From 36fb2b942a08d58290b1d6ea1aec6d01f8e096b7 Mon Sep 17 00:00:00 2001
From: Federico Angelilli <code@fedang.net>
Date: Mon, 13 Nov 2023 22:50:39 +0100
Subject: Render correctly 'circular' corners with `xcb-shape`

---
 x11.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 51 insertions(+), 1 deletion(-)

(limited to 'x11.c')

diff --git a/x11.c b/x11.c
index 551e7d7..9a13bd9 100644
--- a/x11.c
+++ b/x11.c
@@ -9,8 +9,9 @@
 #include <xcb/xcb_icccm.h>
 #include <xcb/xcb_ewmh.h>
 #include <xcb/xcb_xrm.h>
-#include <xcb/randr.h>
 #include <xcb/xcb_errors.h>
+#include <xcb/randr.h>
+#include <xcb/shape.h>
 
 #include "x11.h"
 #include "log.h"
@@ -473,6 +474,53 @@ void window_resize(Window *win, int width, int height)
     wm_set_size(win);
 }
 
+static void window_paint_corners(Window *win)
+{
+    // TODO: Actually make this a parameter
+    int radius = win->height / 2;
+    double degree = M_PI / 180.0;
+
+    // TODO: Check this value
+    int depth = 1;
+
+    xcb_pixmap_t bitmap = xcb_generate_id(win->connection);
+    xcb_create_pixmap(win->connection, depth, bitmap, win->window, win->width, win->height);
+    log_debug("Xcb pixmap created [id=%u]", bitmap);
+
+    cairo_surface_t *surface = cairo_xcb_surface_create_for_bitmap(win->connection,
+                                                                   win->screen,
+                                                                   bitmap,
+                                                                   win->width,
+                                                                   win->height);
+
+    cairo_t *cr = cairo_create(surface);
+
+    cairo_set_antialias(cr, CAIRO_ANTIALIAS_NONE);
+    cairo_set_operator(cr, CAIRO_OPERATOR_SOURCE);
+
+    cairo_set_source_rgba(cr, 0, 0, 0, 0);
+    cairo_paint(cr);
+
+    // TODO: Decouple somewhat drawing and X11
+    cairo_set_source_rgba(cr, 1, 1, 1, 1);
+    cairo_arc(cr, radius, radius, radius, 90.0 * degree, 270 * degree);
+    cairo_arc(cr, win->width - radius, radius, radius, 270 * degree, 450 * degree);
+    cairo_fill(cr);
+
+    log_debug("Xcb shape painted");
+
+    cairo_show_page(cr);
+    cairo_destroy(cr);
+    cairo_surface_flush(surface);
+    cairo_surface_destroy(surface);
+
+    xcb_shape_mask(win->connection, XCB_SHAPE_SO_SET, XCB_SHAPE_SK_BOUNDING, win->window, 0, 0, bitmap);
+    xcb_shape_select_input(win->connection, win->window, XCB_SHAPE_NOTIFY);
+    log_debug("Xcb shape mask configured");
+
+    xcb_free_pixmap(win->connection, bitmap);
+}
+
 void window_paint_surface(Window *win, cairo_surface_t *surface, int width, int height)
 {
     cairo_xcb_surface_set_size(win->surface, width, height);
@@ -482,6 +530,8 @@ void window_paint_surface(Window *win, cairo_surface_t *surface, int width, int
     cairo_paint(win->cr);
     cairo_show_page(win->cr);
 
+    window_paint_corners(win);
+
     xcb_circulate_window(win->connection, XCB_CIRCULATE_RAISE_LOWEST, win->window);
     xcb_flush(win->connection);
 }
-- 
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