feat(splitter): improve splitter theme (#15684)

Author: didimmova

projects/igniteui-angular/src/lib/core/styles/components/splitter/_splitter-theme.scss

@@ -42,16 +42,27 @@
     }
 
     $theme: digest-schema($splitter-schema);
-    $meta: map.get($theme, '_meta');
+    $variant: map.get($theme, '_meta', 'theme');
 
     @if not($handle-color) and $bar-color {
-        $handle-color: text-contrast($bar-color);
+        $handle-color: adaptive-contrast(var(--bar-color));
     }
 
     @if not($expander-color) and $bar-color {
-        $expander-color: text-contrast($bar-color);
+        $expander-color: adaptive-contrast(var(--bar-color));
     }
 
+    @if $variant != 'indigo' {
+        @if not($focus-color) and $bar-color {
+            $focus-color: hsl(from var(--bar-color) h s calc(l * 0.7));
+        }
+    } @else {
+        @if not($focus-color) and $bar-color {
+            $focus-color: var(--bar-color);
+        }
+    }
+
+
     @return extend($theme, (
         name: $name,
         bar-color: $bar-color,
@@ -60,10 +71,6 @@
         border-radius: $border-radius,
         focus-color: $focus-color,
         size: $size,
-        theme: map.get($schema, '_meta', 'theme'),
-        _meta: map.merge(if($meta, $meta, ()), (
-            variant: map.get($schema, '_meta', 'theme')
-        )),
     ));
 }
 
@@ -77,7 +84,7 @@
     $debug-hitbox: false;
     $hitbox-debug-color: rgba(coral, .24);
 
-    $variant: map.get($theme, '_meta', 'variant');
+    $variant: map.get($theme, '_meta', 'theme');
 
     //splitter-size + borders
     $splitter-size: unitless(map.get($theme, 'size')) + 2;