Fix T94415: Nodes: poor selection behavior inside frame nodes

Previously, node selection made no distinction between a frame node and
other nodes. So a frame node would be selected by their whole rect or
center (depending on box/lasso/circle select). As a consequence of this,
box and lasso could not pratically be started inside a frame node (with
the intention to select a subset of contained child nodes) because the
frame would be selected immediately and tweak-transforming started.
Circle selecting would always contain the frame node as well (making
transforming a subset of nodes without also transforming the whole frame
impossible).

Now change selection behavior so that for all selection modes only the
border [the margin area that is automatically added around all nodes,
see note below] of a frame node is considered in selection. This makes
for a much more intuitive experience when arranging nodes inside frames.

note: to make the area of interest for selection/moving more obvious,
the cursor changes when hovering over (as is done for resizing).
note: this also makes the resize margin consistent with other nodes.
note: this also fixes right resize border (was exclusive instead of
inclusive as every other border)

Also fixes T46540.

1 files changed, 7 insertions, 0 deletions

diff --git a/source/blender/editors/space_node/node_draw.cc b/source/blender/editors/space_node/node_draw.cc
index 2ab0a3fff44..e290316af1f 100644
--- a/source/blender/editors/space_node/node_draw.cc
+++ b/source/blender/editors/space_node/node_draw.cc
@@ -2272,6 +2272,13 @@ void node_set_cursor(wmWindow &win, SpaceNode &snode, const float2 &cursor)
   if (node) {
     NodeResizeDirection dir = node_get_resize_direction(node, cursor[0], cursor[1]);
     wmcursor = node_get_resize_cursor(dir);
+    /* We want to indicate that Frame nodes can be moved/selected on their borders. */
+    if (node->type == NODE_FRAME && dir == NODE_RESIZE_NONE) {
+      const rctf frame_inside = node_frame_rect_inside(*node);
+      if (!BLI_rctf_isect_pt(&frame_inside, cursor[0], cursor[1])) {
+        wmcursor = WM_CURSOR_NSEW_SCROLL;
+      }
+    }
   }
 
   WM_cursor_set(&win, wmcursor);