From 44c0f1eaf67f4966d79def6862e3a9e56cbc038d Mon Sep 17 00:00:00 2001
From: Yi donghoon <icq4ever@gmail.com>
Date: Mon, 29 Jun 2026 14:14:42 +0900
Subject: [PATCH] feat: expose current k4a_capture via getNativeCapture()

Retain the per-frame k4a_capture as an Impl member (released on the next
successful capture or in closeDevice) and add getNativeCapture() alongside
the existing native-handle escape hatch. This lets a separate addon feed
the same capture into k4abt_tracker_enqueue_capture() for (i.e. body tracking),
sharing the single capture instead of opening the device twice.

No behavior change for existing depth/color/IR/point-cloud use; verified
example-basic still renders the live point cloud on a Femto Bolt (via the
Orbbec K4A Wrapper).
---
 src/tcxAzureKinect.cpp | 17 +++++++++++++++--
 src/tcxAzureKinect.h   |  9 +++++++++
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/src/tcxAzureKinect.cpp b/src/tcxAzureKinect.cpp
index fc4229e..cf97e36 100644
--- a/src/tcxAzureKinect.cpp
+++ b/src/tcxAzureKinect.cpp
@@ -26,6 +26,7 @@ struct AzureKinect::Impl {
     k4a_transformation_t       transformation = nullptr;
     k4a_calibration_t          calibration{};
     k4a_device_configuration_t config{};
+    k4a_capture_t              capture        = nullptr;  // most recent frame, held for getNativeCapture()
 };
 
 AzureKinect::AzureKinect(uint32_t deviceIndex)
@@ -38,6 +39,7 @@ AzureKinect::~AzureKinect() = default;
 k4a_device_t AzureKinect::getNativeDevice() const { return impl_->device; }
 const k4a_calibration_t& AzureKinect::getNativeCalibration() const { return impl_->calibration; }
 k4a_transformation_t AzureKinect::getNativeTransformation() const { return impl_->transformation; }
+k4a_capture_t AzureKinect::getNativeCapture() const { return impl_->capture; }
 
 // -----------------------------------------------------------------------------
 bool AzureKinect::openDevice() {
@@ -105,6 +107,10 @@ bool AzureKinect::openDevice() {
 }
 
 void AzureKinect::closeDevice() {
+    if (impl_->capture) {
+        k4a_capture_release(impl_->capture);
+        impl_->capture = nullptr;
+    }
     if (impl_->transformation) {
         k4a_transformation_destroy(impl_->transformation);
         impl_->transformation = nullptr;
@@ -124,9 +130,14 @@ StreamFreshness AzureKinect::captureInto(DepthFrame& dst) {
     if (k4a_device_get_capture(impl_->device, &cap, kCaptureTimeoutMs)
             != K4A_WAIT_RESULT_SUCCEEDED) {
         if (cap) k4a_capture_release(cap);
-        return fresh;  // timeout / no frame
+        return fresh;  // timeout / no frame; keep the previously held capture
     }
 
+    // Retain this capture for getNativeCapture() (e.g. k4abt body tracking shares
+    // the single capture). Release the one held from the previous frame first.
+    if (impl_->capture) k4a_capture_release(impl_->capture);
+    impl_->capture = cap;
+
     k4a_image_t depthImg = k4a_capture_get_depth_image(cap);
     if (depthImg) {
         const int w = k4a_image_get_width_pixels(depthImg);
@@ -206,7 +217,9 @@ StreamFreshness AzureKinect::captureInto(DepthFrame& dst) {
         k4a_image_release(irImg);
     }
 
-    k4a_capture_release(cap);
+    // cap is NOT released here — it is retained as impl_->capture and freed on the
+    // next successful capture or in closeDevice(), so getNativeCapture() can hand
+    // it to k4abt for the current frame.
     return fresh;
 }
 
diff --git a/src/tcxAzureKinect.h b/src/tcxAzureKinect.h
index 43c7119..7fe6b9d 100644
--- a/src/tcxAzureKinect.h
+++ b/src/tcxAzureKinect.h
@@ -54,6 +54,15 @@ class AzureKinect : public DepthCamera {
     const k4a_calibration_t& getNativeCalibration() const;
     k4a_transformation_t     getNativeTransformation() const;
 
+    // The k4a_capture behind the most recent successful frame, retained until the
+    // next one is grabbed — e.g. to feed k4abt_tracker_enqueue_capture() for body
+    // tracking, sharing the single capture instead of opening the device twice.
+    // Null before the first frame / after closeDevice(); the backend owns it, do
+    // NOT release it. In threaded mode (setThreaded(true)) it is swapped on the
+    // grab thread, so read it on the thread that drives update() — or run
+    // non-threaded when handing it to the body tracker.
+    k4a_capture_t            getNativeCapture() const;
+
 protected:
     bool openDevice() override;
     void closeDevice() override;