[graphics] implement raylib-based canvas [draft]

etc/plugins/TGuiFactory/P030_TRaylibGuiFactory.C

@@ -0,0 +1,5 @@
+void P030_TRaylibGuiFactory()
+{
+   gPluginMgr->AddHandler("TGuiFactory", "raylib", "ROOT::Experimental::TRaylibGuiFactory",
+      "ROOTRaylibCanvas", "TRaylibGuiFactory()");
+}

gui/CMakeLists.txt

@@ -12,6 +12,8 @@ add_subdirectory(guihtml)
 add_subdirectory(recorder)
 add_subdirectory(treemap)
 
+add_subdirectory(raylibcanvas)
+
 if(webgui)
    if(cefweb)
       add_subdirectory(cefdisplay)

gui/raylibcanvas/CMakeLists.txt

@@ -0,0 +1,90 @@
+# Copyright (C) 1995-2026, Rene Brun and Fons Rademakers.
+# All rights reserved.
+#
+# For the licensing terms see $ROOTSYS/LICENSE.
+# For the list of contributors see $ROOTSYS/README/CREDITS.
+
+############################################################################
+# CMakeLists.txt file for building ROOT gui/raylibcanvas package
+############################################################################
+
+# Find raylib - expects raylib.h in include path and libraylib.a/so on library path
+# On Debian/Ubuntu: sudo apt-get install libraylib-dev
+# On Arch:          sudo pacman -S raylib
+# Or build from source: https://github.com/raysan5/raylib
+
+find_path(RAYLIB_INCLUDE_DIR raylib.h
+  PATHS /usr/include /usr/local/include /opt/raylib/include
+  DOC "raylib include directory")
+
+find_library(RAYLIB_LIBRARY NAMES raylib raylib.lib libraylib.a libraylib.so
+  PATHS /usr/lib /usr/local/lib /opt/raylib/lib
+  DOC "raylib library path")
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(raylib
+  REQUIRED_VARS RAYLIB_LIBRARY RAYLIB_INCLUDE_DIR)
+
+if(NOT RAYLIB_FOUND)
+  if(fail-on-missing)
+    message(FATAL_ERROR "Could NOT find raylib")
+  else()
+    message(WARNING "raylib not found, disabling option 'raylibcanvas'")
+    set(raylibcanv OFF CACHE BOOL "Disabled because raylib not found" FORCE)
+    return()
+  endif()
+endif()
+
+# Raylib links against GLFW, OpenGL, and platform libs
+# On Linux: dl, rt, m, pthread, X11, GL
+set(RAYLIB_LINK_LIBRARIES ${RAYLIB_LIBRARY})
+if(CMAKE_SYSTEM_NAME STREQUAL "Linux")
+  find_library(GLFW_LIBRARY glfw HINTS /usr/lib /usr/local/lib)
+  find_library(X11_LIBRARY X11 HINTS /usr/lib /usr/local/lib)
+  find_library(GL_LIBRARY GL HINTS /usr/lib /usr/local/lib)
+  if(GLFW_LIBRARY)
+    list(APPEND RAYLIB_LINK_LIBRARIES ${GLFW_LIBRARY})
+  endif()
+  if(X11_LIBRARY)
+    list(APPEND RAYLIB_LINK_LIBRARIES ${X11_LIBRARY})
+  endif()
+  if(GL_LIBRARY)
+    list(APPEND RAYLIB_LINK_LIBRARIES ${GL_LIBRARY})
+  endif()
+  list(APPEND RAYLIB_LINK_LIBRARIES dl rt m pthread)
+endif()
+
+set(RAYLIB_IMPORTED_TARGET raylib::raylib)
+if(NOT TARGET ${RAYLIB_IMPORTED_TARGET})
+  add_library(${RAYLIB_IMPORTED_TARGET} INTERFACE IMPORTED)
+  set_target_properties(${RAYLIB_IMPORTED_TARGET} PROPERTIES
+    INTERFACE_INCLUDE_DIRECTORIES "${RAYLIB_INCLUDE_DIR}"
+    INTERFACE_LINK_LIBRARIES "${RAYLIB_LINK_LIBRARIES}")
+endif()
+
+ROOT_STANDARD_LIBRARY_PACKAGE(ROOTRaylibCanvas
+  HEADERS
+    TRaylibCanvas.h
+    TRaylibPadPainter.h
+    TRaylibGuiFactory.h
+  SOURCES
+    src/TRaylibCanvas.cxx
+    src/TRaylibPadPainter.cxx
+    src/TRaylibGuiFactory.cxx
+  LIBRARIES
+    ${RAYLIB_IMPORTED_TARGET}
+  DEPENDENCIES
+    Core
+    Gpad
+)
+
+target_include_directories(ROOTRaylibCanvas PRIVATE ${RAYLIB_INCLUDE_DIR})
+
+# Platform-specific linker flags for raylib
+if(CMAKE_SYSTEM_NAME STREQUAL "Linux")
+  target_link_options(ROOTRaylibCanvas PRIVATE -pthread)
+elseif(CMAKE_SYSTEM_NAME STREQUAL "Windows")
+  target_link_libraries(ROOTRaylibCanvas PRIVATE gdi32 winmm opengl32)
+elseif(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
+  target_link_libraries(ROOTRaylibCanvas PRIVATE "-framework Cocoa" "-framework IOKit" "-framework OpenGL")
+endif()

gui/raylibcanvas/inc/LinkDef.h

@@ -0,0 +1,14 @@
+#ifdef __CLING__
+
+#pragma link off all globals;
+#pragma link off all classes;
+#pragma link off all functions;
+
+// #pragma link C++ nestedclasses;
+// #pragma link C++ nestedtypedefs;
+
+#pragma link C++ class ROOT::Experimental::TRaylibCanvas+;
+#pragma link C++ class ROOT::Experimental::TRaylibPadPainter+;
+#pragma link C++ class ROOT::Experimental::TRaylibGuiFactory+;
+
+#endif

gui/raylibcanvas/inc/TRaylibCanvas.h

@@ -0,0 +1,106 @@
+// Author: Sergey Linev, GSI  06/08/2026
+
+/*************************************************************************
+ * Copyright (C) 1995-2026, Rene Brun and Fons Rademakers.               *
+ * All rights reserved.                                                  *
+ *                                                                       *
+ * For the licensing terms see $ROOTSYS/LICENSE.                         *
+ * For the list of contributors see $ROOTSYS/README/CREDITS.             *
+ *************************************************************************/
+
+#ifndef ROOT_TRaylibCanvas
+#define ROOT_TRaylibCanvas
+
+#include "TCanvasImp.h"
+#include "TString.h"
+#include <string>
+
+class TTimer;
+
+namespace ROOT {
+namespace Experimental {
+
+class TRaylibPadPainter;
+
+/** \class TRaylibCanvas
+    \ingroup raylibcanvas
+    \brief TCanvasImp ABI implementation for raylib immediate-mode rendering
+
+    Manages a single raylib window. Each canvas shares the same window
+    (raylib limitation), with viewport switching via SetCameraMode().
+
+    The render loop runs via a TTimer callback that polls input events
+    and triggers BeginDrawing()/EndDrawing() frames.
+*/
+class TRaylibCanvas : public TCanvasImp {
+
+protected:
+   Int_t fWindowWidth = 0;      ///<! window width
+   Int_t fWindowHeight = 0;     ///<! window height
+   Int_t fPosX = 0;             ///<! window x position
+   Int_t fPosY = 0;             ///<! window y position
+   Bool_t fResized = kTRUE;     ///<! if window was resized
+   Bool_t fMenuBar = kTRUE;     ///<! use of menu bar
+   Bool_t fStatusBar = kTRUE;   ///<! use of status bar
+
+   std::string fWindowTitle;    ///<! current window title
+
+   TString fStatusMessage;
+   int fFileMenuSelection = 0;
+   bool fFileDropdownOpen = false;
+
+   static void EnsureRaylibInitialized(int width, int height);
+
+   Bool_t PerformUpdate(Bool_t async) override;
+   TVirtualPadPainter *CreatePadPainter() override;
+
+public:
+   TRaylibCanvas(TCanvas *c, const char *name, Int_t x, Int_t y, UInt_t width, UInt_t height);
+   ~TRaylibCanvas() override;
+
+   // Window lifecycle
+   Int_t InitWindow() override;
+   void Close() override;
+   void Show() override;
+
+   // Geometry
+   UInt_t GetWindowGeometry(Int_t &x, Int_t &y, UInt_t &w, UInt_t &h) override;
+   void GetCanvasGeometry(Int_t wid, UInt_t &w, UInt_t &h) override;
+   void ResizeCanvasWindow(Int_t wid) override;
+   void UpdateDisplay(Int_t = 0, Bool_t = kFALSE) override;
+
+   // UI elements (noop — raylib draws them manually if needed)
+   void ShowMenuBar(Bool_t on = kTRUE) override { fMenuBar = on; fResized = kTRUE; }
+   void ShowStatusBar(Bool_t on = kTRUE) override { fStatusBar = on; fResized = kTRUE; }
+   void ShowEditor(Bool_t = kTRUE) override {}
+   void ShowToolBar(Bool_t = kTRUE) override {}
+   void ShowToolTips(Bool_t = kTRUE) override {}
+
+   void ForceUpdate() override;
+
+   void SetWindowPosition(Int_t x, Int_t y) override;
+   void SetWindowSize(UInt_t w, UInt_t h) override;
+   void SetWindowTitle(const char *newTitle) override;
+   void SetCanvasSize(UInt_t w, UInt_t h) override;
+   void Iconify() override;
+   void RaiseWindow() override;
+
+   Bool_t HasEditor() const override { return kFALSE; }
+   Bool_t HasMenuBar() const override { return fMenuBar; }
+   Bool_t HasStatusBar() const override { return fStatusBar; }
+   Bool_t HasToolBar() const override { return kFALSE; }
+   Bool_t HasToolTips() const override { return kFALSE; }
+
+   void RunRaylib();
+
+   // Static factory
+   static TCanvasImp *NewCanvas(TCanvas *c, const char *name, Int_t x, Int_t y,
+                                UInt_t width, UInt_t height);
+
+   ClassDefOverride(TRaylibCanvas, 0) // raylib implementation for TCanvasImp
+};
+
+} // namespace Experimental
+} // namespace ROOT
+
+#endif

gui/raylibcanvas/inc/TRaylibGuiFactory.h

@@ -0,0 +1,44 @@
+// Author: Sergey Linev, GSI  06/08/2026
+
+/*************************************************************************
+ * Copyright (C) 1995-2026, Rene Brun and Fons Rademakers.               *
+ * All rights reserved.                                                  *
+ *                                                                       *
+ * For the licensing terms see $ROOTSYS/LICENSE.                         *
+ * For the list of contributors see $ROOTSYS/README/CREDITS.             *
+ *************************************************************************/
+
+#ifndef ROOT_TRaylibGuiFactory
+#define ROOT_TRaylibGuiFactory
+
+#include "TGuiFactory.h"
+
+namespace ROOT {
+namespace Experimental {
+
+/** \class TRaylibGuiFactory
+    \ingroup raylibcanvas
+
+    Factory for ROOT GUI components using raylib as the rendering backend.
+    Provides specialization for TCanvasImp class.
+*/
+class TRaylibGuiFactory : public TGuiFactory {
+
+public:
+   TRaylibGuiFactory(const char *name = "raylib", const char *title = "ROOT Raylib Gui");
+   ~TRaylibGuiFactory() override = default;
+
+   Bool_t UseVirtualX() const override { return kFALSE; }
+
+   TCanvasImp *CreateCanvasImp(TCanvas *c, const char *title,
+                                UInt_t width, UInt_t height) override;
+   TCanvasImp *CreateCanvasImp(TCanvas *c, const char *title,
+                                Int_t x, Int_t y, UInt_t width, UInt_t height) override;
+
+   ClassDefOverride(TRaylibGuiFactory, 0) // raylib gui factory
+};
+
+} // namespace Experimental
+} // namespace ROOT
+
+#endif