[feat] acknowledge remote input and wait for visual changes

libs/controller/src/frame_observation.cpp

@@ -0,0 +1,28 @@
+#include "frame_image.h"
+#include <stdexcept>
+
+namespace crossdesk {
+uint64_t FrameSignature(const DecodedFrame &frame, ImageRegion region) {
+  if (!frame.width || !frame.height || (frame.width & 1) || (frame.height & 1) ||
+      region.x < 0 || region.y < 0 || region.width <= 0 || region.height <= 0 ||
+      uint64_t(region.x) + region.width > frame.width ||
+      uint64_t(region.y) + region.height > frame.height ||
+      frame.nv12.size() < size_t(frame.width) * frame.height * 3 / 2)
+    throw std::invalid_argument("INVALID_REGION");
+  uint64_t hash = 14695981039346656037ULL;
+  const auto row = [&](size_t offset, int count) {
+    for (int x = 0; x < count; ++x) {
+      hash ^= frame.nv12[offset + x];
+      hash *= 1099511628211ULL;
+    }
+  };
+  for (int y = region.y; y < region.y + region.height; ++y)
+    row(size_t(y) * frame.width + region.x, region.width);
+  const int chroma_x = region.x & ~1;
+  const int chroma_end = (region.x + region.width + 1) & ~1;
+  for (int y = region.y / 2; y < (region.y + region.height + 1) / 2; ++y)
+    row(size_t(frame.width) * frame.height + size_t(y) * frame.width + chroma_x,
+        chroma_end - chroma_x);
+  return hash;
+}
+} // namespace crossdesk