[gnome-builder/wip/gtk4-port: 1372/1774] libide/webkit: allow transforms of buffer content

[Christian Hergert <chergert src gnome org>]

commit 903ae2dbd239558cca1d8d916ac45e08d807eb70
Author: Christian Hergert <chergert redhat com>
Date:   Mon Jun 6 13:31:36 2022 -0700

    libide/webkit: allow transforms of buffer content
    
    This will be needed for things like reStructuredText and markdown preview.

 src/libide/webkit/ide-webkit-page.c                | 30 +++++++++++++++++++---
 src/libide/webkit/ide-webkit-page.h                | 28 ++++++++++++--------
 .../gbp-html-preview-workspace-addin.c             |  2 +-
 3 files changed, 45 insertions(+), 15 deletions(-)
---
diff --git a/src/libide/webkit/ide-webkit-page.c b/src/libide/webkit/ide-webkit-page.c
index 3647effb4..ab8cb5ae9 100644
--- a/src/libide/webkit/ide-webkit-page.c
+++ b/src/libide/webkit/ide-webkit-page.c
@@ -40,8 +40,11 @@ typedef struct
   GSimpleActionGroup *actions;
 
   /* Used for pages linked to buffers */
-  GtkTextBuffer      *buffer;
-  guint               queued_update_source;
+  GtkTextBuffer        *buffer;
+  IdeHtmlTransformFunc  transform_func;
+  gpointer              transform_data;
+  GDestroyNotify        transform_data_destroy;
+  guint                 queued_update_source;
 } IdeWebkitPagePrivate;
 
 enum {
@@ -340,6 +343,14 @@ ide_webkit_page_dispose (GObject *object)
   IdeWebkitPage *self = (IdeWebkitPage *)object;
   IdeWebkitPagePrivate *priv = ide_webkit_page_get_instance_private (self);
 
+  if (priv->transform_data_destroy)
+    {
+      GDestroyNotify notify = g_steal_pointer (&priv->transform_data_destroy);
+      gpointer data = g_steal_pointer (&priv->transform_data);
+      priv->transform_func = NULL;
+      notify (data);
+    }
+
   g_clear_object (&priv->actions);
   g_clear_object (&priv->buffer);
   g_clear_handle_id (&priv->queued_update_source, g_source_remove);
@@ -603,6 +614,12 @@ ide_webkit_page_do_update_cb (gpointer user_data)
   if (IDE_IS_BUFFER (priv->buffer))
     base_uri = g_file_get_uri (ide_buffer_get_file (IDE_BUFFER (priv->buffer)));
 
+  if (priv->transform_func != NULL)
+    {
+      g_autofree char *input = g_steal_pointer (&text);
+      text = priv->transform_func (input, priv->transform_data);
+    }
+
   webkit_web_view_load_html (priv->web_view, text, base_uri);
 
   return G_SOURCE_REMOVE;
@@ -625,7 +642,10 @@ ide_webkit_page_buffer_changed_cb (IdeWebkitPage *self,
 }
 
 IdeWebkitPage *
-ide_webkit_page_new_for_buffer (GtkTextBuffer *buffer)
+ide_webkit_page_new_for_buffer (GtkTextBuffer        *buffer,
+                                IdeHtmlTransformFunc  transform_func,
+                                gpointer              transform_data,
+                                GDestroyNotify        transform_data_destroy)
 {
   IdeWebkitPage *self;
   IdeWebkitPagePrivate *priv;
@@ -635,6 +655,10 @@ ide_webkit_page_new_for_buffer (GtkTextBuffer *buffer)
   self = ide_webkit_page_new ();
   priv = ide_webkit_page_get_instance_private (self);
 
+  priv->transform_func = transform_func;
+  priv->transform_data = transform_data;
+  priv->transform_data_destroy = transform_data_destroy;
+
   priv->buffer = g_object_ref (buffer);
   g_signal_connect_object (buffer,
                            "changed",
diff --git a/src/libide/webkit/ide-webkit-page.h b/src/libide/webkit/ide-webkit-page.h
index 5b704e46a..26e47335c 100644
--- a/src/libide/webkit/ide-webkit-page.h
+++ b/src/libide/webkit/ide-webkit-page.h
@@ -26,6 +26,9 @@ G_BEGIN_DECLS
 
 #define IDE_TYPE_WEBKIT_PAGE (ide_webkit_page_get_type())
 
+typedef char *(*IdeHtmlTransformFunc) (const char *input,
+                                       gpointer    user_data);
+
 IDE_AVAILABLE_IN_ALL
 G_DECLARE_DERIVABLE_TYPE (IdeWebkitPage, ide_webkit_page, IDE, WEBKIT_PAGE, IdePage)
 
@@ -37,24 +40,27 @@ struct _IdeWebkitPageClass
 IDE_AVAILABLE_IN_ALL
 IdeWebkitPage *ide_webkit_page_new                   (void);
 IDE_AVAILABLE_IN_ALL
-IdeWebkitPage *ide_webkit_page_new_for_buffer        (GtkTextBuffer *buffer);
+IdeWebkitPage *ide_webkit_page_new_for_buffer        (GtkTextBuffer        *buffer,
+                                                      IdeHtmlTransformFunc  transform_func,
+                                                      gpointer              transform_data,
+                                                      GDestroyNotify        transform_data_destroy);
 IDE_AVAILABLE_IN_ALL
-void           ide_webkit_page_load_uri              (IdeWebkitPage *self,
-                                                      const char    *uri);
+void           ide_webkit_page_load_uri              (IdeWebkitPage        *self,
+                                                      const char           *uri);
 IDE_AVAILABLE_IN_ALL
-gboolean       ide_webkit_page_focus_address         (IdeWebkitPage *self);
+gboolean       ide_webkit_page_focus_address         (IdeWebkitPage        *self);
 IDE_AVAILABLE_IN_ALL
-gboolean       ide_webkit_page_get_show_toolbar      (IdeWebkitPage *self);
+gboolean       ide_webkit_page_get_show_toolbar      (IdeWebkitPage        *self);
 IDE_AVAILABLE_IN_ALL
-void           ide_webkit_page_set_show_toolbar      (IdeWebkitPage *self,
-                                                      gboolean       show_toolbar);
+void           ide_webkit_page_set_show_toolbar      (IdeWebkitPage        *self,
+                                                      gboolean              show_toolbar);
 IDE_AVAILABLE_IN_ALL
-void           ide_webkit_page_go_back               (IdeWebkitPage *self);
+void           ide_webkit_page_go_back               (IdeWebkitPage        *self);
 IDE_AVAILABLE_IN_ALL
-void           ide_webkit_page_go_forward            (IdeWebkitPage *self);
+void           ide_webkit_page_go_forward            (IdeWebkitPage        *self);
 IDE_AVAILABLE_IN_ALL
-void           ide_webkit_page_reload                (IdeWebkitPage *self);
+void           ide_webkit_page_reload                (IdeWebkitPage        *self);
 IDE_AVAILABLE_IN_ALL
-void           ide_webkit_page_reload_ignoring_cache (IdeWebkitPage *self);
+void           ide_webkit_page_reload_ignoring_cache (IdeWebkitPage        *self);
 
 G_END_DECLS
diff --git a/src/plugins/html-preview/gbp-html-preview-workspace-addin.c 
b/src/plugins/html-preview/gbp-html-preview-workspace-addin.c
index aad1c796b..c31e4d614 100644
--- a/src/plugins/html-preview/gbp-html-preview-workspace-addin.c
+++ b/src/plugins/html-preview/gbp-html-preview-workspace-addin.c
@@ -226,7 +226,7 @@ live_preview_action (GbpHtmlPreviewWorkspaceAddin *self,
   g_assert (IDE_IS_EDITOR_PAGE (self->editor_page));
 
   buffer = g_signal_group_dup_target (self->buffer_signals);
-  page = ide_webkit_page_new_for_buffer (GTK_TEXT_BUFFER (buffer));
+  page = ide_webkit_page_new_for_buffer (GTK_TEXT_BUFFER (buffer), NULL, NULL, NULL);
   position = ide_page_get_position (IDE_PAGE (self->editor_page));
 
   if (!ide_panel_position_get_column (position, &column))