Android ScrollView HorizontalScrollView 实现全方向(上下左右)反弹效果

自定义控件View :

/**
 * 类功能描述:
 * 具有弹性效果的全方向ScrollView,参考ScrollView与HorizontalScrollView源码
 * 
 */
public class HorizontalScrollView 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 ScrollView
     * knows that it does not have to do anything.
     */
    private boolean mScrollViewMovedFocus;

    /**
     * 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 ScrollView around. This is
     * not the same as 'is being flinged', which can be checked by
     * mScroller.isFinished() (flinging begins when the user lifts his finger).
     */
    private boolean mIsBeingDragged = false;

    /**
     * Determines speed during touch scrolling
     */
    private VelocityTracker mVelocityTracker;

    /**
     * When set to true, the scroll view measure its child to make it fill the currently
     * visible area.
     */
    private boolean mFillViewport;

    /**
     * Whether arrow scrolling is animated.
     */
    private boolean mSmoothScrollingEnabled = true;

    private int mTouchSlop;
    private int mMinimumVelocity;
    private int mMaximumVelocity;

    /**
     * ID of the active pointer. This is used to retain consistency during
     * drags/flings if multiple pointers are used.
     */
    private int mActivePointerId = INVALID_POINTER;

    /**
     * Sentinel value for no current active pointer.
     * Used by {@link #mActivePointerId}.
     */
    private static final int INVALID_POINTER = -1;

    private boolean mFlingEnabled = true;

    public HorizontalScrollView(Context context) {
        this(context, null);
    }

    public HorizontalScrollView(Context context, AttributeSet attrs) {
        super(context, attrs);
        initScrollView();
    }

    @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 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;
    }

    @Override
    protected float getBottomFadingEdgeStrength() {
        if (getChildCount() == 0) {
            return 0.0f;
        }

        final int length = getVerticalFadingEdgeLength();
        final int bottomEdge = getHeight() - getPaddingBottom();
        final int span = getChildAt(0).getBottom() - getScrollY() - bottomEdge;
        if (span < length) {
            return span / (float)length;
        }

        return 1.0f;
    }

    /**
     * @return The maximum amount this scroll view will scroll in response to
     *   an arrow event.
     */
    public int getMaxScrollAmountV() {
        return (int)(MAX_SCROLL_FACTOR * (getBottom() - getTop()));
    }

    public int getMaxScrollAmountH() {
        return (int)(MAX_SCROLL_FACTOR * (getRight() - getLeft()));
    }

    private void initScrollView() {
        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("ScrollView can host only one direct child");
        }

        super.addView(child);
    }

    @Override
    public void addView(View child, int index) {
        if (getChildCount() > 0) {
            throw new IllegalStateException("ScrollView can host only one direct child");
        }

        super.addView(child, index);
    }

    @Override
    public void addView(View child, ViewGroup.LayoutParams params) {
        if (getChildCount() > 0) {
            throw new IllegalStateException("ScrollView can host only one direct child");
        }

        super.addView(child, params);
    }

    @Override
    public void addView(View child, int index, ViewGroup.LayoutParams params) {
        if (getChildCount() > 0) {
            throw new IllegalStateException("ScrollView can host only one direct child");
        }

        super.addView(child, index, params);
    }

    /**
     * @return Returns true this ScrollView can be scrolled
     */
    private boolean canScrollV() {
        View child = getChildAt(0);
        if (child != null) {
            int childHeight = child.getHeight();
            return getHeight() < childHeight + getPaddingTop() + getPaddingBottom();
        }
        return false;
    }

    private boolean canScrollH() {
        View child = getChildAt(0);
        if (child != null) {
            int childWidth = child.getWidth();
            return getWidth() < childWidth + getPaddingLeft() + getPaddingRight();
        }
        return false;
    }

    /**
     * Indicates whether this ScrollView's content is stretched to fill the viewport.
     *
     * @return True if the content fills the viewport, false otherwise.
     */
    public boolean isFillViewport() {
        return mFillViewport;
    }

    /**
     * Indicates this ScrollView whether it should stretch its content height to fill
     * the viewport or not.
     *
     * @param fillViewport True to stretch the content's height to the viewport's
     *        boundaries, false otherwise.
     */
    public void setFillViewport(boolean fillViewport) {
        if (fillViewport != mFillViewport) {
            mFillViewport = fillViewport;
            requestLayout();
        }
    }

    /**
     * @return Whether arrow scrolling will animate its transition.
     */
    public boolean isSmoothScrollingEnabled() {
        return mSmoothScrollingEnabled;
    }

    /**
     * Set whether arrow scrolling will animate its transition.
     * @param smoothScrollingEnabled whether arrow scrolling will animate its transition
     */
    public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) {
        mSmoothScrollingEnabled = smoothScrollingEnabled;
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);

        if (!mFillViewport) {
            return;
        }

        final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
        final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
        if (heightMode == MeasureSpec.UNSPECIFIED && widthMode == MeasureSpec.UNSPECIFIED) {
            return;
        }

        if (getChildCount() > 0) {
            final View child = getChildAt(0);
            int height = getMeasuredHeight();
            int width = getMeasuredWidth();
            if (child.getMeasuredHeight() < height || child.getMeasuredWidth() < width) {
                width -= getPaddingLeft();
                width -= getPaddingRight();
                int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY);

                height -= getPaddingTop();
                height -= getPaddingBottom();
                int childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(height,
                        MeasureSpec.EXACTLY);

                child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
            }
        }
    }

    @Override
    public boolean dispatchKeyEvent(KeyEvent event) {
        // Let the focused view and/or our descendants get the key first
        return super.dispatchKeyEvent(event) || executeKeyEvent(event);
    }

    /**
     * You can call this function yourself to have the scroll view perform
     * scrolling from a key event, just as if the event had been dispatched to
     * it by the view hierarchy.
     *
     * @param event The key event to execute.
     * @return Return true if the event was handled, else false.
     */
    public boolean executeKeyEvent(KeyEvent event) {
        mTempRect.setEmpty();

        boolean handled = false;

        if (event.getAction() == KeyEvent.ACTION_DOWN) {
            switch (event.getKeyCode()) {
                case KeyEvent.KEYCODE_DPAD_LEFT:
                    if (canScrollH()) {
                        if (!event.isAltPressed()) {
                            handled = arrowScrollH(View.FOCUS_LEFT);
                        } else {
                            handled = fullScrollH(View.FOCUS_LEFT);
                        }
                    }
                    break;
                case KeyEvent.KEYCODE_DPAD_RIGHT:
                    if (canScrollH()) {
                        if (!event.isAltPressed()) {
                            handled = arrowScrollH(View.FOCUS_RIGHT);
                        } else {
                            handled = fullScrollH(View.FOCUS_RIGHT);
                        }
                    }
                    break;
                case KeyEvent.KEYCODE_DPAD_UP:
                    if (canScrollV()) {
                        if (!event.isAltPressed()) {
                            handled = arrowScrollV(View.FOCUS_UP);
                        } else {
                            handled = fullScrollV(View.FOCUS_UP);
                        }
                    }
                    break;
                case KeyEvent.KEYCODE_DPAD_DOWN:
                    if (canScrollV()) {
                        if (!event.isAltPressed()) {
                            handled = arrowScrollV(View.FOCUS_DOWN);
                        } else {
                            handled = fullScrollV(View.FOCUS_DOWN);
                        }
                    }
                    break;
            }
        }
        return handled;
    }

    private boolean inChild(int x, int y) {
        if (getChildCount() > 0) {
            final int scrollX = getScrollX();
            final int scrollY = getScrollY();
            final View child = getChildAt(0);
            return !(y < child.getTop() - scrollY || y >= child.getBottom() - scrollY
                    || x < child.getLeft() - scrollX || x >= child.getRight() - scrollX);
        }
        return false;
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        /*
         * This method JUST determines whether we want to intercept the motion.
         * If we return true, onMotionEvent will be called and we do the actual
         * scrolling there.
         */

        /*
         * Shortcut the most recurring case: the user is in the dragging state
         * and he is moving his finger. We want to intercept this motion.
         */
        final int action = ev.getAction();
        if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) {
            return true;
        }

        switch (action & 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.
                 */

                /*
                 * Locally do absolute value. mLastMotionY is set to the y value
                 * of the down event.
                 */
                final int activePointerId = mActivePointerId;
                if (activePointerId == INVALID_POINTER) {
                    // If we don't have a valid id, the touch down wasn't on
                    // content.
                    break;
                }

                final int pointerIndex = ev.findPointerIndex(activePointerId);
                final float y = ev.getY(pointerIndex);
                final int yDiff = (int)Math.abs(y - mLastMotionY);
                if (yDiff > mTouchSlop) {
                    mIsBeingDragged = true;
                    mLastMotionY = y;
                }
                final float x = ev.getX(pointerIndex);
                final int xDiff = (int)Math.abs(x - mLastMotionX);
                if (xDiff > mTouchSlop) {
                    mIsBeingDragged = true;
                    mLastMotionX = x;
                }
                break;
            }

            case MotionEvent.ACTION_DOWN: {
                final float x = ev.getX();
                final float y = ev.getY();
                if (!inChild((int)x, (int)y)) {
                    mIsBeingDragged = false;
                    break;
                }

                /*
                 * Remember location of down touch. ACTION_DOWN always refers to
                 * pointer index 0.
                 */
                mLastMotionY = y;
                mLastMotionX = x;
                mActivePointerId = ev.getPointerId(0);

                /*
                 * 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;
                mActivePointerId = INVALID_POINTER;
                break;
            case MotionEvent.ACTION_POINTER_UP:
                onSecondaryPointerUp(ev);
                break;
        }

        /*
         * The only time we want to intercept motion events is if we are in the
         * drag mode.
         */
        return mIsBeingDragged;
    }

    private boolean scrollableOutsideTouch = false;

    /**
     * 设置scroller是否可以滑动内容当触屏事件在chileview之外 default:false
     * @param b true-可以,false-不可
     */
    public void setScrollableOutsideChile(boolean b) {
        scrollableOutsideTouch = b;
    }

    private boolean flexible = true;

    /**
     * 设置是否可有弹性效果
     * @param b true-可以,false-不可
     */
    public void setFlexible(boolean b) {
        flexible = b;
    }

    private long lastEvenTime;

    @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 (mVelocityTracker == null) {
            mVelocityTracker = VelocityTracker.obtain();
        }
        mVelocityTracker.addMovement(ev);

        final int action = ev.getAction();

        switch (action & MotionEvent.ACTION_MASK) {
            case MotionEvent.ACTION_DOWN: {
                final float x = ev.getX();
                final float y = ev.getY();
                if (!(mIsBeingDragged = inChild((int)x, (int)y)) && !scrollableOutsideTouch) {
                    return false;
                }
                // 阻止测试人员暴力测试
                if (System.currentTimeMillis() - lastEvenTime < 200) {
                    ev.setAction(MotionEvent.ACTION_CANCEL);
                }
                lastEvenTime = System.currentTimeMillis();
                /*
                 * 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;
                mActivePointerId = ev.getPointerId(0);
                break;
            }
            case MotionEvent.ACTION_MOVE:
                if (mIsBeingDragged || scrollableOutsideTouch) {
                    // Scroll to follow the motion event
                    final int activePointerIndex = ev.findPointerIndex(mActivePointerId);
                    final float y = ev.getY(activePointerIndex);
                    final int deltaY = (int)(mLastMotionY - y);
                    mLastMotionY = y;

                    final float x = ev.getX(activePointerIndex);
                    final int deltaX = (int)(mLastMotionX - x);
                    mLastMotionX = x;
                    // 全方向滚动
                    scrollBy(deltaX, deltaY);
                    // 当滚动到边界时就不会再滚动,这时移动布局
                    if (isNeedMove() && flexible) {
                        if (normal.isEmpty()) {
                            // 保存正常的布局属性
                            normal.set(inner.getLeft(), inner.getTop(), inner.getRight(),
                                    inner.getBottom());
                        }
                        // 移动布局
                        inner.layout(inner.getLeft() - deltaX / 2, inner.getTop() - deltaY / 2,
                                inner.getRight() - deltaX / 2, inner.getBottom() - deltaY / 2);
                    }
                }
                break;
            case MotionEvent.ACTION_UP:
                if (mIsBeingDragged || scrollableOutsideTouch) {
                    if (mFlingEnabled) {
                        final VelocityTracker velocityTracker = mVelocityTracker;
                        velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);
                        int initialVelocitx = (int)velocityTracker.getXVelocity(mActivePointerId);
                        int initialVelocity = (int)velocityTracker.getYVelocity(mActivePointerId);

                        if (getChildCount() > 0) {
                            if (Math.abs(initialVelocitx) > initialVelocitx
                                    || Math.abs(initialVelocity) > mMinimumVelocity) {
                                fling(-initialVelocitx, -initialVelocity);
                            }

                        }
                    }
                    if (isNeedAnimation()) {
                        animation();
                    }
                    mActivePointerId = INVALID_POINTER;
                    mIsBeingDragged = false;

                    if (mVelocityTracker != null) {
                        mVelocityTracker.recycle();
                        mVelocityTracker = null;
                    }
                }
                break;
            case MotionEvent.ACTION_CANCEL:
                if (mIsBeingDragged && getChildCount() > 0) {
                    mActivePointerId = INVALID_POINTER;
                    mIsBeingDragged = false;
                    if (mVelocityTracker != null) {
                        mVelocityTracker.recycle();
                        mVelocityTracker = null;
                    }
                }
                break;
            case MotionEvent.ACTION_POINTER_UP:
                onSecondaryPointerUp(ev);
                break;
        }
        return true;
    }

    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.
            final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
            mLastMotionX = ev.getX(newPointerIndex);
            mLastMotionY = ev.getY(newPointerIndex);
            mActivePointerId = ev.getPointerId(newPointerIndex);
            if (mVelocityTracker != null) {
                mVelocityTracker.clear();
            }
        }
    }

    /**
     * 

* Finds the next focusable component that fits in the specified bounds. *

* * @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 findFocusableViewInBoundsV(boolean topFocus, int top, int bottom) { List focusables = getFocusables(View.FOCUS_FORWARD); View focusCandidate = null; /* * A fully contained focusable is one where its top is below the bound's * top, and its bottom is above the bound's bottom. A partially * contained focusable is one where some part of it is within the * bounds, but it also has some part that is not within bounds. A fully * contained focusable is preferred to a partially contained focusable. */ boolean foundFullyContainedFocusable = false; int count = focusables.size(); for (int i = 0; i < count; i++) { View view = focusables.get(i); int viewTop = view.getTop(); int viewBottom = view.getBottom(); if (top < viewBottom && viewTop < bottom) { /* * the focusable is in the target area, it is a candidate for * focusing */ final boolean viewIsFullyContained = (top < viewTop) && (viewBottom < bottom); if (focusCandidate == null) { /* No candidate, take this one */ focusCandidate = view; foundFullyContainedFocusable = viewIsFullyContained; } else { final boolean viewIsCloserToBoundary = (topFocus && viewTop < focusCandidate .getTop()) || (!topFocus && viewBottom > focusCandidate.getBottom()); if (foundFullyContainedFocusable) { if (viewIsFullyContained && viewIsCloserToBoundary) { /* * We're dealing with only fully contained views, so * it has to be closer to the boundary to beat our * candidate */ focusCandidate = view; } } else { if (viewIsFullyContained) { /* * Any fully contained view beats a partially * contained view */ focusCandidate = view; foundFullyContainedFocusable = true; } else if (viewIsCloserToBoundary) { /* * Partially contained view beats another partially * contained view if it's closer */ focusCandidate = view; } } } } } return focusCandidate; } private View findFocusableViewInBoundsH(boolean leftFocus, int left, int right) { List focusables = getFocusables(View.FOCUS_FORWARD); View focusCandidate = null; /* * A fully contained focusable is one where its left is below the * bound's left, and its right is above the bound's right. 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 viewLeft = view.getLeft(); int viewRight = view.getRight(); if (left < viewRight && viewLeft < right) { /* * the focusable is in the target area, it is a candidate for * focusing */ final boolean viewIsFullyContained = (left < viewLeft) && (viewRight < right); if (focusCandidate == null) { /* No candidate, take this one */ focusCandidate = view; foundFullyContainedFocusable = viewIsFullyContained; } else { final boolean viewIsCloserToBoundary = (leftFocus && viewLeft < focusCandidate .getLeft()) || (!leftFocus && viewRight > focusCandidate.getRight()); if (foundFullyContainedFocusable) { if (viewIsFullyContained && viewIsCloserToBoundary) { /* * We're dealing with only fully contained views, so * it has to be closer to the boundary to beat our * candidate */ focusCandidate = view; } } else { if (viewIsFullyContained) { /* * Any fully contained view beats a partially * contained view */ focusCandidate = view; foundFullyContainedFocusable = true; } else if (viewIsCloserToBoundary) { /* * Partially contained view beats another partially * contained view if it's closer */ focusCandidate = view; } } } } } return focusCandidate; } /** *

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.

* * @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 fullScrollV(int direction) { boolean down = direction == View.FOCUS_DOWN; int height = getHeight(); mTempRect.top = 0; mTempRect.bottom = height; if (down) { int count = getChildCount(); if (count > 0) { View view = getChildAt(count - 1); mTempRect.bottom = view.getBottom(); mTempRect.top = mTempRect.bottom - height; } } return scrollAndFocusV(direction, mTempRect.top, mTempRect.bottom); } public boolean fullScrollH(int direction) { boolean right = direction == View.FOCUS_RIGHT; int width = getWidth(); mTempRect.left = 0; mTempRect.right = width; if (right) { int count = getChildCount(); if (count > 0) { View view = getChildAt(0); mTempRect.right = view.getRight(); mTempRect.left = mTempRect.right - width; } } return scrollAndFocusH(direction, mTempRect.left, mTempRect.right); } /** *

Scrolls the view to make the area defined by top and * bottom 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.

* * @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 scrollAndFocusV(int direction, int top, int bottom) { boolean handled = true; int height = getHeight(); int containerTop = getScrollY(); int containerBottom = containerTop + height; boolean up = direction == View.FOCUS_UP; View newFocused = findFocusableViewInBoundsV(up, top, bottom); if (newFocused == null) { newFocused = this; } if (top >= containerTop && bottom <= containerBottom) { handled = false; } else { int delta = up ? (top - containerTop) : (bottom - containerBottom); doScrollY(delta); } if (newFocused != findFocus() && newFocused.requestFocus(direction)) { mScrollViewMovedFocus = true; mScrollViewMovedFocus = false; } return handled; } private boolean scrollAndFocusH(int direction, int left, int right) { boolean handled = true; int width = getWidth(); int containerLeft = getScrollX(); int containerRight = containerLeft + width; boolean goLeft = direction == View.FOCUS_LEFT; View newFocused = findFocusableViewInBoundsH(goLeft, left, right); if (newFocused == null) { newFocused = this; } if (left >= containerLeft && right <= containerRight) { handled = false; } else { int delta = goLeft ? (left - containerLeft) : (right - containerRight); doScrollX(delta); } if (newFocused != findFocus() && newFocused.requestFocus(direction)) { mScrollViewMovedFocus = true; mScrollViewMovedFocus = 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 arrowScrollV(int direction) { View currentFocused = findFocus(); if (currentFocused == this) currentFocused = null; View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); final int maxJump = getMaxScrollAmountV(); if (nextFocused != null && isWithinDeltaOfScreenV(nextFocused, maxJump, getHeight())) { nextFocused.getDrawingRect(mTempRect); offsetDescendantRectToMyCoords(nextFocused, mTempRect); int scrollDelta = computeScrollDeltaToGetChildRectOnScreenV(mTempRect); doScrollY(scrollDelta); nextFocused.requestFocus(direction); } else { // no new focus int scrollDelta = maxJump; if (direction == View.FOCUS_UP && getScrollY() < scrollDelta) { scrollDelta = getScrollY(); } else if (direction == View.FOCUS_DOWN) { if (getChildCount() > 0) { int daBottom = getChildAt(0).getBottom(); int screenBottom = getScrollY() + getHeight(); if (daBottom - screenBottom < maxJump) { scrollDelta = daBottom - screenBottom; } } } if (scrollDelta == 0) { return false; } doScrollY(direction == View.FOCUS_DOWN ? scrollDelta : -scrollDelta); } if (currentFocused != null && currentFocused.isFocused() && isOffScreenV(currentFocused)) { // previously focused item still has focus and is off screen, give // it up (take it back to ourselves) // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we // are sure to get it) final int descendantFocusability = getDescendantFocusability(); // save setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); requestFocus(); setDescendantFocusability(descendantFocusability); // restore } return true; } public boolean arrowScrollH(int direction) { View currentFocused = findFocus(); if (currentFocused == this) currentFocused = null; View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); final int maxJump = getMaxScrollAmountH(); if (nextFocused != null && isWithinDeltaOfScreenH(nextFocused, maxJump)) { nextFocused.getDrawingRect(mTempRect); offsetDescendantRectToMyCoords(nextFocused, mTempRect); int scrollDelta = computeScrollDeltaToGetChildRectOnScreenH(mTempRect); doScrollX(scrollDelta); nextFocused.requestFocus(direction); } else { // no new focus int scrollDelta = maxJump; if (direction == View.FOCUS_LEFT && getScrollX() < scrollDelta) { scrollDelta = getScrollX(); } else if (direction == View.FOCUS_RIGHT && getChildCount() > 0) { int daRight = getChildAt(0).getRight(); int screenRight = getScrollX() + getWidth(); if (daRight - screenRight < maxJump) { scrollDelta = daRight - screenRight; } } if (scrollDelta == 0) { return false; } doScrollX(direction == View.FOCUS_RIGHT ? scrollDelta : -scrollDelta); } if (currentFocused != null && currentFocused.isFocused() && isOffScreenH(currentFocused)) { // previously focused item still has focus and is off screen, give // it up (take it back to ourselves) // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we // are sure to get it) final int descendantFocusability = getDescendantFocusability(); // save setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); requestFocus(); setDescendantFocusability(descendantFocusability); // restore } return true; } /** * @return whether the descendant of this scroll view is scrolled off * screen. */ private boolean isOffScreenV(View descendant) { return !isWithinDeltaOfScreenV(descendant, 0, getHeight()); } private boolean isOffScreenH(View descendant) { return !isWithinDeltaOfScreenH(descendant, 0); } /** * @return whether the descendant of this scroll view is within delta * pixels of being on the screen. */ private boolean isWithinDeltaOfScreenV(View descendant, int delta, int height) { descendant.getDrawingRect(mTempRect); offsetDescendantRectToMyCoords(descendant, mTempRect); return (mTempRect.bottom + delta) >= getScrollY() && (mTempRect.top - delta) <= (getScrollY() + height); } private boolean isWithinDeltaOfScreenH(View descendant, int delta) { descendant.getDrawingRect(mTempRect); offsetDescendantRectToMyCoords(descendant, mTempRect); return (mTempRect.right + delta) >= getScrollX() && (mTempRect.left - delta) <= (getScrollX() + getWidth()); } /** * Smooth scroll by a Y delta * * @param delta the number of pixels to scroll by on the Y axis */ private void doScrollY(int delta) { if (delta != 0) { if (mSmoothScrollingEnabled) { smoothScrollBy(0, delta); } else { scrollBy(0, delta); } } } private void doScrollX(int delta) { if (delta != 0) { if (mSmoothScrollingEnabled) { smoothScrollBy(delta, 0); } else { scrollBy(delta, 0); } } } /** * 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 void smoothScrollBy(int dx, int dy) { if (getChildCount() == 0) { // Nothing to do. return; } long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; if (duration > ANIMATED_SCROLL_GAP) { final int height = getHeight() - getPaddingBottom() - getPaddingTop(); final int bottom = getChildAt(0).getHeight(); final int maxY = Math.max(0, bottom - height); final int scrollY = getScrollY(); dy = Math.max(0, Math.min(scrollY + dy, maxY)) - scrollY; final int width = getWidth() - getPaddingRight() - getPaddingLeft(); final int right = getChildAt(0).getWidth(); final int maxX = Math.max(0, right - width); final int scrollX = getScrollX(); dx = Math.max(0, Math.min(scrollX + dx, maxX)) - scrollX; mScroller.startScroll(scrollX, scrollY, dx, dy); 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()); } /** *

The scroll range of a scroll view is the overall height of all of its * children.

*/ @Override protected int computeVerticalScrollRange() { final int count = getChildCount(); final int contentHeight = getHeight() - getPaddingBottom() - getPaddingTop(); if (count == 0) { return contentHeight; } return getChildAt(0).getBottom(); } @Override protected int computeHorizontalScrollRange() { final int count = getChildCount(); final int contentWidth = getWidth() - getPaddingLeft() - getPaddingRight(); if (count == 0) { return contentWidth; } return getChildAt(0).getRight(); } @Override protected int computeVerticalScrollOffset() { return Math.max(0, super.computeVerticalScrollOffset()); } @Override protected int computeHorizontalScrollOffset() { return Math.max(0, super.computeHorizontalScrollOffset()); } @Override protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) { int childWidthMeasureSpec; int childHeightMeasureSpec; childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); 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 = MeasureSpec.makeMeasureSpec(lp.leftMargin + lp.rightMargin, MeasureSpec.UNSPECIFIED); 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 x = mScroller.getCurrX(); int y = mScroller.getCurrY(); if (getChildCount() > 0) { View child = getChildAt(0); x = clamp(x, getWidth() - getPaddingRight() - getPaddingLeft(), child.getWidth()); y = clamp(y, getHeight() - getPaddingBottom() - getPaddingTop(), child.getHeight()); super.scrollTo(x, y); // getHeight()- child.getHeight()=y ->底部 y=0 ->顶端 // 惯性强度 mScroller.getDuration() } awakenScrollBars(); // 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 ScrollView coordinates */ offsetDescendantRectToMyCoords(child, mTempRect); int scrollDeltaV = computeScrollDeltaToGetChildRectOnScreenV(mTempRect); int scrollDeltaH = computeScrollDeltaToGetChildRectOnScreenH(mTempRect); if (scrollDeltaH != 0 || scrollDeltaV != 0) { scrollBy(scrollDeltaH, scrollDeltaV); } } /** * 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 deltaV = computeScrollDeltaToGetChildRectOnScreenV(rect); final int deltaH = computeScrollDeltaToGetChildRectOnScreenH(rect); final boolean scroll = deltaH != 0 || deltaV != 0; if (scroll) { if (immediate) { scrollBy(deltaH, deltaV); } else { smoothScrollBy(deltaH, deltaV); } } 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 computeScrollDeltaToGetChildRectOnScreenV(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; } protected int computeScrollDeltaToGetChildRectOnScreenH(Rect rect) { if (getChildCount() == 0) return 0; int width = getWidth(); int screenLeft = getScrollX(); int screenRight = screenLeft + width; int fadingEdge = getHorizontalFadingEdgeLength(); // leave room for left fading edge as long as rect isn't at very left if (rect.left > 0) { screenLeft += fadingEdge; } // leave room for right fading edge as long as rect isn't at very right if (rect.right < getChildAt(0).getWidth()) { screenRight -= fadingEdge; } int scrollXDelta = 0; if (rect.right > screenRight && rect.left > screenLeft) { // need to move right to get it in view: move right just enough so // that the entire rectangle is in view (or at least the first // screen size chunk). if (rect.width() > width) { // just enough to get screen size chunk on scrollXDelta += (rect.left - screenLeft); } else { // get entire rect at right of screen scrollXDelta += (rect.right - screenRight); } // make sure we aren't scrolling beyond the end of our content int right = getChildAt(0).getRight(); int distanceToRight = right - screenRight; scrollXDelta = Math.min(scrollXDelta, distanceToRight); } else if (rect.left < screenLeft && rect.right < screenRight) { // need to move right to get it in view: move right just enough so // that // entire rectangle is in view (or at least the first screen // size chunk of it). if (rect.width() > width) { // screen size chunk scrollXDelta -= (screenRight - rect.right); } else { // entire rect at left scrollXDelta -= (screenLeft - rect.left); } // make sure we aren't scrolling any further than the left our // content scrollXDelta = Math.max(scrollXDelta, -getScrollX()); } return scrollXDelta; } @Override public void requestChildFocus(View child, View focused) { if (!mScrollViewMovedFocus) { 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_RIGHT; // } else if (direction == View.FOCUS_BACKWARD) { // direction = View.FOCUS_LEFT; // } final View nextFocus = previouslyFocusedRect == null ? FocusFinder.getInstance() .findNextFocus(this, null, direction) : FocusFinder.getInstance() .findNextFocusFromRect(this, previouslyFocusedRect, direction); if (nextFocus == null) { return false; } // if (isOffScreenH(nextFocus)) { // return false; // } return nextFocus.requestFocus(direction, previouslyFocusedRect); } @Override public boolean requestChildRectangleOnScreen(View child, Rect rectangle, boolean immediate) { // offset into coordinate space of this scroll view rectangle.offset(child.getLeft() - child.getScrollX(), child.getTop() - child.getScrollY()); return scrollToChildRect(rectangle, immediate); } @Override public void requestLayout() { mIsLayoutDirty = true; super.requestLayout(); } @Override protected void onLayout(boolean changed, int l, int t, int r, int b) { super.onLayout(changed, l, t, r, b); mIsLayoutDirty = false; // Give a child focus if it needs it if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) { scrollToChild(mChildToScrollTo); } mChildToScrollTo = null; // 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. if (isWithinDeltaOfScreenV(currentFocused, 0, oldh)) { currentFocused.getDrawingRect(mTempRect); offsetDescendantRectToMyCoords(currentFocused, mTempRect); int scrollDelta = computeScrollDeltaToGetChildRectOnScreenV(mTempRect); doScrollY(scrollDelta); } final int maxJump = getRight() - getLeft(); if (isWithinDeltaOfScreenH(currentFocused, maxJump)) { currentFocused.getDrawingRect(mTempRect); offsetDescendantRectToMyCoords(currentFocused, mTempRect); int scrollDelta = computeScrollDeltaToGetChildRectOnScreenH(mTempRect); doScrollX(scrollDelta); } } /** * 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/cursor 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 width = getWidth() - getPaddingRight() - getPaddingLeft(); int right = getChildAt(0).getWidth(); int height = getHeight() - getPaddingBottom() - getPaddingTop(); int bottom = getChildAt(0).getHeight(); mScroller.fling(getScrollX(), getScrollY(), velocityX, velocityY, 0, Math.max(0, right - width), 0, Math.max(0, bottom - height)); // final boolean movingDown = velocityX > 0 || velocityY > 0; // // View newFocused = // findFocusableViewInMyBoundsV(movingDown, mScroller.getFinalY(), // findFocus()); // if (newFocused == null) { // newFocused = this; // } // // if (newFocused != findFocus() // && newFocused.requestFocus(movingDown ? View.FOCUS_DOWN : // View.FOCUS_UP)) { // mScrollViewMovedFocus = true; // mScrollViewMovedFocus = false; // } invalidate(); } } /** * {@inheritDoc} * *

This version also clamps the scrolling to the bounds of our child. */ @Override public void scrollTo(int x, int y) { // we rely on the fact the View.scrollBy calls scrollTo. if (getChildCount() > 0) { View child = getChildAt(0); x = clamp(x, getWidth() - getPaddingRight() - getPaddingLeft(), child.getWidth()); y = clamp(y, getHeight() - getPaddingBottom() - getPaddingTop(), child.getHeight()); if (x != getScrollX() || y != getScrollY()) { super.scrollTo(x, y); } } } private 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; } public boolean isFlingEnabled() { return mFlingEnabled; } public void setFlingEnabled(boolean flingEnabled) { this.mFlingEnabled = flingEnabled; } /** scrollview内容与属性记录*/ private View inner; private Rect normal = new Rect(); @Override protected void onFinishInflate() { if (getChildCount() > 0) { inner = getChildAt(0); } } // 是否需要开启动画 public boolean isNeedAnimation() { return !normal.isEmpty(); } // 开启动画移动 public void animation() { // 开启移动动画 TranslateAnimation ta = new TranslateAnimation(0, -inner.getLeft(), 0, -inner.getTop()); ta.setDuration(200); inner.startAnimation(ta); // 设置回到正常的布局位置 new Handler().postDelayed(new Runnable() { public void run() { inner.clearAnimation(); inner.layout(normal.left, normal.top, normal.right, normal.bottom); normal.setEmpty(); } }, 200); } // 是否需要移动布局 public boolean isNeedMove() { int offsetX = inner.getMeasuredWidth() - getWidth(); int scrollX = getScrollX(); if (scrollX == 0 || scrollX == offsetX) { return true; } int offsetY = inner.getMeasuredHeight() - getHeight(); int scrollY = getScrollY(); if (scrollY == 0 || scrollY == offsetY) { return true; } return false; } }


实现很简单,这里就不做太多解释!



你可能感兴趣的:(Android,学习)