CODEWITHSUNDEEP
javaswtjface
ohmu
ohmu

Reputation: 19752

How do you utilize SWT's Hi-DPI support for widget sizing?

Does SWT (or JFace) have a public convenience method for converting conventional units to their scaled counterparts? I've found mention of a DPIUtil class but that's part of an internal namespace

If there's not a convenience method available, then is there a reliable way to access the zoom level? I see there's Device#getDeviceZoom() but that is protected. There is Device#getDPI() which is public so it might be useful. Does that take scaling into consideration, or is it naïve and just declares that DPI is 96 for everything?

I'm applying default sizing hints to some panels and I'd like them to take the monitor scaling setting into consideration. E.g., Say on a regular display I want the default to be 300px, but at 150% scaling I want to calculate it to be 450px. The calculation is obviously simple but I need the multiplier.

NOTE: This is related but different from my previous question How do you utilize SWT's Hi-DPI support for icons? because SWT provides classes to specifically handle this with images.

Upvotes: 0

Views: 422

Answers (1)

greg-449
greg-449

Reputation: 111142

I haven't found anything other than DPIUtil for determining the scale (zoom) factor.

But you don't normally need this information. Specifying a size of 300px will be automatically scaled to 450px by SWT on a 150 scaled device (and any 150 scaled image you provide will be used). I have an iMac with two screens - a 5k screen scaled at 200 and a 2.5k screen not scaled - SWT apps appear the same size on both.

The scaling is actually done in the OS rather than SWT (at least that is how it works on macOS). The OS scales up the sizes, renders fonts at the higher resolution and uses the high resolution images if available. So programs don't need to do anything other than provide hi-res images.

This way even old programs that don't know about zoomed displays still appear at a sensible size.

Upvotes: 1

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