Rename toolbox to platform.

PiperOrigin-RevId: 838701951
Change-Id: I339eafd35d919710cb47bb04e9a8e29f92739513

src/experimental/platform/window.h

@@ -0,0 +1,101 @@
+// Copyright 2025 DeepMind Technologies Limited
+//
+// 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.
+
+#ifndef MUJOCO_SRC_EXPERIMENTAL_PLATFORM_WINDOW_H_
+#define MUJOCO_SRC_EXPERIMENTAL_PLATFORM_WINDOW_H_
+
+#include <string>
+#include <string_view>
+
+#include "experimental/platform/helpers.h"
+#include <SDL_video.h>
+
+namespace mujoco::platform {
+
+// Platform-independent window abstraction using SDL2.
+//
+// Initializes the SDL2 and ImGui libraries, creates/owns the native window, and
+// handles events from the window.
+class Window {
+ public:
+  // Configures the window for the specified rendering backend.
+  enum RenderConfig {
+    kClassicOpenGL,
+    kFilamentVulkan,
+    kFilamentOpenGL,
+    kFilamentWebGL,
+  };
+
+  struct Config {
+    RenderConfig render_config = kClassicOpenGL;
+    bool enable_keyboard = true;
+  };
+
+  Window(std::string_view title, int width, int height, Config config,
+         const LoadAssetFn& load_asset_fn);
+  ~Window();
+
+  Window(const Window&) = delete;
+  Window& operator=(const Window&) = delete;
+
+  // The status of the window.
+  enum Status {
+    kRunning,
+    kQuitting,
+  };
+
+  // Processes all pendings window events and prepares ImGui for input handling
+  // and GUI rendering. Returns the status of the window.
+  Status NewFrame();
+
+  // Finalizes ImGui input handling. Must call NewFrame first.
+  void EndFrame();
+
+  // Swaps and presents the window buffer.
+  void Present();
+
+  // Sets the title of the window.
+  void SetTitle(std::string_view title);
+
+  // Returns information related to the current size of the window.
+  int GetWidth() const { return width_; }
+  int GetHeight() const { return height_; }
+  float GetScale() const { return scale_; }
+  float GetAspectRatio() const {
+    return height_ > 0
+               ? static_cast<float>(width_) / static_cast<float>(height_)
+               : 1.0f;
+  }
+
+  // Returns the path to a file that was dropped on the window. Once called,
+  // the value will be cleared until the next time a file is dropped.
+  std::string GetDropFile();
+
+  // Returns the handle to the underlying native window.
+  void* GetNativeWindowHandle() { return native_window_; }
+
+ private:
+  int width_ = 0;
+  int height_ = 0;
+  float scale_ = 1.0f;
+  Config config_;
+  void* native_window_ = nullptr;
+  SDL_Window* sdl_window_ = nullptr;
+  bool should_exit_ = false;
+  std::string drop_file_;
+};
+
+}  // namespace mujoco::platform
+
+#endif  // MUJOCO_SRC_EXPERIMENTAL_PLATFORM_WINDOW_H_