From a3370be15d7c467010091946a085216c50af54b6 Mon Sep 17 00:00:00 2001
From: Robby Findler <robby@racket-lang.org>
Date: Wed, 18 Jun 2014 01:20:05 -0500
Subject: [PATCH] fix bitmap rotate/flip interaction

closes PR 14585
---
 .../htdp-lib/2htdp/private/image-more.rkt          | 14 +++++++++-----
 .../htdp-pkgs/htdp-test/2htdp/tests/test-image.rkt |  5 +++++
 2 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/pkgs/htdp-pkgs/htdp-lib/2htdp/private/image-more.rkt b/pkgs/htdp-pkgs/htdp-lib/2htdp/private/image-more.rkt
index 7937f5f1c4..3440192cd4 100644
--- a/pkgs/htdp-pkgs/htdp-lib/2htdp/private/image-more.rkt
+++ b/pkgs/htdp-pkgs/htdp-lib/2htdp/private/image-more.rkt
@@ -775,10 +775,9 @@
            [flipped? (flip-flipped? atomic-shape)])
        (make-flip flipped? 
                   (make-ibitmap (ibitmap-raw-bitmap bitmap)
-                                (bring-between (if flipped? 
-                                                   (- (ibitmap-angle bitmap) θ)
-                                                   (+ (ibitmap-angle bitmap) θ))
-                                               360)
+                                (bring-between 
+                                 (+ (ibitmap-angle bitmap) θ)
+                                 360)
                                 (ibitmap-x-scale bitmap)
                                 (ibitmap-y-scale bitmap)
                                 (make-hash))))]))
@@ -911,8 +910,13 @@
     [(text? atomic-shape)
      (error 'flip "cannot flip shapes that contain text")]
     [(flip? atomic-shape)
+     (define bitmap (flip-shape atomic-shape))
      (make-flip (not (flip-flipped? atomic-shape))
-                (flip-shape atomic-shape))]))
+                (make-ibitmap (ibitmap-raw-bitmap bitmap)
+                              (bring-between (- (ibitmap-angle bitmap)) 360)
+                              (ibitmap-x-scale bitmap)
+                              (ibitmap-y-scale bitmap)
+                              (make-hash)))]))
 
 (define (flip-point point) (make-point (point-x point) (- (point-y point))))
 (define (flip-points points) (map flip-point points))
diff --git a/pkgs/htdp-pkgs/htdp-test/2htdp/tests/test-image.rkt b/pkgs/htdp-pkgs/htdp-test/2htdp/tests/test-image.rkt
index 56ac9cbf64..43ec6a60be 100644
--- a/pkgs/htdp-pkgs/htdp-test/2htdp/tests/test-image.rkt
+++ b/pkgs/htdp-pkgs/htdp-test/2htdp/tests/test-image.rkt
@@ -1603,6 +1603,11 @@
       =>
       (to-img (make-object image-snip% green-blue-20x10-bitmap)))
 
+(let ([b (freeze (beside (rectangle 4 8 "solid" "blue") (rectangle 4 8 "solid" "red")))])
+  (test (flip-vertical (rotate 90 b))
+        =>
+        (rotate -90 b)))
+
 ;; make sure that raw image snips are equal to image snips
 (let ([i1 (make-object image-snip% (collection-file-path "bug09.png" "icons"))]
       [i2 (make-object image-snip% (collection-file-path "bug09.png" "icons"))])