<summary>
Get a block of text immediately preceding the specified position.
</summary>
<param name="textPosition">Position immediately after the last position of the chunk to obtain.</param>
<param name="textString">Address that receives a pointer to the text block
at the specified position.</param>
<param name="textLength">Number of UTF16 units of the retrieved block.
The length returned is from the given position to the front of
the block.</param>
<returns>Pointer to the first character at (textPosition - textLength).
NULL indicates no chunk available at the specified position, either
because textPosition == 0,the textPosition > the entire text content
length, or the queried position is not mapped into the app's backing
store.</returns>
<remarks>
Although apps can implement sparse textual content that only maps part of
the backing store, the app must map any text that is in the range passed
to any analysis functions.
</remarks>
<summary> Get a block of text immediately preceding the specified position. </summary> <param name="textPosition">Position immediately after the last position of the chunk to obtain.</param> <param name="textString">Address that receives a pointer to the text block at the specified position.</param> <param name="textLength">Number of UTF16 units of the retrieved block. The length returned is from the given position to the front of the block.</param> <returns>Pointer to the first character at (textPosition - textLength). NULL indicates no chunk available at the specified position, either because textPosition == 0,the textPosition > the entire text content length, or the queried position is not mapped into the app's backing store.</returns> <remarks> Although apps can implement sparse textual content that only maps part of the backing store, the app must map any text that is in the range passed to any analysis functions. </remarks>