feat: implement inpainting functionality with mask handling

- Added `createMaskedPixelReplacementSource` function to handle pixel replacement using inpainting.
- Introduced `buildInpaintBundle` to prepare inpainting data including mask generation and validation.
- Created utility functions for mask operations such as `applyMaskedContentModeToRgba`, `expandRectWithinBounds`, and others for mask manipulation.
- Developed tests for inpainting preparation and mask raster utilities to ensure functionality and correctness.
- Implemented mask raster operations including inversion, feathering, blurring, and more.

view/generate/inpaintPrep.test.ts

@@ -0,0 +1,36 @@
+import { describe, expect, test } from "bun:test";
+import { applyMaskedContentModeToRgba } from "./inpaintPrep";
+
+describe("inpaint prep", () => {
+  test("converts only masked original pixels to grayscale", () => {
+    const pixels = new Uint8ClampedArray([
+      255, 0, 0, 255,
+      0, 0, 255, 255,
+    ]);
+    const mask = new Uint8ClampedArray([255, 0]);
+
+    const next = applyMaskedContentModeToRgba(pixels, 2, 1, mask, "original");
+
+    expect(next[0]).toBe(next[1]);
+    expect(next[1]).toBe(next[2]);
+    expect(Array.from(next.slice(4, 8))).toEqual([0, 0, 255, 255]);
+  });
+
+  test("uses an edge map inside the mask without recoloring unmasked context", () => {
+    const pixels = new Uint8ClampedArray([
+      255, 0, 0, 255,
+      0, 255, 0, 255,
+      0, 0, 255, 255,
+      255, 255, 0, 255,
+    ]);
+    const mask = new Uint8ClampedArray([255, 0, 0, 0]);
+
+    const next = applyMaskedContentModeToRgba(pixels, 2, 2, mask, "edges");
+
+    expect(next[0]).toBe(next[1]);
+    expect(next[1]).toBe(next[2]);
+    expect(Array.from(next.slice(4, 8))).toEqual([0, 255, 0, 255]);
+    expect(Array.from(next.slice(8, 12))).toEqual([0, 0, 255, 255]);
+    expect(Array.from(next.slice(12, 16))).toEqual([255, 255, 0, 255]);
+  });
+});