UI: Icon number indicator for data-blocks

Adds the possibility of having a little number on top of icons.

At the moment this is used for:
* Outliner
* Node Editor bread-crumb
* Node Group node header

For the outliner there is almost no functional change. It is mostly a refactor
to handle the indicators as part of the icon shader instead of the outliner
draw code. (note that this was already recently changed in a5d3b648e3e2).

The difference is that now we use rounded border rectangle instead of
circles, and we can go up to 999 elements.

So for the outliner this shows the number of collapsed elements of a
certain type (e.g., mesh objects inside a collapsed collection).

For the node editors is being used to show the use count for the data-block.
This is important for the node editor, so users know whether the node-group
they are editing (or are about to edit) is used elsewhere. This is
particularly important when the Node Options are hidden, which is the
default for node groups appended from the asset libraries.

---

Note: This can be easily enabled for ID templates which can then be part
of T84669. It just need to call UI_but_icon_indicator_number_set in the
function template_add_button_search_menu.

---

Special thanks Clément Foucault for the help figuring out the shader,
Julian Eisel for the help navigating the UI code, and Pablo Vazquez for
the collaboration in this design solution.

For images showing the result check the Differential Revision.
Differential Revision: https://developer.blender.org/D16284

1 files changed, 11 insertions, 1 deletions

diff --git a/source/blender/editors/include/UI_interface_icons.h b/source/blender/editors/include/UI_interface_icons.h
index a1a98a4b08c..9669e242dac 100644
--- a/source/blender/editors/include/UI_interface_icons.h
+++ b/source/blender/editors/include/UI_interface_icons.h
@@ -27,6 +27,12 @@ typedef struct IconFile {
   int index;
 } IconFile;
 
+typedef struct IconTextOverlay {
+  char text[5];
+} IconTextOverlay;
+
+#define UI_NO_ICON_OVERLAY_TEXT NULL
+
 #define ICON_DEFAULT_HEIGHT 16
 #define ICON_DEFAULT_WIDTH 16
 
@@ -105,7 +111,8 @@ void UI_icon_draw_ex(float x,
                      float alpha,
                      float desaturate,
                      const uchar mono_color[4],
-                     bool mono_border);
+                     bool mono_border,
+                     const struct IconTextOverlay *text_overlay);
 
 void UI_icons_free(void);
 void UI_icons_free_drawinfo(void *drawinfo);
@@ -124,6 +131,9 @@ int UI_icon_from_library(const struct ID *id);
 int UI_icon_from_object_mode(int mode);
 int UI_icon_color_from_collection(const struct Collection *collection);
 
+void UI_icon_text_overlay_init_from_count(struct IconTextOverlay *text_overlay,
+                                          const int icon_indicator_number);
+
 #ifdef __cplusplus
 }
 #endif