Faster method for combining image files

Using the create() syntax caused us to create an unnecessary base image
upon which we overlaid our pieces. By instead starting with one of our
pieces, we can remove a step and some CPU cycles.

Author: rylnd

src/lib/imaging.ts

@@ -8,18 +8,9 @@ const maxSize = 400;
 export const parseSize = parseSizeFactory(minSize, maxSize);
 
 export const combine = (face: Face) =>
-  sharp({
-    create: {
-      width: maxSize,
-      height: maxSize,
-      channels: 4,
-      background: face.color,
-    },
-  }).composite([
-    { input: face.eyes },
-    { input: face.mouth },
-    { input: face.nose },
-  ]);
+  sharp(face.eyes)
+    .composite([{ input: face.mouth }, { input: face.nose }])
+    .flatten({ background: face.color });
 
 export const resize = (rawSize: string) => {
   const size = parseSize(rawSize);