flatpak: Add libadwaita carousel patch for testing

Add the patch for now to get more test exposure

Issue #11

build-aux/flatpak/libadwaita-issue-597.patch

@@ -0,0 +1,59 @@
+From b2c52f258757e37a74a95c109431f6af8cda8f91 Mon Sep 17 00:00:00 2001
+From: Sophie Herold <sophie@hemio.de>
+Date: Wed, 7 Dec 2022 17:42:06 +0100
+Subject: [PATCH] carousel: give new child a snap_point immediately
+
+Fixes #457, #597
+---
+ src/adw-carousel.c | 21 ++++++++++++++++++++-
+ 1 file changed, 20 insertions(+), 1 deletion(-)
+
+diff --git a/src/adw-carousel.c b/src/adw-carousel.c
+index 47ea9475..5a9816f9 100644
+--- a/src/adw-carousel.c
++++ b/src/adw-carousel.c
+@@ -1207,6 +1207,8 @@ adw_carousel_insert (AdwCarousel *self,
+ {
+   ChildInfo *info;
+   GList *next_link = NULL;
++  double snap_point = 0;
++  GList *children;
+ 
+   g_return_if_fail (ADW_IS_CAROUSEL (self));
+   g_return_if_fail (GTK_IS_WIDGET (widget));
+@@ -1214,7 +1216,8 @@ adw_carousel_insert (AdwCarousel *self,
+ 
+   info = g_new0 (ChildInfo, 1);
+   info->widget = widget;
+-  info->size = 0;
++  // set a minimal size to give child it's own snap_point from the beginning
++  info->size = 0.00001;
+   info->adding = TRUE;
+ 
+   if (position >= 0)
+@@ -1230,6 +1233,22 @@ adw_carousel_insert (AdwCarousel *self,
+     gtk_widget_set_parent (widget, GTK_WIDGET (self));
+   }
+ 
++  // work around this usually happening in measure which can be too late
++  for (children = self->children; children; children = children->next) {
++    ChildInfo *child_info = children->data;
++
++    child_info->snap_point = snap_point + child_info->size - 1;
++
++    snap_point += child_info->size;
++
++    if (child_info == self->animation_target_child)
++      adw_spring_animation_set_value_to (ADW_SPRING_ANIMATION (self->animation),
++                                         child_info->snap_point);
++  }
++
++  // start animation from correct size
++  info->size = 0;
++
+   gtk_widget_queue_allocate (GTK_WIDGET (self));
+ 
+   animate_child_resize (self, info, 1, self->reveal_duration);
+-- 
+GitLab
+

build-aux/flatpak/org.gnome.Loupe.Devel.json

@@ -91,6 +91,22 @@
                 }
             ]
         },
+        /* Use patched libadwaita version to test the fix */
+        {
+            "name": "libadwaita",
+            "buildsystem": "meson",
+            "sources": [
+                {
+                    "type": "git",
+                    "url": "https://gitlab.gnome.org/GNOME/libadwaita.git",
+                    "branch": "main"
+                },
+                {
+                    "type": "patch",
+                    "path": "libadwaita-issue-597.patch"
+                }
+            ]
+        },
         {
             "name" : "loupe",
             "builddir" : true,