| // Copyright 2016 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "core/layout/ng/inline/ng_line_breaker.h" |
| |
| #include "core/layout/ng/inline/ng_bidi_paragraph.h" |
| #include "core/layout/ng/inline/ng_inline_break_token.h" |
| #include "core/layout/ng/inline/ng_inline_node.h" |
| #include "core/layout/ng/ng_box_fragment.h" |
| #include "core/layout/ng/ng_constraint_space.h" |
| #include "core/layout/ng/ng_constraint_space_builder.h" |
| #include "core/layout/ng/ng_floats_utils.h" |
| #include "core/layout/ng/ng_length_utils.h" |
| #include "core/layout/ng/ng_positioned_float.h" |
| #include "core/style/ComputedStyle.h" |
| #include "platform/fonts/shaping/ShapingLineBreaker.h" |
| |
| namespace blink { |
| |
| NGLineBreaker::NGLineBreaker( |
| NGInlineNode node, |
| const NGConstraintSpace& space, |
| Vector<NGPositionedFloat>* positioned_floats, |
| Vector<scoped_refptr<NGUnpositionedFloat>>* unpositioned_floats, |
| NGExclusionSpace* exclusion_space, |
| unsigned handled_float_index, |
| const NGInlineBreakToken* break_token) |
| : node_(node), |
| constraint_space_(space), |
| positioned_floats_(positioned_floats), |
| unpositioned_floats_(unpositioned_floats), |
| exclusion_space_(exclusion_space), |
| break_iterator_(node.Text()), |
| shaper_(node.Text().Characters16(), node.Text().length()), |
| spacing_(node.Text()), |
| handled_floats_end_item_index_(handled_float_index), |
| base_direction_(node_.BaseDirection()), |
| in_line_height_quirks_mode_(node.InLineHeightQuirksMode()) { |
| if (break_token) { |
| item_index_ = break_token->ItemIndex(); |
| offset_ = break_token->TextOffset(); |
| previous_line_had_forced_break_ = break_token->IsForcedBreak(); |
| node.AssertOffset(item_index_, offset_); |
| } |
| } |
| |
| // @return if this is the "first formatted line". |
| // https://www.w3.org/TR/CSS22/selector.html#first-formatted-line |
| bool NGLineBreaker::IsFirstFormattedLine() const { |
| if (item_index_ || offset_) |
| return false; |
| return node_.GetLayoutBlockFlow()->CanContainFirstFormattedLine(); |
| } |
| |
| // Compute the base direction for bidi algorithm for this line. |
| void NGLineBreaker::ComputeBaseDirection() { |
| // If 'unicode-bidi' is not 'plaintext', use the base direction of the block. |
| if (!previous_line_had_forced_break_ || |
| node_.Style().GetUnicodeBidi() != UnicodeBidi::kPlaintext) |
| return; |
| // If 'unicode-bidi: plaintext', compute the base direction for each paragraph |
| // (separated by forced break.) |
| const String& text = node_.Text(); |
| if (text.Is8Bit()) |
| return; |
| size_t end_offset = text.find(kNewlineCharacter, offset_); |
| base_direction_ = NGBidiParagraph::BaseDirectionForString(node_.Text( |
| offset_, end_offset == kNotFound ? text.length() : end_offset)); |
| } |
| |
| // Initialize internal states for the next line. |
| void NGLineBreaker::PrepareNextLine(const NGLayoutOpportunity& opportunity, |
| NGLineInfo* line_info) { |
| NGInlineItemResults* item_results = &line_info->Results(); |
| item_results->clear(); |
| line_info->SetStartOffset(offset_); |
| line_info->SetLineStyle(node_, constraint_space_, IsFirstFormattedLine(), |
| previous_line_had_forced_break_); |
| SetCurrentStyle(line_info->LineStyle()); |
| ComputeBaseDirection(); |
| line_info->SetBaseDirection(base_direction_); |
| |
| line_.is_after_forced_break = false; |
| line_.should_create_line_box = false; |
| |
| // Use 'text-indent' as the initial position. This lets tab positions to align |
| // regardless of 'text-indent'. |
| line_.position = line_info->TextIndent(); |
| |
| line_.opportunity = opportunity; |
| line_.line_left_bfc_offset = opportunity.LineStartOffset(); |
| line_.line_right_bfc_offset = opportunity.LineEndOffset(); |
| bfc_block_offset_ = opportunity.BlockStartOffset(); |
| } |
| |
| bool NGLineBreaker::NextLine(const NGLayoutOpportunity& opportunity, |
| NGLineInfo* line_info) { |
| bfc_block_offset_ = constraint_space_.BfcOffset().block_offset; |
| |
| PrepareNextLine(opportunity, line_info); |
| BreakLine(line_info); |
| line_info->SetEndOffset(offset_); |
| |
| // TODO(kojii): When editing, or caret is enabled, trailing spaces at wrap |
| // point should not be removed. For other cases, we can a) remove, b) leave |
| // characters without glyphs, or c) leave both characters and glyphs without |
| // measuring. Need to decide which one works the best. |
| SkipCollapsibleWhitespaces(); |
| |
| if (line_info->Results().IsEmpty()) |
| return false; |
| |
| // TODO(kojii): There are cases where we need to PlaceItems() without creating |
| // line boxes. These cases need to be reviewed. |
| if (line_.should_create_line_box) { |
| if (!line_.CanFit() && |
| node_.GetLayoutBlockFlow()->ShouldTruncateOverflowingText()) { |
| TruncateOverflowingText(line_info); |
| } |
| |
| ComputeLineLocation(line_info); |
| } |
| |
| return true; |
| } |
| |
| void NGLineBreaker::BreakLine(NGLineInfo* line_info) { |
| NGInlineItemResults* item_results = &line_info->Results(); |
| const Vector<NGInlineItem>& items = |
| node_.Items(line_info->UseFirstLineStyle()); |
| LineBreakState state = LineBreakState::kNotBreakable; |
| |
| while (item_index_ < items.size()) { |
| #if DCHECK_IS_ON() |
| if (!item_results->IsEmpty() && (state == LineBreakState::kIsBreakable || |
| state == LineBreakState::kNotBreakable)) { |
| DCHECK_EQ(item_results->back().prohibit_break_after, |
| state == LineBreakState::kNotBreakable); |
| } |
| #endif |
| |
| // CloseTag prohibits to break before. |
| const NGInlineItem& item = items[item_index_]; |
| if (item.Type() == NGInlineItem::kCloseTag) { |
| state = HandleCloseTag(item, item_results); |
| continue; |
| } |
| |
| if (state == LineBreakState::kBreakAfterTrailings) { |
| line_info->SetIsLastLine(false); |
| return; |
| } |
| if (state == LineBreakState::kIsBreakable && !line_.CanFit()) |
| return HandleOverflow(line_info); |
| |
| item_results->push_back( |
| NGInlineItemResult(&item, item_index_, offset_, item.EndOffset())); |
| NGInlineItemResult* item_result = &item_results->back(); |
| if (item.Type() == NGInlineItem::kText) { |
| state = HandleText(line_info, item, item_result); |
| #if DCHECK_IS_ON() |
| item_result->CheckConsistency(); |
| #endif |
| } else if (item.Type() == NGInlineItem::kAtomicInline) { |
| state = HandleAtomicInline(item, item_result, *line_info); |
| } else if (item.Type() == NGInlineItem::kControl) { |
| state = HandleControlItem(item, item_result); |
| if (state == LineBreakState::kForcedBreak) { |
| line_.is_after_forced_break = true; |
| line_info->SetIsLastLine(true); |
| return; |
| } |
| } else if (item.Type() == NGInlineItem::kOpenTag) { |
| HandleOpenTag(item, item_result); |
| state = LineBreakState::kNotBreakable; |
| } else if (item.Type() == NGInlineItem::kFloating) { |
| state = HandleFloat(item, item_result); |
| } else if (item.Length()) { |
| // For other items with text (e.g., bidi controls), use their text to |
| // determine the break opportunity. |
| item_result->prohibit_break_after = |
| !break_iterator_.IsBreakable(item_result->end_offset); |
| state = item_result->prohibit_break_after ? LineBreakState::kNotBreakable |
| : LineBreakState::kIsBreakable; |
| MoveToNextOf(item); |
| } else { |
| if (item.Type() == NGInlineItem::kListMarker) |
| line_.should_create_line_box = true; |
| item_result->prohibit_break_after = true; |
| state = LineBreakState::kNotBreakable; |
| MoveToNextOf(item); |
| } |
| } |
| if (!line_.CanFit()) |
| return HandleOverflow(line_info); |
| line_info->SetIsLastLine(true); |
| } |
| |
| // Re-compute the current position from NGInlineItemResults. |
| // The current position is usually updated as NGLineBreaker builds |
| // NGInlineItemResults. This function re-computes it when it was lost. |
| void NGLineBreaker::UpdatePosition(const NGInlineItemResults& results) { |
| LayoutUnit position; |
| for (const NGInlineItemResult& item_result : results) |
| position += item_result.inline_size; |
| line_.position = position; |
| } |
| |
| void NGLineBreaker::ComputeLineLocation(NGLineInfo* line_info) const { |
| LayoutUnit bfc_line_offset = line_.line_left_bfc_offset; |
| LayoutUnit available_width = line_.AvailableWidth(); |
| |
| // Indenting should move the current position to compute the size of |
| // tabulations. Since it is computed and stored in NGInlineItemResult, |
| // adjust the positoin of the line box to simplify placing items. |
| if (LayoutUnit text_indent = line_info->TextIndent()) { |
| // Move the line box by indent. Negative indents are ink overflow, let the |
| // line box overflow from the container box. |
| if (IsLtr(line_info->BaseDirection())) |
| bfc_line_offset += text_indent; |
| available_width -= text_indent; |
| } |
| |
| // Negative margins can make the position negative, but the inline size is |
| // always positive or 0. |
| line_info->SetLineBfcOffset({bfc_line_offset, bfc_block_offset_}, |
| available_width, |
| line_.position.ClampNegativeToZero()); |
| } |
| |
| bool NGLineBreaker::IsFirstBreakOpportunity(unsigned offset, |
| const NGLineInfo& line_info) const { |
| return break_iterator_.NextBreakOpportunity(line_info.StartOffset() + 1) >= |
| offset; |
| } |
| |
| NGLineBreaker::LineBreakState NGLineBreaker::ComputeIsBreakableAfter( |
| NGInlineItemResult* item_result) const { |
| if (auto_wrap_ && break_iterator_.IsBreakable(item_result->end_offset)) { |
| DCHECK(!item_result->prohibit_break_after); |
| return LineBreakState::kIsBreakable; |
| } |
| item_result->prohibit_break_after = true; |
| return LineBreakState::kNotBreakable; |
| } |
| |
| NGLineBreaker::LineBreakState NGLineBreaker::HandleText( |
| NGLineInfo* line_info, |
| const NGInlineItem& item, |
| NGInlineItemResult* item_result) { |
| DCHECK_EQ(item.Type(), NGInlineItem::kText); |
| DCHECK(item.TextShapeResult()); |
| line_.should_create_line_box = true; |
| |
| LayoutUnit available_width = line_.AvailableWidth(); |
| |
| // If the start offset is at the item boundary, try to add the entire item. |
| if (offset_ == item.StartOffset()) { |
| item_result->inline_size = |
| item.TextShapeResult()->SnappedWidth().ClampNegativeToZero(); |
| LayoutUnit next_position = line_.position + item_result->inline_size; |
| if (!auto_wrap_ || next_position <= available_width) { |
| item_result->shape_result = item.TextShapeResult(); |
| item_result->no_break_opportunities_inside = !auto_wrap_; |
| line_.position = next_position; |
| MoveToNextOf(item); |
| return ComputeIsBreakableAfter(item_result); |
| } |
| } |
| |
| if (auto_wrap_) { |
| // Try to break inside of this text item. |
| BreakText(item_result, item, available_width - line_.position, line_info); |
| LayoutUnit next_position = line_.position + item_result->inline_size; |
| bool is_overflow = next_position > available_width; |
| line_.position = next_position; |
| item_result->no_break_opportunities_inside = is_overflow; |
| if (item_result->end_offset < item.EndOffset()) |
| offset_ = item_result->end_offset; |
| else |
| MoveToNextOf(item); |
| if (item_result->end_offset < item.EndOffset() || |
| item_result->has_hanging_spaces) { |
| // The break point found. If it fits, break this line after including |
| // trailing objects (end margins etc.) |
| if (!is_overflow) |
| return LineBreakState::kBreakAfterTrailings; |
| |
| // If overflow, proceed to the possible break point before start |
| // rewinding. TODO(kojii): This could be more efficient if we knew there |
| // was a break opportunity and that rewind will succeed. |
| return LineBreakState::kIsBreakable; |
| } |
| |
| DCHECK(is_overflow || item_result->start_offset != item.StartOffset()); |
| return item_result->prohibit_break_after ? LineBreakState::kNotBreakable |
| : LineBreakState::kIsBreakable; |
| } |
| |
| // Add the rest of the item if !auto_wrap. |
| // Because the start position may need to reshape, run ShapingLineBreaker |
| // with max available width. |
| DCHECK_NE(offset_, item.StartOffset()); |
| BreakText(item_result, item, LayoutUnit::Max(), line_info); |
| DCHECK_EQ(item_result->end_offset, item.EndOffset()); |
| item_result->no_break_opportunities_inside = true; |
| item_result->prohibit_break_after = true; |
| line_.position += item_result->inline_size; |
| MoveToNextOf(item); |
| return LineBreakState::kNotBreakable; |
| } |
| |
| void NGLineBreaker::BreakText(NGInlineItemResult* item_result, |
| const NGInlineItem& item, |
| LayoutUnit available_width, |
| NGLineInfo* line_info) { |
| DCHECK_EQ(item.Type(), NGInlineItem::kText); |
| item.AssertOffset(item_result->start_offset); |
| |
| // TODO(kojii): We need to instantiate ShapingLineBreaker here because it |
| // has item-specific info as context. Should they be part of ShapeLine() to |
| // instantiate once, or is this just fine since instatiation is not |
| // expensive? |
| DCHECK_EQ(item.TextShapeResult()->StartIndexForResult(), item.StartOffset()); |
| DCHECK_EQ(item.TextShapeResult()->EndIndexForResult(), item.EndOffset()); |
| ShapingLineBreaker breaker(&shaper_, &item.Style()->GetFont(), |
| item.TextShapeResult(), &break_iterator_, |
| &spacing_, hyphenation_); |
| if (!enable_soft_hyphen_) |
| breaker.DisableSoftHyphen(); |
| available_width = std::max(LayoutUnit(0), available_width); |
| ShapingLineBreaker::Result result; |
| scoped_refptr<ShapeResult> shape_result = |
| breaker.ShapeLine(item_result->start_offset, available_width, &result); |
| DCHECK_GT(shape_result->NumCharacters(), 0u); |
| if (result.has_hanging_spaces) { |
| item_result->has_hanging_spaces = true; |
| // Hanging spaces do not expand min-content. Handle them simliar to visual |
| // overflow. Some details are different, but it's the closest behavior. |
| item_result->inline_size = available_width; |
| DCHECK(!result.is_hyphenated); |
| } else { |
| item_result->inline_size = |
| shape_result->SnappedWidth().ClampNegativeToZero(); |
| |
| // If overflow and no break opportunities exist, and if 'word-wrap: |
| // break-word', try to break at every grapheme cluster boundary. |
| if (item_result->inline_size > available_width && break_if_overflow_ && |
| break_iterator_.BreakType() == LineBreakType::kNormal && |
| IsFirstBreakOpportunity(result.break_offset, *line_info)) { |
| break_iterator_.SetBreakType(LineBreakType::kBreakCharacter); |
| BreakText(item_result, item, available_width, line_info); |
| break_iterator_.SetBreakType(LineBreakType::kNormal); |
| return; |
| } |
| |
| if (result.is_hyphenated) { |
| AppendHyphen(*item.Style(), line_info); |
| item_result->inline_size = |
| shape_result->SnappedWidth().ClampNegativeToZero(); |
| // TODO(kojii): Implement when adding a hyphen caused overflow. |
| // crbug.com/714962: Should be removed when switched to NGPaint. |
| item_result->text_end_effect = NGTextEndEffect::kHyphen; |
| } |
| } |
| item_result->end_offset = result.break_offset; |
| item_result->shape_result = std::move(shape_result); |
| DCHECK_GT(item_result->end_offset, item_result->start_offset); |
| |
| // * If width <= available_width: |
| // * If offset < item.EndOffset(): the break opportunity to fit is found. |
| // * If offset == item.EndOffset(): the break opportunity at the end fits, |
| // or the first break opportunity is beyond the end. |
| // There may be room for more characters. |
| // * If width > available_width: The first break opporunity does not fit. |
| // offset is the first break opportunity, either inside, at the end, or |
| // beyond the end. |
| if (item_result->end_offset < item.EndOffset()) { |
| item_result->prohibit_break_after = false; |
| } else { |
| DCHECK_EQ(item_result->end_offset, item.EndOffset()); |
| item_result->prohibit_break_after = |
| !break_iterator_.IsBreakable(item_result->end_offset); |
| } |
| } |
| |
| void NGLineBreaker::AppendHyphen(const ComputedStyle& style, |
| NGLineInfo* line_info) { |
| TextDirection direction = style.Direction(); |
| String hyphen_string = style.HyphenString(); |
| hyphen_string.Ensure16Bit(); |
| HarfBuzzShaper shaper(hyphen_string.Characters16(), hyphen_string.length()); |
| scoped_refptr<ShapeResult> hyphen_result = |
| shaper.Shape(&style.GetFont(), direction); |
| line_info->SetLineEndShapeResult(std::move(hyphen_result), &style); |
| } |
| |
| // Measure control items; new lines and tab, that are similar to text, affect |
| // layout, but do not need shaping/painting. |
| NGLineBreaker::LineBreakState NGLineBreaker::HandleControlItem( |
| const NGInlineItem& item, |
| NGInlineItemResult* item_result) { |
| DCHECK_EQ(item.Length(), 1u); |
| line_.should_create_line_box = true; |
| |
| UChar character = node_.Text()[item.StartOffset()]; |
| switch (character) { |
| case kNewlineCharacter: |
| MoveToNextOf(item); |
| return LineBreakState::kForcedBreak; |
| case kTabulationCharacter: { |
| DCHECK(item.Style()); |
| const ComputedStyle& style = *item.Style(); |
| const Font& font = style.GetFont(); |
| item_result->inline_size = |
| font.TabWidth(style.GetTabSize(), line_.position); |
| line_.position += item_result->inline_size; |
| MoveToNextOf(item); |
| // TODO(kojii): Implement break around the tab character. |
| return LineBreakState::kIsBreakable; |
| } |
| case kZeroWidthSpaceCharacter: |
| // <wbr> tag creates break opportunities regardless of auto_wrap. |
| MoveToNextOf(item); |
| return LineBreakState::kIsBreakable; |
| } |
| NOTREACHED(); |
| return LineBreakState::kIsBreakable; |
| } |
| |
| NGLineBreaker::LineBreakState NGLineBreaker::HandleAtomicInline( |
| const NGInlineItem& item, |
| NGInlineItemResult* item_result, |
| const NGLineInfo& line_info) { |
| DCHECK_EQ(item.Type(), NGInlineItem::kAtomicInline); |
| line_.should_create_line_box = true; |
| |
| item_result->layout_result = |
| NGBlockNode(ToLayoutBox(item.GetLayoutObject())) |
| .LayoutAtomicInline(constraint_space_, line_info.UseFirstLineStyle()); |
| DCHECK(item_result->layout_result->PhysicalFragment()); |
| |
| item_result->inline_size = |
| NGFragment(constraint_space_.GetWritingMode(), |
| *item_result->layout_result->PhysicalFragment()) |
| .InlineSize(); |
| |
| DCHECK(item.Style()); |
| item_result->margins = |
| ComputeMarginsForVisualContainer(constraint_space_, *item.Style()); |
| item_result->inline_size += item_result->margins.InlineSum(); |
| |
| line_.position += item_result->inline_size; |
| MoveToNextOf(item); |
| return ComputeIsBreakableAfter(item_result); |
| } |
| |
| // Performs layout and positions a float. |
| // |
| // If there is a known available_width (e.g. something has resolved the |
| // container BFC offset) it will attempt to position the float on the current |
| // line. |
| // Additionally updates the available_width for the line as the float has |
| // (probably) consumed space. |
| // |
| // If the float is too wide *or* we already have UnpositionedFloats we add it |
| // as an UnpositionedFloat. This should be positioned *immediately* after we |
| // are done with the current line. |
| // We have this check if there are already UnpositionedFloats as we aren't |
| // allowed to position a float "above" another float which has come before us |
| // in the document. |
| // |
| // TODO(glebl): Add the support of clearance for inline floats. |
| NGLineBreaker::LineBreakState NGLineBreaker::HandleFloat( |
| const NGInlineItem& item, |
| NGInlineItemResult* item_result) { |
| // When rewind occurs, an item may be handled multiple times. |
| // Since floats are put into a separate list, avoid handling same floats |
| // twice. |
| // Ideally rewind can take floats out of floats list, but the difference is |
| // sutble compared to the complexity. |
| if (item_index_ < handled_floats_end_item_index_) { |
| MoveToNextOf(item); |
| return ComputeIsBreakableAfter(item_result); |
| } |
| |
| NGBlockNode node(ToLayoutBox(item.GetLayoutObject())); |
| |
| const ComputedStyle& float_style = node.Style(); |
| NGBoxStrut margins = |
| ComputeMarginsForContainer(constraint_space_, float_style); |
| |
| // TODO(ikilpatrick): Add support for float break tokens inside an inline |
| // layout context. |
| scoped_refptr<NGUnpositionedFloat> unpositioned_float = |
| NGUnpositionedFloat::Create(constraint_space_.AvailableSize(), |
| constraint_space_.PercentageResolutionSize(), |
| constraint_space_.BfcOffset().line_offset, |
| constraint_space_.BfcOffset().line_offset, |
| margins, node, |
| /* break_token */ nullptr); |
| |
| LayoutUnit inline_margin_size = |
| (ComputeInlineSizeForUnpositionedFloat(constraint_space_, |
| unpositioned_float.get()) + |
| margins.InlineSum()) |
| .ClampNegativeToZero(); |
| |
| // The float should be positioned after the current line if: |
| // - It can't fit. |
| // - It will be moved down due to block-start edge alignment. |
| // - It will be moved down due to clearance. |
| bool float_after_line = |
| !line_.CanFit(inline_margin_size) || |
| exclusion_space_->LastFloatBlockStart() > bfc_block_offset_ || |
| exclusion_space_->ClearanceOffset(float_style.Clear()) > |
| bfc_block_offset_; |
| |
| // Check if we already have a pending float. That's because a float cannot be |
| // higher than any block or floated box generated before. |
| if (!unpositioned_floats_->IsEmpty() || float_after_line) { |
| unpositioned_floats_->push_back(std::move(unpositioned_float)); |
| } else { |
| LayoutUnit origin_block_offset = bfc_block_offset_; |
| |
| NGPositionedFloat positioned_float = PositionFloat( |
| origin_block_offset, constraint_space_.BfcOffset().block_offset, |
| unpositioned_float.get(), constraint_space_, exclusion_space_); |
| positioned_floats_->push_back(positioned_float); |
| |
| DCHECK_EQ(positioned_float.bfc_offset.block_offset, |
| bfc_block_offset_ + margins.block_start); |
| |
| if (float_style.Floating() == EFloat::kLeft) { |
| line_.line_left_bfc_offset = std::max( |
| line_.line_left_bfc_offset, |
| positioned_float.bfc_offset.line_offset + inline_margin_size - |
| margins.LineLeft(TextDirection::kLtr)); |
| } else { |
| line_.line_right_bfc_offset = |
| std::min(line_.line_right_bfc_offset, |
| positioned_float.bfc_offset.line_offset - |
| margins.LineLeft(TextDirection::kLtr)); |
| } |
| |
| DCHECK_GE(line_.line_left_bfc_offset, LayoutUnit()); |
| DCHECK_GE(line_.line_right_bfc_offset, LayoutUnit()); |
| DCHECK_GE(line_.AvailableWidth(), LayoutUnit()); |
| } |
| |
| MoveToNextOf(item); |
| return ComputeIsBreakableAfter(item_result); |
| } |
| |
| void NGLineBreaker::HandleOpenTag(const NGInlineItem& item, |
| NGInlineItemResult* item_result) { |
| item_result->prohibit_break_after = true; |
| |
| DCHECK(item.Style()); |
| const ComputedStyle& style = *item.Style(); |
| item_result->needs_box_when_empty = false; |
| if (style.HasBorder() || style.HasPadding() || |
| (style.HasMargin() && item.HasStartEdge())) { |
| NGBoxStrut borders = ComputeBorders(constraint_space_, style); |
| NGBoxStrut paddings = ComputePadding(constraint_space_, style); |
| item_result->borders_paddings_block_start = |
| borders.block_start + paddings.block_start; |
| item_result->borders_paddings_block_end = |
| borders.block_end + paddings.block_end; |
| if (item.HasStartEdge()) { |
| item_result->margins = |
| ComputeMarginsForContainer(constraint_space_, style); |
| item_result->inline_size = item_result->margins.inline_start + |
| borders.inline_start + paddings.inline_start; |
| line_.position += item_result->inline_size; |
| |
| // While the spec defines "non-zero margins, padding, or borders" prevents |
| // line boxes to be zero-height, tests indicate that only inline direction |
| // of them do so. See should_create_line_box_. |
| // Force to create a box, because such inline boxes affect line heights. |
| item_result->needs_box_when_empty = |
| item_result->inline_size || |
| (item_result->margins.inline_start && !in_line_height_quirks_mode_); |
| line_.should_create_line_box |= item_result->needs_box_when_empty; |
| } |
| } |
| item_result->needs_box_when_empty |= |
| style.CanContainAbsolutePositionObjects() || |
| style.CanContainFixedPositionObjects(); |
| SetCurrentStyle(style); |
| MoveToNextOf(item); |
| } |
| |
| NGLineBreaker::LineBreakState NGLineBreaker::HandleCloseTag( |
| const NGInlineItem& item, |
| NGInlineItemResults* item_results) { |
| item_results->push_back( |
| NGInlineItemResult(&item, item_index_, offset_, item.EndOffset())); |
| NGInlineItemResult* item_result = &item_results->back(); |
| |
| item_result->needs_box_when_empty = false; |
| if (item.HasEndEdge()) { |
| DCHECK(item.Style()); |
| const ComputedStyle& style = *item.Style(); |
| item_result->margins = ComputeMarginsForContainer(constraint_space_, style); |
| NGBoxStrut borders = ComputeBorders(constraint_space_, style); |
| NGBoxStrut paddings = ComputePadding(constraint_space_, style); |
| item_result->inline_size = item_result->margins.inline_end + |
| borders.inline_end + paddings.inline_end; |
| line_.position += item_result->inline_size; |
| |
| item_result->needs_box_when_empty = |
| item_result->inline_size || |
| (item_result->margins.inline_end && !in_line_height_quirks_mode_); |
| line_.should_create_line_box |= item_result->needs_box_when_empty; |
| } |
| DCHECK(item.GetLayoutObject() && item.GetLayoutObject()->Parent()); |
| bool was_auto_wrap = auto_wrap_; |
| SetCurrentStyle(item.GetLayoutObject()->Parent()->StyleRef()); |
| MoveToNextOf(item); |
| |
| // Prohibit break before a close tag by setting prohibit_break_after to the |
| // previous result. |
| // TODO(kojii): There should be a result before close tag, but there are cases |
| // that doesn't because of the way we handle trailing spaces. This needs to be |
| // revisited. |
| if (item_results->size() >= 2) { |
| NGInlineItemResult* last = &(*item_results)[item_results->size() - 2]; |
| if (was_auto_wrap == auto_wrap_) { |
| item_result->prohibit_break_after = last->prohibit_break_after; |
| last->prohibit_break_after = true; |
| return item_result->prohibit_break_after ? LineBreakState::kNotBreakable |
| : LineBreakState::kIsBreakable; |
| } |
| last->prohibit_break_after = true; |
| } |
| return ComputeIsBreakableAfter(item_result); |
| } |
| |
| // Handles when the last item overflows. |
| // At this point, item_results does not fit into the current line, and there |
| // are no break opportunities in item_results.back(). |
| void NGLineBreaker::HandleOverflow(NGLineInfo* line_info) { |
| HandleOverflow(line_info, line_.AvailableWidth(), false); |
| } |
| |
| void NGLineBreaker::HandleOverflow(NGLineInfo* line_info, |
| LayoutUnit available_width, |
| bool force_break_anywhere) { |
| NGInlineItemResults* item_results = &line_info->Results(); |
| LayoutUnit width_to_rewind = line_.position - available_width; |
| DCHECK_GT(width_to_rewind, 0); |
| |
| // Keep track of the shortest break opportunity. |
| unsigned break_before = 0; |
| |
| // Search for a break opportunity that can fit. |
| for (unsigned i = item_results->size(); i;) { |
| NGInlineItemResult* item_result = &(*item_results)[--i]; |
| |
| // Try to break after this item. |
| if (i < item_results->size() - 1 && !item_result->prohibit_break_after) { |
| if (width_to_rewind <= 0) { |
| line_.position = available_width + width_to_rewind; |
| return Rewind(line_info, i + 1); |
| } |
| break_before = i + 1; |
| } |
| |
| // Try to break inside of this item. |
| LayoutUnit next_width_to_rewind = |
| width_to_rewind - item_result->inline_size; |
| DCHECK(item_result->item); |
| const NGInlineItem& item = *item_result->item; |
| if (item.Type() == NGInlineItem::kText && next_width_to_rewind < 0 && |
| (!item_result->no_break_opportunities_inside || force_break_anywhere)) { |
| // When the text fits but its right margin does not, the break point |
| // must not be at the end. |
| LayoutUnit item_available_width = |
| std::min(-next_width_to_rewind, item_result->inline_size - 1); |
| SetCurrentStyle(*item.Style()); |
| if (force_break_anywhere) |
| break_iterator_.SetBreakType(LineBreakType::kBreakCharacter); |
| BreakText(item_result, item, item_available_width, line_info); |
| #if DCHECK_IS_ON() |
| item_result->CheckConsistency(); |
| #endif |
| if (item_result->inline_size <= item_available_width) { |
| DCHECK(item_result->end_offset < item.EndOffset() || |
| (item_result->end_offset == item.EndOffset() && |
| item_result->has_hanging_spaces)); |
| DCHECK(!item_result->prohibit_break_after); |
| DCHECK_LE(i + 1, item_results->size()); |
| if (i + 1 == item_results->size()) { |
| line_.position = |
| available_width + next_width_to_rewind + item_result->inline_size; |
| } else { |
| Rewind(line_info, i + 1); |
| } |
| return; |
| } |
| } |
| |
| width_to_rewind = next_width_to_rewind; |
| } |
| |
| // Reaching here means that the rewind point was not found. |
| |
| // Let this line overflow. |
| // If there was a break opporunity, the overflow should stop there. |
| if (break_before) |
| return Rewind(line_info, break_before); |
| |
| line_info->SetIsLastLine(item_index_ >= node_.Items().size()); |
| } |
| |
| void NGLineBreaker::Rewind(NGLineInfo* line_info, unsigned new_end) { |
| NGInlineItemResults* item_results = &line_info->Results(); |
| DCHECK_LT(new_end, item_results->size()); |
| |
| // TODO(ikilpatrick): Add DCHECK that we never rewind past any floats. |
| |
| if (new_end) { |
| // Use |results[new_end - 1].end_offset| because it may have been truncated |
| // and may not be equal to |results[new_end].start_offset|. |
| MoveToNextOf((*item_results)[new_end - 1]); |
| } else { |
| // When rewinding all items, use |results[0].start_offset|. |
| const NGInlineItemResult& first_remove = (*item_results)[new_end]; |
| item_index_ = first_remove.item_index; |
| offset_ = first_remove.start_offset; |
| } |
| |
| // TODO(kojii): Should we keep results for the next line? We don't need to |
| // re-layout atomic inlines. |
| item_results->Shrink(new_end); |
| |
| line_info->SetIsLastLine(false); |
| UpdatePosition(line_info->Results()); |
| } |
| |
| // Truncate overflowing text and append ellipsis. |
| void NGLineBreaker::TruncateOverflowingText(NGLineInfo* line_info) { |
| // The ellipsis is styled according to the line style. |
| const Font& font = line_info->LineStyle().GetFont(); |
| const SimpleFontData* font_data = font.PrimaryFont(); |
| DCHECK(font_data); |
| String ellipsis = |
| font_data && font_data->GlyphForCharacter(kHorizontalEllipsisCharacter) |
| ? String(&kHorizontalEllipsisCharacter, 1) |
| : String(u"..."); |
| HarfBuzzShaper shaper(ellipsis.Characters16(), ellipsis.length()); |
| scoped_refptr<ShapeResult> shape_result = |
| shaper.Shape(&font, line_info->BaseDirection()); |
| |
| // Truncate the line to (available_width - ellipsis_width) using 'line-break: |
| // anywhere'. |
| unsigned saved_item_index = item_index_; |
| unsigned saved_offset = offset_; |
| HandleOverflow(line_info, |
| line_.AvailableWidth() - shape_result->SnappedWidth(), true); |
| |
| // Restore item_index/offset to before HandleOverflow(). |
| item_index_ = saved_item_index; |
| offset_ = saved_offset; |
| |
| // The ellipsis should appear at the logical end of the line. |
| // This is stored seprately from other results so that it can be appended |
| // after bidi reorder. |
| line_info->SetLineEndShapeResult(std::move(shape_result), |
| &line_info->LineStyle()); |
| } |
| |
| void NGLineBreaker::SetCurrentStyle(const ComputedStyle& style) { |
| auto_wrap_ = style.AutoWrap(); |
| |
| if (auto_wrap_) { |
| break_iterator_.SetLocale(style.LocaleForLineBreakIterator()); |
| |
| switch (style.WordBreak()) { |
| case EWordBreak::kNormal: |
| break_if_overflow_ = style.OverflowWrap() == EOverflowWrap::kBreakWord; |
| break_iterator_.SetBreakType(LineBreakType::kNormal); |
| break; |
| case EWordBreak::kBreakAll: |
| break_if_overflow_ = false; |
| break_iterator_.SetBreakType(LineBreakType::kBreakAll); |
| break; |
| case EWordBreak::kBreakWord: |
| break_if_overflow_ = true; |
| break_iterator_.SetBreakType(LineBreakType::kNormal); |
| break; |
| case EWordBreak::kKeepAll: |
| break_if_overflow_ = false; |
| break_iterator_.SetBreakType(LineBreakType::kKeepAll); |
| break; |
| } |
| break_iterator_.SetBreakSpace(style.BreakOnlyAfterWhiteSpace() |
| ? BreakSpaceType::kAfter |
| : BreakSpaceType::kBeforeSpace); |
| |
| enable_soft_hyphen_ = style.GetHyphens() != Hyphens::kNone; |
| hyphenation_ = style.GetHyphenation(); |
| } |
| |
| spacing_.SetSpacing(style.GetFontDescription()); |
| } |
| |
| void NGLineBreaker::MoveToNextOf(const NGInlineItem& item) { |
| offset_ = item.EndOffset(); |
| item_index_++; |
| } |
| |
| void NGLineBreaker::MoveToNextOf(const NGInlineItemResult& item_result) { |
| offset_ = item_result.end_offset; |
| item_index_ = item_result.item_index; |
| DCHECK(item_result.item); |
| if (offset_ == item_result.item->EndOffset()) |
| item_index_++; |
| } |
| |
| void NGLineBreaker::SkipCollapsibleWhitespaces() { |
| const Vector<NGInlineItem>& items = node_.Items(); |
| if (item_index_ >= items.size()) |
| return; |
| const NGInlineItem& item = items[item_index_]; |
| if (item.Type() != NGInlineItem::kText || !item.Style()->CollapseWhiteSpace()) |
| return; |
| |
| DCHECK_LT(offset_, item.EndOffset()); |
| if (node_.Text()[offset_] == kSpaceCharacter) { |
| // Skip one whitespace. Collapsible spaces are collapsed to single space in |
| // NGInlineItemBuilder, so this removes all collapsible spaces. |
| offset_++; |
| if (offset_ == item.EndOffset()) |
| item_index_++; |
| } |
| } |
| |
| scoped_refptr<NGInlineBreakToken> NGLineBreaker::CreateBreakToken( |
| std::unique_ptr<const NGInlineLayoutStateStack> state_stack) const { |
| const Vector<NGInlineItem>& items = node_.Items(); |
| if (item_index_ >= items.size()) |
| return NGInlineBreakToken::Create(node_); |
| return NGInlineBreakToken::Create(node_, item_index_, offset_, |
| line_.is_after_forced_break, |
| std::move(state_stack)); |
| } |
| |
| } // namespace blink |
