CODEWITHSUNDEEP
macosretina-display
avalys
avalys

Reputation: 3752

How to display 1:1 on a rMBP when not running in "Best for Retina"

Let's say I have a rMBP, and an image that is 1000x1000 pixels.

If I display the image onscreen at 1:1 while running the MBP in "Best for Retina" mode, it will be displayed 1:1 on the actual retina display pixels (i.e. it will take up the same screen real estate as a 500x500 image on a 1440x900 screen).

However, if I then switch to one of the "scaled" resolution modes, e.g. 1680x1050, the system no longer displays the image 1:1, but scales it down (it occupies the same screen real estate as a 500x500 image on a 1680x1050 screen).

I would like a way to have the image continue to display 1:1 on the retina display, regardless of the system resolution in use. I realize that I could calculate an appropriate "scaled" size, and scale the image up so that when it is scaled back down it corresponds to a 1:1 mapping, but this results in a noticeable quality degradation.

When running the MBP in the "scaled" resolutions, does Apple not provide any way to control the on-screen pixels directly (bypassing the scaling for just a part of the screen)?

Upvotes: 3

Views: 653

Answers (2)

exclipy
exclipy

Reputation: 1508

Here are the APIs for addressing the pixels directly:

https://developer.apple.com/library/mac/documentation/GraphicsAnimation/Conceptual/HighResolutionOSX/CapturingScreenContents/CapturingScreenContents.html#//apple_ref/doc/uid/TP40012302-CH10-SW1

Upvotes: 0

user149341
user149341

Reputation:

No. Display scaling occurs at a very low level within the GPU and affects the entire display; there is no way to bypass it for part of the screen.

Look at it this way: If you set the resolution of an ordinary laptop's display to, say, 800x600, there is no way to display an image at the native resolution of the LCD, or to render content inside the black pillarboxes on the sides of the display. For all intents and purposes, the LCD is 800x600 while it's set to that resolution; the fact that it's actually (say) an 1440x900 display is temporarily forgotten.

The same principle applies to the MacBook Pro Retina display. The nature of the scaling is a little more complicated, but the "original" resolution of the display is still forgotten when you apply scaling, and there is no way to render directly to it.

Upvotes: 1

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