Rendered window content size is out of sync and padded

[Abdillah]

I run the raquote-winit example in GNOME with Wayland and get the following result.

It is padded and the size is out of sync. This is the case in animated render.

For static render, at the first render (before the cursor enter or interact), the size is fine. But soon as I touch the window, it goes out of sync and padded as in the picture.

The padded is actually passing through, as my cursor become and edit handle on top of a terminal.

[parasyte]

Hi!

The border is expected when scaling to non-integer multiples.

When you say "the size is fine" on what I presume is the first frame shown... I assume you say this because it doesn't have a border in this case. That would actually be a bug. The image should always have a border when the window surface size is not an exact integer multiple of the pixel buffer size.

Measuring the frame size in your screenshot, it is exactly 400x400, which is the requested size in the demo:

pixels/examples/raqote-winit/src/main.rs

Lines 16 to 17 in 9f7896c

	const WIDTH: u32 = 400;
	const HEIGHT: u32 = 400;

Measuring the window's inner size, it is something like 420x445. The border is 100% correct in the screenshot.

Without more information, I can only guess that there are two issues:

1. The window is not created with an appropriate size. According to the winit docs, setting the window's inner size is supported on Wayland. The size is configured here in the raqote demo:

   pixels/examples/raqote-winit/src/main.rs

   Lines 23 to 31 in 9f7896c

   	let window = {
   	let size = LogicalSize::new(WIDTH as f64, HEIGHT as f64);
   	WindowBuilder::new()
   	.with_title("Hello Raqote")
   	.with_inner_size(size)
   	.with_min_inner_size(size)
   	.build(&event_loop)
   	.unwrap()
   	};

2. The surface is resized "late". Maybe the window manager only sends the resize event to the window after the first interaction. The resize event is handled here:

   pixels/examples/raqote-winit/src/main.rs

   Lines 77 to 80 in 9f7896c

   	// Resize the window
   	if let Some(size) = input.window_resized() {
   	pixels.resize_surface(size.width, size.height);
   	}

Both of these are entirely contained in the example code, so the main library crate isn't affected. And because the issue described cannot be reproduced on Windows or macOS, it sounds like this is just another Wayland snowflake behavior as implemented in winit. (There are a lot of Wayland-only issues that we've already addressed, you can see some examples by going through the closed issues.)

This needs some more information and a closer investigation. But at the moment, I think the bug is not quite what is described in the OP.

[Abdillah]

Thanks! You're right down to the pixel. it is true that the resize event is send upon interaction.

The solution in my code (not the example, though) is to add similar to the raqote-winit, by listening to resize event and then add pixels.resize_buffer as well because it what makes the padding gone completely.

[parasyte]

Just keep in mind that the resize_buffer() method changes the physical resolution of the pixel frame buffer instead of just scaling. There is an open PR that attempts to implement non-integer scaling (while maintaining the highest quality sharp pixel definition): #262. The PR has some unresolved issues.

[Abdillah]

resize_buffer() method changes the physical resolution

Right, on the raqote-winit demo, I tried to resize the buffer but forgot that the DrawingTarget must be resized too. The result was such distortion.

There is an open PR that attempts to implement non-integer scaling

That would be a great feature.

My main concern in the OP has been solved, so closing this..