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, 3 insertions, 2 deletions

diff --git a/source/blender/editors/space_node/drawnode.cc b/source/blender/editors/space_node/drawnode.cc
index 94da7d55e5d..30f2cc970bd 100644
--- a/source/blender/editors/space_node/drawnode.cc
+++ b/source/blender/editors/space_node/drawnode.cc
@@ -231,7 +231,6 @@ static void node_buts_math(uiLayout *layout, bContext *UNUSED(C), PointerRNA *pt
 NodeResizeDirection node_get_resize_direction(const bNode *node, const int x, const int y)
 {
   if (node->type == NODE_FRAME) {
-    const float size = 10.0f;
     NodeFrame *data = (NodeFrame *)node->storage;
 
     /* shrinking frame size is determined by child nodes */
@@ -242,7 +241,9 @@ NodeResizeDirection node_get_resize_direction(const bNode *node, const int x, co
     NodeResizeDirection dir = NODE_RESIZE_NONE;
 
     const rctf &totr = node->totr;
-    if (x >= totr.xmax - size && x < totr.xmax && y >= totr.ymin && y < totr.ymax) {
+    const float size = NODE_RESIZE_MARGIN;
+
+    if (x > totr.xmax - size && x <= totr.xmax && y >= totr.ymin && y < totr.ymax) {
       dir |= NODE_RESIZE_RIGHT;
     }
     if (x >= totr.xmin && x < totr.xmin + size && y >= totr.ymin && y < totr.ymax) {