Using raster images with scale factor

[Studiedlist]

I want to use my application with high dpi screens, and so need to use scaling factor. But when I do so, all raster images are rendered upscaled.

(You can clearly see how font on raster image is upscaled)

Is it possible to somehow render raster images taking scale factor into account?

[Studiedlist]

I have managed to solve this.

All you have to do is to provide image with dimensions adjusted for scale factor, and enable image scaling by setting image-fit to fill, contain or cover.

Consider this example:

Image {
	width: floor(parent.width / 1px) * 1px;
	height: floor(parent.height / 1px) * 1px;
	image-fit: contain;
	source: Boards.render_board(
		board, 
		self.width * ScaleFactor.value,
		self.height * ScaleFactor.value,
		{ show_rulers: true }
	);
}

* ScaleFactor is global exported by my program, where value is set by rust code to represent SLINT_SCALE_FACTOR

Here, render_board callback returns an image with dimensions that are greater than element width and height by ScaleFactor.value times.

Then, as far as I understand, slint would scale this image down to fit Image element area, but this scaling is cancelled out with global scale factor, and so image ends up being rendered without upscale.