egl: Implement EGL_MESA_x11_native_visual_id

EGL 1.5 specification requires to not match on EGL_NATIVE_VISUAL_ID.

EGL_MESA_x11_native_visual_id extension allows us to remove this
restriction for X11, where we need to match EGL_NATIVE_VISUAL_ID to find
visuals which allow blending.

The reasoning is that on X11, compositors use the visual as "magic bit"
to decide whether to alpha-blend surface contents.
Unlike on most (all?) other windowing systems, requesting an alpha channel
for the config alone does not already imply blending on the compositor
level.

Thus, in order to allow clients to explicitly request configs with
"magic bit" and, similar to GLX, to order configs in a way so clients
not requesting alpha-blending do not get it by accident, do match
visual ids.

Note that one consequence of this is that more configs get
reported to clients.

Based on a patch by Freya Gentz <zegentzy@protonmail.com>, see
https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/2376

Signed-off-by: Robert Mader <robert.mader@posteo.de>
Signed-off-by: David Heidelberg <david.heidelberg@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9989>

docs/_static/specs/EGL_MESA_x11_native_visual_id.txt

@@ -0,0 +1,80 @@
+Name
+
+    MESA_x11_native_visual_id
+
+Name Strings
+
+    EGL_MESA_x11_native_visual_id
+
+Contact
+
+    Eric Engestrom <eric@engestrom.ch>
+
+Status
+
+    Complete, shipping.
+
+Version
+
+    Version 2, May 10, 2024
+
+Number
+
+    EGL Extension #TBD
+
+Extension Type
+
+    EGL display extension
+
+Dependencies
+
+    None.  This extension is written against the
+    wording of the EGL 1.5 specification.
+
+Overview
+
+    This extension allows EGL_NATIVE_VISUAL_ID to be used in
+    eglChooseConfig() for a display of type EGL_PLATFORM_X11_EXT.
+
+IP Status
+
+    Open-source; freely implementable.
+
+New Types
+
+    None
+
+New Procedures and Functions
+
+    None
+
+New Tokens
+
+    None
+
+In section 3.4.1.1 "Selection of EGLConfigs" of the EGL 1.5
+Specification, replace:
+
+    If EGL_MAX_PBUFFER_WIDTH, EGL_MAX_PBUFFER_HEIGHT,
+    EGL_MAX_PBUFFER_PIXELS, or EGL_NATIVE_VISUAL_ID are specified in
+    attrib list, then they are ignored [...]
+
+with:
+
+    If EGL_MAX_PBUFFER_WIDTH, EGL_MAX_PBUFFER_HEIGHT,
+    or EGL_MAX_PBUFFER_PIXELS are specified in attrib list, then they
+    are ignored [...]. EGL_NATIVE_VISUAL_ID is ignored except on
+    a display of type EGL_PLATFORM_X11_EXT when EGL_ALPHA_SIZE is
+    greater than zero.
+
+Issues
+
+    None.
+
+Revision History
+
+    Version 1, March 27, 2024 (Eric Engestrom)
+        Initial draft
+    Version 2, May 10, 2024 (David Heidelberg)
+	add EGL_ALPHA_SIZE condition
+	add Extension type and set it to display extension

src/egl/drivers/dri2/egl_dri2.c

@@ -288,6 +288,13 @@ dri2_get_dri_config(struct dri2_egl_config *conf, EGLint surface_type,
 static EGLBoolean
 dri2_match_config(const _EGLConfig *conf, const _EGLConfig *criteria)
 {
+#ifdef HAVE_X11_PLATFORM
+   if (conf->Display->Platform == _EGL_PLATFORM_X11 &&
+       conf->AlphaSize > 0 &&
+       conf->NativeVisualID != criteria->NativeVisualID)
+      return EGL_FALSE;
+#endif
+
    if (_eglCompareConfigs(conf, criteria, NULL, EGL_FALSE) != 0)
       return EGL_FALSE;
 
@@ -836,6 +843,8 @@ dri2_setup_screen(_EGLDisplay *disp)
             disp->Extensions.MESA_image_dma_buf_export = EGL_TRUE;
       }
 
+      disp->Extensions.MESA_x11_native_visual_id = EGL_TRUE;
+
       disp->Extensions.KHR_image_base = EGL_TRUE;
       disp->Extensions.KHR_gl_renderbuffer_image = EGL_TRUE;
       disp->Extensions.KHR_gl_texture_2D_image = EGL_TRUE;

src/egl/main/eglapi.c

@@ -594,6 +594,7 @@ _eglCreateExtensionsString(_EGLDisplay *disp)
    _EGL_CHECK_EXTENSION(MESA_gl_interop);
    _EGL_CHECK_EXTENSION(MESA_image_dma_buf_export);
    _EGL_CHECK_EXTENSION(MESA_query_driver);
+   _EGL_CHECK_EXTENSION(MESA_x11_native_visual_id);
 
    _EGL_CHECK_EXTENSION(NOK_swap_region);
    _EGL_CHECK_EXTENSION(NOK_texture_from_pixmap);

src/egl/main/egldisplay.h

@@ -146,6 +146,7 @@ struct _egl_extensions {
    EGLBoolean MESA_gl_interop;
    EGLBoolean MESA_image_dma_buf_export;
    EGLBoolean MESA_query_driver;
+   EGLBoolean MESA_x11_native_visual_id;
 
    EGLBoolean NOK_swap_region;
    EGLBoolean NOK_texture_from_pixmap;