Add EGL-based backend for wxGLCanvas

Among other things, this enables wxGLCanvas to be used natively on
Wayland.

Closes https://github.com/wxWidgets/wxWidgets/pull/2038

Closes #17702.

build/bakefiles/files.bkl

@@ -3191,10 +3191,12 @@ IMPORTANT: please read docs/tech/tn0016.txt before modifying this file!
     <if cond="TOOLKIT=='OSX_IPHONE'">src/osx/iphone/glcanvas.mm src/osx/glcanvas_osx.cpp</if>
     <if cond="TOOLKIT=='COCOA'">src/cocoa/glcanvas.mm</if>
     <if cond="TOOLKIT=='GTK' and TOOLKIT_VERSION=='4' and PLATFORM_WIN32=='0'">
+        src/unix/glegl.cpp
         src/unix/glx11.cpp
         src/gtk/glcanvas.cpp
     </if>
     <if cond="TOOLKIT=='GTK' and TOOLKIT_VERSION=='3' and PLATFORM_WIN32=='0'">
+        src/unix/glegl.cpp
         src/unix/glx11.cpp
         src/gtk/glcanvas.cpp
     </if>
@@ -3222,10 +3224,12 @@ IMPORTANT: please read docs/tech/tn0016.txt before modifying this file!
     <if cond="TOOLKIT=='COCOA'">wx/cocoa/glcanvas.h</if>
     <if cond="TOOLKIT=='GTK' and TOOLKIT_VERSION=='4'">
         wx/gtk/glcanvas.h
+        wx/unix/glegl.h
         wx/unix/glx11.h
     </if>
     <if cond="TOOLKIT=='GTK' and TOOLKIT_VERSION=='3'">
         wx/gtk/glcanvas.h
+        wx/unix/glegl.h
         wx/unix/glx11.h
     </if>
     <if cond="TOOLKIT=='GTK' and TOOLKIT_VERSION=='2'">

build/cmake/files.cmake

@@ -3036,11 +3036,13 @@ set(OPENGL_MSW_HDR
 set(OPENGL_GTK_SRC
     src/gtk/glcanvas.cpp
     src/unix/glx11.cpp
+    src/unix/glegl.cpp
 )
 
 set(OPENGL_GTK_HDR
     wx/gtk/glcanvas.h
     wx/unix/glx11.h
+    wx/unix/glegl.h
 )
 
 set(OPENGL_OSX_COCOA_SRC

build/cmake/init.cmake

@@ -385,6 +385,9 @@ if(wxUSE_GUI)
             set(OPENGL_LIBRARIES "-framework OpenGLES" "-framework QuartzCore")
         else()
             find_package(OpenGL)
+            if(WXGTK3 AND OpenGL_EGL_FOUND)
+                set(wxUSE_GLCANVAS_EGL ON)
+            endif()
         endif()
         if(NOT OPENGL_FOUND)
             message(WARNING "opengl not found, wxGLCanvas won't be available")

build/cmake/setup.h.in

@@ -549,6 +549,8 @@
 
 #cmakedefine01 wxUSE_GLCANVAS
 
+#cmakedefine01 wxUSE_GLCANVAS_EGL
+
 #cmakedefine01 wxUSE_RICHTEXT
 
 

build/files

@@ -2973,10 +2973,12 @@ OPENGL_MSW_SRC =
 
 OPENGL_GTK_HDR =
     wx/gtk/glcanvas.h
+    wx/unix/glegl.h
     wx/unix/glx11.h
 
 OPENGL_GTK_SRC =
     src/gtk/glcanvas.cpp
+    src/unix/glegl.cpp
     src/unix/glx11.cpp
 
 OPENGL_MSW_HDR =