Add sandbox demos: demo_error_check_end_frame_recover[.cpp & .py]

bindings/imgui_bundle/demos_cpp/sandbox/demo_error_check_end_frame_recover.cpp

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+// This demo show how we can call ImGui::ErrorCheckEndFrameRecover()
+// to recover from errors originating when ImGui::End() is not called (for example when an exception is raised)
+
+#include "hello_imgui.h"
+#include "imgui.h"
+#include "imgui_internal.h"
+
+void SubWindowGui()
+{
+    ImGui::SetNextWindowSize(ImVec2(600.f, 200.f));
+    ImGui::Begin("Sub window");
+    ImGui::Text("The button below will raise an exception which lead to imgui.end() not being called");
+
+    if (ImGui::Button("Raise exception")) { // This button raises an exception that bypasses `ImGui::End()`
+        throw std::runtime_error("Argh");
+    }
+    ImGui::End();
+}
+
+void Gui()
+{
+    try
+    {
+        ImGui::Text("Hello");
+        SubWindowGui();
+    }
+    catch (const std::runtime_error& e)
+    {
+        std::cout << "Ouch, caught an exception: " << e.what() << std::endl;
+    }
+}
+
+// By default, ImGui::ErrorCheckEndFrameRecover() uses a C-Style callback with va_args, such as below
+void MyEndFrameErrorCallback_CStyle(void* user_data, const char* fmt, ...)
+{
+    printf("MyEndFrameErrorCallback_CStyle ==> ");
+
+    va_list args;
+    va_start(args, fmt);
+    vprintf(fmt, args);
+    va_end(args);
+
+    printf("\n");
+};
+
+// ImGui Bundle provides a fork of ImGui where another version of ImGui::ErrorCheckEndFrameRecover()
+// can use a simpler C++ style callback, such a below
+// (only available if IMGUI_BUNDLE_PYTHON_API is defined)
+void MyEndFrameErrorCallback(const std::string& message)
+{
+    printf("MyEndFrameErrorCallback ==> %s\n", message.c_str());
+};
+
+
+
+int main()
+{
+    HelloImGui::RunnerParams runnerParams;
+    runnerParams.callbacks.ShowGui = Gui;
+
+    // you can use either the C style or the C++ style callback
+    runnerParams.callbacks.BeforeImGuiRender = [](){ ImGui::ErrorCheckEndFrameRecover(MyEndFrameErrorCallback_CStyle); };
+    // runnerParams.callbacks.BeforeImGuiRender = [](){ ImGui::ErrorCheckEndFrameRecover(MyEndFrameErrorCallback); };
+
+    HelloImGui::Run(runnerParams);
+    return 0;
+}

bindings/imgui_bundle/demos_python/sandbox/demo_error_check_end_frame_recover.py

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+# This demo show how we can call ImGui::ErrorCheckEndFrameRecover()
+# to recover from errors originating when ImGui::End() is not called (for example when an exception is raised)
+
+from imgui_bundle import hello_imgui, imgui
+
+
+def sub_window_gui():
+    imgui.set_next_window_size((600, 200))
+    imgui.begin("Sub window")
+    imgui.text_wrapped("The button below will raise an exception which lead to imgui.end() not being called")
+
+    if imgui.button("Raise exception"): # This button raises an exception that bypasses `ìmgui.end()`
+        raise RuntimeError("Argh")
+    imgui.end()
+
+
+def gui():
+    try:
+        imgui.text("Hello")
+        sub_window_gui()
+    except RuntimeError as e:
+        print(f"Ouch, caught an exception: {e}")
+
+
+# ImGui Bundle provides a fork of ImGui
+# where imgui.internal.error_check_end_frame_recover() can use a simple callback, such a below:
+def my_end_frame_error_callback(message):
+    print("my_end_frame_error_callback ==> " + message)
+
+
+def main():
+
+    runner_params = hello_imgui.RunnerParams()
+    runner_params.callbacks.show_gui = gui
+
+    runner_params.callbacks.before_imgui_render = lambda: imgui.internal.error_check_end_frame_recover(my_end_frame_error_callback)
+
+    hello_imgui.run(runner_params)
+
+
+if __name__ == "__main__":
+    main()