Merge pull request #26293 from SeptimiuIoachimNeagaIntel:EISW-140103_optimization_flag

G-API: Introduce level optimization flag for ONNXRT backend #26293

### Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [x] The PR is proposed to the proper branch
- [ ] There is a reference to the original bug report and related work
- [ ] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
      Patch to opencv_extra has the same branch name.
- [x] The feature is well documented and sample code can be built with the project CMake

modules/gapi/src/backends/onnx/bindings_onnx.cpp

@@ -63,6 +63,12 @@ cv::gapi::onnx::PyParams::cfgSessionOptions(const std::map<std::string, std::str
     return *this;
 }
 
+cv::gapi::onnx::PyParams&
+cv::gapi::onnx::PyParams::cfgOptLevel(const int opt_level) {
+    m_priv->cfgOptLevel(opt_level);
+    return *this;
+}
+
 cv::gapi::GBackend cv::gapi::onnx::PyParams::backend() const {
     return m_priv->backend();
 }

modules/gapi/src/backends/onnx/gonnxbackend.cpp

@@ -701,6 +701,26 @@ namespace cv {
 namespace gimpl {
 namespace onnx {
 
+static GraphOptimizationLevel convertToGraphOptimizationLevel(const int opt_level) {
+    switch (opt_level) {
+    case ORT_DISABLE_ALL:
+        return ORT_DISABLE_ALL;
+    case ORT_ENABLE_BASIC:
+        return ORT_ENABLE_BASIC;
+    case ORT_ENABLE_EXTENDED:
+        return ORT_ENABLE_EXTENDED;
+    case ORT_ENABLE_ALL:
+        return ORT_ENABLE_ALL;
+    default:
+        if (opt_level > ORT_ENABLE_ALL) {  // relax constraint
+            return ORT_ENABLE_ALL;
+        }
+        else {
+            cv::util::throw_error(std::invalid_argument("Invalid argument opt_level = " + std::to_string(opt_level)));
+        }
+    }
+}
+
 ONNXCompiled::ONNXCompiled(const gapi::onnx::detail::ParamDesc &pp)
     : params(pp) {
     // Validate input parameters before allocating any resources
@@ -726,6 +746,10 @@ ONNXCompiled::ONNXCompiled(const gapi::onnx::detail::ParamDesc &pp)
     if (pp.disable_mem_pattern) {
         session_options.DisableMemPattern();
     }
+
+    if (pp.opt_level.has_value()) {
+        session_options.SetGraphOptimizationLevel(convertToGraphOptimizationLevel(pp.opt_level.value()));
+    }
     this_env = Ort::Env(ORT_LOGGING_LEVEL_WARNING, "");
 #ifndef _WIN32
     this_session = Ort::Session(this_env, params.model_path.data(), session_options);