-show the scrollbars at this point, which scrollTo will do, // so we replicate most of scrollTo here. // // It's a little odd to call onScrollChanged from inside the // drawing. // // It is, except when you remember that computeScroll() is used to // animate scrolling. So unless we want to defer the // onScrollChanged() // until the end of the animated scrolling, we don't really have a // choice here. // // I agree. The alternative, which I think would be worse, is to // post // something and tell the subclasses later. This is bad because // there // will be a window where mScrollX/Y is different from what the app // thinks it is. // int oldX = getScrollX(); int oldY = getScrollY(); int x = mScroller.getCurrX(); int y = mScroller.getCurrY(); if (getChildCount() > 0) { View child = getChildAt(0); scrollTo(clamp(x, getWidth() - getPaddingRight() - getPaddingLeft(), child.getWidth()), clamp(y, getHeight() - getPaddingBottom() - getPaddingTop(), child.getHeight())); } else { scrollTo(x, y); } if (oldX != getScrollX() || oldY != getScrollY()) { onScrollChanged(getScrollX(), getScrollY(), oldX, oldY); } // Keep on drawing until the animation has finished. postInvalidate(); } } /** * 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 TwoDScrollView 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 (!mTwoDScrollViewMovedFocus) { 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. * * This is more expensive than the default {@link android.view.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; } 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; // Calling this with the present values causes it to re-clam them scrollTo(getScrollX(), getScrollY()); } @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. currentFocused.getDrawingRect(mTempRect); offsetDescendantRectToMyCoords(currentFocused, mTempRect); int scrollDeltaX = computeScrollDeltaToGetChildRectOnScreen(mTempRect); int scrollDeltaY = computeScrollDeltaToGetChildRectOnScreen(mTempRect); doScroll(scrollDeltaX, scrollDeltaY); } /** * Return true if child is an descendant of parent, (or equal to the * parent). */ private 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/curor is moving down the screen, which means * we want to scroll towards the top. */ public void fling(int velocityX, int velocityY) { if (getChildCount() > 0) { int height = getHeight() - getPaddingBottom() - getPaddingTop(); int bottom = getChildAt(0).getHeight(); int width = getWidth() - getPaddingRight() - getPaddingLeft(); int right = getChildAt(0).getWidth(); mScroller.fling(getScrollX(), getScrollY(), velocityX, velocityY, 0, right - width, 0, bottom - height); final boolean movingDown = velocityY > 0; final boolean movingRight = velocityX > 0; View newFocused = findFocusableViewInMyBounds(movingRight, mScroller.getFinalX(), movingDown, mScroller.getFinalY(), findFocus()); if (newFocused == null) { newFocused = this; } if (newFocused != findFocus() && newFocused.requestFocus(movingDown ? View.FOCUS_DOWN : View.FOCUS_UP)) { mTwoDScrollViewMovedFocus = true; mTwoDScrollViewMovedFocus = false; } awakenScrollBars(mScroller.getDuration()); invalidate(); } } /** * {@inheritDoc} * * <p> * This version also clamps the scrolling to the bounds of our child. */ 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 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; } }