From 97174913e09db464d3020c50cbf223d2fe823d3d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Ekl=C3=B6f?= <daniel@ekloef.se>
Date: Mon, 13 Dec 2021 19:15:17 +0100
Subject: [PATCH 1/2] wayland: estimate scaled (logical) width/height, if not
 provided
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This makes us slightly more resilient against a missing XDG output
interface.

We use the “real” (the physical) dimensions, combined with the scaling
factor, to estimate the logical dimensions.

This works out correctly with  non-fractional scaling, but not
otherwise.
---
 wayland.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/wayland.c b/wayland.c
index dd313813..85f00b98 100644
--- a/wayland.c
+++ b/wayland.c
@@ -385,13 +385,19 @@ output_update_ppi(struct monitor *mon)
         break;
     }
 
-    mon->ppi.scaled.x = mon->dim.px_scaled.width / x_inches;
-    mon->ppi.scaled.y = mon->dim.px_scaled.height / y_inches;
+    int scaled_width = mon->dim.px_scaled.width;
+    int scaled_height = mon->dim.px_scaled.height;
 
-    float px_diag = sqrt(
-        pow(mon->dim.px_scaled.width, 2) +
-        pow(mon->dim.px_scaled.height, 2));
+    if (scaled_width == 0 && scaled_height == 0 && mon->scale > 0) {
+        /* Estimate scaled width/height if none has been provided */
+        scaled_width = mon->dim.px_real.width / mon->scale;
+        scaled_height = mon->dim.px_real.height / mon->scale;
+    }
 
+    mon->ppi.scaled.x = scaled_width / x_inches;
+    mon->ppi.scaled.y = scaled_height / y_inches;
+
+    float px_diag = sqrt(pow(scaled_width, 2) + pow(scaled_height, 2));
     mon->dpi = px_diag / mon->inch * mon->scale;
 }
 

From 01a417660d4a1d8d52c3fb0c8a79556623a7cc24 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Ekl=C3=B6f?= <daniel@ekloef.se>
Date: Mon, 13 Dec 2021 19:17:48 +0100
Subject: [PATCH 2/2] wayland: add wl_output.name() and wl_output.description()

These are new in version 4 of the wl_output interface (first included
in wayland-1.20).

This allows us to get the name and description of the outputs, also on
compositors without the XDG output interface.
---
 wayland.c | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/wayland.c b/wayland.c
index 85f00b98..61e2dfdf 100644
--- a/wayland.c
+++ b/wayland.c
@@ -452,11 +452,38 @@ output_scale(void *data, struct wl_output *wl_output, int32_t factor)
     output_update_ppi(mon);
 }
 
+#if defined(WL_OUTPUT_NAME_SINCE_VERSION)
+static void
+output_name(void *data, struct wl_output *wl_output, const char *name)
+{
+    struct monitor *mon = data;
+    free(mon->name);
+    mon->name = name != NULL ? xstrdup(name) : NULL;
+}
+#endif
+
+#if defined(WL_OUTPUT_DESCRIPTION_SINCE_VERSION)
+static void
+output_description(void *data, struct wl_output *wl_output,
+                   const char *description)
+{
+    struct monitor *mon = data;
+    free(mon->description);
+    mon->description = description != NULL ? xstrdup(description) : NULL;
+}
+#endif
+
 static const struct wl_output_listener output_listener = {
     .geometry = &output_geometry,
     .mode = &output_mode,
     .done = &output_done,
     .scale = &output_scale,
+#if defined(WL_OUTPUT_NAME_SINCE_VERSION)
+    .name = &output_name,
+#endif
+#if defined(WL_OUTPUT_DESCRIPTION_SINCE_VERSION)
+    .description = &output_description,
+#endif
 };
 
 static void
@@ -970,7 +997,7 @@ handle_global(void *data, struct wl_registry *registry,
             return;
 
         struct wl_output *output = wl_registry_bind(
-            wayl->registry, name, &wl_output_interface, min(version, 3));
+            wayl->registry, name, &wl_output_interface, min(version, 4));
 
         tll_push_back(
             wayl->monitors,