Wayland: text is garbled on non-scaled monitors

[matejdro]

Issue description

When using dunst with Sway and using multiple monitors, where at least one monitor is using scaling, dunst's text will be garbled on non-scaled monitors:

On scaled monitors it appears fine:

Installation info

• Version: Dunst - A customizable and lightweight notification-daemon 1.10.0 (2024-02-19)
• Install type: package
• Window manager / Desktop environment: sway version 1.9
• Distro: Arch

Minimal dunstrc

default + `follow` option enabled to allow displaying on multiple monitors

Setting force_xwayland to true fixes the issue, but it also breaks follow, which makes it an useless workaround.

[bynect]

did you enable per_monitor_dpi?

[matejdro]

Yes, with no effect. From what I can see, this settings is X11-only.

[bynect]

Yes, with no effect. From what I can see, this settings is X11-only.

I am checking the code and it is indeed an x11 only option.

But does the error occur only when the scaled screen is connected?

[matejdro]

Yes, only when the scaled screen is connected. Otherwise, it works fine.

[bynect]

are you able to compile dunst ? I can add some logging in the wl_get_scale function. Unfortunately I can't test it myself because I don't have such wayland environment

[matejdro]

Yes, I can compile it. Feel free to point me to a branch with extra logs.

[bynect]

I have made that small modification in my fork (https://github.com/bynect/dunst/tree/log-scale). If you could try it maybe we can get a better understanding of what's going on

[matejdro]

Sorry this took a while.

Here is log from notification on non-scaled monitor:

WARNING: No icon found in path: 'dialog-information'
DEBUG: [         wake_up:0067] Waking up
DEBUG: [             run:0077] RUN, reason 1
INFO: Idle status queried: 0
DEBUG: [calculate_dimensions:0306] Notification dimensions 300x91
DEBUG: [            draw:0982] Window dimensions 309x97
DEBUG: [  render_content:0748] Layout height 75
DEBUG: [wl_display_surface:0800] Buffer size (scaled) 618x194
DEBUG: [             run:0103] Sleeping for 59992 ms

Here is log from notification on scaled monitor:

WARNING: No icon found in path: 'dialog-information'
DEBUG: [         wake_up:0067] Waking up
DEBUG: [             run:0077] RUN, reason 1
INFO: Idle status queried: 0
DEBUG: [calculate_dimensions:0306] Notification dimensions 300x91
DEBUG: [            draw:0982] Window dimensions 309x97
DEBUG: [  render_content:0748] Layout height 75
DEBUG: [wl_display_surface:0800] Buffer size (scaled) 618x194
DEBUG: [             run:0103] Sleeping for 59991 ms

Scaled monitor = 3840x2160 with 2x scaling
Unscaled monitor = 1920x1080 with no scaling
(so effectively they are the same size)

[bynect]

@matejdro I am very sorry I just noticed that the branch I pointed you was not actually synced with the changes I made.

I added some logging calls in the wl_get_scale function. This time the changes are actually up on github at the aforementioned link, but I will send also the diff

diff --git a/src/wayland/wl.c b/src/wayland/wl.c
index 18a2173..7c792bd 100644
--- a/src/wayland/wl.c
+++ b/src/wayland/wl.c
@@ -896,13 +896,20 @@ double wl_get_scale(void) {
         struct dunst_output *output = get_configured_output();
         if (output) {
                 scale = output->scale;
+
+                LOG_I("Output found, global name = %u, name = %s, scale = %u", output->global_name, output->name, output->scale);
         } else {
+                LOG_I("Output not found!");
+
                 // return the largest scale
                 struct dunst_output *output;
                 wl_list_for_each(output, &ctx.outputs, link) {
                         scale = MAX(output->scale, scale);
+                        LOG_I("Checking output %s (%u) with scale %u", output->name, output->global_name, output->scale);
                 }
         }
+
+        LOG_I("Scale is %d", scale);
         if (scale <= 0)
                 scale = 1;
         return scale;

Could you please test with these changes so I can understand if the monitor are correctly detected

[matejdro]

Both monitors print:

INFO: Output not found!
INFO: Checking output (null) (49) with scale 2
INFO: Checking output (null) (48) with scale 1
INFO: Scale is 2

So, detected scale is 2 at both. If I hardcode that method to return 1, then text is not garbled anymore on the non-scaled monitor, but it is blurry on the scaled one.

from what I can see, the problem seems to be the get_configured_output method? It always returns null when FOLLOW_MOUSE or FOLLOW_KEYBOARD is enabled. There is no actual detection of the currently focused monitor.

[bynect]

Both monitors print:

INFO: Output not found!
INFO: Checking output (null) (49) with scale 2
INFO: Checking output (null) (48) with scale 1
INFO: Scale is 2

So, detected scale is 2 at both. If I hardcode that method to return 1, then text is not garbled anymore on the non-scaled monitor, but it is blurry on the scaled one.

from what I can see, the problem seems to be the get_configured_output method? It always returns null when FOLLOW_MOUSE or FOLLOW_KEYBOARD is enabled. There is no actual detection of the currently focused monitor.

Right, I figured it probably was the monitor detection. I am not an expert in wayland but I'll try looking into it.

Maybe returning the scale of the monitor where the window currently is positioned is a better choice? I don't know the rationale behind the way follow is implemented in wayland