UI: Add initial "grid view"

Part of T98560.
See https://wiki.blender.org/wiki/Source/Interface/Views

Adds all the basic functionality needed for grid views. They display
items in a grid of rows and columns, typically with a preview image and
a label underneath. Think of the main region in the Asset Browser.

Current features:
- Active item
- Notifier listening (also added this to the tree view)
- Performance: Skip adding buttons that are not scrolled into view
  (solves performance problems for big asset libraries, for example).
- Custom item size
- Preview items (items that draw a preview with a label underneath)
- Margins between items scale so the entire region width is filled with
  column, rather than leaving a big empty block at the right if there's
  not enough space for another column (like the File and current Asset
Browser does it).
- "Data-View Item" theme colors. Not shown in the UI yet.

No user visible changes expected since the grid views aren't used for
anything yet.

This was developed as part of a rewrite of the Asset Browser UI
(`asset-browser-grid-view` branch), see T95653. There's no reason to
keep this part in a branch, continuing development in master makes
things easier.

Grid and tree views have a lot of very similar code, so I'm planning to
unify them to a degree. I kept things separate for the start to first
find out how much and what exactly makes sense to override.

1 files changed, 3 insertions, 0 deletions

diff --git a/source/blender/editors/space_file/filesel.c b/source/blender/editors/space_file/filesel.c
index ce36e3e4e4f..e42e1e98660 100644
--- a/source/blender/editors/space_file/filesel.c
+++ b/source/blender/editors/space_file/filesel.c
@@ -983,6 +983,7 @@ void ED_fileselect_init_layout(struct SpaceFile *sfile, ARegion *region)
 
   if (params->display == FILE_IMGDISPLAY) {
     const float pad_fac = compact ? 0.15f : 0.3f;
+    /* Matches UI_preview_tile_size_x()/_y() by default. */
     layout->prv_w = ((float)params->thumbnail_size / 20.0f) * UI_UNIT_X;
     layout->prv_h = ((float)params->thumbnail_size / 20.0f) * UI_UNIT_Y;
     layout->tile_border_x = pad_fac * UI_UNIT_X;
@@ -1009,6 +1010,7 @@ void ED_fileselect_init_layout(struct SpaceFile *sfile, ARegion *region)
   else if (params->display == FILE_VERTICALDISPLAY) {
     int rowcount;
 
+    /* Matches UI_preview_tile_size_x()/_y() by default. */
     layout->prv_w = ((float)params->thumbnail_size / 20.0f) * UI_UNIT_X;
     layout->prv_h = ((float)params->thumbnail_size / 20.0f) * UI_UNIT_Y;
     layout->tile_border_x = 0.4f * UI_UNIT_X;
@@ -1030,6 +1032,7 @@ void ED_fileselect_init_layout(struct SpaceFile *sfile, ARegion *region)
     layout->flag = FILE_LAYOUT_VER;
   }
   else if (params->display == FILE_HORIZONTALDISPLAY) {
+    /* Matches UI_preview_tile_size_x()/_y() by default. */
     layout->prv_w = ((float)params->thumbnail_size / 20.0f) * UI_UNIT_X;
     layout->prv_h = ((float)params->thumbnail_size / 20.0f) * UI_UNIT_Y;
     layout->tile_border_x = 0.4f * UI_UNIT_X;