Loading Custom Font with ImGui

[TrevorCash]

Hi @mosra,

I am loading a custom font with imgui:

            ImGui::CreateContext();

                ImFontConfig fontConfig;
                fontConfig.FontDataOwnedByAtlas = false;
                size_t fileSize;
                auto data = ControlSingleton::GetInstance()->zipResourceManager->AccessResource("Fonts/OpenSans-Bold.ttf", fileSize);
                ImGui::GetIO().Fonts->Clear();
                pAppFont = ImGui::GetIO().Fonts->AddFontFromMemoryTTF(data, fileSize, 16.0, &fontConfig);

                ImGui::GetIO().Fonts->Build();

            _imgui = ImGuiIntegration::Context(Vector2{ windowSize() } / dpiScaling(),
                windowSize(), framebufferSize());

This is in a GLFW application.

I am getting the following texture error:

The data is preset for the font and is persistent for the lifetime of the application.

Are there extra operations needed with texturing?

Thanks,
Trevor

[mosra]

Hey! :)

Are you following the snippet in the docs? In particular, it seems to me that you're creating ImGuiIntegration::Context without telling it to take over the existing ImGui context, which then causes it to create a second ImGui context and then ... it likely blows up due to that mismatch. It seems. In other words, can you try this instead?

//                                 v-------- this ------------
_imgui = ImGuiIntegration::Context(*ImGui::GetCurrentContext(), 
                Vector2{ windowSize() } / dpiScaling(), windowSize(), framebufferSize());

By the way, not sure which commit are you on, but in mosra/magnum-integration@1117d6f I made a change that it no longer stores a pointer to a texture (which causes this kind of nasty crashes) but an OpenGL texture object ID instead. With that change, in case such context/texture mismatch somehow happens again, either due to fonts or any other reason, it will behave robustly and not blow up like that.

[TrevorCash]

Hey :) , I think I am using a new enough commit with the texture changes. Fixing the context bug is working great - thanks.