matplotlib · QuLogic · Feb 8, 2024
diff --git a/lib/matplotlib/tests/test_backend_macosx.py b/lib/matplotlib/tests/test_backend_macosx.py
@@ -3,13 +3,20 @@
 import pytest
 
 import matplotlib as mpl
+from matplotlib import _c_internal_utils
 import matplotlib.pyplot as plt
 try:
     from matplotlib.backends import _macosx
 except ImportError:
     pytest.skip("These are mac only tests", allow_module_level=True)
 
 
+pytestmark = [
+    pytest.mark.skipif(not _c_internal_utils.display_is_valid(),
+                       reason="Display is unavailable")
+]
+
+
 @pytest.mark.backend('macosx')
 def test_cached_renderer():
     # Make sure that figures have an associated renderer after

diff --git a/lib/matplotlib/tests/test_backend_qt.py b/lib/matplotlib/tests/test_backend_qt.py
@@ -305,9 +305,8 @@
     ]:
         reason = None
         missing = [dep for dep in deps if not importlib.util.find_spec(dep)]
-        if (sys.platform == "linux" and
-                not _c_internal_utils.display_is_valid()):
-            reason = "$DISPLAY and $WAYLAND_DISPLAY are unset"
+        if not _c_internal_utils.display_is_valid():
+            reason = "Display is unavailable"
         elif missing:
             reason = "{} cannot be imported".format(", ".join(missing))
         elif env["MPLBACKEND"] == 'macosx' and os.environ.get('TF_BUILD'):

diff --git a/lib/matplotlib/tests/test_backend_tk.py b/lib/matplotlib/tests/test_backend_tk.py
@@ -35,8 +35,8 @@ def _isolated_tk_test(success_count, func=None):
         reason="missing tkinter"
     )
     @pytest.mark.skipif(
-        sys.platform == "linux" and not _c_internal_utils.display_is_valid(),
-        reason="$DISPLAY and $WAYLAND_DISPLAY are unset"
+        not _c_internal_utils.display_is_valid(),
+        reason="Display is unavailable"
     )
     @pytest.mark.xfail(  # https://github.com/actions/setup-python/issues/649
         ('TF_BUILD' in os.environ or 'GITHUB_ACTION' in os.environ) and

diff --git a/lib/matplotlib/tests/test_backends_interactive.py b/lib/matplotlib/tests/test_backends_interactive.py
@@ -55,8 +55,7 @@ def wait_for(self, terminator):
 
 @functools.lru_cache
 def _get_available_interactive_backends():
-    _is_linux_and_display_invalid = (sys.platform == "linux" and
-                                     not _c_internal_utils.display_is_valid())
+    _is_display_invalid = not _c_internal_utils.display_is_valid()
     envs = []
     for deps, env in [
             *[([qt_api],
@@ -74,8 +73,8 @@ def _get_available_interactive_backends():
     ]:
         reason = None
         missing = [dep for dep in deps if not importlib.util.find_spec(dep)]
-        if _is_linux_and_display_invalid:
-            reason = "$DISPLAY and $WAYLAND_DISPLAY are unset"
+        if _is_display_invalid:
+            reason = "Display is unavailable"
         elif missing:
             reason = "{} cannot be imported".format(", ".join(missing))
         elif env["MPLBACKEND"] == 'macosx' and os.environ.get('TF_BUILD'):

diff --git a/lib/matplotlib/tests/test_rcparams.py b/lib/matplotlib/tests/test_rcparams.py
@@ -534,9 +534,7 @@ def test_backend_fallback_headless(tmp_path):
             env=env, check=True, stderr=subprocess.DEVNULL)
 
 
-@pytest.mark.skipif(
-    sys.platform == "linux" and not _c_internal_utils.display_is_valid(),
-    reason="headless")
+@pytest.mark.skipif(not _c_internal_utils.display_is_valid(), reason="headless")
 def test_backend_fallback_headful(tmp_path):
     pytest.importorskip("tkinter")
     env = {**os.environ, "MPLBACKEND": "", "MPLCONFIGDIR": str(tmp_path)}

diff --git a/meson.build b/meson.build
@@ -17,6 +17,10 @@ project(
 
 cc = meson.get_compiler('c')
 cpp = meson.get_compiler('cpp')
+# Objective C is needed for the _c_internal_utils and macosx extension.
+if host_machine.system() == 'darwin'
+  add_languages('objc', native: false)
+endif
 
 # https://mesonbuild.com/Python-module.html
 py_mod = import('python')

diff --git a/src/_c_internal_utils.cpp b/src/_c_internal_utils.cpp
@@ -18,6 +18,12 @@
 #else
 #define UNUSED_ON_NON_WINDOWS Py_UNUSED
 #endif
+#ifdef __APPLE__
+// Defined in _objc_internal_utils.m.
+extern "C" {
+int _macos_display_is_valid(void);
+}
+#endif
 
 namespace py = pybind11;
 using namespace pybind11::literals;
@@ -69,6 +75,8 @@ mpl_display_is_valid(void)
         }
     }
     return false;
+#elif defined(__APPLE__)
+    return _macos_display_is_valid() == 1;
 #else
     return true;
 #endif
@@ -180,6 +188,8 @@ PYBIND11_MODULE(_c_internal_utils, m)
         succeeds, or $WAYLAND_DISPLAY is set and wl_display_connect(NULL)
         succeeds.
 
+        On macOS, returns True if NSScreen::mainScreen is not nil.
+
         On other platforms, always returns True.)""");
     m.def(
         "Win32_GetCurrentProcessExplicitAppUserModelID",

diff --git a/src/_objc_internal_utils.m b/src/_objc_internal_utils.m
@@ -0,0 +1,13 @@
+#include <Cocoa/Cocoa.h>
+
+int
+_macos_display_is_valid(void)
+{
+    NSApplicationLoad();
+    NSScreen *main = [NSScreen mainScreen];
+    if (main != nil) {
+        return 1;
+    } else {
+        return 0;
+    }
+}
diff --git a/src/meson.build b/src/meson.build
@@ -69,6 +69,12 @@ else
   user32 = []
 endif
 
+if host_machine.system() == 'darwin'
+  cocoa = dependency('appleframeworks', modules: 'Cocoa')
+else
+  cocoa = []
+endif
+
 extension_data = {
   '_backend_agg': {
     'subdir': 'matplotlib/backends',
@@ -81,10 +87,11 @@ extension_data = {
   },
   '_c_internal_utils': {
     'subdir': 'matplotlib',
-    'sources': files(
-      '_c_internal_utils.cpp',
-    ),
-    'dependencies': [pybind11_dep, dl, ole32, shell32, user32],
+    'sources': [
+      files('_c_internal_utils.cpp'),
+      (host_machine.system() == 'darwin') ? files('_objc_internal_utils.m') : [],
+    ],
+    'dependencies': [pybind11_dep, dl, ole32, shell32, user32, cocoa],
   },
   'ft2font': {
     'subdir': 'matplotlib',
@@ -182,14 +189,13 @@ foreach ext, kwargs : extension_data
 endforeach
 
 if get_option('macosx') and host_machine.system() == 'darwin'
-  add_languages('objc', native: false)
   py3.extension_module(
     '_macosx',
     subdir: 'matplotlib/backends',
     sources: files(
       '_macosx.m',
     ),
-    dependencies: dependency('appleframeworks', modules: 'Cocoa'),
+    dependencies: [cocoa],
     override_options: ['werror=true'],
     install: true,
   )