fix build error

Signed-off-by: cherry530 <707078654@qq.com>

create-lists-of-nullable-types.patch

@@ -0,0 +1,33 @@
+From 18beaecbbcc066e0d4c889b3aa3ecaa7351f7768 Mon Sep 17 00:00:00 2001
+From: Evgeny Stambulchik <fnevgeny@gmail.com>
+Date: Tue, 25 Apr 2023 16:11:25 +0300
+Subject: [PATCH] Create Lists of nullable types
+
+---
+ src/classes/drawings/drawing_commands.vala | 6 +++---
+ 1 file changed, 3 insertions(+), 3 deletions(-)
+
+diff --git a/src/classes/drawings/drawing_commands.vala b/src/classes/drawings/drawing_commands.vala
+index 77e56e6d..c305a8c5 100644
+--- a/src/classes/drawings/drawing_commands.vala
++++ b/src/classes/drawings/drawing_commands.vala
+@@ -54,8 +54,8 @@ namespace pdfpc {
+         }
+ 
+         public void clear() {
+-            this.drawing_commands = new List<DrawingCommand>();
+-            this.redo_commands = new List<DrawingCommand>();
++            this.drawing_commands = new List<DrawingCommand?>();
++            this.redo_commands = new List<DrawingCommand?>();
+         }
+ 
+         public void add_line(bool is_eraser,
+@@ -70,7 +70,7 @@ namespace pdfpc {
+ 
+             // After adding a new line you can no longer redo the old
+             // path.
+-            this.redo_commands = new List<DrawingCommand>(); // clear
++            this.redo_commands = new List<DrawingCommand?>(); // clear
+ 
+             bool new_path = true;
+             double epsilon = 1e-4; // Less than 0.1 pixel for a 1000x1000 img

pdfpc.spec

@@ -1,12 +1,14 @@
 Name:           pdfpc
 Version:        4.6.0
-Release:        1
+Release:        2
 Summary:        A GTK based presentation viewer application for GNU/Linux
 
 License:        GPL-3.0-or-later
 URL:            https://%{name}.github.io/
 Source0:        https://github.com/%{name}/%{name}/archive/v%{version}.tar.gz
 
+Patch0001:      create-lists-of-nullable-types.patch
+
 BuildRequires:  cmake
 BuildRequires:  gcc
 BuildRequires:  gtk3-devel
@@ -55,6 +57,9 @@ software.
 
 
 %changelog
+* Wed Sep 20 2023 xu_ping <707078654@qq.com> - 4.6.0-2
+- fix build error due to vala upgrade.
+
 * Wed Apr 12 2023 chenchen <chen_aka_jan@163.com> - 4.6.0-1
 - Upgrade pdfpc to 4.6.0