refactor: replace excavateModules with visual layering approach

[scopewu]

Changes:

• Remove excavateModules() function that copied and mutated modules
• Render background rect in SVG using element
• Draw background fillRect in Canvas before rendering image

[scopewu]

Replace data-mutation based excavation with visual layering using background-colored rectangles. This eliminates the need to copy and modify the modules array, improving performance.

[zpao]

Thanks for taking the time to send this!

I thought about doing it this way when we added the embedded image, however because it is possible to have transparency for the background color & the embedded image, we can't just layer like this.

Here are a few screenshots, 2 sets of 2 to show what happens, before & after you changes. For these, I changed the background of the example page and then in code (because most browsers don't support alpha transparency in the color picker), used a background color with transparency. These are just the SVGs but canvas looked the same.

Code changes

diff --git a/examples/full.tsx b/examples/full.tsx
index 854eb42..1248a23 100644
--- a/examples/full.tsx
+++ b/examples/full.tsx
@@ -10,7 +10,7 @@ function FullDemo() {
   );
   const [size, setSize] = useState(128);
   const [fgColor, setFgColor] = useState('#000000');
-  const [bgColor, setBgColor] = useState('#ffffff');
+  const [bgColor, setBgColor] = useState('#ffffff88');
   const [level, setLevel] = useState<ErrorCorrectionLevel>('L');
   const [boostLevel, setBoostLevel] = useState<boolean>(true);
   const [minVersion, setMinVersion] = useState(1);
diff --git a/examples/index.html b/examples/index.html
index 33050b7..fe9f247 100644
--- a/examples/index.html
+++ b/examples/index.html
@@ -11,6 +11,7 @@
       }
       .output {
         margin-left: 1rem;
+        background-color: #c66;
       }
       @media only screen and (max-width: 600px) {
         .container {

1. No other changes, embedded image at 100% opacity

2. Adjusted image opacity in the example UI

So, while I appreciate the time spent and care to dig in and attempt this, I'm going to have to close this out.