ImCoolBar

This repository is a fork of the original aiekick/ImCoolBar. It keeps the original API spirit while fixing hover glitches and enabling smoothing and antialiasing by default (configurable).

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What’s new in this fork

Bug fixes

• Removed the initial Y‑axis “jump” on first hover/unhover.

  • Correct cross‑axis thickness: normal + (hovered - normal) * anim_scale.
  • anim_scale is updated before positioning the window.
  • Predicted thickness used for positioning each frame.
  • First item size is initialized from normal_size (not 0).
  • anchor is clamped to [0..1].

Smoothing (time‑based EMA)

• Enabled by default with a 50 ms half‑life; set to 0 to disable.
• Mouse coordinate filtering with half‑life in milliseconds; frame‑rate invariant.
• anim_scale smoothing to targets 0/1 with its own half‑life; fallback to the old step‑based anim_step when disabled.

Antialiasing (on by default)

• Local AA for this bar’s draw list (AntiAliasedFill|Lines) is enabled by default but can be disabled via config.
• Optional local FrameRounding override for smoother visuals.
• Draw‑list flags and style are restored in EndCoolBar().

Pixel snapping (optional)

• Separate snapping controls for window position and inner item offsets to avoid visible “stepping” (both enabled by default).

Metrics

• Extra debug outputs: MouseSmoothingMs, MouseSmoothingAlpha, AnimSmoothingMs, AnimSmoothingAlpha, current AnimScale, per‑item sizes.

(If applicable) Minor API refactor

• ImCoolBarConfig and flags may live in the global namespace to mirror Dear ImGui style (functions remain in ImGui::). See Migration below.

Result:

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Branches & versioning

• Stable branch: stable — recommended for users.
• Development: main (or dev) — may contain work‑in‑progress changes.
• Releases: tagged as vX.Y.Z.

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Compatibility / docking support

Works with Dear ImGui 1.92 on both docking and non‑docking branches. Docking window flags are enabled automatically when IMGUI_HAS_DOCK is defined, or by defining IMCOOLBAR_HAS_DOCKING before including ImCoolBar.h.

// Define before including the header if you want to force docking host flags
#define IMCOOLBAR_HAS_DOCKING
#include "ImCoolBar.h"

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Minimal sample

// Helper button that sizes itself to the current item width/scale
auto coolbar_button = [](const char* label) -> bool {
    float w = ImGui::GetCoolBarItemWidth();
    return ImGui::Button(label, ImVec2(w, w));
};

ImCoolBarConfig cfg;                     // defaults (50 ms smoothing, AA & pixel snapping on)
cfg.anchor                  = ImVec2(0.5f, 1.0f); // bottom-center of the viewport
cfg.mouse_smoothing_ms      = 120.0f;           // time-based mouse smoothing (default 50, 0 = off)
cfg.anim_smoothing_ms       = 120.0f;           // time-based anim smoothing (default 50, 0 = step mode)
cfg.local_antialiasing      = true;             // local AA just for this bar (default true)
cfg.frame_rounding_override = 6.0f;             // optional per-bar rounding
cfg.snap_window_to_pixels   = true;             // snap window to whole pixels (default true)
cfg.snap_items_to_pixels    = true;             // snap inner item offsets to whole pixels (default true)

if (ImGui::BeginCoolBar("##CoolBarMain", ImCoolBarFlags_Horizontal, cfg)) {
    const char* labels = "ABCDEFGHIJKL";
    for (const char* p = labels; *p; ++p)
        if (ImGui::CoolBarItem())
            (void)coolbar_button(std::string(1, *p).c_str());
    ImGui::EndCoolBar();
}

Result:

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Horizontal & vertical bars in one frame

// Shared smoothing/visuals
ImCoolBarConfig common;                     // defaults (50 ms smoothing, AA & pixel snapping on)
common.mouse_smoothing_ms      = 100.0f;
common.anim_smoothing_ms       = 120.0f;
common.local_antialiasing      = true;      // default true
common.frame_rounding_override = 6.0f;
common.snap_window_to_pixels   = true;      // default true
common.snap_items_to_pixels    = true;      // default true

// Bottom horizontal bar
{
    auto cfg = common; cfg.anchor = ImVec2(0.5f, 1.0f);
    if (ImGui::BeginCoolBar("##CoolBarBottom", ImCoolBarFlags_Horizontal, cfg)) {
        for (char c = 'A'; c <= 'H'; ++c)
            if (ImGui::CoolBarItem()) ImGui::Button(std::string(1, c).c_str(), ImVec2(ImGui::GetCoolBarItemWidth(), ImGui::GetCoolBarItemWidth()));
        ImGui::EndCoolBar();
    }
}

// Left vertical bar
{
    auto cfg = common; cfg.anchor = ImVec2(0.0f, 0.5f);
    if (ImGui::BeginCoolBar("##CoolBarLeft", ImCoolBarFlags_Vertical, cfg)) {
        for (char c = '1'; c <= '6'; ++c)
            if (ImGui::CoolBarItem()) ImGui::Button(std::string(1, c).c_str(), ImVec2(ImGui::GetCoolBarItemWidth(), ImGui::GetCoolBarItemWidth()));
        ImGui::EndCoolBar();
    }
}

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API Reference (public)

// Begin a coolbar window. Returns true while building items.
IMGUI_API bool BeginCoolBar(const char* label,
                            ImCoolBarFlags flags = ImCoolBarFlags_Vertical,
                            const ImCoolBarConfig& cfg = {},
                            ImGuiWindowFlags wflags = ImGuiWindowFlags_None);
IMGUI_API void  EndCoolBar();

// Per-item call. Place your widget when this returns true.
IMGUI_API bool  CoolBarItem();

// Helpers for sizing; valid only inside an active coolbar item.
IMGUI_API float GetCoolBarItemWidth();
IMGUI_API float GetCoolBarItemScale();

// Debug/metrics window
IMGUI_API void  ShowCoolBarMetrics(bool* opened);

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Configuration Reference

Field	Type	Default	Description
anchor	ImVec2	{-1,-1}	Normalized anchor in the viewport; e.g. {0.5,1.0} = bottom center.
normal_size	float	40.0	Base size for items.
hovered_size	float	60.0	Max size when fully hovered.
anim_step	float	0.15	Legacy step per frame for anim_scale (used when EMA disabled).
effect_strength	float	0.5	Strength parameter for hover influence curve.
mouse_smoothing_ms	float	50.0	EMA half‑life for mouse filtering; <=0 disables.
anim_smoothing_ms	float	50.0	EMA half‑life for anim_scale; <=0 uses anim_step.
local_antialiasing	bool	true	Enable AA on this bar’s draw list only (default on).
frame_rounding_override	float	-1.0	<0 keep global; >=0 push per‑bar FrameRounding.
snap_window_to_pixels	bool	true	Snap window position to whole pixels (crisp text).
snap_items_to_pixels	bool	true	Snap inner item offsets; turn off for subpixel smoothness.

Notes

• Mouse/anim smoothing (50 ms half‑life) and local antialiasing are enabled by default; set smoothing to 0 or antialiasing to false to disable.
• EMA alpha per frame: α = 1 - exp(-ln(2) * dt_ms / half_life_ms).
• Subpixel movement is visually smoother with AA and non‑zero rounding.

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Migration (if you use the original API)

Depending on your fork state:

• If ImCoolBarConfig moved to the global namespace, update usages:

  • ImGui::ImCoolBarConfig{...} → ImCoolBarConfig{...}
  • Flags remain ImCoolBarFlags_*.

• If you added an overload taking ImVec2 anchor, you may call:

  ImGui::BeginCoolBar("##CoolBarMain", ImCoolBarFlags_Horizontal, ImVec2(0.5f, 1.0f));

  Otherwise, construct ImCoolBarConfig explicitly.

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Demo app

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Building / integration

• This widget is a tiny pair of .h/.cpp files; just add them to your build with Dear ImGui.

• For docking:

  • Use Dear ImGui’s docking branch or define IMCOOLBAR_HAS_DOCKING yourself.

• Backends: any Dear ImGui backend; for best visual smoothness you may enable MSAA on your renderer.

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License

MIT. See the original license header in the source files.

If you distribute this fork, keep the original MIT license text and copyright notice. You may add your own copyright line for your changes (e.g. © 2025 YourName).

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Credits

• Original work by Stephane Cuillerdier (Aiekick) — aiekick/ImCoolBar.
• Improvements and maintenance in this fork by the community.