add 3 units of padding around printed picts

drracket/drracket/private/language.rkt

@@ -405,21 +405,23 @@
     (dyn pict-ascent)
     (dyn pict-descent)
     (dyn draw-pict)
-
+    (dyn convert-bounds-padding)
+
     (define (mk-pict-snip convertible)
+      (define-values (l-pad t-pad r-pad b-pad) (apply values (convert-bounds-padding)))
       (define pict (pict-convert convertible))
       (define w (pict-width pict))
-      (define aw (abs w))
+      (define aw (+ (abs w) l-pad r-pad))
       (define h (pict-height pict))
-      (define ah (abs h))
-      (define a (pict-ascent pict))
-      (define d (pict-descent pict))
+      (define ah (+ (abs h) t-pad b-pad))
+      (define a (+ (pict-ascent pict) t-pad))
+      (define d (+ (pict-descent pict) b-pad))
       (define rdc (new record-dc%))
       (send rdc set-smoothing 'aligned)
       (send rdc set-clipping-rect 0 0 aw ah)
       (draw-pict pict rdc
-                 (if (< w 0) aw 0)
-                 (if (< h 0) ah 0))
+                 (+ (if (< w 0) aw 0) l-pad)
+                 (+ (if (< h 0) ah 0) t-pad))
       (define recorded-datum (send rdc get-recorded-datum))
       (new pict-snip:pict-snip% [w aw] [h ah] [d d] [a a] [recorded-datum recorded-datum]))
 

drracket/scribblings/drracket/languages.scrbl

@@ -1,7 +1,7 @@
 #lang scribble/doc
 @(require "common.rkt"
           (for-label errortrace/errortrace-lib compiler/cm planet/config
-                     racket/pretty drracket/tool drracket/tool-lib))
+                     racket/pretty drracket/tool drracket/tool-lib pict))
 
 @title[#:tag "languages" #:style 'toc]{Languages}
 
@@ -25,7 +25,7 @@ More generally, when using this mode, the
 ...)]; aside from comments, the @tech{definitions window}
 must contain exactly one module.
 
-@subsection{Initial Environment}
+@subsection[#:tag "Initial Environment"]{Initial Environment}
 
 DrRacket initializes the environment before it starts running the program in
 ways slightly different than the @tt{racket} command-line binary does to reflect
@@ -37,7 +37,8 @@ in the next subsection.
 DrRacket initializes the @racket[pretty-print-size-hook] and @racket[pretty-print-print-hook]
 to specially recognize
 @itemize[@item{@racket[snip%]s, which it just inserts into the editor}
-         @item{convertible values from @racketmodname[pict/convert]}
+         @item{convertible values from @racketmodname[pict/convert], which are rendered
+               with padding specified by @racket[convert-bounds-padding] around the bounding box to reduce edge effects}
          @item{convertible values from @racketmodname[file/convertible] (which it converts to
           png images)}
          @item{numbers that are @racket[exact?] and @racket[real?], but not @racket[integer?],

drracket/scribblings/drracket/printing.scrbl

@@ -89,6 +89,7 @@ the booleans, it determines if there is a @litchar{#} prefix and for
 the empty list, determines if it prints as @racket[empty] or @racket['()].
 
 For any of the output styles, DrRacket sets the
-@racket[global-port-print-handler] so that the @racket[print]
+@racket[global-port-print-handler] (as described in @secref["Initial Environment"])
+so that the @racket[print]
 procedure produces output as selected.