From 3557914356ebcb5f489b470de4f762682d3e02bd Mon Sep 17 00:00:00 2001
From: julian <julian@cypherstack.com>
Date: Wed, 11 Dec 2024 17:42:47 -0600
Subject: [PATCH 1/2] fix: free memory after use

---
 lib/camera_linux.dart | 26 +++++++++++++++++++-------
 1 file changed, 19 insertions(+), 7 deletions(-)

diff --git a/lib/camera_linux.dart b/lib/camera_linux.dart
index 55bf9a5..da3a919 100644
--- a/lib/camera_linux.dart
+++ b/lib/camera_linux.dart
@@ -2,9 +2,11 @@ import 'dart:async';
 import 'dart:convert';
 import 'dart:ffi';
 import 'dart:typed_data';
-import 'camera_linux_bindings_generated.dart';
+
 import 'package:ffi/ffi.dart';
 
+import 'camera_linux_bindings_generated.dart';
+
 class CameraLinux {
   late CameraLinuxBindings _bindings;
 
@@ -24,7 +26,7 @@ class CameraLinux {
   }
 
   // Convert Frame Into Base64
-  String uint8ListToBase64Url(Uint8List data) {
+  String _uint8ListToBase64Url(Uint8List data) {
     String base64String = base64Encode(data);
 
     String base64Url = base64String
@@ -39,14 +41,24 @@ class CameraLinux {
   // Capture The Frame
   Future<String> captureImage() async {
     final lengthPtr = calloc<Int>();
-    Pointer<Uint8> framePointer = _bindings.getLatestFrameBytes(lengthPtr);
-    final latestFrame = getLatestFrameData(framePointer, lengthPtr.value);
-    final base64Image = uint8ListToBase64Url(latestFrame);
-    return base64Image;
+    Pointer<Uint8>? latestFramePtr;
+    try {
+      latestFramePtr = _bindings.getLatestFrameBytes(lengthPtr);
+      final latestFrame = _getLatestFrameData(latestFramePtr, lengthPtr.value);
+      final base64Image = _uint8ListToBase64Url(latestFrame);
+      return base64Image;
+    } catch (_) {
+      rethrow;
+    } finally {
+      calloc.free(lengthPtr);
+      if (latestFramePtr != null) {
+        calloc.free(latestFramePtr);
+      }
+    }
   }
 
   // Get The Latest Frame
-  Uint8List getLatestFrameData(Pointer<Uint8> framePointer, frameSize) {
+  Uint8List _getLatestFrameData(Pointer<Uint8> framePointer, frameSize) {
     List<int> frameList = framePointer.asTypedList(frameSize);
     return Uint8List.fromList(frameList);
   }

From ecb412474c5d240347b04ac1eb9f019802ff7034 Mon Sep 17 00:00:00 2001
From: julian <julian@cypherstack.com>
Date: Wed, 11 Dec 2024 18:11:22 -0600
Subject: [PATCH 2/2] feat: clear last frame on read

---
 src/opencv_wrapper.cpp | 32 +++++++++++++++++++++++---------
 1 file changed, 23 insertions(+), 9 deletions(-)

diff --git a/src/opencv_wrapper.cpp b/src/opencv_wrapper.cpp
index 2b71d80..78ce43b 100644
--- a/src/opencv_wrapper.cpp
+++ b/src/opencv_wrapper.cpp
@@ -2,12 +2,14 @@
 #include <opencv2/opencv.hpp>
 #include <thread>
 #include <atomic>
+#include <mutex>
 
 using namespace std;
 using namespace cv;
     
 std::thread videoThread;
 std::atomic<bool> stopFlag(false);
+std::mutex frameMutex;
 Mat latestFrame;
                 
 // Extern C block to expose the function to C
@@ -22,15 +24,20 @@ extern "C" {
         }
 
         while (!stopFlag.load()) {
-            cap >> latestFrame;
-            if (latestFrame.empty()) {
+            Mat frame;
+            cap >> frame;
+            if (frame.empty()) {
                 printf("Frame is Empty");
                 break;
             }
 
+            {
+                lock_guard<std::mutex> lock(frameMutex);
+                frame.copyTo(latestFrame);
+            }
             std::this_thread::sleep_for(std::chrono::milliseconds(500));
         }
-        cap.release(); 
+        cap.release();
     }
 
  
@@ -55,16 +62,23 @@ extern "C" {
         }
 
         *length = 0;  // Initialize length to 0
-        
-        
-        if (latestFrame.empty()) {
-            printf("Frame Empty");
-            return nullptr;
+
+        Mat frameCopy;
+        {
+            std::lock_guard<std::mutex> lock(frameMutex);
+
+            if (latestFrame.empty()) {
+                printf("Frame Empty\n");
+                return nullptr;
+            }
+
+            frameCopy = latestFrame.clone(); // Clone the frame to avoid race conditions
+            latestFrame.release(); // Clear the frame after it has been fetched
         }
 
         // Encode the frame as JPEG
         vector<uint8_t> buf;
-        bool encodeSuccess = imencode(".jpg", latestFrame, buf);
+        bool encodeSuccess = imencode(".jpg", frameCopy, buf);
 
         // Check if encoding was successful
         if (!encodeSuccess || buf.empty()) {