| // 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. |
| |
| #ifndef NGLayoutAlgorithm_h |
| #define NGLayoutAlgorithm_h |
| |
| #include "core/CoreExport.h" |
| #include "wtf/Allocator.h" |
| #include "wtf/Noncopyable.h" |
| |
| namespace blink { |
| |
| struct MinAndMaxContentSizes; |
| class NGConstraintSpace; |
| class NGPhysicalFragment; |
| |
| // Base class for all LayoutNG algorithms. |
| class CORE_EXPORT NGLayoutAlgorithm |
| : public GarbageCollectedFinalized<NGLayoutAlgorithm> { |
| WTF_MAKE_NONCOPYABLE(NGLayoutAlgorithm); |
| |
| public: |
| NGLayoutAlgorithm() {} |
| virtual ~NGLayoutAlgorithm() {} |
| |
| // Actual layout function. Lays out the children and descendents within the |
| // constraints given by the NGConstraintSpace. Returns a fragment with the |
| // resulting layout information. |
| // This function can not be const because for interruptible layout, we have |
| // to be able to store state information. |
| // Returns true when done; when this function returns false, it has to be |
| // called again. The out parameter will only be set when this function |
| // returns true. |
| virtual bool Layout(NGPhysicalFragment**) = 0; |
| |
| enum MinAndMaxState { Success, Pending, NotImplemented }; |
| |
| // Computes the min-content and max-content intrinsic sizes for the given box. |
| // The result will not take any min-width. max-width or width properties into |
| // account. Implementations can return NotImpplemented in which case the |
| // caller is expected ot synthesize this value from the overflow rect returned |
| // from Layout called with a available width of 0 and LayoutUnit::max(), |
| // respectively. |
| // A Pending return value has the same meaning as a false return from layout, |
| // i.e. it is a request to call this function again. |
| virtual MinAndMaxState ComputeMinAndMaxContentSizes(MinAndMaxContentSizes*) { |
| return NotImplemented; |
| } |
| |
| DEFINE_INLINE_VIRTUAL_TRACE() {} |
| }; |
| |
| } // namespace blink |
| |
| #endif // NGLayoutAlgorithm_h |