imgui_juce

JUCE 1 backend for Dear ImGui 2.

I don't recommend using JUCE for prototyping DSP code, but if you have no better options, using ImGui with this library should make your life a lot easier.

Pros:

• No more listener/attachment/callback bullshit (you won't believe how many layers of callbacks are used just to set a single parameter using APVTS's SliderAttachment).

  You can write declarative code for GUI now:

  ImGui::Text("Hello, world %d", 123);
  if (ImGui::Button("Save"))
    DoStuff();
  

• No more GUI layout positioning bullshit. Spend your time on DSP code.

• It's much easier now to integrate custom non-float parameters into your plugin.

• There are a ton of useful extensions for ImGui you can use for easier debugging. See imnodes 3, implot 4, and the list on ImGui wiki 5.

• You can mix JUCE GUI components and ImGui. ImGui only needs a Component for mouse/keyboard input and a OpenGLContext for rendering. You can, for example, only enable the ImGui component for debugging and disable it in the final release.

Cons:

• GUI is recomputed each frame at 60 FPS, probably less efficient than JUCE, but at least it's using OpenGL.

• JUCE's keypress callbacks are extremely inefficient for ImGui, though you can disable it by setting

  setWantsKeyboardFocus(false);
  

• Component and layout can be less customizable than JUCE. You probably only want to use it for prototyping.

• Slider skew not supported by default. You need to write your own component for that (contributions welcome). ImGui do have logarithmic slider built-in though.

• You need a patched version of ImGui for use in audio plugins (see Note below).

Usage

The backend exposes three functions

#include <imgui_impl_juce/imgui_impl_juce.h>

void ImGui_ImplJuce_Init(juce::Component&, juce::OpenGLContext&);
void ImGui_ImplJuce_Shutdown();
void ImGui_ImplJuce_NewFrame();

You need to create a juce::OpenGLRenderer and call the three functions in

void newOpenGLContextCreated();
void openGLContextClosing();
void renderOpenGL();

respectively. See

./examples/mwe/src/ImGuiComponent.h

for a complete minimal working example.

If you need an audio plugin example, see

./examples/sine/

CMake Usage

If you are using CMake, call add_subdirectory on the current directory after JUCE directory is added. Then link your application target to imgui_imple_juce. For example,

target_link_libraries(app
  # other stuff libs
  PRIVATE
    imgui_impl_juce)

See

./examples/mwe/CMakeLists.txt

for a complete example.

Note

By default ImGui only support a single instance running because it uses a global state

ImGuiContext* GImGui = NULL;

This is probably fine if you are writing a GUI application, but if you are writing an audio plugin, the plugin will crash if you add multiple instances of the plugin in DAW and open two GUIs at the same time.

You need to patch ImGui and make the global state thread local

thread_local ImGuiContext* GImGui = NULL;

in order to support multiple instances of ImGui running at the same time on different threads. See

./examples/sine/patches/imgui/multi_instance.patch

for details.

You need a similar patch if you want to use imnodes or ImPlot in your plugin. For a ImPlot example, see

./examples/scope/patches/implot/multi_instance.patch

License

The imgui_juce library is licensed under the GNU Lesser General Public License v3.0 (LGPLv3).

Examples are placed under public domain.

Donate

If this library saves valuable development time for you, consider donate to support this project:

https://ko-fi.com/krjst