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 blink {
51
52static void adjustClipRectsForChildren(const RenderObject& renderer, ClipRects& clipRects)
53{
54    EPosition position = renderer.style()->position();
55    // A fixed object is essentially the root of its containing block hierarchy, so when
56    // we encounter such an object, we reset our clip rects to the fixedClipRect.
57    if (position == FixedPosition) {
58        clipRects.setPosClipRect(clipRects.fixedClipRect());
59        clipRects.setOverflowClipRect(clipRects.fixedClipRect());
60        clipRects.setFixed(true);
61    } else if (position == RelativePosition) {
62        clipRects.setPosClipRect(clipRects.overflowClipRect());
63    } else if (position == AbsolutePosition) {
64        clipRects.setOverflowClipRect(clipRects.posClipRect());
65    }
66}
67
68static void applyClipRects(const ClipRectsContext& context, RenderObject& renderer, LayoutPoint offset, ClipRects& clipRects)
69{
70    ASSERT(renderer.hasOverflowClip() || renderer.hasClip());
71
72    RenderView* view = renderer.view();
73    ASSERT(view);
74    if (clipRects.fixed() && context.rootLayer->renderer() == view)
75        offset -= view->frameView()->scrollOffsetForFixedPosition();
76
77    if (renderer.hasOverflowClip()) {
78        ClipRect newOverflowClip = toRenderBox(renderer).overflowClipRect(offset, context.scrollbarRelevancy);
79        newOverflowClip.setHasRadius(renderer.style()->hasBorderRadius());
80        clipRects.setOverflowClipRect(intersection(newOverflowClip, clipRects.overflowClipRect()));
81        if (renderer.isPositioned())
82            clipRects.setPosClipRect(intersection(newOverflowClip, clipRects.posClipRect()));
83    }
84
85    if (renderer.hasClip()) {
86        LayoutRect newClip = toRenderBox(renderer).clipRect(offset);
87        clipRects.setPosClipRect(intersection(newClip, clipRects.posClipRect()));
88        clipRects.setOverflowClipRect(intersection(newClip, clipRects.overflowClipRect()));
89        clipRects.setFixedClipRect(intersection(newClip, clipRects.fixedClipRect()));
90    }
91}
92
93RenderLayerClipper::RenderLayerClipper(RenderLayerModelObject& renderer)
94    : m_renderer(renderer)
95{
96}
97
98ClipRects* RenderLayerClipper::clipRectsIfCached(const ClipRectsContext& context) const
99{
100    ASSERT(context.usesCache());
101    if (!m_cache)
102        return 0;
103    ClipRectsCache::Entry& entry = m_cache->get(context.cacheSlot);
104    // FIXME: We used to ASSERT that we always got a consistent root layer.
105    // We should add a test that has an inconsistent root. See
106    // http://crbug.com/366118 for an example.
107    if (context.rootLayer != entry.root)
108        return 0;
109    ASSERT(entry.scrollbarRelevancy == context.scrollbarRelevancy);
110
111#ifdef CHECK_CACHED_CLIP_RECTS
112    // This code is useful to check cached clip rects, but is too expensive to leave enabled in debug builds by default.
113    ClipRectsContext tempContext(context);
114    tempContext.cacheSlot = UncachedClipRects;
115    ClipRects clipRects;
116    calculateClipRects(tempContext, clipRects);
117    ASSERT(clipRects == *entry.clipRects);
118#endif
119
120    return entry.clipRects.get();
121}
122
123ClipRects* RenderLayerClipper::storeClipRectsInCache(const ClipRectsContext& context, ClipRects* parentClipRects, const ClipRects& clipRects) const
124{
125    ClipRectsCache::Entry& entry = cache().get(context.cacheSlot);
126    entry.root = context.rootLayer;
127#if ENABLE(ASSERT)
128    entry.scrollbarRelevancy = context.scrollbarRelevancy;
129#endif
130
131    if (parentClipRects) {
132        // If our clip rects match the clip rects of our parent, we share storage.
133        if (clipRects == *parentClipRects) {
134            entry.clipRects = parentClipRects;
135            return parentClipRects;
136        }
137    }
138
139    entry.clipRects = ClipRects::create(clipRects);
140    return entry.clipRects.get();
141}
142
143ClipRects* RenderLayerClipper::getClipRects(const ClipRectsContext& context) const
144{
145    if (ClipRects* result = clipRectsIfCached(context))
146        return result;
147
148    // Note that it's important that we call getClipRects on our parent
149    // before we call calculateClipRects so that calculateClipRects will hit
150    // the cache.
151    ClipRects* parentClipRects = 0;
152    if (context.rootLayer != m_renderer.layer() && m_renderer.layer()->parent())
153        parentClipRects = m_renderer.layer()->parent()->clipper().getClipRects(context);
154
155    ClipRects clipRects;
156    calculateClipRects(context, clipRects);
157    return storeClipRectsInCache(context, parentClipRects, clipRects);
158}
159
160void RenderLayerClipper::clearClipRectsIncludingDescendants()
161{
162    m_cache = nullptr;
163
164    for (RenderLayer* layer = m_renderer.layer()->firstChild(); layer; layer = layer->nextSibling())
165        layer->clipper().clearClipRectsIncludingDescendants();
166}
167
168void RenderLayerClipper::clearClipRectsIncludingDescendants(ClipRectsCacheSlot cacheSlot)
169{
170    if (m_cache)
171        m_cache->clear(cacheSlot);
172
173    for (RenderLayer* layer = m_renderer.layer()->firstChild(); layer; layer = layer->nextSibling())
174        layer->clipper().clearClipRectsIncludingDescendants(cacheSlot);
175}
176
177LayoutRect RenderLayerClipper::childrenClipRect() const
178{
179    // FIXME: border-radius not accounted for.
180    // FIXME: Regions not accounted for.
181    RenderLayer* clippingRootLayer = clippingRootForPainting();
182    LayoutRect layerBounds;
183    ClipRect backgroundRect, foregroundRect, outlineRect;
184    // Need to use uncached clip rects, because the value of 'dontClipToOverflow' may be different from the painting path (<rdar://problem/11844909>).
185    ClipRectsContext context(clippingRootLayer, UncachedClipRects);
186    calculateRects(context, m_renderer.view()->unscaledDocumentRect(), layerBounds, backgroundRect, foregroundRect, outlineRect);
187    return clippingRootLayer->renderer()->localToAbsoluteQuad(FloatQuad(foregroundRect.rect())).enclosingBoundingBox();
188}
189
190LayoutRect RenderLayerClipper::localClipRect() const
191{
192    // FIXME: border-radius not accounted for.
193    RenderLayer* clippingRootLayer = clippingRootForPainting();
194    LayoutRect layerBounds;
195    ClipRect backgroundRect, foregroundRect, outlineRect;
196    ClipRectsContext context(clippingRootLayer, PaintingClipRects);
197    calculateRects(context, PaintInfo::infiniteRect(), layerBounds, backgroundRect, foregroundRect, outlineRect);
198
199    LayoutRect clipRect = backgroundRect.rect();
200    if (clipRect == PaintInfo::infiniteRect())
201        return clipRect;
202
203    LayoutPoint clippingRootOffset;
204    m_renderer.layer()->convertToLayerCoords(clippingRootLayer, clippingRootOffset);
205    clipRect.moveBy(-clippingRootOffset);
206
207    return clipRect;
208}
209
210void RenderLayerClipper::calculateRects(const ClipRectsContext& context, const LayoutRect& paintDirtyRect, LayoutRect& layerBounds,
211    ClipRect& backgroundRect, ClipRect& foregroundRect, ClipRect& outlineRect, const LayoutPoint* offsetFromRoot) const
212{
213    bool isClippingRoot = m_renderer.layer() == context.rootLayer;
214
215    if (!isClippingRoot && m_renderer.layer()->parent()) {
216        backgroundRect = backgroundClipRect(context);
217        backgroundRect.move(roundedIntSize(context.subPixelAccumulation));
218        backgroundRect.intersect(paintDirtyRect);
219    } else {
220        backgroundRect = paintDirtyRect;
221    }
222
223    foregroundRect = backgroundRect;
224    outlineRect = backgroundRect;
225
226    LayoutPoint offset;
227    if (offsetFromRoot)
228        offset = *offsetFromRoot;
229    else
230        m_renderer.layer()->convertToLayerCoords(context.rootLayer, offset);
231    layerBounds = LayoutRect(offset, m_renderer.layer()->size());
232
233    // Update the clip rects that will be passed to child layers.
234    if (m_renderer.hasOverflowClip()) {
235        // This layer establishes a clip of some kind.
236        if (!isClippingRoot || context.respectOverflowClip == RespectOverflowClip) {
237            foregroundRect.intersect(toRenderBox(m_renderer).overflowClipRect(offset, context.scrollbarRelevancy));
238            if (m_renderer.style()->hasBorderRadius())
239                foregroundRect.setHasRadius(true);
240        }
241
242        // If we establish an overflow clip at all, then go ahead and make sure our background
243        // rect is intersected with our layer's bounds including our visual overflow,
244        // since any visual overflow like box-shadow or border-outset is not clipped by overflow:auto/hidden.
245        if (toRenderBox(m_renderer).hasVisualOverflow()) {
246            // FIXME: Perhaps we should be propagating the borderbox as the clip rect for children, even though
247            //        we may need to inflate our clip specifically for shadows or outsets.
248            // FIXME: Does not do the right thing with CSS regions yet, since we don't yet factor in the
249            // individual region boxes as overflow.
250            LayoutRect layerBoundsWithVisualOverflow = toRenderBox(m_renderer).visualOverflowRect();
251            toRenderBox(m_renderer).flipForWritingMode(layerBoundsWithVisualOverflow); // Layers are in physical coordinates, so the overflow has to be flipped.
252            layerBoundsWithVisualOverflow.moveBy(offset);
253            if (!isClippingRoot || context.respectOverflowClip == RespectOverflowClip)
254                backgroundRect.intersect(layerBoundsWithVisualOverflow);
255        } else {
256            LayoutRect bounds = toRenderBox(m_renderer).borderBoxRect();
257            bounds.moveBy(offset);
258            if (!isClippingRoot || context.respectOverflowClip == RespectOverflowClip)
259                backgroundRect.intersect(bounds);
260        }
261    }
262
263    // CSS clip (different than clipping due to overflow) can clip to any box, even if it falls outside of the border box.
264    if (m_renderer.hasClip()) {
265        // Clip applies to *us* as well, so go ahead and update the damageRect.
266        LayoutRect newPosClip = toRenderBox(m_renderer).clipRect(offset);
267        backgroundRect.intersect(newPosClip);
268        foregroundRect.intersect(newPosClip);
269        outlineRect.intersect(newPosClip);
270    }
271}
272
273void RenderLayerClipper::calculateClipRects(const ClipRectsContext& context, ClipRects& clipRects) const
274{
275    if (!m_renderer.layer()->parent()) {
276        // The root layer's clip rect is always infinite.
277        clipRects.reset(PaintInfo::infiniteRect());
278        return;
279    }
280
281    bool isClippingRoot = m_renderer.layer() == context.rootLayer;
282
283    // For transformed layers, the root layer was shifted to be us, so there is no need to
284    // examine the parent. We want to cache clip rects with us as the root.
285    RenderLayer* parentLayer = !isClippingRoot ? m_renderer.layer()->parent() : 0;
286
287    // Ensure that our parent's clip has been calculated so that we can examine the values.
288    if (parentLayer) {
289        // FIXME: Why don't we just call getClipRects here?
290        if (context.usesCache() && parentLayer->clipper().cachedClipRects(context)) {
291            clipRects = *parentLayer->clipper().cachedClipRects(context);
292        } else {
293            parentLayer->clipper().calculateClipRects(context, clipRects);
294        }
295    } else {
296        clipRects.reset(PaintInfo::infiniteRect());
297    }
298
299    adjustClipRectsForChildren(m_renderer, clipRects);
300
301    // FIXME: This logic looks wrong. We'll apply overflow clip rects even if we were told to IgnoreOverflowClip if m_renderer.hasClip().
302    if ((m_renderer.hasOverflowClip() && (context.respectOverflowClip == RespectOverflowClip || !isClippingRoot)) || m_renderer.hasClip()) {
303        // This offset cannot use convertToLayerCoords, because sometimes our rootLayer may be across
304        // some transformed layer boundary, for example, in the RenderLayerCompositor overlapMap, where
305        // clipRects are needed in view space.
306        applyClipRects(context, m_renderer, roundedLayoutPoint(m_renderer.localToContainerPoint(FloatPoint(), context.rootLayer->renderer())), clipRects);
307    }
308}
309
310static ClipRect backgroundClipRectForPosition(const ClipRects& parentRects, EPosition position)
311{
312    if (position == FixedPosition)
313        return parentRects.fixedClipRect();
314
315    if (position == AbsolutePosition)
316        return parentRects.posClipRect();
317
318    return parentRects.overflowClipRect();
319}
320
321ClipRect RenderLayerClipper::backgroundClipRect(const ClipRectsContext& context) const
322{
323    ASSERT(m_renderer.layer()->parent());
324    ASSERT(m_renderer.view());
325
326    ClipRects parentClipRects;
327    if (m_renderer.layer() == context.rootLayer)
328        parentClipRects.reset(PaintInfo::infiniteRect());
329    else
330        m_renderer.layer()->parent()->clipper().getOrCalculateClipRects(context, parentClipRects);
331
332    ClipRect result = backgroundClipRectForPosition(parentClipRects, m_renderer.style()->position());
333
334    // Note: infinite clipRects should not be scrolled here, otherwise they will accidentally no longer be considered infinite.
335    if (parentClipRects.fixed() && context.rootLayer->renderer() == m_renderer.view() && result != PaintInfo::infiniteRect())
336        result.move(m_renderer.view()->frameView()->scrollOffsetForFixedPosition());
337
338    return result;
339}
340
341void RenderLayerClipper::getOrCalculateClipRects(const ClipRectsContext& context, ClipRects& clipRects) const
342{
343    if (context.usesCache())
344        clipRects = *getClipRects(context);
345    else
346        calculateClipRects(context, clipRects);
347}
348
349RenderLayer* RenderLayerClipper::clippingRootForPainting() const
350{
351    const RenderLayer* current = m_renderer.layer();
352    // FIXME: getting rid of current->hasCompositedLayerMapping() here breaks the
353    // compositing/backing/no-backing-for-clip.html layout test, because there is a
354    // "composited but paints into ancestor" layer involved. However, it doesn't make sense that
355    // that check would be appropriate here but not inside the while loop below.
356    if (current->isPaintInvalidationContainer() || current->hasCompositedLayerMapping())
357        return const_cast<RenderLayer*>(current);
358
359    while (current) {
360        if (current->isRootLayer())
361            return const_cast<RenderLayer*>(current);
362
363        current = current->compositingContainer();
364        ASSERT(current);
365        if (current->transform() || current->isPaintInvalidationContainer())
366            return const_cast<RenderLayer*>(current);
367    }
368
369    ASSERT_NOT_REACHED();
370    return 0;
371}
372
373} // namespace blink
374