Add support for GTK4 to CMake build too

Closes https://github.com/wxWidgets/wxWidgets/pull/1643

build/cmake/modules/FindGTK4.cmake

@@ -0,0 +1,46 @@
+# - Try to find GTK+ 4
+# Once done, this will define
+#
+# GTK4_FOUND - system has GTK+ 4.
+# GTK4_INCLUDE_DIRS - the GTK+ 4. include directories
+# GTK4_LIBRARIES - link these to use GTK+ 4.
+#
+# Copyright (C) 2012 Raphael Kubo da Costa <rakuco@webkit.org>
+# Copyright (C) 2013 Igalia S.L.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+# 1. Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+# notice, this list of conditions and the following disclaimer in the
+# documentation and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER AND ITS CONTRIBUTORS ``AS
+# IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+# THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR ITS
+# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+# OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+# WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+# OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+# ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+find_package(PkgConfig)
+pkg_check_modules(GTK4 QUIET gtk4)
+set(VERSION_OK TRUE)
+if (GTK4_VERSION)
+if (GTK4_FIND_VERSION_EXACT)
+if (NOT("${GTK4_FIND_VERSION}" VERSION_EQUAL "${GTK4_VERSION}"))
+set(VERSION_OK FALSE)
+endif ()
+else ()
+if ("${GTK4_VERSION}" VERSION_LESS "${GTK4_FIND_VERSION}")
+set(VERSION_OK FALSE)
+endif ()
+endif ()
+endif ()
+include(FindPackageHandleStandardArgs)
+FIND_PACKAGE_HANDLE_STANDARD_ARGS(GTK4 DEFAULT_MSG GTK4_INCLUDE_DIRS GTK4_LIBRARIES VERSION_OK)

build/cmake/setup.cmake

@@ -65,10 +65,16 @@ endif()
 
 if(WXGTK)
     # Add GTK version definitions
-    foreach(gtk_version 1.2.7 2.0 2.10 2.18 2.20 3.0)
+    foreach(gtk_version 1.2.7 2.0 2.10 2.18 2.20 3.0 3.90.0)
         if(wxTOOLKIT_VERSION VERSION_GREATER gtk_version)
-            string(REPLACE . "" gtk_version_dotless ${gtk_version})
-            set(__WXGTK${gtk_version_dotless}__ ON)
+            if(gtk_version EQUAL 3.90.0)
+                set(__WXGTK4__ ON)
+            elseif(gtk_version EQUAL 3.0)
+                set(__WXGTK3__ ON)
+            else()
+                string(REPLACE . "" gtk_version_dotless ${gtk_version})
+                set(__WXGTK${gtk_version_dotless}__ ON)
+            endif()
         endif()
     endforeach()
 endif()

build/cmake/toolkit.cmake

@@ -24,11 +24,11 @@ elseif(APPLE AND IPHONE)
     set(wxPLATFORM OSX)
 elseif(APPLE)
     set(wxDEFAULT_TOOLKIT osx_cocoa)
-    set(wxTOOLKIT_OPTIONS osx_cocoa gtk2 gtk3 qt)
+    set(wxTOOLKIT_OPTIONS osx_cocoa gtk2 gtk3 gtk4 qt)
     set(wxPLATFORM OSX)
 elseif(UNIX)
     set(wxDEFAULT_TOOLKIT gtk2)
-    set(wxTOOLKIT_OPTIONS gtk2 gtk3 motif qt)
+    set(wxTOOLKIT_OPTIONS gtk2 gtk3 gtk4 motif qt)
     set(wxPLATFORM UNIX)
 else()
     message(FATAL_ERROR "Unsupported platform")
@@ -72,7 +72,9 @@ if(UNIX AND NOT APPLE AND NOT WIN32)
 endif()
 
 if(WXGTK)
-    if(WXGTK3)
+    if(WXGTK4)
+        set(gtk_lib GTK4)
+    elseif(WXGTK3)
         set(gtk_lib GTK3)
     elseif(WXGTK2)
         set(gtk_lib GTK2)