style.hpp

/*
 * Copyright (c) 2014-2025, NVIDIA CORPORATION.  All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * SPDX-FileCopyrightText: Copyright (c) 2014-2025, NVIDIA CORPORATION.
 * SPDX-License-Identifier: Apache-2.0
 */


#pragma once
#include <cmath>
#include <vector>

#include <imgui/imgui.h>

namespace nvgui {

//--------------------------------------------------------------------------------------------------
// Setting a dark style for the GUI
// The colors were coded in sRGB color space, set the useLinearColor
// flag to convert to linear color space.
inline void setStyle(bool useLinearColor)
{
  typedef ImVec4 (*srgbFunction)(float, float, float, float);
  srgbFunction passthrough = [](float r, float g, float b, float a) -> ImVec4 { return ImVec4(r, g, b, a); };
  srgbFunction toLinear    = [](float r, float g, float b, float a) -> ImVec4 {
    auto toLinearScalar = [](float u) -> float {
      return u <= 0.04045 ? 25 * u / 323.f : powf((200 * u + 11) / 211.f, 2.4f);
    };
    return ImVec4(toLinearScalar(r), toLinearScalar(g), toLinearScalar(b), a);
  };
  srgbFunction srgb = useLinearColor ? toLinear : passthrough;

  ImGui::StyleColorsDark();

  ImGuiStyle& style                  = ImGui::GetStyle();
  style.WindowRounding               = 0.0f;
  style.WindowBorderSize             = 0.0f;
  style.ColorButtonPosition          = ImGuiDir_Right;
  style.FrameRounding                = 2.0f;
  style.FrameBorderSize              = 1.0f;
  style.GrabRounding                 = 4.0f;
  style.IndentSpacing                = 12.0f;
  style.Colors[ImGuiCol_WindowBg]    = srgb(0.2f, 0.2f, 0.2f, 1.0f);
  style.Colors[ImGuiCol_MenuBarBg]   = srgb(0.2f, 0.2f, 0.2f, 1.0f);
  style.Colors[ImGuiCol_ScrollbarBg] = srgb(0.2f, 0.2f, 0.2f, 1.0f);
  style.Colors[ImGuiCol_PopupBg]     = srgb(0.135f, 0.135f, 0.135f, 1.0f);
  style.Colors[ImGuiCol_Border]      = srgb(0.4f, 0.4f, 0.4f, 0.5f);
  style.Colors[ImGuiCol_FrameBg]     = srgb(0.05f, 0.05f, 0.05f, 0.5f);

  // Normal
  ImVec4                normal_color = srgb(0.465f, 0.465f, 0.525f, 1.0f);
  std::vector<ImGuiCol> to_change_nrm;
  to_change_nrm.push_back(ImGuiCol_Header);
  to_change_nrm.push_back(ImGuiCol_SliderGrab);
  to_change_nrm.push_back(ImGuiCol_Button);
  to_change_nrm.push_back(ImGuiCol_CheckMark);
  to_change_nrm.push_back(ImGuiCol_ResizeGrip);
  to_change_nrm.push_back(ImGuiCol_TextSelectedBg);
  to_change_nrm.push_back(ImGuiCol_Separator);
  to_change_nrm.push_back(ImGuiCol_FrameBgActive);
  for(auto c : to_change_nrm)
  {
    style.Colors[c] = normal_color;
  }

  // Active
  ImVec4                active_color = srgb(0.365f, 0.365f, 0.425f, 1.0f);
  std::vector<ImGuiCol> to_change_act;
  to_change_act.push_back(ImGuiCol_HeaderActive);
  to_change_act.push_back(ImGuiCol_SliderGrabActive);
  to_change_act.push_back(ImGuiCol_ButtonActive);
  to_change_act.push_back(ImGuiCol_ResizeGripActive);
  to_change_act.push_back(ImGuiCol_SeparatorActive);
  for(auto c : to_change_act)
  {
    style.Colors[c] = active_color;
  }

  // Hovered
  ImVec4                hovered_color = srgb(0.565f, 0.565f, 0.625f, 1.0f);
  std::vector<ImGuiCol> to_change_hover;
  to_change_hover.push_back(ImGuiCol_HeaderHovered);
  to_change_hover.push_back(ImGuiCol_ButtonHovered);
  to_change_hover.push_back(ImGuiCol_FrameBgHovered);
  to_change_hover.push_back(ImGuiCol_ResizeGripHovered);
  to_change_hover.push_back(ImGuiCol_SeparatorHovered);
  for(auto c : to_change_hover)
  {
    style.Colors[c] = hovered_color;
  }


  style.Colors[ImGuiCol_TitleBgActive]    = srgb(0.465f, 0.465f, 0.465f, 1.0f);
  style.Colors[ImGuiCol_TitleBg]          = srgb(0.125f, 0.125f, 0.125f, 1.0f);
  style.Colors[ImGuiCol_Tab]              = srgb(0.05f, 0.05f, 0.05f, 0.5f);
  style.Colors[ImGuiCol_TabHovered]       = srgb(0.465f, 0.495f, 0.525f, 1.0f);
  style.Colors[ImGuiCol_TabActive]        = srgb(0.282f, 0.290f, 0.302f, 1.0f);
  style.Colors[ImGuiCol_ModalWindowDimBg] = srgb(0.465f, 0.465f, 0.465f, 0.350f);

  //Colors_ext[ImGuiColExt_Warning] = srgb (1.0f, 0.43f, 0.35f, 1.0f);

  ImGui::SetColorEditOptions(ImGuiColorEditFlags_Float | ImGuiColorEditFlags_PickerHueWheel);
}


}  // namespace nvgui