I wasn't aware you could use sourceRectAtTime for boxText, but only for point text. To get a box text's center, you could use the boxTextSize value (an array), so the horizontal center would be boxTextSize[0]/2 and the vertical center would be boxTextSize[1]/2. from page 184 of the AE CS6 Scripting Guide: TextDocument boxText attribute textDocument.boxText Description True if a text layer is a layer of paragraph (bounded) text; otherwise false. Type Boolean; read-only. TextDocument boxTextSize attribute textDocument.boxTextSize Description The size of a paragraph (box) text layer as a [width, height] array of pixel dimensions. Type Array of two integers (minimum value of 1); read/write. Also, c/o David Torno, UgQ, AgileUI, et al: ADBE Text Document boxTextSize attribute
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