Add option folder background opacity

- Closes : #4522

src/com/android/launcher3/folder/Folder.java

@@ -119,6 +119,7 @@ import java.util.stream.Stream;
 
 import app.lawnchair.theme.drawable.DrawableTokens;
 import app.lawnchair.util.EditTextExtensions;
+import app.lawnchair.util.LawnchairUtilsKt;
 
 /**
  * Represents a set of icons chosen by the user or generated by the system.
@@ -286,6 +287,8 @@ public class Folder extends AbstractFloatingView implements ClipPathView, DragSo
         final int paddingLeftRight = dp.folderContentPaddingLeftRight;
 
         mBackground = DrawableTokens.RoundRectFolder.resolve(getContext());
+        var alpha = LawnchairUtilsKt.getFolderBackgroundAlpha(getContext());
+        mBackground.setAlpha(alpha);
 
         mContent = findViewById(R.id.folder_content);
         mContent.setPadding(paddingLeftRight, dp.folderContentPaddingTop, paddingLeftRight, 0);