1/*
2 * Copyright (C) 2011 Google Inc. All rights reserved.
3 * Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies)
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * 1.  Redistributions of source code must retain the above copyright
10 *     notice, this list of conditions and the following disclaimer.
11 * 2.  Redistributions in binary form must reproduce the above copyright
12 *     notice, this list of conditions and the following disclaimer in the
13 *     documentation and/or other materials provided with the distribution.
14 * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
15 *     its contributors may be used to endorse or promote products derived
16 *     from this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
19 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
20 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
21 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
22 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
23 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
24 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
25 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 */
29
30#include "config.h"
31#include "GestureTapHighlighter.h"
32
33#include "Element.h"
34#include "Frame.h"
35#include "FrameView.h"
36#include "GraphicsContext.h"
37#include "GraphicsTypes.h"
38#include "Node.h"
39#include "Page.h"
40#include "RenderBoxModelObject.h"
41#include "RenderInline.h"
42#include "RenderLayer.h"
43#include "RenderObject.h"
44
45namespace WebCore {
46
47namespace {
48
49inline LayoutPoint ownerFrameToMainFrameOffset(const RenderObject* o)
50{
51    ASSERT(o->node());
52    Frame* containingFrame = o->frame();
53    if (!containingFrame)
54        return LayoutPoint();
55
56    Frame* mainFrame = containingFrame->page()->mainFrame();
57
58    LayoutPoint mainFramePoint = mainFrame->view()->windowToContents(containingFrame->view()->contentsToWindow(IntPoint()));
59    return mainFramePoint;
60}
61
62AffineTransform localToAbsoluteTransform(const RenderObject* o)
63{
64    AffineTransform transform;
65    LayoutPoint referencePoint;
66
67    while (o) {
68        RenderObject* nextContainer = o->container();
69        if (!nextContainer)
70            break;
71
72        LayoutSize containerOffset = o->offsetFromContainer(nextContainer, referencePoint);
73        TransformationMatrix t;
74        o->getTransformFromContainer(nextContainer, containerOffset, t);
75
76        transform = t.toAffineTransform() * transform;
77        referencePoint.move(containerOffset);
78        o = nextContainer;
79    }
80
81    return transform;
82}
83
84inline bool contains(const LayoutRect& rect, int x)
85{
86    return !rect.isEmpty() && x >= rect.x() && x <= rect.maxX();
87}
88
89inline bool strikes(const LayoutRect& a, const LayoutRect& b)
90{
91    return !a.isEmpty() && !b.isEmpty()
92        && a.x() <= b.maxX() && b.x() <= a.maxX()
93        && a.y() <= b.maxY() && b.y() <= a.maxY();
94}
95
96inline void shiftXEdgesToContainIfStrikes(LayoutRect& rect, LayoutRect& other, bool isFirst)
97{
98    if (rect.isEmpty())
99        return;
100
101    if (other.isEmpty() || !strikes(rect, other))
102        return;
103
104    LayoutUnit leftSide = std::min(rect.x(), other.x());
105    LayoutUnit rightSide = std::max(rect.maxX(), other.maxX());
106
107    rect.shiftXEdgeTo(leftSide);
108    rect.shiftMaxXEdgeTo(rightSide);
109
110    if (isFirst)
111        other.shiftMaxXEdgeTo(rightSide);
112    else
113        other.shiftXEdgeTo(leftSide);
114}
115
116inline void addHighlightRect(Path& path, const LayoutRect& rect, const LayoutRect& prev, const LayoutRect& next)
117{
118    // The rounding check depends on the rects not intersecting eachother,
119    // or being contained for that matter.
120    ASSERT(!rect.intersects(prev));
121    ASSERT(!rect.intersects(next));
122
123    if (rect.isEmpty())
124        return;
125
126    const int rounding = 4;
127
128    FloatRect copy(rect);
129    copy.inflateX(rounding);
130    copy.inflateY(rounding / 2);
131
132    FloatSize rounded(rounding * 1.8, rounding * 1.8);
133    FloatSize squared(0, 0);
134
135    path.addBeziersForRoundedRect(copy,
136            contains(prev, rect.x()) ? squared : rounded,
137            contains(prev, rect.maxX()) ? squared : rounded,
138            contains(next, rect.x()) ? squared : rounded,
139            contains(next, rect.maxX()) ? squared : rounded);
140}
141
142Path absolutePathForRenderer(RenderObject* const o)
143{
144    ASSERT(o);
145
146    Vector<IntRect> rects;
147    LayoutPoint frameOffset = ownerFrameToMainFrameOffset(o);
148    o->addFocusRingRects(rects, frameOffset);
149
150    if (rects.isEmpty())
151        return Path();
152
153    // The basic idea is to allow up to three different boxes in order to highlight
154    // text with line breaks more nicer than using a bounding box.
155
156    // Merge all center boxes (all but the first and the last).
157    LayoutRect mid;
158
159    // Set the end value to integer. It ensures that no unsigned int overflow occurs
160    // in the test expression, in case of empty rects vector.
161    int end = rects.size() - 1;
162    for (int i = 1; i < end; ++i)
163        mid.uniteIfNonZero(rects.at(i));
164
165    LayoutRect first;
166    LayoutRect last;
167
168    // Add the first box, but merge it with the center boxes if it intersects or if the center box is empty.
169    if (rects.size() && !rects.first().isEmpty()) {
170        // If the mid box is empty at this point, unite it with the first box. This allows the first box to be
171        // united with the last box if they intersect in the following check for last. Not uniting them would
172        // trigger in assert in addHighlighRect due to the first and the last box intersecting, but being passed
173        // as two separate boxes.
174        if (mid.isEmpty() || mid.intersects(rects.first()))
175            mid.unite(rects.first());
176        else {
177            first = rects.first();
178            shiftXEdgesToContainIfStrikes(mid, first, /* isFirst */ true);
179        }
180    }
181
182    // Add the last box, but merge it with the center boxes if it intersects.
183    if (rects.size() > 1 && !rects.last().isEmpty()) {
184        // Adjust center boxes to boundary of last
185        if (mid.intersects(rects.last()))
186            mid.unite(rects.last());
187        else {
188            last = rects.last();
189            shiftXEdgesToContainIfStrikes(mid, last, /* isFirst */ false);
190        }
191    }
192
193    Vector<LayoutRect> drawableRects;
194    if (!first.isEmpty())
195        drawableRects.append(first);
196    if (!mid.isEmpty())
197        drawableRects.append(mid);
198    if (!last.isEmpty())
199        drawableRects.append(last);
200
201    // Clip the overflow rects if needed, before the ring path is formed to
202    // ensure rounded highlight rects. This clipping has the problem with nested
203    // divs with transforms, which could be resolved by proper Path::intersecting.
204    for (int i = drawableRects.size() - 1; i >= 0; --i) {
205        LayoutRect& ringRect = drawableRects.at(i);
206        LayoutPoint ringRectLocation = ringRect.location();
207
208        ringRect.moveBy(-frameOffset);
209
210        RenderLayer* layer = o->enclosingLayer();
211        RenderObject* currentRenderer = o;
212
213        // Check ancestor layers for overflow clip and intersect them.
214        for (; layer; layer = layer->parent()) {
215            RenderLayerModelObject* layerRenderer = layer->renderer();
216
217            if (layerRenderer->hasOverflowClip() && layerRenderer != currentRenderer) {
218                bool containerSkipped = false;
219                // Skip ancestor layers that are not containers for the current renderer.
220                currentRenderer->container(layerRenderer, &containerSkipped);
221                if (containerSkipped)
222                    continue;
223                ringRect.move(currentRenderer->offsetFromAncestorContainer(layerRenderer));
224                currentRenderer = layerRenderer;
225
226                ASSERT(layerRenderer->isBox());
227                ringRect.intersect(toRenderBox(layerRenderer)->borderBoxRect());
228
229                if (ringRect.isEmpty())
230                    break;
231            }
232        }
233
234        if (ringRect.isEmpty()) {
235            drawableRects.remove(i);
236            continue;
237        }
238        // After clipping, reset the original position so that parents' transforms apply correctly.
239        ringRect.setLocation(ringRectLocation);
240    }
241
242    Path path;
243    for (size_t i = 0; i < drawableRects.size(); ++i) {
244        LayoutRect prev = i ? drawableRects.at(i - 1) : LayoutRect();
245        LayoutRect next = i < (drawableRects.size() - 1) ? drawableRects.at(i + 1) : LayoutRect();
246        addHighlightRect(path, drawableRects.at(i), prev, next);
247    }
248
249    path.transform(localToAbsoluteTransform(o));
250    return path;
251}
252
253} // anonymous namespace
254
255namespace GestureTapHighlighter {
256
257Path pathForNodeHighlight(const Node* node)
258{
259    RenderObject* renderer = node->renderer();
260
261    if (!renderer || (!renderer->isBox() && !renderer->isRenderInline()))
262        return Path();
263
264    return absolutePathForRenderer(renderer);
265}
266
267} // namespace GestureTapHighlighter
268
269} // namespace WebCore
270