How to align Text within Graphics?

Question

Consider the code

lin = Graphics[{Red, Line[{{0.5, 0}, {0.5, 1}}]}];
rect = Graphics[{Rectangle[], 
    Inset[Style[Text["aaa"], 20, White, Bold, 
      TextAlignment -> Left]]}];
Show[rect, lin]

I want to start writing from left to right after the red line (or at a given $x$ position), that is

and so that when I had more letter, it writes on the right:

How do I do this? I've tried playing around with TextAlignment or TextJustification with no success.

Answer 1

Add to Inset[] the following arguments : , Center, {Left, Center} :

lin = Graphics[{Red, Line[{{0.5, 0}, {0.5, 1}}]}];
rect = Graphics[{Rectangle[], Inset[
     Style[Text["aaabbb"], 20, White, Bold(*,TextAlignment\[Rule]Left*)]
     , Center, {Left, Center}
     ]}];
Show[rect, lin]