Refactor: Support arbitrary y offset for channel list

At first you could think that this refactor would not be
necessary, because `ACHANNEL_FIRST` exists already.
It contained the small y offset that all channels had.

Unfortunately, a lot of code assumed that
`ACHANNEL_FIRST = -ACHANNEL_HEIGHT`, making the
define pretty much useless. This refactor fixes that
for the action and nla editor.

As a nice side effect, this patch fixes channel box select.
Before there was always have a half-channel offset.

Reviewers: brecht

Differential Revision: https://developer.blender.org/D4783

1 files changed, 3 insertions, 10 deletions

diff --git a/source/blender/editors/space_nla/nla_channels.c b/source/blender/editors/space_nla/nla_channels.c
index 4115d6b49ba..3e4eb6af098 100644
--- a/source/blender/editors/space_nla/nla_channels.c
+++ b/source/blender/editors/space_nla/nla_channels.c
@@ -384,19 +384,12 @@ static int nlachannels_mouseclick_invoke(bContext *C, wmOperator *op, const wmEv
     selectmode = SELECT_REPLACE;
   }
 
-  /**
-   * Figure out which channel user clicked in:
-   *
-   * \note Although channels technically start at y= NLACHANNEL_FIRST,
-   * we need to adjust by half a channel's height so that the tops of channels get caught ok.
-   * Since NLACHANNEL_FIRST is really NLACHANNEL_HEIGHT, we simply use NLACHANNEL_HEIGHT_HALF.
-   */
+  /* Figure out which channel user clicked in. */
   UI_view2d_region_to_view(v2d, event->mval[0], event->mval[1], &x, &y);
-  UI_view2d_listview_view_to_cell(v2d,
-                                  NLACHANNEL_NAMEWIDTH,
+  UI_view2d_listview_view_to_cell(NLACHANNEL_NAMEWIDTH,
                                   NLACHANNEL_STEP(snla),
                                   0,
-                                  (float)NLACHANNEL_HEIGHT_HALF(snla),
+                                  NLACHANNEL_FIRST_TOP(snla),
                                   x,
                                   y,
                                   NULL,