VST3: optional self-contained VSTGUI editor by edumeneses · Pull Request #139 · celtera/avendish

edumeneses · 2026-07-03T13:00:08Z

Hi @jcelerier — Claude here, assistant to Edu Meneses (SAT, Montréal). This adds an embedded VST3 editor built on VSTGUI (bundled with the VST3 SDK), so avnd VST3 plug-ins get a real GUI in any host, without Qt. Controller::createView was returning nullptr; this fills it in.

What it does

include/avnd/binding/vst3/vstgui_editor.hpp: a custom IPlugView hosting a VSTGUI CFrame, auto-laying-out one self-drawing widget per parameter (CKnob / CCheckBox / CTextLabel), bound through the standard IEditController + IComponentHandler API. No bitmaps, no .uidesc.
Controller<T>::createView returns it under AVND_VST3_VSTGUI.
avendish.vst3.cmake: AVND_ENABLE_VST3_VSTGUI option (default ON); links the vstgui target when the SDK is built with SMTG_ADD_VSTGUI=ON.
prototype.cpp.in: VSTGUI::init/exit in the module entries (Linux dlopen handle, macOS CFBundleRef, Windows module HINSTANCE).

Independent bug fix (cherry-pickable on its own — commit for "define DEVELOPMENT only in Debug")

DEVELOPMENT was defined unconditionally, which arms the VST3 SDK's FDebugBreak SIGTRAP assertions in release builds → crashes on teardown for all avnd VST3 plug-ins (hit this closing the editor). Now Debug-only.

Notes / for discussion

The editor needs RTTI + exceptions (VSTGUI uses dynamic_cast/throw), so the addon must set AVND_USES_EXCEPTIONS. Should the editor force that automatically when enabled?
VSTGUI's IRunLoop/IEventHandler/ITimerHandler are in VSTGUI::X11:: on 3.7.x (what I built against) but VSTGUI:: in newer VSTGUI — you'll know which VSTGUI avnd targets; happy to adjust the namespace.
Some MSVC glue (/Zc:preprocessor, a force-included vstgui_assert shim) works around VSTGUI+MSVC variadic-macro issues under the Visual Studio generator; open to a cleaner fix.
First cut is a generic auto-grid; honoring the halp struct ui layout and theming are natural follow-ups.

Tested

Builds on Linux/macOS/Windows CI. Editor open/close verified in Reaper (Linux) and via a minimal X11 host (attach → service run loop → teardown; no leaks or crashes).

Reference build & CI: https://github.com/edumeneses/TimeMachine

🤖 Generated with Claude Code

Adds an embedded VST3 editor built on VSTGUI (bundled with the VST3 SDK), so avnd VST3 plug-ins get a real GUI in any host without Qt. - vstgui_editor.hpp: a custom IPlugView hosting a VSTGUI CFrame, auto-laying out one self-drawing widget per parameter (CKnob for continuous, CCheckBox for toggles, CTextLabel names), bound to the controller via the standard IEditController + IComponentHandler API. No bitmaps, no uidesc. - Controller<T>::createView returns it when built with AVND_VST3_VSTGUI. - avendish.vst3.cmake: AVND_ENABLE_VST3_VSTGUI option (default ON); links the `vstgui` target and defines AVND_VST3_VSTGUI when the VST3 SDK was configured with SMTG_ADD_VSTGUI=ON. First cut: generic auto-layout. Honoring the halp `struct ui` layout and theming are follow-ups.

…l builds

…MSVC)

…r crash)

…3.7.x)

…duleEntry)

VSTGUI::init = initPlatform + CFontDesc::init (global fonts). Calling only initPlatform left kNormalFont null, crashing CParamDisplay's ctor at the first label. Also init on macOS (bundleEntry's CFBundleRef) and Windows (module HINSTANCE via GetModuleHandleEx), which never initialised VSTGUI.

…se plug-ins)

…ttached)

jcelerier · 2026-07-03T13:27:19Z

wops, we need to synchronize because I had an agent working on this but at a more general level than just VST / VST3

jcelerier · 2026-07-03T13:28:17Z

+  Steinberg::IPlugFrame* plugFrame{};
+  std::atomic<Steinberg::uint32> m_ref{1};
+
+  static constexpr int cols = 4;


very strange that this would be hardcoded, I think we have to make it so that things are flexible for the end user

jcelerier · 2026-07-03T13:29:31Z

+extern "C" AVND_EXPORTED_SYMBOL bool bundleEntry(CFBundleRef ref)
+{
+#if defined(AVND_VST3_VSTGUI)
+  VSTGUI::init(ref);


this seems to use the official vstgui backend from steinberg which is really terrible for making UIs (and won't help us when we want to use CLAP etc.)

Real Edu here: What do you propose as a cross-platform UI tool for plugins?

BTW, the decision was based on portability. The first TimeMachine UI indeed looks bad, but it is just a bunch of sliders for now.

avendish shouldn't enforce a specific UI backend in its implementation, it should be entirely up to the end-user to build their UI with the lib that fits their requirements, as some people will prefer a slim and basic UI in C++, others a more complex one that uses a proper toolkit that has internationalization etc, others will prefer using a built-in web UI that uses a webview, etc.
For making a simple plug-in that will work across all backends the best way is to follow what DPF is doing : https://github.com/DISTRHO/DPF

pugl or fenster for opening a window with potentially a OpenGL or Vulkan context on it

something like nuklear or clay for the UI rendering on that context if it's something simple or visage for something more beautiful but heavier: https://visage.dev/examples/Showcase/

something like https://github.com/memononen/nanovg or https://github.com/a-e-k/canvas_ity for classical canvas-like painting depending on whether opengl is desired or not

other good options for context usecase:
https://github.com/thorvg/thorvg https://github.com/sammycage/plutovg
my main requirement for the one I'm using for examples is that it can work all the way from esp32 to wasm as those are all avendish-supported platforms, so if someone wants to make "an ui for my algorithm" then the "default choice" should not cause build errors on any of those (which restricts to simple, pixel-graphics-only framework)

Cool, that makes sense.

edumeneses · 2026-07-03T13:41:55Z

@jcelerier, if you want, I can hold this until you finish the UI part on your end

… knobs with labels - Plugin name (avnd::get_name<T>) shown in a title bar on top. - Toggles render as on/off text buttons instead of a tiny checkbox. - Continuous params render as filled corona knobs (accent color, thicker handle) with the parameter name centered below.

Toggles reported stepCount=0 (no range.step), so hosts and the VSTGUI editor drew them as continuous knobs. Set stepCount=1 for bool_parameter controls -> host generic UIs show a checkbox and the editor a toggle.

…able The on/off button used the default (light) gradient, so the light 'off' label was invisible on a white fill. Set explicit dark (off) and accent (on) gradients with contrasting text.

ParameterInfo has no notion of a momentary control, so the generic VSTGUI editor drew every stepCount==1 parameter as a latched on/off toggle. Add ControllerCommon::isMomentaryParameter(), overridden by the typed Controller from the control's widget enumerators (pushbutton / bang / impulse), and use it in the editor to pick CTextButton kKickStyle: 1 while pressed, 0 on release. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01K8rKjEZfGtrHLkU5iXR4gn

Adds a value readout label per continuous parameter (formatted via the controller's getParamStringByValue), refreshed in valueChanged as the user turns the knob.

processControl only applied the last point of each parameter queue. VSTGUI's kick-style buttons emit press (1) and release (0) back-to-back on mouse-up, so both landed in the same block and the processor only ever saw 0 - momentary buttons never fired at all. For bool parameters, apply the maximum point of the block's queue instead (latching the press for the whole block) and, when the queue ends released, defer the false assignment to the start of the next block. Continuous parameters keep the last-point behavior. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01K8rKjEZfGtrHLkU5iXR4gn

… disabled) The control-object overload of map_control_to_01 gated itself on an unqualified map_control_to_01(t.value), which has no viable overload (the value overloads need explicit <T>), so the requires never held and the overload was always disabled. Every caller (VST3 getParamNormalized, ...) then got 0. Qualify the requires with <T>.

Use 6 columns instead of 4 when a plugin exposes more than 20 parameters, keeping the window height manageable (e.g. 40 parameters: 7 rows instead of 10). Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01K8rKjEZfGtrHLkU5iXR4gn

edumeneses added 16 commits July 3, 2026 08:45

vst3: enable OBJC/OBJCXX for VSTGUI on macOS

b585225

vst3: add VSTGUI include root for editor sources

d66bce3

vst3: fix VSTGUI control construction (CFrame/CKnob/CTextLabel APIs)

3a0ac8a

vst3: strip VSTGUI's macOS -Werror so its internal warnings don't fai…

7f9446c

…l builds

vst3: set MSVC /Zc:preprocessor on the vstgui + module targets

2d4a1a9

vst3: add /Zc:preprocessor at directory scope before the SDK subdir (…

326bd88

…MSVC)

vst3: force-include vstguidebug.h on MSVC to define vstgui_assert

38e07e0

vst3: force-include a vstgui_assert shim on MSVC (fixes C3861 in VSTGUI)

5e80f1c

vst3/vstgui: wire host IRunLoop into VSTGUI on Linux (fixes X11 edito…

4ec5932

…r crash)

vst3/vstgui: include platform_linux.h for VSTGUI IRunLoop types

c17f250

vst3/vstgui: qualify IRunLoop types with VSTGUI::X11 (matches VSTGUI …

8dce65c

…3.7.x)

vst3/vstgui: init VSTGUI platform from the module handle on Linux (Mo…

62955c3

…duleEntry)

vst3: define DEVELOPMENT only in Debug (SIGTRAP asserts crashed relea…

ec4d2e5

…se plug-ins)

vst3/vstgui: compute editor size in ctor (hosts call getSize before a…

3e4983f

…ttached)

jcelerier reviewed Jul 3, 2026

View reviewed changes

Comment thread include/avnd/binding/vst3/vstgui_editor.hpp

jcelerier reviewed Jul 3, 2026

View reviewed changes

edumeneses and others added 8 commits July 3, 2026 09:52

vst3: report boolean controls as stepCount=1 (toggle, not knob)

61e3300

Toggles reported stepCount=0 (no range.step), so hosts and the VSTGUI editor drew them as continuous knobs. Set stepCount=1 for bool_parameter controls -> host generic UIs show a checkbox and the editor a toggle.

vst3/vstgui: set toggle button fill gradients so the label stays read…

8ac25e9

…able The on/off button used the default (light) gradient, so the light 'off' label was invisible on a white fill. Set explicit dark (off) and accent (on) gradients with contrasting text.

vst3/vstgui: show each knob's value under it, live on edit

5fb2571

Adds a value readout label per continuous parameter (formatted via the controller's getParamStringByValue), refreshed in valueChanged as the user turns the knob.

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VST3: optional self-contained VSTGUI editor#139

VST3: optional self-contained VSTGUI editor#139
edumeneses wants to merge 24 commits into
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edumeneses:vst3-vstgui-editor

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edumeneses commented Jul 3, 2026

What it does

Independent bug fix (cherry-pickable on its own — commit for "define DEVELOPMENT only in Debug")

Notes / for discussion

Tested

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jcelerier commented Jul 3, 2026

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