| // Copyright 2017 The Fuchsia Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| library fuchsia.ui.input; |
| |
| // Whether a TextPosition is visually upstream or downstream of its offset. |
| // |
| // For example, when a text position exists at a line break, a single offset has |
| // two visual positions, one prior to the line break (at the end of the first |
| // line) and one after the line break (at the start of the second line). A text |
| // affinity disambiguates between those cases. (Something similar happens with |
| // between runs of bidirectional text.) |
| enum TextAffinity { |
| // The position has affinity for the upstream side of the text position. |
| // |
| // For example, if the offset of the text position is a line break, the |
| // position represents the end of the first line. |
| UPSTREAM = 0; |
| |
| // The position has affinity for the downstream side of the text position. |
| // |
| // For example, if the offset of the text position is a line break, the |
| // position represents the start of the second line. |
| DOWNSTREAM = 1; |
| }; |
| |
| // A range of characters in a string of text. |
| struct TextRange { |
| // The index of the first UTF-16 character in the range. |
| // |
| // If |start| and |end| are both -1, the text range is empty. |
| int64 start = -1; |
| |
| // The next index after the UTF-16 characters in this range. |
| // |
| // If |start| and |end| are both -1, the text range is empty. |
| int64 end = -1; |
| }; |
| |
| // A range of text that represents a selection. |
| // |
| // Text selection is always directional. Direction should be determined by |
| // comparing base and extent. |
| struct TextSelection { |
| // The offset at which the selection originates. |
| // |
| // Might be larger than, smaller than, or equal to extent. |
| int64 base; |
| |
| // The offset at which the selection terminates. |
| // |
| // When the user uses the arrow keys to adjust the selection, this is the |
| // value that changes. Similarly, if the current theme paints a caret on one |
| // side of the selection, this is the location at which to paint the caret. |
| // |
| // Might be larger than, smaller than, or equal to base. |
| int64 extent; |
| |
| // If the the text range is collapsed and has more than one visual location |
| // (e.g., occurs at a line break), which of the two locations to use when |
| // painting the caret. |
| TextAffinity affinity; |
| }; |