Add RoundedCorners border decoration

Wayland only as x11 will render black artefacts.

CHANGELOG

@@ -1,3 +1,4 @@
+2024-07-07: [FEATURE] Add `RoundedCorners` border decoration (Wayland only)
 2024-07-07: [FEATURE] Add `ConditionalBorderWidth` to set border width depending on window conditions
 2024-06-13: [FEATURE] Add new `CustomBorder` to draw window borders with user-defined functions
 2024-06-06: [FEATURE] Add new `ConditionalBorder` to set window border depending on window conditions (name, class etc.)

qtile_extras/layout/decorations/__init__.py

@@ -25,6 +25,7 @@
     CustomBorder,
     GradientBorder,
     GradientFrame,
+    RoundedCorners,
     ScreenGradientBorder,
     SolidEdge,
 )

qtile_extras/layout/decorations/borders.py

@@ -18,6 +18,7 @@
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 # SOFTWARE.
 import inspect
+import math
 
 import cairocffi
 import xcffib.xproto
@@ -573,6 +574,50 @@ def draw(self, surface, bw, x, y, width, height):
             self.func(ctx, bw, width, height)
 
 
+class RoundedCorners(_BorderStyle):
+    """
+    A simple decoration to draw rounded corners.
+
+    .. note::
+
+        This border will not render well on x11 backends as it does not implement transparency.
+        As a result, the border will display with black artefacts in the corners.
+
+    """
+
+    needs_surface = True
+
+    defaults = [
+        ("colour", "00f", "Border colour"),
+    ]
+
+    _screenshots = [
+        ("border_rounded_corners.png", "Rounded corners"),
+    ]
+
+    def __init__(self, **config):
+        _BorderStyle.__init__(self, **config)
+        self.add_defaults(RoundedCorners.defaults)
+
+    def draw(self, surface, bw, x, y, width, height):
+        with cairocffi.Context(surface) as ctx:
+            ctx.translate(x, y)
+
+            radius = bw / 2
+            degrees = math.pi / 180.0
+
+            ctx.new_sub_path()
+            ctx.arc(width - bw, bw, radius, -90 * degrees, 0 * degrees)
+            ctx.arc(width - bw, height - bw, radius, 0 * degrees, 90 * degrees)
+            ctx.arc(bw, height - bw, radius, 90 * degrees, 180 * degrees)
+            ctx.arc(bw, bw, radius, 180 * degrees, 270 * degrees)
+            ctx.close_path()
+
+            ctx.set_line_width(bw)
+            ctx.set_source_rgba(*rgb(self.colour))
+            ctx.stroke()
+
+
 class ConditionalBorderWidth(Configurable):
     """
     A class that allows finer control as to which border width is applied to which window.

test/layout/decorations/test_border_decorations.py

@@ -28,6 +28,7 @@
     CustomBorder,
     GradientBorder,
     GradientFrame,
+    RoundedCorners,
     ScreenGradientBorder,
     SolidEdge,
 )
@@ -74,6 +75,8 @@ class BorderDecorationConfig(Config):
         ConditionalBorder(matches=[(Match(title="three"), "f00")], fallback="00f"),
         ConditionalBorder(matches=[(Match(title="three"), "f00")], fallback=GradientBorder()),
         CustomBorder(func=lambda ctx, bw, x, y: None),
+        RoundedCorners(),
+        RoundedCorners(colour="f00"),
     ],
     indirect=True,
 )