refactor(app): implement canvas-based diff rendering

packages/app/src/git/diff-document/native-hit-testing.ts

@@ -0,0 +1,28 @@
+import { hitTestDiffDocument } from "./hit-testing";
+import type { DiffDocumentModel, DiffHit } from "./types";
+
+export interface SurfaceWindowOrigin {
+  x: number;
+  y: number;
+}
+
+export function hitTestDiffPagePoint(input: {
+  model: DiffDocumentModel;
+  pageX: number;
+  pageY: number;
+  surfaceOrigin: SurfaceWindowOrigin;
+  scrollTop: number;
+  horizontalOffsetForPath: (path: string) => number;
+}): DiffHit | null {
+  const x = input.pageX - input.surfaceOrigin.x;
+  const documentY = input.pageY - input.surfaceOrigin.y + input.scrollTop;
+  const file = input.model.files.find(
+    (entry) => entry.top <= documentY && documentY < entry.bottom,
+  );
+  return hitTestDiffDocument({
+    model: input.model,
+    x,
+    documentY,
+    horizontalOffset: file ? input.horizontalOffsetForPath(file.path) : 0,
+  });
+}