position-of-character-index

Arguments: text-edit-pane index &key bottom position-to-return

Returns the pixel position of the character at index in text-edit-pane.

The returned position object is in stream coordinates, meaning that it is measured from the upper-left corner of the scrollable contents of the window, and so the value will not be affected by the current scroll-position of the window.

text-edit-pane should be a text-edit-pane or rich-edit-pane.

index should be a non-negative integer indicating a character, where 0 indicates the first character in the window, (file-position text-edit-pane) indicates the character immediately to the right of the text cursor, and (file-length text-edit-pane) indicates the hypothetical character just after the last character. (See file-position and file-length.)

If bottom is nil, as it is by default, then the returned position is of the upper-left corner of the character cell. If bottom is true, then it is the lower-left corner instead.

If position-to-return is nil, as it is by default, then a new position object is consed and returned. Otherwise position-to-return may be a position object, in which case it is filled in and returned in order to avoid consing a position object.

For a text-edit-pane with a fixed-width font, the returned value could alternately be derived by calling such functions as line-height, line-number-from-char, and char-from-line-number. So this function is most useful for a rich-edit-pane, which typically has differing line heights and character widths.

See also character-index-at-position.

This example would return the pixel position of the bottom-right corner of the very last character's character cell:

(position-of-character-index
  my-text-edit-pane (file-length my-text-edit-pane)
  :bottom t)

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This page was not revised from the 8.1 page.
Created 2010.1.21.