| /* |
| * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved. |
| * |
| * Portions are Copyright (C) 1998 Netscape Communications Corporation. |
| * |
| * Other contributors: |
| * Robert O'Callahan <roc+@cs.cmu.edu> |
| * David Baron <dbaron@fas.harvard.edu> |
| * Christian Biesinger <cbiesinger@web.de> |
| * Randall Jesup <rjesup@wgate.com> |
| * Roland Mainz <roland.mainz@informatik.med.uni-giessen.de> |
| * Josh Soref <timeless@mac.com> |
| * Boris Zbarsky <bzbarsky@mit.edu> |
| * |
| * This library is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Lesser General Public |
| * License as published by the Free Software Foundation; either |
| * version 2.1 of the License, or (at your option) any later version. |
| * |
| * This library is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * Lesser General Public License for more details. |
| * |
| * You should have received a copy of the GNU Lesser General Public |
| * License along with this library; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| * |
| * Alternatively, the contents of this file may be used under the terms |
| * of either the Mozilla Public License Version 1.1, found at |
| * http://www.mozilla.org/MPL/ (the "MPL") or the GNU General Public |
| * License Version 2.0, found at http://www.fsf.org/copyleft/gpl.html |
| * (the "GPL"), in which case the provisions of the MPL or the GPL are |
| * applicable instead of those above. If you wish to allow use of your |
| * version of this file only under the terms of one of those two |
| * licenses (the MPL or the GPL) and not to allow others to use your |
| * version of this file under the LGPL, indicate your decision by |
| * deletingthe provisions above and replace them with the notice and |
| * other provisions required by the MPL or the GPL, as the case may be. |
| * If you do not delete the provisions above, a recipient may use your |
| * version of this file under any of the LGPL, the MPL or the GPL. |
| */ |
| |
| #include "config.h" |
| #include "core/rendering/ScrollBehavior.h" |
| |
| #include "platform/geometry/LayoutRect.h" |
| |
| namespace WebCore { |
| |
| const ScrollAlignment ScrollAlignment::alignCenterIfNeeded = { noScroll, alignCenter, alignToClosestEdge }; |
| const ScrollAlignment ScrollAlignment::alignToEdgeIfNeeded = { noScroll, alignToClosestEdge, alignToClosestEdge }; |
| const ScrollAlignment ScrollAlignment::alignCenterAlways = { alignCenter, alignCenter, alignCenter }; |
| const ScrollAlignment ScrollAlignment::alignTopAlways = { alignTop, alignTop, alignTop }; |
| const ScrollAlignment ScrollAlignment::alignBottomAlways = { alignBottom, alignBottom, alignBottom }; |
| |
| #define MIN_INTERSECT_FOR_REVEAL 32 |
| |
| LayoutRect ScrollAlignment::getRectToExpose(const LayoutRect& visibleRect, const LayoutRect& exposeRect, const ScrollAlignment& alignX, const ScrollAlignment& alignY) |
| { |
| // Determine the appropriate X behavior. |
| ScrollBehavior scrollX; |
| LayoutRect exposeRectX(exposeRect.x(), visibleRect.y(), exposeRect.width(), visibleRect.height()); |
| LayoutUnit intersectWidth = intersection(visibleRect, exposeRectX).width(); |
| if (intersectWidth == exposeRect.width() || intersectWidth >= MIN_INTERSECT_FOR_REVEAL) { |
| // If the rectangle is fully visible, use the specified visible behavior. |
| // If the rectangle is partially visible, but over a certain threshold, |
| // then treat it as fully visible to avoid unnecessary horizontal scrolling |
| scrollX = getVisibleBehavior(alignX); |
| } else if (intersectWidth == visibleRect.width()) { |
| // If the rect is bigger than the visible area, don't bother trying to center. Other alignments will work. |
| scrollX = getVisibleBehavior(alignX); |
| if (scrollX == alignCenter) |
| scrollX = noScroll; |
| } else if (intersectWidth > 0) { |
| // If the rectangle is partially visible, but not above the minimum threshold, use the specified partial behavior |
| scrollX = getPartialBehavior(alignX); |
| } else { |
| scrollX = getHiddenBehavior(alignX); |
| } |
| |
| if (scrollX == alignToClosestEdge) { |
| // Closest edge is the right in two cases: |
| // (1) exposeRect to the right of and smaller than visibleRect |
| // (2) exposeRect to the left of and larger than visibleRect |
| if ((exposeRect.maxX() > visibleRect.maxX() && exposeRect.width() < visibleRect.width()) |
| || (exposeRect.maxX() < visibleRect.maxX() && exposeRect.width() > visibleRect.width())) { |
| scrollX = alignRight; |
| } |
| } |
| |
| // Given the X behavior, compute the X coordinate. |
| LayoutUnit x; |
| if (scrollX == noScroll) |
| x = visibleRect.x(); |
| else if (scrollX == alignRight) |
| x = exposeRect.maxX() - visibleRect.width(); |
| else if (scrollX == alignCenter) |
| x = exposeRect.x() + (exposeRect.width() - visibleRect.width()) / 2; |
| else |
| x = exposeRect.x(); |
| |
| // Determine the appropriate Y behavior. |
| ScrollBehavior scrollY; |
| LayoutRect exposeRectY(visibleRect.x(), exposeRect.y(), visibleRect.width(), exposeRect.height()); |
| LayoutUnit intersectHeight = intersection(visibleRect, exposeRectY).height(); |
| if (intersectHeight == exposeRect.height()) { |
| // If the rectangle is fully visible, use the specified visible behavior. |
| scrollY = getVisibleBehavior(alignY); |
| } else if (intersectHeight == visibleRect.height()) { |
| // If the rect is bigger than the visible area, don't bother trying to center. Other alignments will work. |
| scrollY = getVisibleBehavior(alignY); |
| if (scrollY == alignCenter) |
| scrollY = noScroll; |
| } else if (intersectHeight > 0) { |
| // If the rectangle is partially visible, use the specified partial behavior |
| scrollY = getPartialBehavior(alignY); |
| } else { |
| scrollY = getHiddenBehavior(alignY); |
| } |
| |
| if (scrollY == alignToClosestEdge) { |
| // Closest edge is the bottom in two cases: |
| // (1) exposeRect below and smaller than visibleRect |
| // (2) exposeRect above and larger than visibleRect |
| if ((exposeRect.maxY() > visibleRect.maxY() && exposeRect.height() < visibleRect.height()) |
| || (exposeRect.maxY() < visibleRect.maxY() && exposeRect.height() > visibleRect.height())) { |
| scrollY = alignBottom; |
| } |
| } |
| |
| // Given the Y behavior, compute the Y coordinate. |
| LayoutUnit y; |
| if (scrollY == noScroll) |
| y = visibleRect.y(); |
| else if (scrollY == alignBottom) |
| y = exposeRect.maxY() - visibleRect.height(); |
| else if (scrollY == alignCenter) |
| y = exposeRect.y() + (exposeRect.height() - visibleRect.height()) / 2; |
| else |
| y = exposeRect.y(); |
| |
| return LayoutRect(LayoutPoint(x, y), visibleRect.size()); |
| } |
| |
| }; // namespace WebCore |