Menu: WebM previews in the file browser (Ozone/XMB)

1316b60 made .webm decodable by the thumbnail pipeline, but only wired
it up for playlist thumbnails. Highlighting a .webm in the file browser
still showed nothing, because the 'file is its own thumbnail' preview
path that images use is gated four times on image-ness, in series:

- ozone_selection_changed / xmb selection handling only trigger the
  imageviewer preview for FILE_TYPE_IMAGEVIEWER/FILE_TYPE_IMAGE, and
  .webm entries are typed FILE_TYPE_WEBM / FILE_TYPE_MOVIE (with a
  media player compiled in) or FILE_TYPE_PLAIN (without)
- xmb_set_thumbnail_content's imageviewer branch re-checks
  FILE_TYPE_IMAGEVIEWER
- gfx_thumbnail_set_content_image rejects anything whose
  path_is_media_type is not RARCH_CONTENT_IMAGE
- gfx_thumbnail_update_path's imageviewer special case requires
  RARCH_CONTENT_IMAGE before using the file itself as the thumbnail

Open all four for WebM. The menu-driver checks use
image_texture_get_type(entry.path) == IMAGE_TYPE_WEBM rather than the
entry type, so they work regardless of how the file was typed (and
compile away to a false constant without HAVE_RWEBM, since the type
can then never be returned). File typing itself is untouched: OK on a
.webm still launches the media player as before, and the movie icon
is kept.

Unlike an image, the whole WebM must be read to decode a frame, and
file-browser content is arbitrarily large, so gfx_thumbnail_update_path
additionally refuses files past GFX_THUMB_ANIM_MAX_FILE (64 MiB), the
same cap the animation decoder enforces.

MaterialUI has no filebrowser preview mechanism for images either, so
there is nothing to extend there; its playlist thumbnails already
animate via 1316b60.

gfx/gfx_thumbnail.c

@@ -1845,7 +1845,10 @@ bool gfx_thumbnail_set_content_image(
    if ((!img_dir || !*img_dir) || (!img_name || !*img_name))
       return false;
 
-   if (path_is_media_type(img_name) != RARCH_CONTENT_IMAGE)
+   /* Images, and WebM files (whose video track the thumbnail pipeline
+    * decodes like an animated WebP), can serve as their own thumbnail */
+   if (   (path_is_media_type(img_name) != RARCH_CONTENT_IMAGE)
+       && (image_texture_get_type(img_name) != IMAGE_TYPE_WEBM))
       return false;
 
    /* Cache content image name */
@@ -2134,6 +2137,15 @@ bool gfx_thumbnail_update_path(
       if (path_is_media_type(path_data->content_path) == RARCH_CONTENT_IMAGE)
          strlcpy(thumbnail_path,
                path_data->content_path, PATH_MAX_LENGTH * sizeof(char));
+      /* A WebM file is likewise its own (animated) thumbnail, but unlike
+       * an image the entire file must be read to decode it, so refuse
+       * anything past the animation decoder's file-size cap */
+      else if (   (image_texture_get_type(path_data->content_path)
+                     == IMAGE_TYPE_WEBM)
+               && (path_get_size(path_data->content_path)
+                     <= GFX_THUMB_ANIM_MAX_FILE))
+         strlcpy(thumbnail_path,
+               path_data->content_path, PATH_MAX_LENGTH * sizeof(char));
    }
    else
    {

menu/drivers/ozone.c

@@ -12073,10 +12073,14 @@ static void ozone_selection_changed(ozone_handle_t *ozone, bool allow_animation)
          {
             menu_entry_t entry;
             MENU_ENTRY_INITIALIZE(entry);
+            entry.flags |= MENU_ENTRY_FLAG_PATH_ENABLED;
             menu_entry_get(&entry, 0, selection, NULL, true);
 
             if (   (entry.type == FILE_TYPE_IMAGEVIEWER)
-                || (entry.type == FILE_TYPE_IMAGE))
+                || (entry.type == FILE_TYPE_IMAGE)
+                /* WebM files preview like images: the thumbnail
+                 * pipeline decodes their video track */
+                || (image_texture_get_type(entry.path) == IMAGE_TYPE_WEBM))
             {
                ozone_set_thumbnail_content(ozone, "imageviewer");
                update_thumbnails = true;

menu/drivers/xmb.c

@@ -1902,7 +1902,8 @@ static void xmb_set_thumbnail_content(void *data, const char *s)
 
          if (     *entry.path
                && (node->fullpath && *node->fullpath)
-               && entry.type == FILE_TYPE_IMAGEVIEWER)
+               && (   (entry.type == FILE_TYPE_IMAGEVIEWER)
+                   || (image_texture_get_type(entry.path) == IMAGE_TYPE_WEBM)))
          {
             gfx_thumbnail_set_content_image(menu_st->thumbnail_path_data,
                   node->fullpath, entry.path);
@@ -2237,10 +2238,14 @@ static void xmb_selection_pointer_changed(
             {
                menu_entry_t entry;
                MENU_ENTRY_INITIALIZE(entry);
+               entry.flags |= MENU_ENTRY_FLAG_PATH_ENABLED;
                menu_entry_get(&entry, 0, selection, NULL, true);
 
                if (     (entry.type == FILE_TYPE_IMAGEVIEWER)
-                     || (entry.type == FILE_TYPE_IMAGE))
+                     || (entry.type == FILE_TYPE_IMAGE)
+                     /* WebM files preview like images: the thumbnail
+                      * pipeline decodes their video track */
+                     || (image_texture_get_type(entry.path) == IMAGE_TYPE_WEBM))
                {
                   xmb_set_thumbnail_content(xmb, "imageviewer");
                   update_thumbnails = true;