81 lines
4.2 KiB
C#
81 lines
4.2 KiB
C#
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using System;
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using System.Windows;
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using System.Windows.Documents;
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using System.Collections.Generic;
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namespace DBToolControls {
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public static class WordBreaker {
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/// <summary>
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/// Returns a TextRange covering a word containing or following this TextPointer.
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/// </summary>
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/// <remarks>
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/// If this TextPointer is within a word or at start of word, the containing word range is returned.
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/// If this TextPointer is between two words, the following word range is returned.
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/// If this TextPointer is at trailing word boundary, the following word range is returned.
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/// </remarks>
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///
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public static TextRange GetWordRange(TextPointer position) {
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TextRange wordRange = null;
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TextPointer wordStartPosition = null;
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TextPointer wordEndPosition = null;
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// Go forward first, to find word end position.
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wordEndPosition = GetPositionAtWordBoundary(position, /*wordBreakDirection*/LogicalDirection.Forward);
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if (wordEndPosition != null) {
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// Then travel backwards, to find word start position.
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wordStartPosition = GetPositionAtWordBoundary(wordEndPosition, /*wordBreakDirection*/LogicalDirection.Backward);
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}
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if (wordStartPosition != null && wordEndPosition != null) {
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wordRange = new TextRange(wordStartPosition, wordEndPosition);
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}
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return wordRange;
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}
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/// <summary>
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/// 1. When wordBreakDirection = Forward, returns a position at the end of the word,
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/// i.e. a position with a wordBreak character (space) following it.
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/// 2. When wordBreakDirection = Backward, returns a position at the start of the word,
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/// i.e. a position with a wordBreak character (space) preceeding it.
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/// 3. Returns null when there is no workbreak in the requested direction.
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/// </summary>
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///
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private static TextPointer GetPositionAtWordBoundary(TextPointer position, LogicalDirection wordBreakDirection) {
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if (!position.IsAtInsertionPosition) {
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position = position.GetInsertionPosition(wordBreakDirection);
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}
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TextPointer navigator = position;
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while (navigator != null && !IsPositionNextToWordBreak(navigator, wordBreakDirection)) {
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navigator = navigator.GetNextInsertionPosition(wordBreakDirection);
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}
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return navigator;
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}
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// Helper for GetPositionAtWordBoundary.
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// Returns true when passed TextPointer is next to a wordBreak in requested direction.
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private static bool IsPositionNextToWordBreak(TextPointer position, LogicalDirection wordBreakDirection) {
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bool isAtWordBoundary = false;
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// Skip over any formatting.
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if (position.GetPointerContext(wordBreakDirection) != TextPointerContext.Text) {
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position = position.GetInsertionPosition(wordBreakDirection);
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}
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if (position.GetPointerContext(wordBreakDirection) == TextPointerContext.Text) {
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LogicalDirection oppositeDirection = (wordBreakDirection == LogicalDirection.Forward) ?
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LogicalDirection.Backward : LogicalDirection.Forward;
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char[] runBuffer = new char[1];
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char[] oppositeRunBuffer = new char[1];
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position.GetTextInRun(wordBreakDirection, runBuffer, /*startIndex*/0, /*count*/1);
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position.GetTextInRun(oppositeDirection, oppositeRunBuffer, /*startIndex*/0, /*count*/1);
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if (SyntaxProvider.Delimiters.Contains(runBuffer[0]) && !(SyntaxProvider.Delimiters.Contains(oppositeRunBuffer[0]))) {
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isAtWordBoundary = true;
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}
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} else {
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// If we're not adjacent to text then we always want to consider this position a "word break".
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// In practice, we're most likely next to an embedded object or a block boundary.
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isAtWordBoundary = true;
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}
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return isAtWordBoundary;
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}
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}
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}
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