blob: a376aeedf382e07771d0827fd2a1d2a87a88044c [file] [log] [blame]
// 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 "third_party/blink/renderer/core/layout/fragmentainer_iterator.h"
#include "third_party/blink/renderer/core/layout/layout_multi_column_set.h"
namespace blink {
FragmentainerIterator::FragmentainerIterator(
const LayoutFlowThread& flow_thread,
const LayoutRect& physical_bounding_box_in_flow_thread,
const LayoutRect& clip_rect_in_multicol_container)
: flow_thread_(flow_thread),
clip_rect_in_multicol_container_(clip_rect_in_multicol_container),
current_fragmentainer_group_index_(0) {
// Put the bounds into flow thread-local coordinates by flipping it first.
// This is how rectangles typically are represented in layout, i.e. with the
// block direction coordinate flipped, if writing mode is vertical-rl.
LayoutRect bounds_in_flow_thread = physical_bounding_box_in_flow_thread;
flow_thread_.FlipForWritingMode(bounds_in_flow_thread);
if (flow_thread_.IsHorizontalWritingMode()) {
logical_top_in_flow_thread_ = bounds_in_flow_thread.Y();
logical_bottom_in_flow_thread_ = bounds_in_flow_thread.MaxY();
} else {
logical_top_in_flow_thread_ = bounds_in_flow_thread.X();
logical_bottom_in_flow_thread_ = bounds_in_flow_thread.MaxX();
}
// Jump to the first interesting column set.
current_column_set_ = flow_thread.ColumnSetAtBlockOffset(
logical_top_in_flow_thread_, LayoutBox::kAssociateWithLatterPage);
if (!current_column_set_) {
SetAtEnd();
return;
}
// Then find the first interesting fragmentainer group.
current_fragmentainer_group_index_ =
current_column_set_->FragmentainerGroupIndexAtFlowThreadOffset(
logical_top_in_flow_thread_, LayoutBox::kAssociateWithLatterPage);
// Now find the first and last fragmentainer we're interested in. We'll also
// clip against the clip rect here. In case the clip rect doesn't intersect
// with any of the fragmentainers, we have to move on to the next
// fragmentainer group, and see if we find something there.
if (!SetFragmentainersOfInterest()) {
MoveToNextFragmentainerGroup();
if (AtEnd())
return;
}
}
void FragmentainerIterator::Advance() {
DCHECK(!AtEnd());
if (current_fragmentainer_index_ < end_fragmentainer_index_) {
current_fragmentainer_index_++;
} else {
// That was the last fragmentainer to visit in this fragmentainer group.
// Advance to the next group.
MoveToNextFragmentainerGroup();
if (AtEnd())
return;
}
}
LayoutSize FragmentainerIterator::PaginationOffset() const {
return CurrentGroup().FlowThreadTranslationAtOffset(
FragmentainerLogicalTopInFlowThread(),
LayoutBox::kAssociateWithLatterPage, CoordinateSpaceConversion::kVisual);
}
LayoutUnit FragmentainerIterator::FragmentainerLogicalTopInFlowThread() const {
DCHECK(!AtEnd());
const auto& group = CurrentGroup();
return group.LogicalTopInFlowThread() +
current_fragmentainer_index_ * group.ColumnLogicalHeight();
}
LayoutRect FragmentainerIterator::ClipRectInFlowThread() const {
DCHECK(!AtEnd());
LayoutRect clip_rect = CurrentGroup().FlowThreadPortionOverflowRectAt(
current_fragmentainer_index_);
flow_thread_.FlipForWritingMode(clip_rect);
return clip_rect;
}
const MultiColumnFragmentainerGroup& FragmentainerIterator::CurrentGroup()
const {
DCHECK(!AtEnd());
return current_column_set_
->FragmentainerGroups()[current_fragmentainer_group_index_];
}
void FragmentainerIterator::MoveToNextFragmentainerGroup() {
do {
current_fragmentainer_group_index_++;
if (current_fragmentainer_group_index_ >=
current_column_set_->FragmentainerGroups().size()) {
// That was the last fragmentainer group in this set. Advance to the next.
current_column_set_ = current_column_set_->NextSiblingMultiColumnSet();
current_fragmentainer_group_index_ = 0;
if (!current_column_set_ ||
current_column_set_->LogicalTopInFlowThread() >=
logical_bottom_in_flow_thread_) {
SetAtEnd();
return; // No more sets or next set out of range. We're done.
}
}
if (CurrentGroup().LogicalTopInFlowThread() >=
logical_bottom_in_flow_thread_) {
// This fragmentainer group doesn't intersect with the range we're
// interested in. We're done.
SetAtEnd();
return;
}
} while (!SetFragmentainersOfInterest());
}
bool FragmentainerIterator::SetFragmentainersOfInterest() {
const MultiColumnFragmentainerGroup& group = CurrentGroup();
// Figure out the start and end fragmentainers for the block range we're
// interested in. We might not have to walk the entire fragmentainer group.
group.ColumnIntervalForBlockRangeInFlowThread(
logical_top_in_flow_thread_, logical_bottom_in_flow_thread_,
current_fragmentainer_index_, end_fragmentainer_index_);
if (HasClipRect()) {
// Now intersect with the fragmentainers that actually intersect with the
// visual clip rect, to narrow it down even further. The clip rect needs to
// be relative to the current fragmentainer group.
LayoutRect clip_rect = clip_rect_in_multicol_container_;
LayoutSize offset = group.FlowThreadTranslationAtOffset(
group.LogicalTopInFlowThread(), LayoutBox::kAssociateWithFormerPage,
CoordinateSpaceConversion::kVisual);
clip_rect.Move(-offset);
unsigned first_fragmentainer_in_clip_rect, last_fragmentainer_in_clip_rect;
group.ColumnIntervalForVisualRect(clip_rect,
first_fragmentainer_in_clip_rect,
last_fragmentainer_in_clip_rect);
// If the two fragmentainer intervals are disjoint, there's nothing of
// interest in this fragmentainer group.
if (first_fragmentainer_in_clip_rect > end_fragmentainer_index_ ||
last_fragmentainer_in_clip_rect < current_fragmentainer_index_)
return false;
if (current_fragmentainer_index_ < first_fragmentainer_in_clip_rect)
current_fragmentainer_index_ = first_fragmentainer_in_clip_rect;
if (end_fragmentainer_index_ > last_fragmentainer_in_clip_rect)
end_fragmentainer_index_ = last_fragmentainer_in_clip_rect;
}
DCHECK_GE(end_fragmentainer_index_, current_fragmentainer_index_);
return true;
}
} // namespace blink