完美滑动顶部固定ScrollView,合并可以上拉,下拉加载更多

先看效果:

主要处理:

使用PullToRefreshScrollView修改内部的scrollView源码,更换成可以固定顶部的自定义scrollView

@Override
    protected ScrollView createRefreshableView(Context context, AttributeSet attrs) {
        ScrollView scrollView;
        if (VERSION.SDK_INT >= VERSION_CODES.GINGERBREAD) {
            //TODO  修改代码 添加滑动固定顶部标题sv
            scrollView = new InternalScrollViewSDK9(context, attrs);
//          scrollView = new FloatScrollView(context, attrs);
        } else {
            scrollView = new ScrollView(context, attrs);
        }

        scrollView.setId(R.id.scrollview);
        return scrollView;
    }

下面是scrollview的代码:

        public static final String FLOAT = "float";

        private ArrayList<View> stickyViews;
        private View currentlyStickingView;
        private float stickyViewTopOffset;
        private int stickyViewLeftOffset;
        private boolean redirectTouchesToStickyView;
        private boolean clippingToPadding;
        private boolean clipToPaddingHasBeenSet;

        private final Runnable invalidateRunnable = new Runnable() {

            @Override
            public void run() {
                if (currentlyStickingView != null) {
                    int l = getLeftForViewRelativeOnlyChild(currentlyStickingView);
                    int t = getBottomForViewRelativeOnlyChild(currentlyStickingView);
                    int r = getRightForViewRelativeOnlyChild(currentlyStickingView);
                    int b = (int) (getScrollY() + (currentlyStickingView.getHeight() + stickyViewTopOffset));
                    invalidate(l, t, r, b);
                }
                postDelayed(this, 16);
            }
        };

        public void setup() {
            stickyViews = new ArrayList<View>();
        }

        private int getLeftForViewRelativeOnlyChild(View v) {
            int left = v.getLeft();
            while (v.getParent() != getChildAt(0)) {
                v = (View) v.getParent();
                left += v.getLeft();
            }
            return left;
        }

        private int getTopForViewRelativeOnlyChild(View v) {
            int top = v.getTop();
            while (v.getParent() != getChildAt(0)) {
                v = (View) v.getParent();
                top += v.getTop();
            }
            return top;
        }

        private int getRightForViewRelativeOnlyChild(View v) {
            int right = v.getRight();
            while (v.getParent() != getChildAt(0)) {
                v = (View) v.getParent();
                right += v.getRight();
            }
            return right;
        }

        private int getBottomForViewRelativeOnlyChild(View v) {
            int bottom = v.getBottom();
            while (v.getParent() != getChildAt(0)) {
                v = (View) v.getParent();
                bottom += v.getBottom();
            }
            return bottom;
        }

        @Override
        protected void onLayout(boolean changed, int l, int t, int r, int b) {
            super.onLayout(changed, l, t, r, b);
            if (!clipToPaddingHasBeenSet) {
                clippingToPadding = true;
            }
            notifyHierarchyChanged();
        }

        @Override
        public void setClipToPadding(boolean clipToPadding) {
            super.setClipToPadding(clipToPadding);
            clippingToPadding = clipToPadding;
            clipToPaddingHasBeenSet = true;
        }

        @Override
        public void addView(View child) {
            super.addView(child);
            findStickyViews(child);
        }

        @Override
        public void addView(View child, int index) {
            super.addView(child, index);
            findStickyViews(child);
        }

        @Override
        public void addView(View child, int index, android.view.ViewGroup.LayoutParams params) {
            super.addView(child, index, params);
            findStickyViews(child);
        }

        @Override
        public void addView(View child, int width, int height) {
            super.addView(child, width, height);
            findStickyViews(child);
        }

        @Override
        public void addView(View child, android.view.ViewGroup.LayoutParams params) {
            super.addView(child, params);
            findStickyViews(child);
        }

        @Override
        protected void dispatchDraw(Canvas canvas) {
            super.dispatchDraw(canvas);
            if (currentlyStickingView != null) {
                canvas.save();
                canvas.translate(getPaddingLeft() + stickyViewLeftOffset, getScrollY() + stickyViewTopOffset + (clippingToPadding ? getPaddingTop() : 0));

                canvas.clipRect(0, (clippingToPadding ? -stickyViewTopOffset : 0), getWidth(), currentlyStickingView.getHeight());
                currentlyStickingView.draw(canvas);
                canvas.restore();
            }
        }

        @Override
        public boolean dispatchTouchEvent(MotionEvent ev) {
            if (ev.getAction() == MotionEvent.ACTION_DOWN) {
                redirectTouchesToStickyView = true;
            }

            if (redirectTouchesToStickyView) {
                redirectTouchesToStickyView = currentlyStickingView != null;
                if (redirectTouchesToStickyView) {
                    redirectTouchesToStickyView =
                            ev.getY() <= (currentlyStickingView.getHeight() + stickyViewTopOffset) &&
                                    ev.getX() >= getLeftForViewRelativeOnlyChild(currentlyStickingView) &&
                                    ev.getX() <= getRightForViewRelativeOnlyChild(currentlyStickingView);
                }
            } else if (currentlyStickingView == null) {
                redirectTouchesToStickyView = false;
            }
            if (redirectTouchesToStickyView) {
                topForViewRelativeOnlyChild = getTopForViewRelativeOnlyChild(currentlyStickingView);
                ev.offsetLocation(0, -1 * ((getScrollY() + stickyViewTopOffset) - topForViewRelativeOnlyChild));
            }
            return super.dispatchTouchEvent(ev);
        }

        private boolean hasNotDoneActionDown = true;

        @Override
        public boolean onTouchEvent(MotionEvent ev) {
            if (redirectTouchesToStickyView) {
                ev.offsetLocation(0, ((getScrollY() + stickyViewTopOffset) - getTopForViewRelativeOnlyChild(currentlyStickingView)));
            }

            if (ev.getAction() == MotionEvent.ACTION_DOWN || ev.getAction() == MotionEvent.ACTION_MOVE) {
                hasNotDoneActionDown = false;
            }

            if (hasNotDoneActionDown) {
                MotionEvent down = MotionEvent.obtain(ev);
                down.setAction(MotionEvent.ACTION_DOWN);
                super.onTouchEvent(down);
                hasNotDoneActionDown = false;
            }

            if (ev.getAction() == MotionEvent.ACTION_UP || ev.getAction() == MotionEvent.ACTION_CANCEL) {
                hasNotDoneActionDown = true;
            }

            return super.onTouchEvent(ev);
        }

        @Override
        protected void onScrollChanged(int l, int t, int oldl, int oldt) {
            super.onScrollChanged(l, t, oldl, oldt);
            doTheStickyThing();
        }

        private void doTheStickyThing() {
            View viewThatShouldStick = null;
            View approachingView = null;
            for (View v : stickyViews) {
                int viewTop = getTopForViewRelativeOnlyChild(v) - getScrollY() + (clippingToPadding ? 0 : getPaddingTop());
                if (viewTop <= 0) {
                    if (viewThatShouldStick == null || viewTop > (getTopForViewRelativeOnlyChild(viewThatShouldStick) - getScrollY() + (clippingToPadding ? 0 : getPaddingTop()))) {
                        viewThatShouldStick = v;
                    }
                } else {
                    if (approachingView == null || viewTop < (getTopForViewRelativeOnlyChild(approachingView) - getScrollY() + (clippingToPadding ? 0 : getPaddingTop()))) {
                        approachingView = v;
                    }
                }
            }
            if (viewThatShouldStick != null) {
                stickyViewTopOffset = approachingView == null ? 0 : Math.min(0, getTopForViewRelativeOnlyChild(approachingView) - getScrollY() + (clippingToPadding ? 0 : getPaddingTop()) - viewThatShouldStick.getHeight());
                if (viewThatShouldStick != currentlyStickingView) {
                    if (currentlyStickingView != null) {
                        stopStickingCurrentlyStickingView();
                    }
                    stickyViewLeftOffset = getLeftForViewRelativeOnlyChild(viewThatShouldStick);
                    startStickingView(viewThatShouldStick);
                }
            } else if (currentlyStickingView != null) {
                stopStickingCurrentlyStickingView();
            }
        }

        private void startStickingView(View viewThatShouldStick) {
            currentlyStickingView = viewThatShouldStick;
        }

        private void stopStickingCurrentlyStickingView() {
            currentlyStickingView = null;
            removeCallbacks(invalidateRunnable);
        }

        private void notifyHierarchyChanged() {
            if (currentlyStickingView != null) {
                stopStickingCurrentlyStickingView();
            }
            stickyViews.clear();
            findStickyViews(getChildAt(0));
            doTheStickyThing();
            invalidate();
        }

        private void findStickyViews(View v) {
            if (v instanceof ViewGroup) {
                ViewGroup vg = (ViewGroup) v;
                for (int i = 0; i < vg.getChildCount(); i++) {
                    String tag = getStringTagForView(vg.getChildAt(i));
                    if (tag != null && tag.contains(FLOAT)) {
                        stickyViews.add(vg.getChildAt(i));
                    } else if (vg.getChildAt(i) instanceof ViewGroup) {
                        findStickyViews(vg.getChildAt(i));
                    }
                }
            } else {
                String tag = (String) v.getTag();
                if (tag != null && tag.contains(FLOAT)) {
                    stickyViews.add(v);
                }
            }
        }

        private String getStringTagForView(View v) {
            Object tagObject = v.getTag();
            return String.valueOf(tagObject);
        }
    }