contrib: add python layout

contrib/layout.py

@@ -0,0 +1,142 @@
+#!/usr/bin/env python3
+#
+# Fibonacci sprial layout for river, implemented in simple python. Reading this
+# code should help you get a basic understanding of how to use river-layout to
+# create a basic layout generator.
+#
+# This depends on pywayland: https://github.com/flacjacket/pywayland/
+#
+# Q: Wow, this looks complicated!
+# A: For simple layouts, you really only need to care about what's in the
+#    layout_handle_layout_demand() function. And the rest isn't as complicated
+#    as it looks.
+
+import mmap
+import time
+from pywayland.client import Display
+from pywayland.protocol.wayland import WlOutput
+try:
+    from pywayland.protocol.river_layout_v3 import RiverLayoutManagerV3
+except:
+    print("Your pywayland package does not have bindings for river-layout-v3.")
+    print("You can add the bindings with the following command:")
+    print("     python3 -m pywayland.scanner -i /usr/share/wayland/wayland.xml river-layout-v3.xml")
+    print("Note that you may need root privileges if you have pywayland installed system-wide.")
+    quit()
+
+layout_manager = None
+outputs = []
+loop = True
+
+def layout_handle_layout_demand(layout, view_count, usable_w, usable_h, tags, serial):
+    x = 0
+    y = 0
+    w = usable_w
+    h = usable_h
+    i = 0
+    while i < view_count:
+        if i == view_count - 1:
+            layout.push_view_dimensions(x, y, w, h, serial)
+        else:
+            if i % 2 == 0:
+                w = int(w/2)
+                if i % 4 == 2:
+                    layout.push_view_dimensions(x + w, y, w, h, serial)
+                else:
+                    layout.push_view_dimensions(x, y, w, h, serial)
+                    x += w
+            else:
+                h = int(h/2)
+                if i % 4 == 3:
+                    layout.push_view_dimensions(x, y + h, w, h, serial)
+                else:
+                    layout.push_view_dimensions(x, y, w, h, serial)
+                    y += h
+
+    # Committing the layout means telling the server that your code is done
+    # laying out windows. Make sure you have pushed exactly the right amount of
+    # view dimensions, a mismatch is a fatal protocol error.
+    # 
+    # You also have to provide a layout name. This is a user facing string that
+    # the server can forward to status bars. You can use it to tell the user
+    # which layout is currently in use. You could also add some status
+    # information status information about your layout, which is what we do here.
+    layout.commit(str(view_count) + " windows layout out by python", serial)
+
+def layout_handle_namespace_in_use(layout):
+    # Oh no, the namespace we choose is already used by another client! All we
+    # can do now is destroy the layout object. Because we are lazy, we just
+    # abort and let our cleanup mechanism destroy it. A more sophisticated
+    # client could instead destroy only the one single affected layout object
+    # and recover from this mishap. Writing such a client is left as an exercise
+    # for the reader.
+    print(f"Namespace already in use!")
+    global loop
+    loop = False
+
+class Output(object):
+    def __init__(self):
+        self.output = None
+        self.layout = None
+        self.id = None
+
+    def destroy(self):
+        if self.layout != None:
+            self.layout.destroy()
+        if self.output != None:
+            self.output.destroy()
+
+    def configure(self):
+        global layout_manager
+        if self.layout == None and layout_manager != None:
+            # We need to set a namespace, which is used to identify our layout.
+            self.layout = layout_manager.get_layout(self.output, "layout.py")
+            self.layout.user_data = self
+            self.layout.dispatcher["layout_demand"] = layout_handle_layout_demand
+            self.layout.dispatcher["namespace_in_use"] = layout_handle_namespace_in_use
+
+def registry_handle_global(registry, id, interface, version):
+    global layout_manager
+    global output
+    if interface == 'river_layout_manager_v3':
+        layout_manager = registry.bind(id, RiverLayoutManagerV3, version)
+    elif interface == 'wl_output':
+        output = Output()
+        output.output = registry.bind(id, WlOutput, version)
+        output.id = id
+        output.configure()
+        outputs.append(output)
+
+def registry_handle_global_remove(registry, id):
+    for output in outputs:
+        if output.id == id:
+            output.destroy()
+            outputs.remove(output)
+
+display = Display()
+display.connect()
+
+registry = display.get_registry()
+registry.dispatcher["global"] = registry_handle_global
+registry.dispatcher["global_remove"] = registry_handle_global_remove
+
+display.dispatch(block=True)
+display.roundtrip()
+
+if layout_manager == None:
+    print("No layout_manager, aborting")
+    quit()
+
+for output in outputs:
+    output.configure()
+
+while loop and display.dispatch(block=True) != -1:
+    pass
+
+# Destroy outputs
+for output in outputs:
+    output.destroy()
+    outputs.remove(output)
+
+display.disconnect()
+