[evolution] ECellTree: Limit deep threads indent up to 70% of the cell width

[Milan Crha <mcrha src gnome org>]

commit db4d5edd65a06dc6bfdaa4dde5af9062793b8659
Author: Milan Crha <mcrha redhat com>
Date:   Wed Aug 7 18:33:42 2019 +0200

    ECellTree: Limit deep threads indent up to 70% of the cell width
    
    This makes sure the cell text and expanders are always visible,
    instead of getting out of the view.
    
    Related to https://gitlab.gnome.org/GNOME/evolution/issues/550

 src/e-util/e-cell-tree.c | 32 ++++++++++++++++++++++++--------
 1 file changed, 24 insertions(+), 8 deletions(-)
---
diff --git a/src/e-util/e-cell-tree.c b/src/e-util/e-cell-tree.c
index 73de283a41..7d5c56a9d3 100644
--- a/src/e-util/e-cell-tree.c
+++ b/src/e-util/e-cell-tree.c
@@ -102,16 +102,32 @@ visible_depth_of_node (ETableModel *model,
  * if the path is not expandable, then max_width needs to change as
  * well. */
 static gint
-offset_of_node (ETableModel *table_model,
-                gint row)
+offset_of_node (ECellTreeView *tree_view,
+               ETableModel *table_model,
+               gint row,
+               gint view_col)
 {
        ETreeModel *tree_model = e_cell_tree_get_tree_model (table_model, row);
        ETreePath path = e_cell_tree_get_node (table_model, row);
        gint visible_depth;
 
        visible_depth = visible_depth_of_node (table_model, row);
-       if (visible_depth >= 0 ||
-           e_tree_model_node_is_expandable (tree_model, path)) {
+       if (visible_depth >= 0 || e_tree_model_node_is_expandable (tree_model, path)) {
+               if (visible_depth > 0) {
+                       gint width = 0;
+
+                       e_table_item_get_cell_geometry (
+                               tree_view->cell_view.e_table_item_view,
+                               &row, &view_col, NULL, NULL, &width, NULL);
+
+                       if (width > 0) {
+                               /* Use up to 70% of the column width */
+                               gint max_depth = (width * 70 / 100) / INDENT_AMOUNT;
+
+                               visible_depth = MIN (visible_depth, max_depth);
+                       }
+               }
+
                return (MAX (visible_depth, 1)) * INDENT_AMOUNT;
        } else {
                return 0;
@@ -287,7 +303,7 @@ ect_draw (ECellView *ecell_view,
 
                node = e_cell_tree_get_node (ecell_view->e_table_model, row);
 
-               offset = offset_of_node (ecell_view->e_table_model, row);
+               offset = offset_of_node (tree_view, ecell_view->e_table_model, row, view_col);
                subcell_offset = offset;
 
                /*
@@ -432,7 +448,7 @@ ect_event (ECellView *ecell_view,
        ETreeModel *tree_model = e_cell_tree_get_tree_model (ecell_view->e_table_model, row);
        ETreeTableAdapter *etta = e_cell_tree_get_tree_table_adapter (ecell_view->e_table_model, row);
        ETreePath node = e_cell_tree_get_node (ecell_view->e_table_model, row);
-       gint offset = offset_of_node (ecell_view->e_table_model, row);
+       gint offset = offset_of_node (tree_view, ecell_view->e_table_model, row, view_col);
        gint result;
 
        layout = GTK_LAYOUT (tree_view->canvas);
@@ -578,7 +594,7 @@ ect_max_width (ECellView *ecell_view,
                ETreeTableAdapter *tree_table_adapter = e_cell_tree_get_tree_table_adapter 
(ecell_view->e_table_model, row);
 #endif
 
-               offset = offset_of_node (ecell_view->e_table_model, row);
+               offset = offset_of_node (tree_view, ecell_view->e_table_model, row, view_col);
                subcell_offset = offset;
 
                width = subcell_offset;
@@ -674,7 +690,7 @@ ect_print (ECellView *ecell_view,
                ETreeModel *tree_model = e_cell_tree_get_tree_model (ecell_view->e_table_model, row);
                ETreeTableAdapter *tree_table_adapter = e_cell_tree_get_tree_table_adapter 
(ecell_view->e_table_model, row);
                ETreePath node = e_cell_tree_get_node (ecell_view->e_table_model, row);
-               gint offset = offset_of_node (ecell_view->e_table_model, row);
+               gint offset = offset_of_node (tree_view, ecell_view->e_table_model, row, view_col);
                gint subcell_offset = offset;
                gboolean expandable = e_tree_model_node_is_expandable (tree_model, node);