Java Code Examples for android.support.v4.view.ViewCompat#canScrollVertically()

private void handleVertical(View target, int dy, int[] consumed) {
    // dy>0 往左滑动 dy<0往右滑动
    boolean hiddenTop = dy > 0 && getScrollY() < MAX_WIDTH && !ViewCompat
            .canScrollVertically(target, -1);
    boolean showTop = dy < 0 && !ViewCompat.canScrollVertically(target, -1);
    boolean hiddenBottom = dy < 0 && getScrollY() > MAX_WIDTH && !ViewCompat
            .canScrollVertically(target, 1);
    boolean showBottom = dy > 0 && !ViewCompat.canScrollVertically(target, 1);
    if (hiddenTop || showTop || hiddenBottom || showBottom) {
        scrollBy(0, dy / mDrag);
        consumed[1] = dy;
    }

    // 限制错位问题
    if (dy > 0 && getScrollY() > MAX_WIDTH && !ViewCompat.canScrollVertically(target, -1)) {
        scrollTo(0, MAX_WIDTH);
    }
    if (dy < 0 && getScrollY() < MAX_WIDTH && !ViewCompat.canScrollVertically(target, 1)) {
        scrollTo(0, MAX_WIDTH);
    }
}
 

public boolean canChildScrollDown() {
    if (android.os.Build.VERSION.SDK_INT < 14) {
        if (mTarget instanceof AbsListView) {
            final AbsListView absListView = (AbsListView) mTarget;
            try {
                if (absListView.getCount() > 0) {
                    if (absListView.getLastVisiblePosition() + 1 == absListView.getCount()) {
                        int lastIndex = absListView.getLastVisiblePosition() - absListView.getFirstVisiblePosition();
                        return absListView.getChildAt(lastIndex).getBottom() == absListView.getPaddingBottom();
                    }
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
            return true;
        } else {
            return true;
        }
    } else {
        return ViewCompat.canScrollVertically(mTarget, 1);
    }
}
 

private boolean canScrollDown(View view)
{
    if (android.os.Build.VERSION.SDK_INT < 14)
    {
        if (view instanceof AbsListView)
        {
            final AbsListView absListView = (AbsListView) view;
            return absListView.getChildCount() > 0
                    && (absListView.getLastVisiblePosition() < absListView.getChildCount() - 1
                    || absListView.getChildAt(absListView.getChildCount() - 1).getBottom() > absListView.getPaddingBottom());
        } else
        {
            return ViewCompat.canScrollVertically(view, 1) || view.getScrollY() < 0;
        }
    } else
    {
        return ViewCompat.canScrollVertically(view, 1);
    }
}
 

/**
 * 是否可以滑动，direction为负数时表示向下滑动，反之表示向上滑动。
 * @param direction                         direction
 * @return
 */
protected boolean canChildScrollVertically(int direction) {
    if (mTarget instanceof AbsListView) {
        return canListViewScroll((AbsListView) mTarget);
    } else if (mTarget instanceof FrameLayout || mTarget instanceof RelativeLayout ||
            mTarget instanceof LinearLayout) {
        View child;
        for (int i = 0; i < ((ViewGroup) mTarget).getChildCount(); i++) {
            child = ((ViewGroup) mTarget).getChildAt(i);
            if (child instanceof AbsListView) {
                return canListViewScroll((AbsListView) child);
            }
        }
    }
    return ViewCompat.canScrollVertically(mTarget, -direction);
}
 

/**
 * @return Whether it is possible for the child view of this layout to
 * scroll up. Override this if the child view is a custom view.
 */
public boolean canChildScrollUp() {
    if (android.os.Build.VERSION.SDK_INT < 14) {
        if (mTarget instanceof AbsListView) {
            final AbsListView absListView = (AbsListView) mTarget;
            return absListView.getChildCount() > 0
                    && (absListView.getFirstVisiblePosition() > 0 || absListView.getChildAt(0)
                    .getTop() < absListView.getPaddingTop());
        } else {
            //Log.d(TAG, "canChildScrollUp :"+ mTarget.getScrollY()+" "+mTarget);
            boolean flag = mTarget.getScrollY() > 0;
            if (mTarget instanceof RecyclerView) {
                RecyclerView rv = (RecyclerView) mTarget;
                int firstVisiblePosition = rv.getChildPosition(rv.getChildAt(0));
                if (firstVisiblePosition == 0)
                    return rv.getChildAt(0).getTop() == 0 ? false : true;
                else
                    return true;
            }
            return flag;//ViewCompat.canScrollVertically(mTarget, -1);
        }
    } else {
        return ViewCompat.canScrollVertically(mTarget, -1);
    }
}
 

/**
 * 用来判断是否可以下拉
 * 手指在屏幕上该方法才有效
 */
public static boolean canChildScrollUp(View mChildView) {
    if (mChildView == null) {
        return false;
    }
    if (Build.VERSION.SDK_INT < 14) {
        if (mChildView instanceof AbsListView) {
            final AbsListView absListView = (AbsListView) mChildView;
            return absListView.getChildCount() > 0
                    && (absListView.getFirstVisiblePosition() > 0 || absListView.getChildAt(0)
                    .getTop() < absListView.getPaddingTop());
        } else {
            return ViewCompat.canScrollVertically(mChildView, -1) || mChildView.getScrollY() > 0;
        }
    } else {
        return ViewCompat.canScrollVertically(mChildView, -1);
    }
}
 

/**
 * Tests scrollability within child views of v given a delta of dx.
 *
 * @param v View to test for horizontal scrollability
 * @param checkV Whether the view v passed should itself be checked for scrollability (true),
 *               or just its children (false).
 * @param dx Delta scrolled in pixels along the X axis
 * @param dy Delta scrolled in pixels along the Y axis
 * @param x X coordinate of the active touch point
 * @param y Y coordinate of the active touch point
 * @return true if child views of v can be scrolled by delta of dx.
 */
protected boolean canScroll(View v, boolean checkV, int dx, int dy, int x, int y) {
    if (v instanceof ViewGroup) {
        final ViewGroup group = (ViewGroup) v;
        final int scrollX = v.getScrollX();
        final int scrollY = v.getScrollY();
        final int count = group.getChildCount();
        // Count backwards - let topmost views consume scroll distance first.
        for (int i = count - 1; i >= 0; i--) {
            // TODO: Add versioned support here for transformed views.
            // This will not work for transformed views in Honeycomb+
            final View child = group.getChildAt(i);
            if (x + scrollX >= child.getLeft() && x + scrollX < child.getRight() &&
                    y + scrollY >= child.getTop() && y + scrollY < child.getBottom() &&
                    canScroll(child, true, dx, dy, x + scrollX - child.getLeft(),
                            y + scrollY - child.getTop())) {
                return true;
            }
        }
    }

    return checkV && (ViewCompat.canScrollHorizontally(v, -dx) ||
            ViewCompat.canScrollVertically(v, -dy));
}
 

/**
 * Tests scrollability within child views of v given a delta of dy.
 *
 * @param v View to test for horizontal scrollability
 * @param checkV Whether the view v passed should itself be checked for scrollability (true),
 *               or just its children (false).
 * @param dy Delta scrolled in pixels
 * @param x X coordinate of the active touch point
 * @param y Y coordinate of the active touch point
 * @return true if child views of v can be scrolled by delta of dx.
 */
protected boolean canScroll(View v, boolean checkV, int dy, int x, int y) {
    if (v instanceof ViewGroup) {
        final ViewGroup group = (ViewGroup) v;
        final int scrollX = v.getScrollX();
        final int scrollY = v.getScrollY();
        final int count = group.getChildCount();
        // Count backwards - let topmost views consume scroll distance first.
        for (int i = count - 1; i >= 0; i--) {
            // TODO: Add versioned support here for transformed views.
            // This will not work for transformed views in Honeycomb+
            final View child = group.getChildAt(i);
            if (x + scrollX >= child.getLeft() && x + scrollX < child.getRight() &&
                    y + scrollY >= child.getTop() && y + scrollY < child.getBottom() &&
                    canScroll(child, true, dy, x + scrollX - child.getLeft(),
                            y + scrollY - child.getTop())) {
                return true;
            }
        }
    }

    return checkV && ViewCompat.canScrollVertically(v, -dy);
}
 

/**
 * Tests scrollability within child views of v given a delta of dx.
 *
 * @param v View to test for horizontal scrollability
 * @param checkV Whether the view v passed should itself be checked for scrollability (true),
 *               or just its children (false).
 * @param dx Delta scrolled in pixels along the X axis
 * @param dy Delta scrolled in pixels along the Y axis
 * @param x X coordinate of the active touch point
 * @param y Y coordinate of the active touch point
 * @return true if child views of v can be scrolled by delta of dx.
 */
protected boolean canScroll(View v, boolean checkV, int dx, int dy, int x, int y) {
    if (v instanceof ViewGroup) {
        final ViewGroup group = (ViewGroup) v;
        final int scrollX = v.getScrollX();
        final int scrollY = v.getScrollY();
        final int count = group.getChildCount();
        // Count backwards - let topmost views consume scroll distance first.
        for (int i = count - 1; i >= 0; i--) {
            // TODO: Add versioned support here for transformed views.
            // This will not work for transformed views in Honeycomb+
            final View child = group.getChildAt(i);
            if (x + scrollX >= child.getLeft() && x + scrollX < child.getRight() &&
                    y + scrollY >= child.getTop() && y + scrollY < child.getBottom() &&
                    canScroll(child, true, dx, dy, x + scrollX - child.getLeft(),
                            y + scrollY - child.getTop())) {
                return true;
            }
        }
    }

    return checkV && (ViewCompat.canScrollHorizontally(v, -dx) ||
            ViewCompat.canScrollVertically(v, -dy));
}
 

/**
 * Tests scrollability within child views of v given a delta of dy.
 *
 * @param v View to test for vertical scrollability
 * @param checkV Whether the view v passed should itself be checked for scrollability (true),
 * or just its children (false).
 * @param dy Delta scrolled in pixels
 * @param x X coordinate of the active touch point
 * @param y Y coordinate of the active touch point
 * @return true if child views of v can be scrolled by delta of dy.
 */
protected boolean canScroll(View v, boolean checkV, int dy, int x, int y) {
    if (v instanceof ViewGroup) {
        final ViewGroup group = (ViewGroup) v;
        final int scrollX = v.getScrollX();
        final int scrollY = v.getScrollY();
        final int count = group.getChildCount();
        // Count backwards - let topmost views consume scroll distance first.
        for (int i = count - 1; i >= 0; i--) {
            // TODO: Add versioned support here for transformed views.
            // This will not work for transformed views in Honeycomb+
            final View child = group.getChildAt(i);
            if (x + scrollX >= child.getLeft() && x + scrollX < child.getRight() &&
                    y + scrollY >= child.getTop() && y + scrollY < child.getBottom() &&
                    canScroll(child, true, dy, x + scrollX - child.getLeft(),
                            y + scrollY - child.getTop())) {
                return true;
            }
        }
    }

    return checkV && ViewCompat.canScrollVertically(v, -dy);
}
 

/**
 * Tests scrollability within child views of v given a delta of dx.
 *
 * @param v      View to test for horizontal scrollability
 * @param checkV Whether the view v passed should itself be checked for scrollability (true),
 *               or just its children (false).
 * @param dy     Delta scrolled in pixels
 * @param x      X coordinate of the active touch point
 * @param y      Y coordinate of the active touch point
 * @return true if child views of v can be scrolled by delta of dx.
 */
protected boolean canScroll(View v, boolean checkV, int dy, int x, int y) {
    if (v instanceof ViewGroup) {
        final ViewGroup group = (ViewGroup) v;
        final int scrollX = v.getScrollX();
        final int scrollY = v.getScrollY();
        final int count = group.getChildCount();
        // Count backwards - let topmost views consume scroll distance first.
        for (int i = count - 1; i >= 0; i--) {
            // TODO: Add versioned support here for transformed views.
            // This will not work for transformed views in Honeycomb+
            final View child = group.getChildAt(i);
            if (y + scrollY >= child.getTop() && y + scrollY < child.getBottom() &&
                    x + scrollX >= child.getLeft() && x + scrollX < child.getRight() &&
                    canScroll(child, true, dy, x + scrollX - child.getLeft(),
                            y + scrollY - child.getTop())) {
                return true;
            }
        }
    }

    return checkV && ViewCompat.canScrollVertically(v, -dy);
}
 

/**
 * Tests scrollability within child views of v given a delta of dx.
 *
 * @param v      View to test for horizontal scrollability
 * @param checkV Whether the view v passed should itself be checked for
 *               scrollability (true), or just its children (false).
 * @param dx     Delta scrolled in pixels along the X axis
 * @param dy     Delta scrolled in pixels along the Y axis
 * @param x      X coordinate of the active touch point
 * @param y      Y coordinate of the active touch point
 * @return true if child views of v can be scrolled by delta of dx.
 */
protected boolean canScroll(View v, boolean checkV, int dx, int dy, int x, int y) {
    if (v instanceof ViewGroup) {
        final ViewGroup group = (ViewGroup) v;
        final int scrollX = v.getScrollX();
        final int scrollY = v.getScrollY();
        final int count = group.getChildCount();
        // Count backwards - let topmost views consume scroll distance
        // first.
        for (int i = count - 1; i >= 0; i--) {
            // TODO: Add versioned support here for transformed views.
            // This will not work for transformed views in Honeycomb+
            final View child = group.getChildAt(i);
            if (x + scrollX >= child.getLeft()
                    && x + scrollX < child.getRight()
                    && y + scrollY >= child.getTop()
                    && y + scrollY < child.getBottom()
                    && canScroll(child, true, dx, dy, x + scrollX - child.getLeft(), y
                    + scrollY - child.getTop())) {
                return true;
            }
        }
    }

    return checkV
            && (ViewCompat.canScrollHorizontally(v, -dx) || ViewCompat.canScrollVertically(v,
            -dy));
}
 

/**
 * Tests scrollability within child views of v given a delta of dx.
 *
 * @param v      View to test for horizontal scrollability
 * @param checkV Whether the view v passed should itself be checked for
 *               scrollability (true), or just its children (false).
 * @param dx     Delta scrolled in pixels along the X axis
 * @param dy     Delta scrolled in pixels along the Y axis
 * @param x      X coordinate of the active touch point
 * @param y      Y coordinate of the active touch point
 * @return true if child views of v can be scrolled by delta of dx.
 */
protected boolean canScroll(View v, boolean checkV, int dx, int dy, int x, int y) {
    if (v instanceof ViewGroup) {
        final ViewGroup group = (ViewGroup) v;
        final int scrollX = v.getScrollX();
        final int scrollY = v.getScrollY();
        final int count = group.getChildCount();
        // Count backwards - let topmost views consume scroll distance
        // first.
        for (int i = count - 1; i >= 0; i--) {
            // TODO: Add versioned support here for transformed views.
            // This will not work for transformed views in Honeycomb+
            final View child = group.getChildAt(i);
            if (x + scrollX >= child.getLeft()
                    && x + scrollX < child.getRight()
                    && y + scrollY >= child.getTop()
                    && y + scrollY < child.getBottom()
                    && canScroll(child, true, dx, dy, x + scrollX - child.getLeft(), y
                    + scrollY - child.getTop())) {
                return true;
            }
        }
    }

    return checkV
            && (ViewCompat.canScrollHorizontally(v, -dx) || ViewCompat.canScrollVertically(v,
            -dy));
}
 

/**
 * @return Whether it is possible for the child view of this layout to
 * scroll up. Override this if the child view is a custom view.
 */
public boolean canChildScrollUp() {
    if (android.os.Build.VERSION.SDK_INT < 14) {
        if (mTarget instanceof AbsListView) {
            final AbsListView absListView = (AbsListView) mTarget;
            return absListView.getChildCount() > 0
                    && (absListView.getFirstVisiblePosition() > 0 || absListView.getChildAt(0)
                    .getTop() < absListView.getPaddingTop());
        } else {
            return mTarget.getScrollY() > 0;
        }
    } else {
        return ViewCompat.canScrollVertically(mTarget, -1);
    }
}
 

/**
 * @return Whether it is possible for the child view of this layout to
 * scroll up. Override this if the child view is a custom view.
 */
public boolean canChildScrollUp() {
    if (android.os.Build.VERSION.SDK_INT < 14) {
        if (mTarget instanceof AbsListView) {
            final AbsListView absListView = (AbsListView) mTarget;
            return absListView.getChildCount() > 0 &&
                    (absListView.getFirstVisiblePosition() > 0 ||
                            absListView.getChildAt(0).getTop() < absListView.getPaddingTop());
        } else {
            return mTarget.getScrollY() > 0;
        }
    } else {
        return ViewCompat.canScrollVertically(mTarget, -1);
    }
}
 

private boolean canChildScrollUp() {
    if (android.os.Build.VERSION.SDK_INT < 14) {
        if (contentView instanceof AbsListView) {
            final AbsListView absListView = (AbsListView) contentView;
            return absListView.getChildCount() > 0
                    && (absListView.getFirstVisiblePosition() > 0 || absListView.getChildAt(0)
                    .getTop() < absListView.getPaddingTop());
        } else {
            return ViewCompat.canScrollVertically(contentView, -1) || contentView.getScrollY() > 0;
        }
    } else {
        /*return true can  swipe up*/
        return ViewCompat.canScrollVertically(contentView, -1);
    }
}
 

private static boolean canListViewScrollUp(ListView listView) {
    if (android.os.Build.VERSION.SDK_INT >= 14) {
        // For ICS and above we can call canScrollVertically() to determine this
        return ViewCompat.canScrollVertically(listView, -1);
    } else {
        // Pre-ICS we need to manually check the first visible item and the child view's top
        // value
        return listView.getChildCount() > 0 &&
                (listView.getFirstVisiblePosition() > 0
                        || listView.getChildAt(0).getTop() < listView.getPaddingTop());
    }
}
 

private boolean canChildScrollUp() {
    if (android.os.Build.VERSION.SDK_INT < 14) {
        if (mTarget instanceof AbsListView) {
            final AbsListView absListView = (AbsListView) mTarget;
            return absListView.getChildCount() > 0
                    && (absListView.getFirstVisiblePosition() > 0 || absListView.getChildAt(0)
                    .getTop() < absListView.getPaddingTop());
        } else {
            return mTarget.getScrollY() > 0;
        }
    } else {
        return ViewCompat.canScrollVertically(mTarget, -1);
    }
}
 

@Override
protected boolean isReadyForPullStart() {
	return !ViewCompat.canScrollVertically(getRefreshableView(),-1);
}
 

private boolean canListViewScrollUp(ListView listView) {

            // Should not be able to swipe refresh while loading or while scrolling
            return mArticleListAdapter != null && mArticleListAdapter.isEmpty() || ViewCompat.canScrollVertically(listView, -1);

        }