text(or textedge) coordinate have negative value

When i use stream to parse a pdf and show the text plot,there have many negative values in the plot and the plot looks irrelevant to the actual pdf content.
Some negative values like:
, , , ,

plot like this:

Start by reproducing the stream parsing and text plot described in the issue, using the reported TextEdge values as the initial symptom. Trace how those coordinates reach the plot and compare them with the source PDF; done means the plotted text matches the PDF content and the reported invalid negative coordinates are handled correctly.

Written by the indexing model from the issue text.