53 lines
1.4 KiB
JavaScript
53 lines
1.4 KiB
JavaScript
/**
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* Copyright (c) 2013-present, Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under the BSD-style license found in the
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* LICENSE file in the root directory of this source tree. An additional grant
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* of patent rights can be found in the PATENTS file in the same directory.
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*
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* @providesModule moveSelectionBackward
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* @format
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*
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*/
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'use strict';
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/**
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* Given a collapsed selection, move the focus `maxDistance` backward within
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* the selected block. If the selection will go beyond the start of the block,
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* move focus to the end of the previous block, but no further.
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*
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* This function is not Unicode-aware, so surrogate pairs will be treated
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* as having length 2.
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*/
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function moveSelectionBackward(editorState, maxDistance) {
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var selection = editorState.getSelection();
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var content = editorState.getCurrentContent();
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var key = selection.getStartKey();
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var offset = selection.getStartOffset();
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var focusKey = key;
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var focusOffset = 0;
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if (maxDistance > offset) {
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var keyBefore = content.getKeyBefore(key);
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if (keyBefore == null) {
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focusKey = key;
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} else {
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focusKey = keyBefore;
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var blockBefore = content.getBlockForKey(keyBefore);
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focusOffset = blockBefore.getText().length;
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}
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} else {
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focusOffset = offset - maxDistance;
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}
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return selection.merge({
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focusKey: focusKey,
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focusOffset: focusOffset,
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isBackward: true
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});
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}
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module.exports = moveSelectionBackward; |