[evolution] I#550 - Mail: Compress flat thread indentation

[Milan Crha <mcrha src gnome org>]

commit c86f63fb1489764257dd1eeb3c5054030b695b82
Author: Milan Crha <mcrha redhat com>
Date:   Tue Dec 1 11:38:27 2020 +0100

    I#550 - Mail: Compress flat thread indentation
    
    Closes https://gitlab.gnome.org/GNOME/evolution/-/issues/550

 data/org.gnome.evolution.mail.gschema.xml.in   |  5 ++
 src/mail/message-list.c                        | 73 +++++++++++++++++++++++++-
 src/mail/message-list.h                        |  3 ++
 src/modules/settings/e-settings-message-list.c |  5 ++
 4 files changed, 84 insertions(+), 2 deletions(-)
---
diff --git a/data/org.gnome.evolution.mail.gschema.xml.in b/data/org.gnome.evolution.mail.gschema.xml.in
index 353d0cf3af..b692ef2825 100644
--- a/data/org.gnome.evolution.mail.gschema.xml.in
+++ b/data/org.gnome.evolution.mail.gschema.xml.in
@@ -467,6 +467,11 @@
       <_summary>Whether sort thread children always ascending</_summary>
       <_description>This setting specifies whether the thread children should be sorted always ascending, 
rather than using the same sort order as in the thread root level.</_description>
     </key>
+    <key name="thread-compress" type="b">
+      <default>true</default>
+      <_summary>Whether to compress thread level</_summary>
+      <_description>Set to true to compress thread levels for flat conversations, to make the level not so 
deep.</_description>
+    </key>
     <key name="sort-accounts-alpha" type="b">
       <default>true</default>
       <_summary>Sort accounts alphabetically in a folder tree</_summary>
diff --git a/src/mail/message-list.c b/src/mail/message-list.c
index 7da8992cfd..9ab9c6c4a5 100644
--- a/src/mail/message-list.c
+++ b/src/mail/message-list.c
@@ -106,6 +106,7 @@ struct _MessageListPrivate {
        gboolean show_junk;
        gboolean thread_latest;
        gboolean thread_subject;
+       gboolean thread_compress;
        gboolean any_row_changed; /* save state before regen list when this is set to true */
        gboolean show_subject_above_sender;
        gboolean regen_selects_unread;
@@ -194,7 +195,8 @@ enum {
        PROP_SHOW_JUNK,
        PROP_SHOW_SUBJECT_ABOVE_SENDER,
        PROP_THREAD_LATEST,
-       PROP_THREAD_SUBJECT
+       PROP_THREAD_SUBJECT,
+       PROP_THREAD_COMPRESS
 };
 
 /* Forward Declarations */
@@ -3132,6 +3134,12 @@ message_list_set_property (GObject *object,
                                MESSAGE_LIST (object),
                                g_value_get_boolean (value));
                        return;
+
+               case PROP_THREAD_COMPRESS:
+                       message_list_set_thread_compress (
+                               MESSAGE_LIST (object),
+                               g_value_get_boolean (value));
+                       return;
        }
 
        G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
@@ -3213,6 +3221,13 @@ message_list_get_property (GObject *object,
                                message_list_get_thread_subject (
                                MESSAGE_LIST (object)));
                        return;
+
+               case PROP_THREAD_COMPRESS:
+                       g_value_set_boolean (
+                               value,
+                               message_list_get_thread_compress (
+                               MESSAGE_LIST (object)));
+                       return;
        }
 
        G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
@@ -3426,7 +3441,25 @@ static guint
 message_list_depth (ETreeModel *tree_model,
                     ETreePath path)
 {
-       return g_node_depth ((GNode *) path);
+       guint depth;
+
+       depth = g_node_depth ((GNode *) path);
+
+       if (depth > 1 && message_list_get_thread_compress (MESSAGE_LIST (tree_model))) {
+               GNode *node = ((GNode *) path)->parent;
+
+               while (node && !G_NODE_IS_ROOT (node)) {
+                       if (G_NODE_IS_ROOT (node->parent))
+                               break;
+
+                       if (!node->prev && !node->next)
+                               depth--;
+
+                       node = node->parent;
+               }
+       }
+
+       return depth;
 }
 
 static gboolean
@@ -3928,6 +3961,18 @@ message_list_class_init (MessageListClass *class)
                        G_PARAM_CONSTRUCT |
                        G_PARAM_STATIC_STRINGS));
 
+       g_object_class_install_property (
+               object_class,
+               PROP_THREAD_COMPRESS,
+               g_param_spec_boolean (
+                       "thread-compress",
+                       "Thread Compress",
+                       "Compress flat threads",
+                       TRUE,
+                       G_PARAM_READWRITE |
+                       G_PARAM_CONSTRUCT |
+                       G_PARAM_STATIC_STRINGS));
+
        gtk_widget_class_install_style_property (
                GTK_WIDGET_CLASS (class),
                g_param_spec_boxed (
@@ -5517,6 +5562,30 @@ message_list_set_thread_subject (MessageList *message_list,
        g_object_notify (G_OBJECT (message_list), "thread-subject");
 }
 
+gboolean
+message_list_get_thread_compress (MessageList *message_list)
+{
+       g_return_val_if_fail (IS_MESSAGE_LIST (message_list), FALSE);
+
+       return message_list->priv->thread_compress;
+}
+
+void
+message_list_set_thread_compress (MessageList *message_list,
+                                 gboolean thread_compress)
+{
+       g_return_if_fail (IS_MESSAGE_LIST (message_list));
+
+       if ((thread_compress ? 1 : 0) == (message_list->priv->thread_compress ? 1 : 0))
+               return;
+
+       message_list->priv->thread_compress = thread_compress;
+
+       g_object_notify (G_OBJECT (message_list), "thread-compress");
+
+       gtk_widget_queue_draw (GTK_WIDGET (message_list));
+}
+
 gboolean
 message_list_get_regen_selects_unread (MessageList *message_list)
 {
diff --git a/src/mail/message-list.h b/src/mail/message-list.h
index bbb7100fad..0244250024 100644
--- a/src/mail/message-list.h
+++ b/src/mail/message-list.h
@@ -190,6 +190,9 @@ void                message_list_set_thread_latest  (MessageList *message_list,
 gboolean       message_list_get_thread_subject (MessageList *message_list);
 void           message_list_set_thread_subject (MessageList *message_list,
                                                 gboolean thread_subject);
+gboolean       message_list_get_thread_compress(MessageList *message_list);
+void           message_list_set_thread_compress(MessageList *message_list,
+                                                gboolean thread_compress);
 gboolean       message_list_get_regen_selects_unread
                                                (MessageList *message_list);
 void           message_list_set_regen_selects_unread
diff --git a/src/modules/settings/e-settings-message-list.c b/src/modules/settings/e-settings-message-list.c
index 22018c7b54..febcddbb5e 100644
--- a/src/modules/settings/e-settings-message-list.c
+++ b/src/modules/settings/e-settings-message-list.c
@@ -76,6 +76,11 @@ settings_message_list_constructed (GObject *object)
                message_list, "sort-children-ascending",
                G_SETTINGS_BIND_GET);
 
+       g_settings_bind (
+               settings, "thread-compress",
+               message_list, "thread-compress",
+               G_SETTINGS_BIND_GET);
+
        /* This setting only controls the initial message list
         * state when in threaded mode, so just apply it here. */
        message_list_set_expanded_default (