[layoutng] Support computing min-content and max-content

third_party/WebKit/Source/core/layout/ng/ng_box.cc

 // 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/ng_box.h"
 
 #include "core/layout/LayoutBlockFlow.h"
 #include "core/layout/ng/layout_ng_block_flow.h"
 #include "core/layout/ng/ng_block_layout_algorithm.h"
+#include "core/layout/ng/ng_constraint_space_builder.h"
 #include "core/layout/ng/ng_constraint_space.h"
 #include "core/layout/ng/ng_direction.h"
 #include "core/layout/ng/ng_fragment.h"
 #include "core/layout/ng/ng_fragment_builder.h"
 #include "core/layout/ng/ng_length_utils.h"
 #include "core/layout/ng/ng_writing_mode.h"
 
 namespace blink {
 
 NGBox::NGBox(LayoutObject* layout_object)
@@ skipping 36 matching lines @@
     fragment_ = RunOldLayout(*constraint_space);
   }
   *out = new NGFragment(constraint_space->WritingMode(),
                         FromPlatformDirection(Style()->direction()),
                         fragment_.get());
   // Reset algorithm for future use
   algorithm_ = nullptr;
   return true;
 }
 
+void NGBox::ComputeMinAndMaxContentSizes(NGFragment** min_content,
+                                         NGFragment** max_content) {
+  NGConstraintSpaceBuilder builder(
+      FromPlatformWritingMode(Style()->getWritingMode()));
+  builder.SetContainerSize(NGLogicalSize(LayoutUnit(), LayoutUnit()));

[Gleb Lanbin, 2016/10/31 19:52:47]

nit. you can chain SetContainerSize call to line above.

[cbiesinger, 2016/11/01 19:10:03]

I'd rather not chain something to the constructor like that

+  NGConstraintSpace* constraint_space = new NGConstraintSpace(
+      FromPlatformWritingMode(Style()->getWritingMode()),
+      FromPlatformDirection(Style()->direction()), builder.ToConstraintSpace());

[eae, 2016/10/31 19:30:25]

Presumably once Ian's work is done this will be
builder.ToConstraintSpace.ToLogicalConstraintSpace or something, right? Might
want to add a TODO.

[cbiesinger, 2016/11/01 19:10:03]

Ah, is that the plan? Added a TODO.

+
+  NGLayoutAlgorithm* algorithm =
+      new NGBlockLayoutAlgorithm(Style(), FirstChild(), constraint_space);
+  if (algorithm->ComputeMinAndMaxContentSizes(min_content, max_content) ==

[Gleb Lanbin, 2016/10/31 19:52:47]

IMO it's a bit confusing that we have 2 almost identical public functions with
the same name. If a person is not familiar with the code then they would
probably would be interested to know what's the difference between those 2
functions?

[cbiesinger, 2016/11/01 19:10:03]

Renamed this one to ComputeOrSynthesizeMinAndMaxContentSizes

+      NGLayoutAlgorithm::Success)
+    return;
+
+  // Have to synthesize this value.
+  NGPhysicalFragment* fragment;
+  while (!algorithm->Layout(&fragment))
+    continue;
+
+  HeapVector<Member<const NGPhysicalFragmentBase>> empty;

[Gleb Lanbin, 2016/10/31 19:52:47]

may be add an additional constructor to NGPhysicalFragment? otherwise it's not
clear why we pass an empty, unused? list of children here and below.

[cbiesinger, 2016/11/01 19:10:03]

Removed this entirely due to other changes.

+  fragment =
+      new NGPhysicalFragment(fragment->OverflowSize(), fragment->OverflowSize(),
+                             empty, NGMarginStrut());
+
+  *min_content =
+      new NGFragment(FromPlatformWritingMode(Style()->getWritingMode()),
+                     FromPlatformDirection(Style()->direction()), fragment);
+
+  // Now, redo with infinite space for max_content
+  builder.SetContainerSize(NGLogicalSize(LayoutUnit::max(), LayoutUnit()));
+  constraint_space = new NGConstraintSpace(
+      FromPlatformWritingMode(Style()->getWritingMode()),
+      FromPlatformDirection(Style()->direction()), builder.ToConstraintSpace());
+
+  algorithm =
+      new NGBlockLayoutAlgorithm(Style(), FirstChild(), constraint_space);
+  while (!algorithm->Layout(&fragment))
+    continue;
+
+  fragment =
+      new NGPhysicalFragment(fragment->OverflowSize(), fragment->OverflowSize(),
+                             empty, NGMarginStrut());
+  *max_content =
+      new NGFragment(FromPlatformWritingMode(Style()->getWritingMode()),
+                     FromPlatformDirection(Style()->direction()), fragment);
+}
+
 const ComputedStyle* NGBox::Style() const {
   if (style_)
     return style_.get();
   DCHECK(layout_box_);
   return layout_box_->style();
 }
 
 NGBox* NGBox::NextSibling() {
   if (!next_sibling_) {
     LayoutObject* next_sibling =
@@ skipping 14 matching lines @@
 }
 
 void NGBox::SetNextSibling(NGBox* sibling) {
   next_sibling_ = sibling;
 }
 
 void NGBox::SetFirstChild(NGBox* child) {
   first_child_ = child;
 }
 
+DEFINE_TRACE(NGBox) {
+  visitor->trace(algorithm_);
+  visitor->trace(fragment_);
+  visitor->trace(next_sibling_);
+  visitor->trace(first_child_);
+}
+
 void NGBox::PositionUpdated() {
   if (!layout_box_)
     return;
   DCHECK(layout_box_->parent()) << "Should be called on children only.";
 
   layout_box_->setX(fragment_->LeftOffset());
   layout_box_->setY(fragment_->TopOffset());
 
   if (layout_box_->isFloating() && layout_box_->parent()->isLayoutBlockFlow()) {
     FloatingObject* floating_object = toLayoutBlockFlow(layout_box_->parent())
@@ skipping 69 matching lines @@
       .SetBlockSize(layout_box_->logicalHeight())
       .SetDirection(FromPlatformDirection(layout_box_->styleRef().direction()))
       .SetWritingMode(
           FromPlatformWritingMode(layout_box_->styleRef().getWritingMode()))
       .SetInlineOverflow(overflow.width())
       .SetBlockOverflow(overflow.height());
   return builder.ToFragment();
 }
 
 }  // namespace blink