android.view.View#canScrollHorizontally ( )源码实例Demo

private boolean canScrollLeft(View view, float x, float y) {
    if (view instanceof ViewGroup) {
        ViewGroup vg = (ViewGroup) view;
        for (int i = 0; i < vg.getChildCount(); i++) {
            View child = vg.getChildAt(i);
            int childLeft = child.getLeft() - view.getScrollX();
            int childTop = child.getTop() - view.getScrollY();
            int childRight = child.getRight() - view.getScrollX();
            int childBottom = child.getBottom() - view.getScrollY();
            boolean intersects = x > childLeft && x < childRight && y > childTop && y < childBottom;
            if (intersects && canScrollLeft(child, x - childLeft, y - childTop)) {
                return true;
            }
        }
    }
    return view.canScrollHorizontally(-1);
}
 

private boolean canScrollRight(View view, float x, float y) {
    if (view instanceof ViewGroup) {
        ViewGroup vg = (ViewGroup) view;
        for (int i = 0; i < vg.getChildCount(); i++) {
            View child = vg.getChildAt(i);
            int childLeft = child.getLeft() - view.getScrollX();
            int childTop = child.getTop() - view.getScrollY();
            int childRight = child.getRight() - view.getScrollX();
            int childBottom = child.getBottom() - view.getScrollY();
            boolean intersects = x > childLeft && x < childRight && y > childTop && y < childBottom;
            if (intersects && canScrollRight(child, x - childLeft, y - childTop)) {
                return true;
            }
        }
    }
    return view.canScrollHorizontally(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
 * @param x      X coordinate of the active touch point
 * @param y      Y coordinate of the active touch point
 * @return true if child views of v can be scrolled by delta of dx.
 */
protected boolean canScroll(View v, boolean checkV, int dx, int x, int y) {
    if (v instanceof ViewGroup) {
        final ViewGroup group = (ViewGroup) v;
        final int scrollX = v.getScrollX();
        final int scrollY = v.getScrollY();
        final int count = group.getChildCount();
        // Count backwards - let topmost views consume scroll distance first.
        for (int i = count - 1; i >= 0; i--) {
            // 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, x + scrollX - child.getLeft(),
                    y + scrollY - child.getTop())) {
                return true;
            }
        }
    }

    return checkV && v.canScrollHorizontally(-dx);
}
 

@Override
public boolean isNotYetInEdgeCannotMoveHeader(
        SmoothRefreshLayout parent, @Nullable View child, @Nullable IRefreshView header) {
    if (child == null) {
        if (parent.isVerticalOrientation()) {
            return !mFullyExpanded;
        } else {
            return true;
        }
    } else {
        if (parent.isVerticalOrientation()) {
            return !mFullyExpanded || child.canScrollVertically(-1);
        } else {
            return child.canScrollHorizontally(-1);
        }
    }
}
 

@Override
public boolean isNotYetInEdgeCannotMoveFooter(
        SmoothRefreshLayout parent, @Nullable View child, @Nullable IRefreshView footer) {
    if (child == null) {
        if (parent.isVerticalOrientation()) {
            return !mFullyCollapsed;
        } else {
            return true;
        }
    } else {
        if (parent.isVerticalOrientation()) {
            return !mFullyCollapsed || child.canScrollVertically(1);
        } else {
            return child.canScrollHorizontally(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
 * @param x      X coordinate of the active touch point
 * @param y      Y coordinate of the active touch point
 * @return true if child views of v can be scrolled by delta of dx.
 */
protected boolean canScroll(View v, boolean checkV, int dx, int x, int y) {
    if (v instanceof ViewGroup) {
        final ViewGroup group = (ViewGroup) v;
        final int scrollX = v.getScrollX();
        final int scrollY = v.getScrollY();
        final int count = group.getChildCount();
        // Count backwards - let topmost views consume scroll distance first.
        for (int i = count - 1; i >= 0; i--) {
            final View child = group.getChildAt(i);
            if (x + scrollX >= child.getLeft() && x + scrollX < child.getRight() &&
                    y + scrollY >= child.getTop() && y + scrollY < child.getBottom() &&
                    canScroll(child, true, dx, x + scrollX - child.getLeft(),
                            y + scrollY - child.getTop())) {
                return true;
            }
        }
    }
    return checkV && v.canScrollHorizontally(-dx);
}
 

/**
 * 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 && (v.canScrollHorizontally(-dx) ||
            v.canScrollVertically(-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 && (v.canScrollHorizontally(-dx) || v.canScrollVertically(-dy));
}
 

public static boolean canScrollLeft(@NonNull View targetView) {
    if (android.os.Build.VERSION.SDK_INT < 14) {
        if (targetView instanceof AbsListView) {
            final ViewGroup viewGroup = (ViewGroup) targetView;
            final AbsListView absListView = (AbsListView) targetView;
            return viewGroup.getChildCount() > 0
                    && (absListView.getFirstVisiblePosition() > 0
                    || viewGroup.getChildAt(0).getTop() < targetView.getPaddingTop());
        } else {
            return targetView.getScrollY() > 0;
        }
    } else {
        return targetView.canScrollHorizontally(-1);
    }
}
 

public static boolean canScrollRight(@NonNull View targetView) {
    if (android.os.Build.VERSION.SDK_INT < 14) {
        if (targetView instanceof AbsListView) {
            final ViewGroup viewGroup = (ViewGroup) targetView;
            final AbsListView absListView = (AbsListView) targetView;
            final int childCount = viewGroup.getChildCount();
            return childCount > 0 && (absListView.getLastVisiblePosition() < childCount - 1
                    || viewGroup.getChildAt(childCount - 1).getBottom() > targetView.getPaddingBottom());
        } else {
            return targetView.getScrollY() < 0;
        }
    } else {
        return targetView.canScrollHorizontally(1);
    }
}
 

@Override
public boolean isNotYetInEdgeCannotMoveHeader() {
    View targetView = getScrollTargetView();
    if (mInEdgeCanMoveHeaderCallBack != null) {
        return mInEdgeCanMoveHeaderCallBack.isNotYetInEdgeCannotMoveHeader(
                this, targetView, mHeaderView);
    }
    return targetView != null && targetView.canScrollHorizontally(-1);
}
 

@Override
public boolean isNotYetInEdgeCannotMoveFooter() {
    final View targetView = getScrollTargetView();
    if (mInEdgeCanMoveFooterCallBack != null) {
        return mInEdgeCanMoveFooterCallBack.isNotYetInEdgeCannotMoveFooter(
                this, targetView, mHeaderView);
    }
    return targetView != null && targetView.canScrollHorizontally(1);
}
 

@Override
public void onNestedScrollAccepted(@NonNull View child, @NonNull View target, int axes, int type) {
    isBeingNestedScrolling = true;
    if ((!target.canScrollHorizontally(-1) && !target.canScrollHorizontally(1))
            || swipeDistance != 0) {
        nestedScrollingDistance = nestedScrollingTrigger;
    } else {
        nestedScrollingDistance = 0;
    }
}
 

@Override
		protected boolean canScroll(View webView, boolean checkV, int dx, int x, int y) {
			if (webView instanceof HorizontalSlideWebView) {
//			Log.d(TAG, "dx: " + dx + " x:" + x + " y:" + y);
				return webView.canScrollHorizontally(y); // 不再兼容 API < 14
			} else {
				return super.canScroll(webView, checkV, dx, x, y);
			}
		}
 

/**
 * 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
            && (v.canScrollHorizontally(-dx) || v.canScrollVertically(-dy));
}
 

@Override
public int scrollHorizontallyBy(int dx, RecyclerView.Recycler recycler, RecyclerView.State state) {
    final int layoutDirection = dx > 0 ? 1 : -1;
    View currView = getCurrentPageView();
    //check if we need to work with the child view
    if (recyclerView != null && currView != null && currView.canScrollHorizontally(layoutDirection)
            && ((layoutDirection == 1 && currView.getLeft() <= 0) ||
            (layoutDirection == -1 && currView.getRight() >= currView.getWidth()))
            ) {
        dOffset = 0;
        if (lastTouchEvent != null) {
            currView.dispatchTouchEvent(lastTouchEvent);
            lastTouchEvent = null;
        }
        ViewCompat.setOverScrollMode(recyclerView, ViewCompat.OVER_SCROLL_NEVER);

        if ((layoutDirection == 1 && currView.getLeft() < 0) || (layoutDirection == -1 && currView.getRight() > currView.getWidth())) {
            adjust();
        }
        return 0;
    } else if (Math.abs(dOffset + dx) < triggPx &&
            recyclerView != null && currView != null &&
            currView.getLeft() == 0 && currView.getRight() == currView.getWidth()
            ) {
        dOffset += dx;
        if (lastTouchEvent != null) {
            currView.dispatchTouchEvent(lastTouchEvent);
            lastTouchEvent = null;
        }
        ViewCompat.setOverScrollMode(recyclerView, ViewCompat.OVER_SCROLL_NEVER);
        return 0;
    } else {
        dOffset = 0;
        ViewCompat.setOverScrollMode(recyclerView, ViewCompat.OVER_SCROLL_ALWAYS);
        return super.scrollHorizontallyBy(dx, recycler, state);
    }
}
 

public static boolean a(View view, int i)
{
    return view.canScrollHorizontally(i);
}
 

public static boolean canScrollHorizontally(View v, int direction) {
    return v.canScrollHorizontally(direction);
}
 

/**
 * view是否已经滚动到最左边
 *
 * @param view
 * @return
 */
public static boolean isScrollToLeft(View view)
{
    return !view.canScrollHorizontally(-1);
}
 

/**
 * view是否已经滚动到最右边
 *
 * @param view
 * @return
 */
public static boolean isScrollToRight(View view)
{
    return !view.canScrollHorizontally(1);
}