Add stream API presence utils.

PiperOrigin-RevId: 570901832

mediapipe/framework/api2/stream/BUILD

@@ -237,6 +237,28 @@ cc_test(
     ],
 )
 
+cc_library(
+    name = "presence",
+    hdrs = ["presence.h"],
+    deps = [
+        "//mediapipe/calculators/core:packet_presence_calculator",
+        "//mediapipe/framework/api2:builder",
+    ],
+)
+
+cc_test(
+    name = "presence_test",
+    srcs = ["presence_test.cc"],
+    deps = [
+        ":presence",
+        "//mediapipe/framework:calculator_cc_proto",
+        "//mediapipe/framework/api2:builder",
+        "//mediapipe/framework/port:gtest",
+        "//mediapipe/framework/port:gtest_main",
+        "//mediapipe/framework/port:parse_text_proto",
+    ],
+)
+
 cc_library(
     name = "rect_transformation",
     srcs = ["rect_transformation.cc"],

mediapipe/framework/api2/stream/presence.h

@@ -0,0 +1,19 @@
+#ifndef MEDIAPIPE_FRAMEWORK_API2_STREAM_PRESENCE_H_
+#define MEDIAPIPE_FRAMEWORK_API2_STREAM_PRESENCE_H_
+
+#include "mediapipe/framework/api2/builder.h"
+
+namespace mediapipe::api2::builder {
+
+// Updates @graph to emit a stream containing `bool` packets, where each packet
+// indicates whether @stream has a packet with corresponding timestamp or not.
+template <typename T>
+Stream<bool> IsPresent(Stream<T> stream, Graph& graph) {
+  auto& presence_node = graph.AddNode("PacketPresenceCalculator");
+  stream.ConnectTo(presence_node.In("PACKET"));
+  return presence_node.Out("PRESENCE").Cast<bool>();
+}
+
+}  // namespace mediapipe::api2::builder
+
+#endif  // MEDIAPIPE_FRAMEWORK_API2_STREAM_PRESENCE_H_

mediapipe/framework/api2/stream/presence_test.cc

@@ -0,0 +1,33 @@
+#include "mediapipe/framework/api2/stream/presence.h"
+
+#include "mediapipe/framework/api2/builder.h"
+#include "mediapipe/framework/calculator.pb.h"
+#include "mediapipe/framework/port/gmock.h"
+#include "mediapipe/framework/port/gtest.h"
+#include "mediapipe/framework/port/parse_text_proto.h"
+
+namespace mediapipe::api2::builder {
+namespace {
+
+TEST(Presence, VerifyConfig) {
+  Graph graph;
+
+  Stream<int> stream = graph.In("STREAM").Cast<int>();
+  stream.SetName("stream_to_check");
+  Stream<bool> is_present_stream = IsPresent(stream, graph);
+  is_present_stream.SetName("is_present_stream");
+
+  EXPECT_THAT(
+      graph.GetConfig(),
+      EqualsProto(mediapipe::ParseTextProtoOrDie<CalculatorGraphConfig>(R"pb(
+        node {
+          calculator: "PacketPresenceCalculator"
+          input_stream: "PACKET:stream_to_check"
+          output_stream: "PRESENCE:is_present_stream"
+        }
+        input_stream: "STREAM:stream_to_check"
+      )pb")));
+}
+
+}  // namespace
+}  // namespace mediapipe::api2::builder