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Serenity Operating System
1/*
2 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 *
8 * 1. Redistributions of source code must retain the above copyright notice, this
9 * list of conditions and the following disclaimer.
10 *
11 * 2. Redistributions in binary form must reproduce the above copyright notice,
12 * this list of conditions and the following disclaimer in the documentation
13 * and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
16 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
18 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
21 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
22 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
23 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
24 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include <LibGUI/Painter.h>
28#include <LibHTML/CSS/StyleResolver.h>
29#include <LibHTML/DOM/Element.h>
30#include <LibHTML/Layout/LayoutBlock.h>
31#include <LibHTML/Layout/LayoutInline.h>
32#include <LibHTML/Layout/LayoutReplaced.h>
33#include <LibHTML/Layout/LayoutText.h>
34#include <math.h>
35
36LayoutBlock::LayoutBlock(const Node* node, NonnullRefPtr<StyleProperties> style)
37 : LayoutBox(node, move(style))
38{
39}
40
41LayoutBlock::~LayoutBlock()
42{
43}
44
45LayoutNode& LayoutBlock::inline_wrapper()
46{
47 if (!last_child() || !last_child()->is_block() || last_child()->node() != nullptr) {
48 append_child(adopt(*new LayoutBlock(nullptr, style_for_anonymous_block())));
49 last_child()->set_children_are_inline(true);
50 }
51 return *last_child();
52}
53
54void LayoutBlock::layout()
55{
56 compute_width();
57 compute_position();
58
59 if (children_are_inline())
60 layout_inline_children();
61 else
62 layout_block_children();
63
64 compute_height();
65}
66
67void LayoutBlock::layout_block_children()
68{
69 ASSERT(!children_are_inline());
70 float content_height = 0;
71 for_each_child([&](auto& child) {
72 // FIXME: What should we do here? Something like a <table> might have a bunch of useless text children..
73 if (child.is_inline())
74 return;
75 auto& child_block = static_cast<LayoutBlock&>(child);
76 child_block.layout();
77 content_height = child_block.rect().bottom() + child_block.box_model().full_margin().bottom - rect().top();
78 });
79 rect().set_height(content_height);
80}
81
82void LayoutBlock::layout_inline_children()
83{
84 ASSERT(children_are_inline());
85 m_line_boxes.clear();
86 for_each_child([&](auto& child) {
87 ASSERT(child.is_inline());
88 child.split_into_lines(*this);
89 });
90
91 for (auto& line_box : m_line_boxes) {
92 line_box.trim_trailing_whitespace();
93 }
94
95 float min_line_height = style().line_height();
96 float line_spacing = min_line_height - style().font().glyph_height();
97 float content_height = 0;
98
99 // FIXME: This should be done by the CSS parser!
100 CSS::ValueID text_align = CSS::ValueID::Left;
101 auto text_align_string = style().string_or_fallback(CSS::PropertyID::TextAlign, "left");
102 if (text_align_string == "center")
103 text_align = CSS::ValueID::Center;
104 else if (text_align_string == "left")
105 text_align = CSS::ValueID::Left;
106 else if (text_align_string == "right")
107 text_align = CSS::ValueID::Right;
108 else if (text_align_string == "justify")
109 text_align = CSS::ValueID::Justify;
110
111 for (auto& line_box : m_line_boxes) {
112 float max_height = min_line_height;
113 for (auto& fragment : line_box.fragments()) {
114 max_height = max(max_height, fragment.rect().height());
115 }
116
117 float x_offset = x();
118 float excess_horizontal_space = (float)width() - line_box.width();
119
120 switch (text_align) {
121 case CSS::ValueID::Center:
122 x_offset += excess_horizontal_space / 2;
123 break;
124 case CSS::ValueID::Right:
125 x_offset += excess_horizontal_space;
126 break;
127 case CSS::ValueID::Left:
128 case CSS::ValueID::Justify:
129 default:
130 break;
131 }
132
133 float excess_horizontal_space_including_whitespace = excess_horizontal_space;
134 int whitespace_count = 0;
135 if (text_align == CSS::ValueID::Justify) {
136 for (auto& fragment : line_box.fragments()) {
137 if (fragment.is_justifiable_whitespace()) {
138 ++whitespace_count;
139 excess_horizontal_space_including_whitespace += fragment.rect().width();
140 }
141 }
142 }
143
144 float justified_space_width = whitespace_count ? (excess_horizontal_space_including_whitespace / (float)whitespace_count) : 0;
145
146 for (size_t i = 0; i < line_box.fragments().size(); ++i) {
147 auto& fragment = line_box.fragments()[i];
148 // Vertically align everyone's bottom to the line.
149 // FIXME: Support other kinds of vertical alignment.
150 fragment.rect().set_x(roundf(x_offset + fragment.rect().x()));
151 fragment.rect().set_y(y() + content_height + (max_height - fragment.rect().height()) - (line_spacing / 2));
152
153 if (text_align == CSS::ValueID::Justify) {
154 if (fragment.is_justifiable_whitespace()) {
155 if (fragment.rect().width() != justified_space_width) {
156 float diff = justified_space_width - fragment.rect().width();
157 fragment.rect().set_width(justified_space_width);
158 // Shift subsequent sibling fragments to the right to adjust for change in width.
159 for (size_t j = i + 1; j < line_box.fragments().size(); ++j) {
160 line_box.fragments()[j].rect().move_by(diff, 0);
161 }
162 }
163 }
164 }
165
166 if (is<LayoutReplaced>(fragment.layout_node()))
167 const_cast<LayoutReplaced&>(to<LayoutReplaced>(fragment.layout_node())).set_rect(fragment.rect());
168
169 float final_line_box_width = 0;
170 for (auto& fragment : line_box.fragments())
171 final_line_box_width += fragment.rect().width();
172 line_box.m_width = final_line_box_width;
173 }
174
175 content_height += max_height;
176 }
177
178 rect().set_height(content_height);
179}
180
181void LayoutBlock::compute_width()
182{
183 auto& style = this->style();
184
185 auto auto_value = Length();
186 auto zero_value = Length(0, Length::Type::Absolute);
187
188 Length margin_left;
189 Length margin_right;
190 Length border_left;
191 Length border_right;
192 Length padding_left;
193 Length padding_right;
194
195 auto try_compute_width = [&](const auto& a_width) {
196 Length width = a_width;
197#ifdef HTML_DEBUG
198 dbg() << " Left: " << margin_left << "+" << border_left << "+" << padding_left;
199 dbg() << "Right: " << margin_right << "+" << border_right << "+" << padding_right;
200#endif
201 margin_left = style.length_or_fallback(CSS::PropertyID::MarginLeft, zero_value);
202 margin_right = style.length_or_fallback(CSS::PropertyID::MarginRight, zero_value);
203 border_left = style.length_or_fallback(CSS::PropertyID::BorderLeftWidth, zero_value);
204 border_right = style.length_or_fallback(CSS::PropertyID::BorderRightWidth, zero_value);
205 padding_left = style.length_or_fallback(CSS::PropertyID::PaddingLeft, zero_value);
206 padding_right = style.length_or_fallback(CSS::PropertyID::PaddingRight, zero_value);
207
208 float total_px = 0;
209 for (auto& value : { margin_left, border_left, padding_left, width, padding_right, border_right, margin_right }) {
210 total_px += value.to_px();
211 }
212
213#ifdef HTML_DEBUG
214 dbg() << "Total: " << total_px;
215#endif
216
217 // 10.3.3 Block-level, non-replaced elements in normal flow
218 // If 'width' is not 'auto' and 'border-left-width' + 'padding-left' + 'width' + 'padding-right' + 'border-right-width' (plus any of 'margin-left' or 'margin-right' that are not 'auto') is larger than the width of the containing block, then any 'auto' values for 'margin-left' or 'margin-right' are, for the following rules, treated as zero.
219 if (width.is_auto() && total_px > containing_block()->width()) {
220 if (margin_left.is_auto())
221 margin_left = zero_value;
222 if (margin_right.is_auto())
223 margin_right = zero_value;
224 }
225
226 // 10.3.3 cont'd.
227 auto underflow_px = containing_block()->width() - total_px;
228
229 if (width.is_auto()) {
230 if (margin_left.is_auto())
231 margin_left = zero_value;
232 if (margin_right.is_auto())
233 margin_right = zero_value;
234 if (underflow_px >= 0) {
235 width = Length(underflow_px, Length::Type::Absolute);
236 } else {
237 width = zero_value;
238 margin_right = Length(margin_right.to_px() + underflow_px, Length::Type::Absolute);
239 }
240 } else {
241 if (!margin_left.is_auto() && !margin_right.is_auto()) {
242 margin_right = Length(margin_right.to_px() + underflow_px, Length::Type::Absolute);
243 } else if (!margin_left.is_auto() && margin_right.is_auto()) {
244 margin_right = Length(underflow_px, Length::Type::Absolute);
245 } else if (margin_left.is_auto() && !margin_right.is_auto()) {
246 margin_left = Length(underflow_px, Length::Type::Absolute);
247 } else { // margin_left.is_auto() && margin_right.is_auto()
248 auto half_of_the_underflow = Length(underflow_px / 2, Length::Type::Absolute);
249 margin_left = half_of_the_underflow;
250 margin_right = half_of_the_underflow;
251 }
252 }
253 return width;
254 };
255
256 auto specified_width = style.length_or_fallback(CSS::PropertyID::Width, auto_value);
257
258 // 1. The tentative used width is calculated (without 'min-width' and 'max-width')
259 auto used_width = try_compute_width(specified_width);
260
261 // 2. The tentative used width is greater than 'max-width', the rules above are applied again,
262 // but this time using the computed value of 'max-width' as the computed value for 'width'.
263 auto specified_max_width = style.length_or_fallback(CSS::PropertyID::MaxWidth, auto_value);
264 if (!specified_max_width.is_auto()) {
265 if (used_width.to_px() > specified_max_width.to_px()) {
266 used_width = try_compute_width(specified_max_width);
267 }
268 }
269
270 // 3. If the resulting width is smaller than 'min-width', the rules above are applied again,
271 // but this time using the value of 'min-width' as the computed value for 'width'.
272 auto specified_min_width = style.length_or_fallback(CSS::PropertyID::MinWidth, auto_value);
273 if (!specified_min_width.is_auto()) {
274 if (used_width.to_px() < specified_min_width.to_px()) {
275 used_width = try_compute_width(specified_min_width);
276 }
277 }
278
279 rect().set_width(used_width.to_px());
280 box_model().margin().left = margin_left;
281 box_model().margin().right = margin_right;
282 box_model().border().left = border_left;
283 box_model().border().right = border_right;
284 box_model().padding().left = padding_left;
285 box_model().padding().right = padding_right;
286}
287
288void LayoutBlock::compute_position()
289{
290 auto& style = this->style();
291
292 auto auto_value = Length();
293 auto zero_value = Length(0, Length::Type::Absolute);
294
295 auto width = style.length_or_fallback(CSS::PropertyID::Width, auto_value);
296
297 box_model().margin().top = style.length_or_fallback(CSS::PropertyID::MarginTop, zero_value);
298 box_model().margin().bottom = style.length_or_fallback(CSS::PropertyID::MarginBottom, zero_value);
299 box_model().border().top = style.length_or_fallback(CSS::PropertyID::BorderTopWidth, zero_value);
300 box_model().border().bottom = style.length_or_fallback(CSS::PropertyID::BorderBottomWidth, zero_value);
301 box_model().padding().top = style.length_or_fallback(CSS::PropertyID::PaddingTop, zero_value);
302 box_model().padding().bottom = style.length_or_fallback(CSS::PropertyID::PaddingBottom, zero_value);
303 rect().set_x(containing_block()->x() + box_model().margin().left.to_px() + box_model().border().left.to_px() + box_model().padding().left.to_px());
304
305 float top_border = -1;
306 if (previous_sibling() != nullptr) {
307 auto& previous_sibling_rect = previous_sibling()->rect();
308 auto& previous_sibling_style = previous_sibling()->box_model();
309 top_border = previous_sibling_rect.y() + previous_sibling_rect.height();
310 top_border += previous_sibling_style.full_margin().bottom;
311 } else {
312 top_border = containing_block()->y();
313 }
314 rect().set_y(top_border + box_model().full_margin().top);
315}
316
317void LayoutBlock::compute_height()
318{
319 auto& style = this->style();
320
321 auto height_property = style.property(CSS::PropertyID::Height);
322 if (!height_property.has_value())
323 return;
324 auto height_length = height_property.value()->to_length();
325 if (height_length.is_absolute())
326 rect().set_height(height_length.to_px());
327}
328
329void LayoutBlock::render(RenderingContext& context)
330{
331 if (!is_visible())
332 return;
333
334 LayoutBox::render(context);
335
336 if (children_are_inline()) {
337 for (auto& line_box : m_line_boxes) {
338 for (auto& fragment : line_box.fragments()) {
339 if (context.should_show_line_box_borders())
340 context.painter().draw_rect(enclosing_int_rect(fragment.rect()), Color::Green);
341 fragment.render(context);
342 }
343 }
344 }
345}
346
347HitTestResult LayoutBlock::hit_test(const Gfx::Point& position) const
348{
349 if (!children_are_inline())
350 return LayoutBox::hit_test(position);
351
352 HitTestResult result;
353 for (auto& line_box : m_line_boxes) {
354 for (auto& fragment : line_box.fragments()) {
355 if (enclosing_int_rect(fragment.rect()).contains(position)) {
356 return { fragment.layout_node(), fragment.text_index_at(position.x()) };
357 }
358 }
359 }
360 return {};
361}
362
363NonnullRefPtr<StyleProperties> LayoutBlock::style_for_anonymous_block() const
364{
365 auto new_style = StyleProperties::create();
366
367 style().for_each_property([&](auto property_id, auto& value) {
368 if (StyleResolver::is_inherited_property(property_id))
369 new_style->set_property(property_id, value);
370 });
371
372 return new_style;
373}
374
375LineBox& LayoutBlock::ensure_last_line_box()
376{
377 if (m_line_boxes.is_empty())
378 m_line_boxes.append(LineBox());
379 return m_line_boxes.last();
380}
381
382LineBox& LayoutBlock::add_line_box()
383{
384 m_line_boxes.append(LineBox());
385 return m_line_boxes.last();
386}