Popup anchor system refinement by Murmele · Pull Request #4646 · rust-windowing/winit

Murmele · 2026-07-27T14:24:28Z

Implement possibility to change the anchor properties of a popup on wayland and imitate the behaviour for other platforms which do not support such anchoring system

Added an entry to the changelog module if knowledge of this change could be valuable to users
Updated documentation to reflect any user-facing changes, including notes of platform-specific behavior
Created or updated an example program if it would help users understand this functionality

Tested on:

Windows
Wayland
MacOs
~~X11~~ Does not support popups

… macos

…tion

…pup trait

#Conflicts: # winit-appkit/src/window_delegate.rs # winit/src/changelog/unreleased.md

… popups only

ogoffart

I wonder if it wouldn't be better to have a single with_positioner on the WindowAttribute / Window instead of many setter.
And use the WindowPositioner stuct.

ogoffart · 2026-08-11T06:14:59Z

 use dpi::{
    LogicalPosition, LogicalSize, PhysicalInsets, PhysicalPosition, PhysicalSize, Position, Size,
 };
+pub use positioner::{WindowAnchor, WindowConstraintAdjustment, WindowGravity, place_window};


i don't think place_window should be public API

This depends on the usage. If it should be possible to reuse it in other software like for the ChildWindow in Slint or if we wanna make a copy of the algorithm on the slint side

But we can't re-use it for ChildWindow in Slint because slint-core don't depend on winit on purpose.

in fact, the implementation of that function might be better placed in winit-common

winit-common is also not possible, because it depends on winit-core. It has to be public, because otherwise the winit-win32 and winit-appkit cannot use it

ogoffart · 2026-08-11T06:22:44Z

+
+        self.set_outer_position(Position::Logical(origin));
+        if size != current_size {
+            let _ = self.request_surface_size(Size::Logical(size));


that's the inner size. but current_size use get_outer_size

There are other inconsistency like that.

Thanks I changed

ogoffart · 2026-08-11T06:27:57Z

+
+        let userdata = unsafe { util::get_window_long(hwnd, GWL_USERDATA) };
+        if userdata != 0 {
+            let userdata = unsafe { &*(userdata as *const WindowData) };


seems dangerous to do if there are window that are not handled by winit, we need to filter that.

public_window_callback will be called only for windows we handle otherwise this function is never called. We must be not take ownership of the pointer because of that this pattern. Also used a few times already in the code

ogoffart · 2026-08-11T06:30:19Z

+        monitor_position.y - parent_origin.y,
+    )
+    .to_logical::<f64>(scale_factor);
+    let clip_size = monitor_size.to_logical::<f64>(scale_factor);


is the monitor size the right thing, or should it be the availiable space?
Depends if the window or popup can be placed over, say, the taskbar

Good point, I have to check also for multiwindow systems

I used the work area instead of the display, otherwise it disappears behind the taskbar instead of flipping / sliding (if enabled)

Murmele · 2026-08-12T05:29:40Z

@ogoffart Thanks for the feedback. I will go through it

…having many single functions

Murmele · 2026-08-12T07:37:53Z

I wonder if it wouldn't be better to have a single with_positioner on the WindowAttribute / Window instead of many setter. And use the WindowPositioner stuct.

Good idea, it looks much cleaner now with the positioner struct used directly

…lacement

ogoffart

maybe there should be an example?

ogoffart · 2026-08-12T08:29:47Z

 use dpi::{
    LogicalPosition, LogicalSize, PhysicalInsets, PhysicalPosition, PhysicalSize, Position, Size,
 };
+pub use positioner::{WindowAnchor, WindowConstraintAdjustment, WindowGravity, place_window};


But we can't re-use it for ChildWindow in Slint because slint-core don't depend on winit on purpose.

in fact, the implementation of that function might be better placed in winit-common

ogoffart · 2026-08-12T08:31:04Z

+    anchor: WindowAnchor,
+    gravity: WindowGravity,
+    constraint_adjustment: WindowConstraintAdjustment,
+    (anchor_position, anchor_size): (LogicalPosition<f64>, LogicalSize<f64>),
+    offset: LogicalPosition<f64>,


Can we use a WindowPositioner here instead of many arguments?

yep, I will change

ogoffart · 2026-08-12T08:38:51Z

+/// platform-specific behavior, and [`WindowPositioner::default`] for the values used when
+/// [`WindowAttributes::with_positioner`] is never called.
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub struct WindowPositioner {


form an API evolution point of view, i wonder if this should be #[non_exhaustive]

Or is the positioning protocol set in stone anyway and there will never be extra fields?

The wayland protocol can envolve, so it is a good idea to make it non_exhaustive

ogoffart · 2026-08-12T09:03:25Z

+                    // An anchored window's position is parent-relative; it's applied in
+                    // `WindowDelegate::new` (after the delegate exists) via the shared
+                    // translation in `set_outer_position`.
+                    _ if anchored => NSPoint::new(0.0, 0.0),


but if you don't specify a position and there is no parent, it should be in the center of the screen (i think that's the current behavior in master)

thanks, changed

Previously every close request left the event_loop which is not correct when only a popup closes

Reason: otherwise the popup might disappear behind the task bar

Murmele · 2026-08-12T19:31:57Z

But we can't re-use it for ChildWindow in Slint because slint-core don't depend on winit on purpose. in fact, the implementation of that function might be better placed in winit-common

winit-common depends on winit-core so we cannot use this as well. It has to be public otherwise the winit-win32 crate and the macos crate are not able to access it

Murmele added 3 commits July 27, 2026 16:36

initial commit to implement anchoring system for wayland, windows and…

9794833

… macos

format

8811d69

no need to use a Cell for is_popup because it is set only at construc…

5d024a7

…tion

Murmele force-pushed the popup-anchor branch from 6c08ead to 5d024a7 Compare July 27, 2026 14:36

Fix clippy

4a9308f

Murmele mentioned this pull request Jul 27, 2026

Popup anchor system refinement #4645

Closed

8 tasks

Murmele added 6 commits July 27, 2026 16:48

fix clippy

560eb35

fix clippy macos

341dd07

add changelog entry

56940ab

fix clippy

a55d69f

fix clippy

73decb4

fix comment

988acf9

Murmele marked this pull request as ready for review July 28, 2026 05:51

Murmele requested review from MarijnS95, daxpedda, jackpot51, kchibisov and madsmtm as code owners July 28, 2026 05:51

Murmele added 3 commits July 28, 2026 14:47

Merge branch 'master' into popup-anchor

1aebc58

move anchoring system into the window trait instead of a dedicated po…

ae560bc

…pup trait

Merge remote-tracking branch 'refs/remotes/origin/popup-anchor'

e553980

#Conflicts: # winit-appkit/src/window_delegate.rs # winit/src/changelog/unreleased.md

Murmele commented Aug 10, 2026

View reviewed changes

Comment thread winit-appkit/src/window_delegate.rs Outdated

Comment thread winit-appkit/src/window_delegate.rs Outdated

Murmele added 3 commits August 10, 2026 08:11

Windows, MacOs: rename popup_ to window_ because it is not limited to…

2473c80

… popups only

Windows, MacOs: rename popup_ to window_ because it is not limited to…

10af000

… popups only

format

0f964a9

Murmele commented Aug 10, 2026

View reviewed changes

Comment thread winit-appkit/src/window_delegate.rs Outdated

Comment thread winit-core/src/window/positioner.rs Outdated

Comment thread winit-core/src/window.rs Outdated

Murmele added 4 commits August 10, 2026 09:06

add another test

088108b

fix clipping of the trailing edge

c917127

fix review

e08fa07

revert unrelated comparsions

9bb2335

use default to align with windows and macos

359d97c

ogoffart reviewed Aug 11, 2026

View reviewed changes

Murmele added 2 commits August 12, 2026 07:38

align with rest of the code

04aa8bb

create a single function with_positioner passing a struct instead of …

5a029a7

…having many single functions

Murmele added 2 commits August 12, 2026 10:09

fix consistent usage of inner and outer surface size for the anchor p…

b3aedb6

…lacement

instead of an option for the positioner anchor rect use a proper default

96d63bd

ogoffart reviewed Aug 12, 2026

View reviewed changes

Murmele added 5 commits August 12, 2026 13:20

make WindowPositioner non exhaustive

b8cf23d

Revert taking userdata as Box otherwise I am taking ownership

a925329

use directly the positioner to place_window

c25d553

center windows if there is no parent

f9a8991

add example

909e239

Murmele force-pushed the popup-anchor branch from 4e5083a to 909e239 Compare August 12, 2026 12:25

Murmele added 5 commits August 12, 2026 14:27

add dot

72f4558

fix example when clicking outside of the window

7a49836

Previously every close request left the event_loop which is not correct when only a popup closes

use the work area instead of the display area for clipping.

78e5a1f

Reason: otherwise the popup might disappear behind the task bar

fix format

e043dc4

fix clippy

c106f19

Murmele requested a review from ogoffart August 12, 2026 14:47

format

47b63f2

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Murmele Aug 12, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Murmele commented Aug 12, 2026

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