Wayland support by forcing x11 (#470)

* Wayland support wip

* Make glfw and qt work by forcing x11

* tweaks

* Fix test

* Update docs

* Move some stuff to new gui utils module

* force x11 on Wayland for wx too

* Fix comment

* Forcing an empty commit.

---------

Co-authored-by: Korijn van Golen <[email protected]>

docs/start.rst

@@ -65,10 +65,9 @@ On MacOS you need at least 10.13 (High Sierra) to have Metal/Vulkan support.
 Linux
 +++++
 
-On Linux, it's advisable to install the proprietary drivers of your GPU
-(if you have a dedicated GPU). You may need to ``apt install
-mesa-vulkan-drivers``. Wayland support is currently broken (we could use
-a hand to fix this).
+On Linux, it's advisable to install the proprietary drivers of your GPU (if you
+have a dedicated GPU). You may need to ``apt install mesa-vulkan-drivers``. On
+Wayland, wgpu-py requires XWayland (available by default on most distributions).
 
 Binary wheels for Linux are only available for **manylinux_2_24**.
 This means that the installation requires ``pip >= 20.3``, and you need

examples/triangle_subprocess.py

@@ -12,6 +12,7 @@
 """
 
 import sys
+import json
 import time
 import subprocess
 
@@ -23,14 +24,14 @@
 
 code = """
 import sys
+import json
 from PySide6 import QtWidgets  # Use either PySide6 or PyQt6
 from wgpu.gui.qt import WgpuCanvas
 
 app = QtWidgets.QApplication([])
 canvas = WgpuCanvas(title="wgpu triangle in Qt subprocess")
 
-print(canvas.get_window_id())
-#print(canvas.get_display_id())
+print(json.dumps(canvas.get_surface_info()))
 print(canvas.get_physical_size())
 sys.stdout.flush()
 
@@ -41,15 +42,15 @@
 class ProxyCanvas(WgpuCanvasBase):
     def __init__(self):
         super().__init__()
-        self._window_id = int(p.stdout.readline().decode())
+        self._surface_info = json.loads(p.stdout.readline().decode())
         self._psize = tuple(
             int(x) for x in p.stdout.readline().decode().strip().strip("()").split(",")
         )
         print(self._psize)
         time.sleep(0.2)
 
-    def get_window_id(self):
-        return self._window_id
+    def get_surface_info(self):
+        return self._surface_info
 
     def get_physical_size(self):
         return self._psize

tests/test_gui_base.py

@@ -248,7 +248,7 @@ def handler(event):
 
 
 def test_weakbind():
-    weakbind = wgpu.gui.base.weakbind
+    weakbind = wgpu.gui._gui_utils.weakbind
 
     xx = []
 

tests/test_gui_glfw.py

@@ -3,7 +3,6 @@
 like the canvas context and surface texture.
 """
 
-import os
 import sys
 import time
 import weakref
@@ -172,22 +171,33 @@ def __init__(self):
             self.window = glfw.create_window(300, 200, "canvas", None, None)
             self._present_context = None
 
-        def get_window_id(self):
+        def get_surface_info(self):
             if sys.platform.startswith("win"):
-                return int(glfw.get_win32_window(self.window))
+                return {
+                    "platform": "windows",
+                    "window": int(glfw.get_win32_window(self.window)),
+                }
             elif sys.platform.startswith("darwin"):
-                return int(glfw.get_cocoa_window(self.window))
+                return {
+                    "platform": "cocoa",
+                    "window": int(glfw.get_cocoa_window(self.window)),
+                }
             elif sys.platform.startswith("linux"):
-                is_wayland = "wayland" in os.getenv("XDG_SESSION_TYPE", "").lower()
+                is_wayland = hasattr(glfw, "get_wayland_display")
                 if is_wayland:
-                    return int(glfw.get_wayland_window(self.window))
+                    return {
+                        "platform": "wayland",
+                        "window": int(glfw.get_wayland_window(self.window)),
+                        "display": int(glfw.get_wayland_display()),
+                    }
                 else:
-                    return int(glfw.get_x11_window(self.window))
+                    return {
+                        "platform": "x11",
+                        "window": int(glfw.get_x11_window(self.window)),
+                        "display": int(glfw.get_x11_display()),
+                    }
             else:
-                raise RuntimeError(f"Cannot get GLFW window id on {sys.platform}.")
-
-        def get_display_id(self):
-            return wgpu.WgpuCanvasInterface.get_display_id(self)
+                raise RuntimeError(f"Cannot get GLFW surafce info on {sys.platform}.")
 
         def get_physical_size(self):
             psize = glfw.get_framebuffer_size(self.window)

wgpu/backends/wgpu_native/_api.py

@@ -198,8 +198,7 @@ def request_adapter(
         # able to create a surface texture for it (from this adapter).
         surface_id = ffi.NULL
         if canvas is not None:
-            window_id = canvas.get_window_id()
-            if window_id:  # e.g. could be an off-screen canvas
+            if canvas.get_surface_info():  # e.g. could be an off-screen canvas
                 surface_id = canvas.get_context()._get_surface_id()
 
         # ----- Select backend

wgpu/backends/wgpu_native/_helpers.py

@@ -1,7 +1,6 @@
 """Utilities used in the wgpu-native backend.
 """
 
-import os
 import sys
 import ctypes
 
@@ -96,12 +95,18 @@ def get_surface_id_from_canvas(canvas):
     """Get an id representing the surface to render to. The way to
     obtain this id differs per platform and GUI toolkit.
     """
-    win_id = canvas.get_window_id()
+
+    # Use cached
+    surface_id = getattr(canvas, "_wgpu_surface_id", None)
+    if surface_id:
+        return surface_id
+
+    surface_info = canvas.get_surface_info()
 
     if sys.platform.startswith("win"):  # no-cover
         struct = ffi.new("WGPUSurfaceDescriptorFromWindowsHWND *")
         struct.hinstance = ffi.NULL
-        struct.hwnd = ffi.cast("void *", int(win_id))
+        struct.hwnd = ffi.cast("void *", int(surface_info["window"]))
         struct.chain.sType = lib.WGPUSType_SurfaceDescriptorFromWindowsHWND
 
     elif sys.platform.startswith("darwin"):  # no-cover
@@ -115,7 +120,7 @@ def get_surface_id_from_canvas(canvas):
         #     [ns_window.contentView setLayer:metal_layer];
         #     surface = wgpu_create_surface_from_metal_layer(metal_layer);
         # }
-        window = ctypes.c_void_p(win_id)
+        window = ctypes.c_void_p(surface_info["window"])
 
         cw = ObjCInstance(window)
         try:
@@ -156,26 +161,25 @@ def get_surface_id_from_canvas(canvas):
         struct.chain.sType = lib.WGPUSType_SurfaceDescriptorFromMetalLayer
 
     elif sys.platform.startswith("linux"):  # no-cover
-        display_id = canvas.get_display_id()
-        is_wayland = "wayland" in os.getenv("XDG_SESSION_TYPE", "").lower()
-        is_xcb = False
-        if is_wayland:
-            # todo: wayland seems to be broken right now
+        platform = surface_info.get("platform", "x11")
+        if platform == "x11":
+            struct = ffi.new("WGPUSurfaceDescriptorFromXlibWindow *")
+            struct.display = ffi.cast("void *", surface_info["display"])
+            struct.window = int(surface_info["window"])
+            struct.chain.sType = lib.WGPUSType_SurfaceDescriptorFromXlibWindow
+        elif platform == "wayland":
             struct = ffi.new("WGPUSurfaceDescriptorFromWaylandSurface *")
-            struct.display = ffi.cast("void *", display_id)
-            struct.surface = ffi.cast("void *", win_id)
+            struct.display = ffi.cast("void *", surface_info["display"])
+            struct.surface = ffi.cast("void *", surface_info["window"])
             struct.chain.sType = lib.WGPUSType_SurfaceDescriptorFromWaylandSurface
-        elif is_xcb:
+        elif platform == "xcb":
             # todo: xcb untested
             struct = ffi.new("WGPUSurfaceDescriptorFromXcbWindow *")
-            struct.connection = ffi.NULL  # ?? ffi.cast("void *", display_id)
-            struct.window = int(win_id)
+            struct.connection = ffi.cast("void *", surface_info["connection"])  # ??
+            struct.window = int(surface_info["window"])
             struct.chain.sType = lib.WGPUSType_SurfaceDescriptorFromXlibWindow
         else:
-            struct = ffi.new("WGPUSurfaceDescriptorFromXlibWindow *")
-            struct.display = ffi.cast("void *", display_id)
-            struct.window = int(win_id)
-            struct.chain.sType = lib.WGPUSType_SurfaceDescriptorFromXlibWindow
+            raise RuntimeError("Unexpected Linux surface platform '{platform}'.")
 
     else:  # no-cover
         raise RuntimeError("Cannot get surface id: unsupported platform.")
@@ -184,7 +188,11 @@ def get_surface_id_from_canvas(canvas):
     surface_descriptor.label = ffi.NULL
     surface_descriptor.nextInChain = ffi.cast("WGPUChainedStruct *", struct)
 
-    return lib.wgpuInstanceCreateSurface(get_wgpu_instance(), surface_descriptor)
+    surface_id = lib.wgpuInstanceCreateSurface(get_wgpu_instance(), surface_descriptor)
+
+    # Cache and return
+    canvas._wgpu_surface_id = surface_id
+    return surface_id
 
 
 # The functions below are copied from codegen/utils.py

wgpu/gui/__init__.py

@@ -2,6 +2,7 @@
 Code to provide a canvas to render to.
 """
 
+from . import _gui_utils  # noqa: F401
 from .base import WgpuCanvasInterface, WgpuCanvasBase, WgpuAutoGui  # noqa: F401
 from .offscreen import WgpuOffscreenCanvasBase  # noqa: F401
 

wgpu/gui/_gui_utils.py

@@ -0,0 +1,108 @@
+""" Private gui utilities.
+"""
+
+import os
+import sys
+import weakref
+import logging
+import ctypes.util
+from contextlib import contextmanager
+
+from .._coreutils import error_message_hash
+
+
+logger = logging.getLogger("wgpu")
+
+
+err_hashes = {}
+
+
+@contextmanager
+def log_exception(kind):
+    """Context manager to log any exceptions, but only log a one-liner
+    for subsequent occurances of the same error to avoid spamming by
+    repeating errors in e.g. a draw function or event callback.
+    """
+    try:
+        yield
+    except Exception as err:
+        # Store exc info for postmortem debugging
+        exc_info = list(sys.exc_info())
+        exc_info[2] = exc_info[2].tb_next  # skip *this* function
+        sys.last_type, sys.last_value, sys.last_traceback = exc_info
+        # Show traceback, or a one-line summary
+        msg = str(err)
+        msgh = error_message_hash(msg)
+        if msgh not in err_hashes:
+            # Provide the exception, so the default logger prints a stacktrace.
+            # IDE's can get the exception from the root logger for PM debugging.
+            err_hashes[msgh] = 1
+            logger.error(kind, exc_info=err)
+        else:
+            # We've seen this message before, return a one-liner instead.
+            err_hashes[msgh] = count = err_hashes[msgh] + 1
+            msg = kind + ": " + msg.split("\n")[0].strip()
+            msg = msg if len(msg) <= 70 else msg[:69] + "…"
+            logger.error(msg + f" ({count})")
+
+
+def weakbind(method):
+    """Replace a bound method with a callable object that stores the `self` using a weakref."""
+    ref = weakref.ref(method.__self__)
+    class_func = method.__func__
+    del method
+
+    def proxy(*args, **kwargs):
+        self = ref()
+        if self is not None:
+            return class_func(self, *args, **kwargs)
+
+    proxy.__name__ = class_func.__name__
+    return proxy
+
+
+SYSTEM_IS_WAYLAND = "wayland" in os.getenv("XDG_SESSION_TYPE", "").lower()
+
+if sys.platform.startswith("linux") and SYSTEM_IS_WAYLAND:
+    # Force glfw to use X11. Note that this does not work if glfw is already imported.
+    if "glfw" not in sys.modules:
+        os.environ["PYGLFW_LIBRARY_VARIANT"] = "x11"
+    # Force Qt to use X11. Qt is more flexible - it ok if e.g. PySide6 is already imported.
+    os.environ["QT_QPA_PLATFORM"] = "xcb"
+    # Force wx to use X11, probably.
+    os.environ["GDK_BACKEND"] = "x11"
+
+
+_x11_display = None
+
+
+def get_alt_x11_display():
+    """Get (the pointer to) a process-global x11 display instance."""
+    # Ideally we'd get the real display object used by the GUI toolkit.
+    # But this is not always possible. In that case, using an alt display
+    # object can be used.
+    global _x11_display
+    assert sys.platform.startswith("linux")
+    if _x11_display is None:
+        x11 = ctypes.CDLL(ctypes.util.find_library("X11"))
+        x11.XOpenDisplay.restype = ctypes.c_void_p
+        _x11_display = x11.XOpenDisplay(None)
+    return _x11_display
+
+
+_wayland_display = None
+
+
+def get_alt_wayland_display():
+    """Get (the pointer to) a process-global Wayland display instance."""
+    # Ideally we'd get the real display object used by the GUI toolkit.
+    # This creates a global object, similar to what we do for X11.
+    # Unfortunately, this segfaults, so it looks like the real display object
+    # is needed? Leaving this here for reference.
+    global _wayland_display
+    assert sys.platform.startswith("linux")
+    if _wayland_display is None:
+        wl = ctypes.CDLL(ctypes.util.find_library("wayland-client"))
+        wl.wl_display_connect.restype = ctypes.c_void_p
+        _wayland_display = wl.wl_display_connect(None)
+    return _wayland_display