| // Copyright 2015 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 FragmentationContext_h |
| #define FragmentationContext_h |
| |
| #include "core/CoreExport.h" |
| #include "platform/LayoutUnit.h" |
| #include "platform/geometry/LayoutSize.h" |
| |
| namespace blink { |
| |
| // A fragmentation context is either established by a multicol container, or by |
| // pages when printing. A fragmentation context consists of a series of |
| // fragmentainers. A fragmentainer is simply a column or page, depending on the |
| // type of fragmentation context. [1] |
| // |
| // A couple of methods here take a |blockOffset| parameter. This is the offset |
| // from the start of the fragmentation context, pretending that everything is |
| // laid out in one single strip (and not sliced into pages or columns). |
| // In multicol, this is referred to as the flow thread coordinate space. |
| // |
| // It should be noted that a multicol container may be nested inside another |
| // fragmentation context (another multicol container, or the pages when |
| // printing), although this class doesn't deal with that (it's internal to the |
| // multicol implementation). |
| // |
| // [1] http://www.w3.org/TR/css3-break/#fragmentation-model |
| class CORE_EXPORT FragmentationContext { |
| public: |
| virtual ~FragmentationContext() {} |
| |
| // The height of the fragmentainers may depend on the total height of the |
| // contents (column balancing), in which case false is returned if we haven't |
| // laid out yet. Otherwise, true is returned. |
| virtual bool isFragmentainerLogicalHeightKnown() = 0; |
| |
| // Return the height of the fragmentainer at the specified offset. The |
| // fragmentainer height isn't necessarily uniform all across the fragmentation |
| // context. |
| virtual LayoutUnit fragmentainerLogicalHeightAt(LayoutUnit blockOffset) = 0; |
| |
| // Return how much is left of the fragmentainer at the specified offset. |
| // Callers typically want this information to decide whether some piece of |
| // content fits in this fragmentainer, or if it has to push the content to the |
| // next fragmentainer. |
| virtual LayoutUnit remainingLogicalHeightAt(LayoutUnit blockOffset) = 0; |
| |
| // Return the flow thread of the fragmentation context, if it is a multicol |
| // fragmentation context. Since multicol containers may be nested inside other |
| // fragmentation contexts, sometimes we need to know if it's a multicol |
| // container that we're dealing with. |
| virtual class LayoutMultiColumnFlowThread* associatedFlowThread() { |
| return nullptr; |
| } |
| }; |
| |
| } // namespace blink |
| |
| #endif // FragmentationContext_h |