[mutter] boxes: Add helper to scale rectangles by a double

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 36b46af92f77a28053ce330f1173cf2143870514
Author: Jonas Ådahl <jadahl gmail com>
Date:   Thu Dec 20 16:58:03 2018 +0100

    boxes: Add helper to scale rectangles by a double
    
    And change the similar region scaling helper to use this one.
    
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/362

 src/compositor/region-utils.c | 17 ++---------------
 src/compositor/region-utils.h |  7 +------
 src/core/boxes-private.h      | 11 +++++++++++
 src/core/boxes.c              | 27 +++++++++++++++++++++++++++
 4 files changed, 41 insertions(+), 21 deletions(-)
---
diff --git a/src/compositor/region-utils.c b/src/compositor/region-utils.c
index 1c1bd2664..4d2ae1df0 100644
--- a/src/compositor/region-utils.c
+++ b/src/compositor/region-utils.c
@@ -195,21 +195,8 @@ meta_region_scale_double (cairo_region_t       *region,
     {
       cairo_region_get_rectangle (region, i, &rects[i]);
 
-      switch (rounding_strategy)
-        {
-        case META_ROUNDING_STRATEGY_SHRINK:
-          rects[i].x = (int) ceil (rects[i].x * scale);
-          rects[i].y = (int) ceil (rects[i].y * scale);
-          rects[i].width = (int) floor (rects[i].width * scale);
-          rects[i].height = (int) floor (rects[i].height * scale);
-          break;
-        case META_ROUNDING_STRATEGY_GROW:
-          rects[i].x = (int) floor (rects[i].x * scale);
-          rects[i].y = (int) floor (rects[i].y * scale);
-          rects[i].width = (int) ceil (rects[i].width * scale);
-          rects[i].height = (int) ceil (rects[i].height * scale);
-          break;
-        }
+      meta_rectangle_scale_double (&rects[i], scale, rounding_strategy,
+                                   &rects[i]);
     }
 
   scaled_region = cairo_region_create_rectangles (rects, n_rects);
diff --git a/src/compositor/region-utils.h b/src/compositor/region-utils.h
index 4a9dd8170..473022b7e 100644
--- a/src/compositor/region-utils.h
+++ b/src/compositor/region-utils.h
@@ -26,12 +26,7 @@
 
 #include "backends/meta-backend-types.h"
 #include "clutter/clutter.h"
-
-typedef enum _MetaRoundingStrategy
-{
-  META_ROUNDING_STRATEGY_SHRINK,
-  META_ROUNDING_STRATEGY_GROW,
-} MetaRoundingStrategy;
+#include "core/boxes-private.h"
 
 /**
  * MetaRegionIterator:
diff --git a/src/core/boxes-private.h b/src/core/boxes-private.h
index 0fbed2059..4c6fd08ab 100644
--- a/src/core/boxes-private.h
+++ b/src/core/boxes-private.h
@@ -39,6 +39,12 @@ typedef enum
   FIXED_DIRECTION_Y    = 1 << 1,
 } FixedDirections;
 
+typedef enum _MetaRoundingStrategy
+{
+  META_ROUNDING_STRATEGY_SHRINK,
+  META_ROUNDING_STRATEGY_GROW,
+} MetaRoundingStrategy;
+
 /* Output functions -- note that the output buffer had better be big enough:
  *   rect_to_string:   RECT_LENGTH
  *   region_to_string: (RECT_LENGTH+strlen(separator_string)) *
@@ -219,6 +225,11 @@ GList* meta_rectangle_find_nonintersected_monitor_edges (
 gboolean meta_rectangle_is_adjecent_to (MetaRectangle *rect,
                                         MetaRectangle *other);
 
+void meta_rectangle_scale_double (const MetaRectangle  *rect,
+                                  double                scale,
+                                  MetaRoundingStrategy  rounding_strategy,
+                                  MetaRectangle        *dest);
+
 static inline ClutterRect
 meta_rectangle_to_clutter_rect (MetaRectangle *rect)
 {
diff --git a/src/core/boxes.c b/src/core/boxes.c
index 2725dfcbe..98a8d3586 100644
--- a/src/core/boxes.c
+++ b/src/core/boxes.c
@@ -2044,3 +2044,30 @@ meta_rectangle_is_adjecent_to (MetaRectangle *rect,
   else
     return FALSE;
 }
+
+void
+meta_rectangle_scale_double (const MetaRectangle  *rect,
+                             double                scale,
+                             MetaRoundingStrategy  rounding_strategy,
+                             MetaRectangle        *dest)
+{
+  switch (rounding_strategy)
+    {
+    case META_ROUNDING_STRATEGY_SHRINK:
+      *dest = (MetaRectangle) {
+        .x = (int) ceil (rect->x * scale),
+        .y = (int) ceil (rect->y * scale),
+        .width = (int) floor (rect->width * scale),
+        .height = (int) floor (rect->height * scale),
+      };
+      break;
+    case META_ROUNDING_STRATEGY_GROW:
+      *dest = (MetaRectangle) {
+        .x = (int) floor (rect->x * scale),
+        .y = (int) floor (rect->y * scale),
+        .width = (int) ceil (rect->width * scale),
+        .height = (int) ceil (rect->height * scale),
+      };
+      break;
+    }
+}