private static MeasuredRectangle MeasureBackward(TextCaret caret, ITextCaretMeasurer measurer)
{
if (caret.IsAtBlockStart || caret.Block?.Tag == null)
{
return(MeasuredRectangle.Invalid);
}
return(measurer.MeasureTextPosition(caret.GetPreviousPosition()));
}
private static MeasuredRectangle MeasureForward(TextCaret caret, ITextCaretMeasurer measurer)
{
if (caret.IsAtBlockEnd || caret.Block?.Tag == null)
{
Debug.Assert(!caret.IsAtBlockEnd, "This usually indicates an error");
return(MeasuredRectangle.Invalid);
}
return(measurer.MeasureTextPosition(caret));
}
/// <summary>
/// Get the bounds of the given caret position.
/// </summary>
public static MeasuredRectangle Measure(TextCaret caret, ITextCaretMeasurer measurer)
{
bool isAtBlockStart = caret.IsAtBlockStart;
bool isAtBlockEnd = caret.IsAtBlockEnd;
if (isAtBlockStart && isAtBlockEnd)
{
// if it's empty, there is no character to measure
return(measurer.MeasureSelectionBounds().FlattenLeft());
}
// we want to measure the next character unless the previous character was
// a space (as the text will most likely appear on the next line anyways)
// TODO account for more whitespace
bool shouldMeasureNext = isAtBlockStart ||
(!isAtBlockEnd && caret.GetPreviousPosition().CharacterAfter.Text == " ");
return(shouldMeasureNext
? MeasureForward(caret, measurer).FlattenLeft()
: MeasureBackward(caret, measurer).FlattenRight());
}
