From 1a5c4047dc52fa0132584fc04a884a0a8acdd6a7 Mon Sep 17 00:00:00 2001
From: Robby Findler <robby@racket-lang.org>
Date: Fri, 16 Nov 2012 09:50:54 -0600
Subject: [PATCH] adjust the code that maintains the blue "where am I"
 background coloring in the contour window to make only a single call to
 invalidate-bitmap-cache

It was making two before, which could have pretty similar regions,
leading to two repaints instead of just one. When pushing the down
arrow near the bottom of the visible regions of the definitions text
was causing those two calls to take about 30 milliseconds and after
this change the one call seems to be about half that (but there is
lots of variance so I'm only sure that it helped some, not how much)

original commit: 6fc70a04d8b69f41d82c3bcbeeff26254017052d
---
 collects/framework/private/frame.rkt | 29 ++++++++++++++++++++++------
 1 file changed, 23 insertions(+), 6 deletions(-)

diff --git a/collects/framework/private/frame.rkt b/collects/framework/private/frame.rkt
index 1464406f..f5f11dd6 100644
--- a/collects/framework/private/frame.rkt
+++ b/collects/framework/private/frame.rkt
@@ -1605,12 +1605,12 @@
 
 (define delegatee-text%
   (class* text:basic% (delegatee-text<%>)
-    (inherit get-admin)
     (define start-para #f)
     (define end-para #f)
     (define view-x-b (box 0))
     (define view-width-b (box 0))
-    (inherit paragraph-start-position paragraph-end-position 
+    (inherit get-admin
+             paragraph-start-position paragraph-end-position 
              position-location invalidate-bitmap-cache scroll-to-position
              get-visible-position-range position-paragraph
              last-position)
@@ -1647,15 +1647,32 @@
                   [(v-end-para . <= . end-para)
                    (scroll-to-position (paragraph-end-position end-para))]
                   [else (void)]))))
-          
+          (define the-l #f)
+          (define the-t #f)
+          (define the-r #f)
+          (define the-b #f)
           (when (and old-start-para old-end-para)
             (let-values ([(x y w h) (get-rectangle old-start-para old-end-para)])
               (when x
-                (invalidate-bitmap-cache x y w h))))
+                (set! the-l x)
+                (set! the-t y)
+                (set! the-r (+ x w))
+                (set! the-b (+ y h)))))
           (when (and start-para end-para)
             (let-values ([(x y w h) (get-rectangle start-para end-para)])
-              (when x
-                (invalidate-bitmap-cache x y w h)))))))
+              (cond
+                [(and x the-l)
+                 (set! the-l (min x the-l))
+                 (set! the-t (min y the-t))
+                 (set! the-r (max the-r (+ x w)))
+                 (set! the-b (max the-b (+ y h)))]
+                [x
+                 (set! the-l x)
+                 (set! the-t y)
+                 (set! the-r (+ x w))
+                 (set! the-b (+ y h))])))
+          (when the-l
+            (invalidate-bitmap-cache the-l the-t (- the-r the-l) (- the-b the-t))))))
     
     (define/override (on-paint before? dc left top right bottom dx dy draw-caret)
       (when (and before?