[gimp] app: avoid expensive rotated scale calculation when scale_x == scale_y

[N/A <ell src gnome org>]

commit 26b978d2a8ecf62ffc232e00ac7c1773efb82fc7
Author: Ell <ell_se yahoo com>
Date:   Tue Aug 9 22:25:54 2016 +0000

    app: avoid expensive rotated scale calculation when scale_x == scale_y
    
    Ditto for the rulers' resolution calculation.

 app/display/gimpdisplayshell-rulers.c |   27 ++++++++++++++++++---------
 app/display/gimpdisplayshell-scale.c  |    2 +-
 2 files changed, 19 insertions(+), 10 deletions(-)
---
diff --git a/app/display/gimpdisplayshell-rulers.c b/app/display/gimpdisplayshell-rulers.c
index 610a2ae..c92fd6a 100644
--- a/app/display/gimpdisplayshell-rulers.c
+++ b/app/display/gimpdisplayshell-rulers.c
@@ -69,7 +69,6 @@ gimp_display_shell_rulers_update (GimpDisplayShell *shell)
     {
       gint    image_x, image_y;
       gdouble res_x, res_y;
-      gdouble cos_a, sin_a;
 
       gimp_display_shell_scale_get_image_bounds (shell,
                                                  &image_x, &image_y,
@@ -85,18 +84,28 @@ gimp_display_shell_rulers_update (GimpDisplayShell *shell)
 
       gimp_image_get_resolution (image, &res_x, &res_y);
 
-      cos_a = cos (G_PI * shell->rotate_angle / 180.0);
-      sin_a = sin (G_PI * shell->rotate_angle / 180.0);
-
-      if (shell->dot_for_dot)
+      if (shell->rotate_angle == 0.0 || res_x == res_y)
         {
-          resolution_x = 1.0 / sqrt (SQR (cos_a / res_x) + SQR (sin_a / res_y));
-          resolution_y = 1.0 / sqrt (SQR (cos_a / res_y) + SQR (sin_a / res_x));
+          resolution_x = res_x;
+          resolution_y = res_y;
         }
       else
         {
-          resolution_x = sqrt (SQR (res_x * cos_a) + SQR (res_y * sin_a));
-          resolution_y = sqrt (SQR (res_y * cos_a) + SQR (res_x * sin_a));
+          gdouble cos_a = cos (G_PI * shell->rotate_angle / 180.0);
+          gdouble sin_a = sin (G_PI * shell->rotate_angle / 180.0);
+
+          if (shell->dot_for_dot)
+            {
+              resolution_x = 1.0 / sqrt (SQR (cos_a / res_x) +
+                                         SQR (sin_a / res_y));
+              resolution_y = 1.0 / sqrt (SQR (cos_a / res_y) +
+                                         SQR (sin_a / res_x));
+            }
+          else
+            {
+              resolution_x = sqrt (SQR (res_x * cos_a) + SQR (res_y * sin_a));
+              resolution_y = sqrt (SQR (res_y * cos_a) + SQR (res_x * sin_a));
+            }
         }
     }
   else
diff --git a/app/display/gimpdisplayshell-scale.c b/app/display/gimpdisplayshell-scale.c
index afdfb7d..d193a15 100644
--- a/app/display/gimpdisplayshell-scale.c
+++ b/app/display/gimpdisplayshell-scale.c
@@ -780,7 +780,7 @@ gimp_display_shell_get_rotated_scale (GimpDisplayShell *shell,
 {
   g_return_if_fail (GIMP_IS_DISPLAY_SHELL (shell));
 
-  if (shell->rotate_angle == 0.0)
+  if (shell->rotate_angle == 0.0 || shell->scale_x == shell->scale_y)
     {
       if (scale_x) *scale_x = shell->scale_x;
       if (scale_y) *scale_y = shell->scale_y;