From 68fba458b33d423f45be936fd99b9f100c379c1f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marco=20Trevisan=20=28Trevi=C3=B1o=29?= <mail@3v1n0.net>
Date: Fri, 1 Mar 2019 20:47:07 +0100
Subject: [PATCH] boxes: Ensure we scale to a fully rounded rectangle

In order to scale a rectangle by a double value, we can reuse a ClutterRect
to do the scale computations in floating point math and then to convert it back
using the proper strategy that will take in account the subpixel compensation.

In this way we can be sure that the resulting rectangle can fully contain the
original scaled one.

https://gitlab.gnome.org/GNOME/mutter/merge_requests/469
---
 src/core/boxes.c | 24 +++++-------------------
 1 file changed, 5 insertions(+), 19 deletions(-)

diff --git a/src/core/boxes.c b/src/core/boxes.c
index 400febea1..0e9affec4 100644
--- a/src/core/boxes.c
+++ b/src/core/boxes.c
@@ -2051,25 +2051,11 @@ meta_rectangle_scale_double (const MetaRectangle  *rect,
                              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;
-    }
+  ClutterRect tmp = CLUTTER_RECT_INIT (rect->x, rect->y,
+                                       rect->width, rect->height);
+
+  clutter_rect_scale (&tmp, scale, scale);
+  meta_rectangle_from_clutter_rect (&tmp, rounding_strategy, dest);
 }
 
 void