fix: Camera USB stack crash after second capture

Fixes the bug by calling gp_camera_wait_for_event until timeout.

Author: fzorbach

Photobox/GPhoto2/Source/GPhoto2Camera.cpp

@@ -77,6 +77,10 @@ exec::task<void> GPhoto2Camera::asyncCaptureLoop()
                                  Q_EMIT imageCaptured(image.value());
                              }
                              return image.has_value();
+                         }) //
+                       | stdexec::continues_on(scheduler_->getWorkScheduler()) //
+                       | stdexec::then([this, &context](auto hasValue) {
+                            return GPhoto2::readUntilTimeout(*context);
                          })                           //
                        | exec::repeat_effect_until(); // todo: this now retries forever to capture a image.
                                                       // maybe retry_n times and emit an error?

Photobox/GPhoto2/Source/GPhoto2Integration.cpp

@@ -3,7 +3,9 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 #include "GPhoto2Integration.hpp"
+
 #include <QImage>
+#include <fstream>
 #include <Pbox/Logger.hpp>
 #include "GPhoto2Context.hpp"
 
@@ -109,17 +111,49 @@ std::optional<QImage> captureImage(Context &context)
         gp_camera_capture(context.camera.get(), GP_CAPTURE_IMAGE, &camera_file_path, context.context.get());
     if (ret_val < GP_OK)
     {
-        LOG_ERROR(logger_gphoto2(), "could invoke gphoto2 capture");
+        LOG_ERROR(logger_gphoto2(), "could not invoke gphoto2 capture: {}", ret_val);
         return std::nullopt;
     }
-    gp_camera_file_get(context.camera.get(),
-                       camera_file_path.folder,
-                       camera_file_path.name,
-                       GP_FILE_TYPE_NORMAL,
-                       file.get(),
-                       context.context.get());
+    LOG_INFO(logger_gphoto2(), "captured image to {}", camera_file_path.name);
+
+    const auto file_get_ret_val = gp_camera_file_get(context.camera.get(),
+                                                     camera_file_path.folder,
+                                                     camera_file_path.name,
+                                                     GP_FILE_TYPE_NORMAL,
+                                                     file.get(),
+                                                     context.context.get());
+    if (file_get_ret_val < GP_OK)
+    {
+        LOG_ERROR(logger_gphoto2(), "could not get file: {}", file_get_ret_val);
+    }
 
-    return readImageFromFile(file.get());
+    auto image = readImageFromFile(file.get());
+
+    return image;
+}
+bool readUntilTimeout(Context &context)
+{
+    while (true)
+    {
+        CameraEventType evtype;
+        void *data = nullptr;
+
+        const int ret = gp_camera_wait_for_event(context.camera.get(), 100, &evtype, &data, context.context.get());
+
+        if (ret < GP_OK)
+        {
+            LOG_ERROR(logger_gphoto2(), "could not wait for event: {}", ret);
+            break;
+        }
+
+        if (evtype == GP_EVENT_TIMEOUT)
+        {
+            LOG_DEBUG(logger_gphoto2(), "got timeout event");
+            return true;
+        }
+    }
+
+    return false;
 }
 
 namespace

Photobox/GPhoto2/Source/GPhoto2Integration.hpp

@@ -15,4 +15,6 @@ bool autodetectAndConnectCamera(Context &context);
 std::optional<QImage> capturePreviewImage(Context &context);
 
 std::optional<QImage> captureImage(Context &context);
+
+bool readUntilTimeout(Context &context);
 } // namespace Pbox::GPhoto2

photobox.json

@@ -0,0 +1,26 @@
+{
+  "name": "hochzeit-xyz",
+  "capture_dir": "./output",
+  "fonts": [
+  ],
+  "camera_led": {
+    "uri": "http://192.168.178.99"
+  },
+  "initial_countdown": 2,
+  "remote_triggers": [
+
+  ],
+  "sessions": [
+    {
+      "name": "SingleCaptureSession",
+      "type": "SingleCapture",
+      "print": false,
+      "triggers": [
+        "Display"
+      ],
+      "collage": null
+    }
+  ]
+}
+
+}