C# ITextView.GetPositionAtNextLine方法代码示例

        /// <summary>
        /// Retrieves position at the page boundary from given suggestedX.
        /// </summary>
        /// <param name="pageTop">Whether asking for top of the page or bottom of the page.</param> 
        /// <param name="pageTextView">TextView representing the page.</param>
        /// <param name="position">Position at the beginning/end of the page.</param> 
        /// <param name="suggestedX">Suggested offset in the page.</param> 
        /// <returns>Position at the page boundary from given suggestedX.</returns>
        private ITextPointer GetPositionAtPageBoundary(bool pageTop, ITextView pageTextView, ITextPointer position, double suggestedX) 
        {
            double newSuggestedX;
            int newLinesMoved;
            ITextPointer positionOut; 

            // If moving to the first/last line of the next/previous TextView, there is 
            // special handling needed to position at the right suggestedX. Otherwise, TextView 
            // will return the same position.
            if (pageTop) 
            {
                // Move line down and line up.
                positionOut = pageTextView.GetPositionAtNextLine(position, suggestedX, 1, out newSuggestedX, out newLinesMoved);
                if (newLinesMoved == 1) 
                {
                    positionOut = pageTextView.GetPositionAtNextLine(positionOut, newSuggestedX, -1, out newSuggestedX, out newLinesMoved); 
                } 
                else
                { 
                    // Line down failed, so use the first position of TextView.
                    positionOut = position;
                }
            } 
            else
            { 
                // Move line up and line down. 
                positionOut = pageTextView.GetPositionAtNextLine(position, suggestedX, -1, out newSuggestedX, out newLinesMoved);
                if (newLinesMoved == -1) 
                {
                    positionOut = pageTextView.GetPositionAtNextLine(positionOut, newSuggestedX, 1, out newSuggestedX, out newLinesMoved);
                }
                else 
                {
                    // Line up failed, so use the last position of TextView. 
                    positionOut = position; 
                }
            } 
            return positionOut;
        }

        // <see cref="System.Windows.Documents.TextPointer.MoveToLineBoundary"/>
        internal static int MoveToLineBoundary(ITextPointer thisPointer, ITextView textView, int count, bool respectNonMeargeableInlineStart)
        {
            ITextPointer position;
            double newSuggestedX;

            Invariant.Assert(!thisPointer.IsFrozen, "Can't reposition a frozen pointer!");
            Invariant.Assert(textView != null, "Null TextView!"); // Did you check ITextPointer.HasValidLayout?

            position = textView.GetPositionAtNextLine(thisPointer, Double.NaN, count, out newSuggestedX, out count);

            if (!position.IsAtInsertionPosition)
            {
                if (!respectNonMeargeableInlineStart || 
                    (!IsAtNonMergeableInlineStart(position) && !IsAtNonMergeableInlineEnd(position)))
                {
                    position.MoveToInsertionPosition(position.LogicalDirection);
                }
            }

            if (IsAtRowEnd(position))
            {
                // We will find outselves at a row end when we have incomplete
                // markup like
                //
                //  <TableCell></TableCell> <!-- No inner Run! -->
                //
                // In that case the end-of-row is the entire line.
                thisPointer.MoveToPosition(position);
                thisPointer.SetLogicalDirection(position.LogicalDirection);
            }
            else
            {
                TextSegment lineRange = textView.GetLineRange(position);

                if (!lineRange.IsNull)
                {
                    thisPointer.MoveToPosition(lineRange.Start);
                    thisPointer.SetLogicalDirection(lineRange.Start.LogicalDirection);
                }
                else if (count > 0)
                {
                    // It is possible to get a non-zero return value from ITextView.GetPositionAtNextLine
                    // when moving into a BlockUIContainer.  The container is the "next line" but does
                    // not contain any lines itself -- GetLineRange will return null.
                    thisPointer.MoveToPosition(position);
                    thisPointer.SetLogicalDirection(position.LogicalDirection);
                }
            }

            return count;
        }