Refactor grid and scale indicator text drawing

This affects the timeline, dopesheet, graph editor, sequencer,
clip editor and nla editor.

Removed structs and enums: `V2D_ARG_DUMMY`, `eView2D_Units`,
`eView2D_Clamp`, `eView2D_Gridlines`, `View2DGrid`.

A main goal of this refactor is to get rid of the very generic
`View2DGrid` struct. The drawing code became very complex
because there were many different combinations of settings.

This refactor implements a different approach.
Instead of one very generic API, there are many slighly
different functions that do exactly, what we need in the
different editors. Only very little code is duplicated,
because the API functions compose some shared low level code.

This structure makes the code much easier to debug and change,
because every function has much fewer responsibilities.

Additionally, this refactor fixes some long standing bugs.
E.g. when `Show Seconds` is enabled, you zoom in and pan the view.
Or that the step size between displayed frame numbers was
always `>= 2`, no matter how close you zoom in.

Reviewers: brecht

Differential Revision: https://developer.blender.org/D4776

1 files changed, 4 insertions, 14 deletions

diff --git a/source/blender/editors/space_nla/space_nla.c b/source/blender/editors/space_nla/space_nla.c
index 6c5a046a0cb..b054f550c6c 100644
--- a/source/blender/editors/space_nla/space_nla.c
+++ b/source/blender/editors/space_nla/space_nla.c
@@ -231,9 +231,8 @@ static void nla_main_region_draw(const bContext *C, ARegion *ar)
   Scene *scene = CTX_data_scene(C);
   bAnimContext ac;
   View2D *v2d = &ar->v2d;
-  View2DGrid *grid;
   View2DScrollers *scrollers;
-  short unit = 0, cfra_flag = 0;
+  short cfra_flag = 0;
 
   /* clear and setup matrix */
   UI_ThemeClearColor(TH_BACK);
@@ -242,16 +241,7 @@ static void nla_main_region_draw(const bContext *C, ARegion *ar)
   UI_view2d_view_ortho(v2d);
 
   /* time grid */
-  unit = (snla->flag & SNLA_DRAWTIME) ? V2D_UNIT_SECONDS : V2D_UNIT_FRAMES;
-  grid = UI_view2d_grid_calc(CTX_data_scene(C),
-                             v2d,
-                             unit,
-                             V2D_GRID_CLAMP,
-                             V2D_ARG_DUMMY,
-                             V2D_ARG_DUMMY,
-                             ar->winx,
-                             ar->winy);
-  UI_view2d_grid_draw(v2d, grid, V2D_GRIDLINES_ALL);
+  UI_view2d_draw_lines_x__discrete_frames_or_seconds(v2d, scene, snla->flag & SNLA_DRAWTIME);
 
   ED_region_draw_cb_draw(C, ar, REGION_DRAW_PRE_VIEW);
 
@@ -300,8 +290,8 @@ static void nla_main_region_draw(const bContext *C, ARegion *ar)
   UI_view2d_scrollers_free(scrollers);
 
   /* frame numbers */
-  UI_view2d_grid_draw_numbers_horizontal(scene, v2d, grid, &v2d->hor, unit, true);
-  UI_view2d_grid_free(grid);
+  UI_view2d_draw_scale_x__discrete_frames_or_seconds(
+      ar, v2d, &v2d->hor, scene, snla->flag & SNLA_DRAWTIME);
 
   /* draw current frame number-indicator on top of scrollers */
   if ((snla->flag & SNLA_NODRAWCFRANUM) == 0) {