1 /*
2 * Copyright (C) 2012 Victor Carbune (victor@rosedu.org)
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE COMPUTER, INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26 #include "config.h"
27 #include "core/rendering/RenderVTTCue.h"
28
29 #include "core/html/track/vtt/VTTCue.h"
30 #include "core/rendering/RenderView.h"
31
32 namespace blink {
33
RenderVTTCue(VTTCueBox * element)34 RenderVTTCue::RenderVTTCue(VTTCueBox* element)
35 : RenderBlockFlow(element)
36 , m_cue(element->getCue())
37 {
38 }
39
layout()40 void RenderVTTCue::layout()
41 {
42 RenderBlockFlow::layout();
43
44 // If WebVTT Regions are used, the regular WebVTT layout algorithm is no
45 // longer necessary, since cues having the region parameter set do not have
46 // any positioning parameters. Also, in this case, the regions themselves
47 // have positioning information.
48 if (!m_cue->regionId().isEmpty())
49 return;
50
51 LayoutState state(*this, locationOffset());
52
53 if (m_cue->snapToLines())
54 repositionCueSnapToLinesSet();
55 else
56 repositionCueSnapToLinesNotSet();
57 }
58
findFirstLineBox(InlineFlowBox * & firstLineBox)59 bool RenderVTTCue::findFirstLineBox(InlineFlowBox*& firstLineBox)
60 {
61 if (firstChild()->isRenderInline())
62 firstLineBox = toRenderInline(firstChild())->firstLineBox();
63 else
64 return false;
65
66 return true;
67 }
68
initializeLayoutParameters(InlineFlowBox * firstLineBox,LayoutUnit & step,LayoutUnit & position)69 bool RenderVTTCue::initializeLayoutParameters(InlineFlowBox* firstLineBox, LayoutUnit& step, LayoutUnit& position)
70 {
71 ASSERT(firstChild());
72
73 RenderBlock* parentBlock = containingBlock();
74
75 // 1. Horizontal: Let step be the height of the first line box in boxes.
76 // Vertical: Let step be the width of the first line box in boxes.
77 step = m_cue->getWritingDirection() == VTTCue::Horizontal ? firstLineBox->height() : firstLineBox->width();
78
79 // 2. If step is zero, then jump to the step labeled done positioning below.
80 if (!step)
81 return false;
82
83 // 3. Let line position be the text track cue computed line position.
84 int linePosition = m_cue->calculateComputedLinePosition();
85
86 // 4. Vertical Growing Left: Add one to line position then negate it.
87 if (m_cue->getWritingDirection() == VTTCue::VerticalGrowingLeft)
88 linePosition = -(linePosition + 1);
89
90 // 5. Let position be the result of multiplying step and line position.
91 position = step * linePosition;
92
93 // 6. Vertical Growing Left: Decrease position by the width of the
94 // bounding box of the boxes in boxes, then increase position by step.
95 if (m_cue->getWritingDirection() == VTTCue::VerticalGrowingLeft) {
96 position -= width();
97 position += step;
98 }
99
100 // 7. If line position is less than zero...
101 if (linePosition < 0) {
102 // Horizontal / Vertical: ... then increase position by the
103 // height / width of the video's rendering area ...
104 position += m_cue->getWritingDirection() == VTTCue::Horizontal ? parentBlock->height() : parentBlock->width();
105
106 // ... and negate step.
107 step = -step;
108 }
109
110 return true;
111 }
112
placeBoxInDefaultPosition(LayoutUnit position,bool & switched)113 void RenderVTTCue::placeBoxInDefaultPosition(LayoutUnit position, bool& switched)
114 {
115 // 8. Move all boxes in boxes ...
116 if (m_cue->getWritingDirection() == VTTCue::Horizontal) {
117 // Horizontal: ... down by the distance given by position
118 setY(y() + position);
119 } else {
120 // Vertical: ... right by the distance given by position
121 setX(x() + position);
122 }
123
124 // 9. Default: Remember the position of all the boxes in boxes as their
125 // default position.
126 // FIXME: Why the direct conversion between float and LayoutUnit? crbug.com/350474
127 m_fallbackPosition = FloatPoint(location());
128
129 // 10. Let switched be false.
130 switched = false;
131 }
132
isOutside() const133 bool RenderVTTCue::isOutside() const
134 {
135 return !containingBlock()->absoluteBoundingBoxRect().contains(absoluteContentBox());
136 }
137
isOverlapping() const138 bool RenderVTTCue::isOverlapping() const
139 {
140 for (RenderObject* box = previousSibling(); box; box = box->previousSibling()) {
141 IntRect boxRect = box->absoluteBoundingBoxRect();
142
143 if (absoluteBoundingBoxRect().intersects(boxRect))
144 return true;
145 }
146
147 return false;
148 }
149
shouldSwitchDirection(InlineFlowBox * firstLineBox,LayoutUnit step) const150 bool RenderVTTCue::shouldSwitchDirection(InlineFlowBox* firstLineBox, LayoutUnit step) const
151 {
152 LayoutUnit top = y();
153 LayoutUnit left = x();
154 LayoutUnit bottom = top + firstLineBox->height();
155 LayoutUnit right = left + firstLineBox->width();
156
157 // 12. Horizontal: If step is negative and the top of the first line
158 // box in boxes is now above the top of the video's rendering area,
159 // or if step is positive and the bottom of the first line box in
160 // boxes is now below the bottom of the video's rendering area, jump
161 // to the step labeled switch direction.
162 LayoutUnit parentHeight = containingBlock()->height();
163 if (m_cue->getWritingDirection() == VTTCue::Horizontal && ((step < 0 && top < 0) || (step > 0 && bottom > parentHeight)))
164 return true;
165
166 // 12. Vertical: If step is negative and the left edge of the first line
167 // box in boxes is now to the left of the left edge of the video's
168 // rendering area, or if step is positive and the right edge of the
169 // first line box in boxes is now to the right of the right edge of
170 // the video's rendering area, jump to the step labeled switch direction.
171 LayoutUnit parentWidth = containingBlock()->width();
172 if (m_cue->getWritingDirection() != VTTCue::Horizontal && ((step < 0 && left < 0) || (step > 0 && right > parentWidth)))
173 return true;
174
175 return false;
176 }
177
moveBoxesByStep(LayoutUnit step)178 void RenderVTTCue::moveBoxesByStep(LayoutUnit step)
179 {
180 // 13. Horizontal: Move all the boxes in boxes down by the distance
181 // given by step. (If step is negative, then this will actually
182 // result in an upwards movement of the boxes in absolute terms.)
183 if (m_cue->getWritingDirection() == VTTCue::Horizontal)
184 setY(y() + step);
185
186 // 13. Vertical: Move all the boxes in boxes right by the distance
187 // given by step. (If step is negative, then this will actually
188 // result in a leftwards movement of the boxes in absolute terms.)
189 else
190 setX(x() + step);
191 }
192
switchDirection(bool & switched,LayoutUnit & step)193 bool RenderVTTCue::switchDirection(bool& switched, LayoutUnit& step)
194 {
195 // 15. Switch direction: Move all the boxes in boxes back to their
196 // default position as determined in the step above labeled default.
197 setX(m_fallbackPosition.x());
198 setY(m_fallbackPosition.y());
199
200 // 16. If switched is true, jump to the step labeled done
201 // positioning below.
202 if (switched)
203 return false;
204
205 // 17. Negate step.
206 step = -step;
207
208 // 18. Set switched to true.
209 switched = true;
210 return true;
211 }
212
repositionCueSnapToLinesSet()213 void RenderVTTCue::repositionCueSnapToLinesSet()
214 {
215 InlineFlowBox* firstLineBox;
216 LayoutUnit step;
217 LayoutUnit position;
218
219 if (!findFirstLineBox(firstLineBox))
220 return;
221
222 if (!initializeLayoutParameters(firstLineBox, step, position))
223 return;
224
225 bool switched;
226 placeBoxInDefaultPosition(position, switched);
227
228 // 11. Step loop: If none of the boxes in boxes would overlap any of the boxes
229 // in output and all the boxes in output are within the video's rendering area
230 // then jump to the step labeled done positioning.
231 while (isOutside() || isOverlapping()) {
232 if (!shouldSwitchDirection(firstLineBox, step)) {
233 // 13. Move all the boxes in boxes ...
234 // 14. Jump back to the step labeled step loop.
235 moveBoxesByStep(step);
236 } else if (!switchDirection(switched, step)) {
237 break;
238 }
239
240 // 19. Jump back to the step labeled step loop.
241 }
242
243 // Acommodate extra top and bottom padding, border or margin.
244 // Note: this is supported only for internal UA styling, not through the cue selector.
245 if (hasInlineDirectionBordersPaddingOrMargin()) {
246 IntRect containerRect = containingBlock()->absoluteBoundingBoxRect();
247 IntRect cueRect = absoluteBoundingBoxRect();
248
249 int topOverflow = cueRect.y() - containerRect.y();
250 int bottomOverflow = containerRect.y() + containerRect.height() - cueRect.y() - cueRect.height();
251
252 int adjustment = 0;
253 if (topOverflow < 0)
254 adjustment = -topOverflow;
255 else if (bottomOverflow < 0)
256 adjustment = bottomOverflow;
257
258 if (adjustment)
259 setY(y() + adjustment);
260 }
261 }
262
repositionCueSnapToLinesNotSet()263 void RenderVTTCue::repositionCueSnapToLinesNotSet()
264 {
265 // FIXME: Implement overlapping detection when snap-to-lines is not set. http://wkb.ug/84296
266 }
267
268 } // namespace blink
269
270