1/*
2 * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
3 *
4 * Portions are Copyright (C) 1998 Netscape Communications Corporation.
5 *
6 * Other contributors:
7 *   Robert O'Callahan <roc+@cs.cmu.edu>
8 *   David Baron <dbaron@fas.harvard.edu>
9 *   Christian Biesinger <cbiesinger@web.de>
10 *   Randall Jesup <rjesup@wgate.com>
11 *   Roland Mainz <roland.mainz@informatik.med.uni-giessen.de>
12 *   Josh Soref <timeless@mac.com>
13 *   Boris Zbarsky <bzbarsky@mit.edu>
14 *
15 * This library is free software; you can redistribute it and/or
16 * modify it under the terms of the GNU Lesser General Public
17 * License as published by the Free Software Foundation; either
18 * version 2.1 of the License, or (at your option) any later version.
19 *
20 * This library is distributed in the hope that it will be useful,
21 * but WITHOUT ANY WARRANTY; without even the implied warranty of
22 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
23 * Lesser General Public License for more details.
24 *
25 * You should have received a copy of the GNU Lesser General Public
26 * License along with this library; if not, write to the Free Software
27 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
28 *
29 * Alternatively, the contents of this file may be used under the terms
30 * of either the Mozilla Public License Version 1.1, found at
31 * http://www.mozilla.org/MPL/ (the "MPL") or the GNU General Public
32 * License Version 2.0, found at http://www.fsf.org/copyleft/gpl.html
33 * (the "GPL"), in which case the provisions of the MPL or the GPL are
34 * applicable instead of those above.  If you wish to allow use of your
35 * version of this file only under the terms of one of those two
36 * licenses (the MPL or the GPL) and not to allow others to use your
37 * version of this file under the LGPL, indicate your decision by
38 * deletingthe provisions above and replace them with the notice and
39 * other provisions required by the MPL or the GPL, as the case may be.
40 * If you do not delete the provisions above, a recipient may use your
41 * version of this file under any of the LGPL, the MPL or the GPL.
42 */
43
44#include "config.h"
45#include "core/rendering/RenderLayerClipper.h"
46
47#include "core/rendering/RenderLayer.h"
48#include "core/rendering/RenderView.h"
49
50namespace WebCore {
51
52void RenderLayerClipper::updateClipRects(const ClipRectsContext& clipRectsContext)
53{
54    ClipRectsType clipRectsType = clipRectsContext.clipRectsType;
55    ASSERT(clipRectsType < NumCachedClipRectsTypes);
56    if (m_clipRectsCache && m_clipRectsCache->getClipRects(clipRectsType, clipRectsContext.respectOverflowClip)) {
57        // FIXME: these asserts trigger for squashing. Need to update this code to support squashing as appropriate.
58        ASSERT(clipRectsContext.rootLayer == m_clipRectsCache->m_clipRectsRoot[clipRectsType]);
59        ASSERT(m_clipRectsCache->m_scrollbarRelevancy[clipRectsType] == clipRectsContext.overlayScrollbarSizeRelevancy);
60
61#ifdef CHECK_CACHED_CLIP_RECTS
62        // This code is useful to check cached clip rects, but is too expensive to leave enabled in debug builds by default.
63        ClipRectsContext tempContext(clipRectsContext);
64        tempContext.clipRectsType = TemporaryClipRects;
65        ClipRects clipRects;
66        calculateClipRects(tempContext, clipRects);
67        ASSERT(clipRects == *m_clipRectsCache->getClipRects(clipRectsType, clipRectsContext.respectOverflowClip).get());
68#endif
69        return; // We have the correct cached value.
70    }
71
72    // For transformed layers, the root layer was shifted to be us, so there is no need to
73    // examine the parent. We want to cache clip rects with us as the root.
74    RenderLayer* parentLayer = clipRectsContext.rootLayer != m_renderer->layer() ? m_renderer->layer()->parent() : 0;
75    if (parentLayer)
76        parentLayer->clipper().updateClipRects(clipRectsContext);
77
78    ClipRects clipRects;
79    calculateClipRects(clipRectsContext, clipRects);
80
81    if (!m_clipRectsCache)
82        m_clipRectsCache = adoptPtr(new ClipRectsCache);
83
84    if (parentLayer && parentLayer->clipper().clipRects(clipRectsContext) && clipRects == *parentLayer->clipper().clipRects(clipRectsContext))
85        m_clipRectsCache->setClipRects(clipRectsType, clipRectsContext.respectOverflowClip, parentLayer->clipper().clipRects(clipRectsContext));
86    else
87        m_clipRectsCache->setClipRects(clipRectsType, clipRectsContext.respectOverflowClip, ClipRects::create(clipRects));
88
89#ifndef NDEBUG
90    m_clipRectsCache->m_clipRectsRoot[clipRectsType] = clipRectsContext.rootLayer;
91    m_clipRectsCache->m_scrollbarRelevancy[clipRectsType] = clipRectsContext.overlayScrollbarSizeRelevancy;
92#endif
93}
94
95void RenderLayerClipper::clearClipRectsIncludingDescendants(ClipRectsType typeToClear)
96{
97    // FIXME: it's not clear how this layer not having clip rects guarantees that no descendants have any.
98    if (!m_clipRectsCache)
99        return;
100
101    clearClipRects(typeToClear);
102
103    for (RenderLayer* layer = m_renderer->layer()->firstChild(); layer; layer = layer->nextSibling())
104        layer->clipper().clearClipRectsIncludingDescendants(typeToClear);
105}
106
107void RenderLayerClipper::clearClipRects(ClipRectsType typeToClear)
108{
109    if (typeToClear == AllClipRectTypes) {
110        m_clipRectsCache = nullptr;
111    } else {
112        ASSERT(typeToClear < NumCachedClipRectsTypes);
113        RefPtr<ClipRects> dummy;
114        m_clipRectsCache->setClipRects(typeToClear, RespectOverflowClip, dummy);
115        m_clipRectsCache->setClipRects(typeToClear, IgnoreOverflowClip, dummy);
116    }
117}
118
119void RenderLayerClipper::calculateClipRects(const ClipRectsContext& clipRectsContext, ClipRects& clipRects) const
120{
121    if (!m_renderer->layer()->parent()) {
122        // The root layer's clip rect is always infinite.
123        clipRects.reset(PaintInfo::infiniteRect());
124        return;
125    }
126
127    ClipRectsType clipRectsType = clipRectsContext.clipRectsType;
128    bool useCached = clipRectsType != TemporaryClipRects;
129
130    // For transformed layers, the root layer was shifted to be us, so there is no need to
131    // examine the parent. We want to cache clip rects with us as the root.
132    RenderLayer* parentLayer = clipRectsContext.rootLayer != m_renderer->layer() ? m_renderer->layer()->parent() : 0;
133
134    // Ensure that our parent's clip has been calculated so that we can examine the values.
135    if (parentLayer) {
136        if (useCached && parentLayer->clipper().clipRects(clipRectsContext)) {
137            clipRects = *parentLayer->clipper().clipRects(clipRectsContext);
138        } else {
139            ClipRectsContext parentContext(clipRectsContext);
140            parentContext.overlayScrollbarSizeRelevancy = IgnoreOverlayScrollbarSize; // FIXME: why?
141            parentLayer->clipper().calculateClipRects(parentContext, clipRects);
142        }
143    } else {
144        clipRects.reset(PaintInfo::infiniteRect());
145    }
146
147    // A fixed object is essentially the root of its containing block hierarchy, so when
148    // we encounter such an object, we reset our clip rects to the fixedClipRect.
149    if (m_renderer->style()->position() == FixedPosition) {
150        clipRects.setPosClipRect(clipRects.fixedClipRect());
151        clipRects.setOverflowClipRect(clipRects.fixedClipRect());
152        clipRects.setFixed(true);
153    } else if (m_renderer->style()->hasInFlowPosition()) {
154        clipRects.setPosClipRect(clipRects.overflowClipRect());
155    } else if (m_renderer->style()->position() == AbsolutePosition) {
156        clipRects.setOverflowClipRect(clipRects.posClipRect());
157    }
158
159    // Update the clip rects that will be passed to child layers.
160    if ((m_renderer->hasOverflowClip() && (clipRectsContext.respectOverflowClip == RespectOverflowClip || m_renderer->layer() != clipRectsContext.rootLayer)) || m_renderer->hasClip()) {
161        // This layer establishes a clip of some kind.
162
163        // This offset cannot use convertToLayerCoords, because sometimes our rootLayer may be across
164        // some transformed layer boundary, for example, in the RenderLayerCompositor overlapMap, where
165        // clipRects are needed in view space.
166        LayoutPoint offset;
167        offset = roundedLayoutPoint(m_renderer->localToContainerPoint(FloatPoint(), clipRectsContext.rootLayer->renderer()));
168        RenderView* view = m_renderer->view();
169        ASSERT(view);
170        if (view && clipRects.fixed() && clipRectsContext.rootLayer->renderer() == view) {
171            offset -= view->frameView()->scrollOffsetForFixedPosition();
172        }
173
174        if (m_renderer->hasOverflowClip()) {
175            ClipRect newOverflowClip = toRenderBox(m_renderer)->overflowClipRect(offset, clipRectsContext.region, clipRectsContext.overlayScrollbarSizeRelevancy);
176            if (m_renderer->style()->hasBorderRadius())
177                newOverflowClip.setHasRadius(true);
178            clipRects.setOverflowClipRect(intersection(newOverflowClip, clipRects.overflowClipRect()));
179            if (m_renderer->isPositioned())
180                clipRects.setPosClipRect(intersection(newOverflowClip, clipRects.posClipRect()));
181        }
182        if (m_renderer->hasClip()) {
183            LayoutRect newPosClip = toRenderBox(m_renderer)->clipRect(offset, clipRectsContext.region);
184            clipRects.setPosClipRect(intersection(newPosClip, clipRects.posClipRect()));
185            clipRects.setOverflowClipRect(intersection(newPosClip, clipRects.overflowClipRect()));
186            clipRects.setFixedClipRect(intersection(newPosClip, clipRects.fixedClipRect()));
187        }
188    }
189}
190
191} // namespace WebCore
192