| /* |
| * Copyright (c) 2012, Google Inc. All rights reserved. |
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| |
| #ifndef THIRD_PARTY_BLINK_RENDERER_PLATFORM_TEXT_WRITING_MODE_H_ |
| #define THIRD_PARTY_BLINK_RENDERER_PLATFORM_TEXT_WRITING_MODE_H_ |
| |
| #include <cstdint> |
| #include <iosfwd> |
| #include "third_party/blink/renderer/platform/platform_export.h" |
| |
| namespace blink { |
| |
| // These values are named to match the CSS keywords they correspond to: namely |
| // horizontal-tb, vertical-rl and vertical-lr. |
| // Since these names aren't very self-explanatory, where possible use the |
| // inline utility functions below. |
| enum class WritingMode : uint8_t { |
| kHorizontalTb = 0, |
| kVerticalRl = 1, |
| kVerticalLr = 2, |
| // sideways-rl and sideways-lr are only supported by LayoutNG. |
| kSidewaysRl = 3, |
| kSidewaysLr = 4 |
| }; |
| |
| // Lines have horizontal orientation; modes horizontal-tb. |
| inline bool IsHorizontalWritingMode(WritingMode writing_mode) { |
| return writing_mode == WritingMode::kHorizontalTb; |
| } |
| |
| // Bottom of the line occurs earlier in the block; modes vertical-lr. |
| inline bool IsFlippedLinesWritingMode(WritingMode writing_mode) { |
| return writing_mode == WritingMode::kVerticalLr; |
| } |
| |
| // In flipped-lines writing mode, 'line-over' and 'block-start' don't match. |
| // When dealing with the logical coordinate system in the [line-relative |
| // directions], 'vertical-lr' has 'line-over' on right, which is equivalent to |
| // the 'vertical-rl' in the flow-relative directions. |
| // https://drafts.csswg.org/css-writing-modes-3/#line-directions |
| inline WritingMode ToLineWritingMode(WritingMode writing_mode) { |
| return !IsFlippedLinesWritingMode(writing_mode) ? writing_mode |
| : WritingMode::kVerticalRl; |
| } |
| |
| // Block progression increases in the opposite direction to normal; modes |
| // vertical-rl. |
| inline bool IsFlippedBlocksWritingMode(WritingMode writing_mode) { |
| return writing_mode == WritingMode::kVerticalRl; |
| } |
| |
| // Whether the child and the containing block are parallel to each other. |
| // Example: vertical-rl and vertical-lr |
| inline bool IsParallelWritingMode(WritingMode a, WritingMode b) { |
| return (a == WritingMode::kHorizontalTb) == (b == WritingMode::kHorizontalTb); |
| } |
| |
| PLATFORM_EXPORT std::ostream& operator<<(std::ostream&, WritingMode); |
| |
| } // namespace blink |
| |
| #endif // THIRD_PARTY_BLINK_RENDERER_PLATFORM_TEXT_WRITING_MODE_H_ |