feat: add set_ignore_cursor_events #1884

z4122 · 2021-03-16T16:34:36Z

Tested on all platforms changed
Compilation warnings were addressed
cargo fmt has been run on this branch
cargo doc builds successfully
Added an entry to CHANGELOG.md 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
Updated feature matrix, if new features were added or implemented

On macOS and Windows, added set_ignore_cursor_events to make window catch or ignore mouse events.

maroider

I'd like to test this later, but here's some feedback anyway.

cc @ArturKovacs, @msiglreith

src/window.rs

examples/cursor_grab.rs

CHANGELOG.md

maroider · 2021-03-16T16:53:23Z

src/platform_impl/windows/window_state.rs

@@ -219,6 +221,9 @@ impl WindowFlags {
        if self.contains(WindowFlags::MAXIMIZED) {
            style |= WS_MAXIMIZE;
        }
+        if self.contains(WindowFlags::IGNORE_CURSOR_EVENT) {
+            style_ex |= WS_EX_TRANSPARENT | WS_EX_LAYERED;


In #1815, we decided to remove the WS_EX_LAYERED style as it is documented as being incompatible with the CS_OWNDC window class style.
When I test stuff (not this PR, mind you) on my own machine it seems to work fine, but the documentation nevertheless says it is incompatible.

Good point.. maybe we can get rid of the CS_OWNDC part as it's mainly/only for OpenGL and I believe we can get around it. Will play around with this one a bit in the next days.

Would be nice to have reference link added here regarding hit-test behavior (https://docs.microsoft.com/de-de/windows/win32/winmsg/window-features?redirectedfrom=MSDN#layered-windows)

ArturKovacs · 2021-03-17T07:45:29Z

Please elaborate on what's the benefit of adding this. To me it seems that this is identical to simply not processing mouse events coming from the event loop.

z4122 · 2021-03-17T16:07:34Z

Please elaborate on what's the benefit of adding this. To me it seems that this is identical to simply not processing mouse events coming from the event loop.

We can use this feature to create a transparent floating window uppon some other windows. Then we can draw something or just show something on this window at the same time don't effect user's normal operations. It is useful in situation like screen sharing.

maroider · 2021-03-17T16:31:19Z

A concrete example of a program utilizing something like this is ScreenToGif. I couldn't see if they're using this exact technique by quickly searching through their repository.

There's actually an issue open for this already: #1434.

As noted in #1434, it isn't clear if Winit should explicitly support "overlays", but I think allowing click-through windows should be fairly inoffensive. An X11 implementation in Winit should probably be possible, although I wouldn't block this PR on it.

Also: I think this may warrant an entry in the feature matrix.

msiglreith · 2021-03-17T19:01:35Z

src/window.rs

+    ///
+    /// - **iOS / Android / Web / X11 / Wayland:** Unsupported.
+    #[inline]
+    pub fn set_ignore_cursor_events(&self, ignore: bool) -> Result<(), ExternalError> {


A bit of bikeshedding but I would prefer some affirmative variant of the method name as set_ignore_cursor_events(false) might be hard to read. My suggestion would be set_cursor_hittest.

https://developer.apple.com/documentation/appkit/nswindow/1419354-ignoresmouseevents/
Maybe set_ignore_mouse_events(bool) is better? To keep consistent with system api.

I think that choosing an affirmative name is more useful here than matching the macOS naming. We should probably mention the macOS API in the documentation.

Also note that the MSDN documentation uses "hit testing" to refer to this phenomenon. https://docs.microsoft.com/en-us/windows/win32/winmsg/window-features#layered-windows

src/window.rs

examples/cursor_grab.rs

src/platform_impl/macos/util/async.rs

coderedart · 2021-05-16T11:06:13Z

Just wanted to mention that Qt uses the Qt::WindowTransparentForInput as a widget attribute and I believe it is a much more intuitive name. Or something like input passthrough.

ArturKovacs · 2021-05-16T15:54:41Z

We are starting to go deep into bikeshedding territory; it's a scary place where I don't want to be. @z4122 please rename set_ignore_mouse_events to set_cursor_hittest, and also rename WindowFlags::IGNORE_CURSOR_EVENT to CURSOR_HITTEST, and everything else that's related and I missed.

(WindowTransparentForInput in Qt seems to ignore both mouse and keyboard events but this PR only ignores mouse events)

maroider · 2021-06-21T09:00:43Z

Coming back to this PR after about a month is a bit disorienting, but I believe we're currently blocked on:

Deciding on a name for the Window method
An entry in the feature matrix for the feature
Doing someting about CS_OWNDC (Windows: Check removal of CS_OWNDC style #1893/Windows: Remove owned DC context per window #1910)

kmod-midori · 2021-11-06T10:16:42Z

Is there some way I could help to get this feature merged? I am targeting Windows in particular, although a cross-platform solution is also desired (don't know if we'll ever able to implement this on Linux).

kchibisov · 2022-04-11T17:46:06Z

Closing in favor of #2232.

maroider reviewed Mar 16, 2021

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z4122 force-pushed the feat/add_set_ignore_cursor_events branch from 12e2943 to f726617 Compare March 17, 2021 15:54

z4122 force-pushed the feat/add_set_ignore_cursor_events branch from f726617 to f83a098 Compare March 17, 2021 16:11

msiglreith added DS - macos DS - windows labels Mar 17, 2021

msiglreith reviewed Mar 17, 2021

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ArturKovacs suggested changes Mar 17, 2021

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feat: add set_ignore_cursor_events

a5ab8e6

z4122 force-pushed the feat/add_set_ignore_cursor_events branch from f83a098 to a5ab8e6 Compare May 11, 2021 15:43

coderedart mentioned this pull request May 15, 2021

Input Passthrough emilk/egui#374

Closed

kmod-midori mentioned this pull request Nov 11, 2021

Remove window from taskbar and switcher (e.g. Alt-Tab) / extra style flags on Windows #2059

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msiglreith mentioned this pull request Mar 28, 2022

Add cursor hittest window functionality #2232

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kchibisov closed this Apr 11, 2022

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feat: add set_ignore_cursor_events #1884

feat: add set_ignore_cursor_events #1884

z4122 commented Mar 16, 2021

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feat: add set_ignore_cursor_events #1884

feat: add set_ignore_cursor_events #1884

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