[gnome-builder/wip/gtk4-port: 322/736] libide/gui: add IdeWorkspaceAddin.focus_changed

[Christian Hergert <chergert src gnome org>]

commit 62e7d55c36193dcc88ae1acaee5e212dd4299e39
Author: Christian Hergert <chergert redhat com>
Date:   Fri Apr 1 19:51:46 2022 -0700

    libide/gui: add IdeWorkspaceAddin.focus_changed
    
    This is to be used when the focus page changes within a workspace now that
    the workspaces can have a bit more control without the need to indirect
    through an IdeSurface.
    
    A secondary goal here is to remove the need for IdeEditorAddin and just
    use the IdeWorkspaceAddin directly (or IdeWorkbenchAddin when needed).

 src/libide/gui/ide-workspace-addin.c | 19 +++++++++++++++++++
 src/libide/gui/ide-workspace-addin.h | 20 ++++++++++++++++----
 2 files changed, 35 insertions(+), 4 deletions(-)
---
diff --git a/src/libide/gui/ide-workspace-addin.c b/src/libide/gui/ide-workspace-addin.c
index 301777797..f6acde158 100644
--- a/src/libide/gui/ide-workspace-addin.c
+++ b/src/libide/gui/ide-workspace-addin.c
@@ -87,3 +87,22 @@ ide_workspace_addin_unload (IdeWorkspaceAddin *self,
   if (IDE_WORKSPACE_ADDIN_GET_IFACE (self)->unload)
     IDE_WORKSPACE_ADDIN_GET_IFACE (self)->unload (self, workspace);
 }
+
+/**
+ * ide_workspace_addin_page_changed:
+ * @self: a #IdeWorkspaceAddin
+ * @page: (nullable): an #IdePage or %NULL
+ *
+ * Called when the current page has changed based on focus within
+ * the workspace.
+ */
+void
+ide_workspace_addin_page_changed (IdeWorkspaceAddin *self,
+                                  IdePage           *page)
+{
+  g_return_if_fail (IDE_IS_WORKSPACE_ADDIN (self));
+  g_return_if_fail (!page || IDE_IS_PAGE (page));
+
+  if (IDE_WORKSPACE_ADDIN_GET_IFACE (self)->page_changed)
+    IDE_WORKSPACE_ADDIN_GET_IFACE (self)->page_changed (self, page);
+}
diff --git a/src/libide/gui/ide-workspace-addin.h b/src/libide/gui/ide-workspace-addin.h
index a38964a2b..4c915a841 100644
--- a/src/libide/gui/ide-workspace-addin.h
+++ b/src/libide/gui/ide-workspace-addin.h
@@ -20,6 +20,13 @@
 
 #pragma once
 
+#if !defined (IDE_GUI_INSIDE) && !defined (IDE_GUI_COMPILATION)
+# error "Only <libide-gui.h> can be included directly."
+#endif
+
+#include <libide-core.h>
+
+#include "ide-page.h"
 #include "ide-workspace.h"
 
 G_BEGIN_DECLS
@@ -33,10 +40,12 @@ struct _IdeWorkspaceAddinInterface
 {
   GTypeInterface parent_iface;
 
-  void     (*load)        (IdeWorkspaceAddin *self,
-                           IdeWorkspace      *workspace);
-  void     (*unload)      (IdeWorkspaceAddin *self,
-                           IdeWorkspace      *workspace);
+  void     (*load)          (IdeWorkspaceAddin *self,
+                             IdeWorkspace      *workspace);
+  void     (*unload)        (IdeWorkspaceAddin *self,
+                             IdeWorkspace      *workspace);
+  void     (*page_changed)  (IdeWorkspaceAddin *self,
+                             IdePage           *page);
 };
 
 IDE_AVAILABLE_IN_ALL
@@ -46,6 +55,9 @@ IDE_AVAILABLE_IN_ALL
 void               ide_workspace_addin_unload              (IdeWorkspaceAddin *self,
                                                             IdeWorkspace      *workspace);
 IDE_AVAILABLE_IN_ALL
+void               ide_workspace_addin_page_changed        (IdeWorkspaceAddin *self,
+                                                            IdePage           *page);
+IDE_AVAILABLE_IN_ALL
 IdeWorkspaceAddin *ide_workspace_addin_find_by_module_name (IdeWorkspace      *workspace,
                                                             const gchar       *module_name);