Third-Party Devs Will Be Able to Access iPadOS Apple Pencil Latency Improvements for Art Apps

Apple in iPadOS introduced some performance improvements between the iPad Pro and the Apple Pencil, cutting latency from 20ms to 9ms with the new software.

Third-party developers who make apps that use the ‌Apple Pencil‌ will also be able to take advantage of some of these latency improvements, Apple software development chief Craig Federighi confirmed last week.

ipadproapplepencil
Federighi shared the information in a response to an email sent by Artstudio Pro developer Cladio Juliano, who tweeted what Federighi had to say last week. The info was highlighted today in a tweet by developer Steve Troughton-Smith.

In the email, Federighi explains that third-party developers have had access to predicted touches via UIKit since iOS 9, and with iOS 13, developers will receive the "latest and greatest" touch prediction advancements in minimizing PencilKit drawing latency.

Federighi explains just how Apple introduced the latency improvements, and he points out that there's a small gap of 4ms that developers won't have access to at the current time because Apple didn't have a way to safely expose the capability to developers. From Federighi's email:

Note that we achieve low latency through a combination of several techniques: Metal rendering optimizations, touch prediction, and mid-frame event processing. Third-party developers can achieve similar low-latency drawing experiences by taking advantage of Metal rendering and touch prediction best practices covered in the WWDC Sessions I've referenced below.

With these you can achieve nearly all of the improvements you've seen in PencilKit drawing with your own renderer. (There does remain a small gap: 4 ms of our improvement comes from a technique called mid-frame event processing; we are looking for ways to expose this capability to third party engines in the future, but for this year this one was only safely achievable through tight integration within our frameworks).

For developers, the WWDC sessions Federighi suggests include PencilKit, Adopting Predicted Touches, and Metal Performance Optimization.

In a nutshell, the information shared by Federighi confirms that third-party apps that take advantage of the ‌Apple Pencil‌ will be getting some of the same latency improvements that we'll be seeing when using the ‌Apple Pencil‌ within native functions like Markup.

The ‌Apple Pencil‌ latency improvements are built into iPadOS, the version of iOS 13 that is designed to run on the iPad. All of Apple's current iPads support the ‌Apple Pencil‌. ‌iPad Pro‌ models work with the ‌Apple Pencil‌ 2, while the 6th-generation ‌iPad‌, iPad mini, and iPad Air work with the original ‌Apple Pencil‌.

Top Rated Comments

thisisnotmyname Avatar
21 months ago
I would have expected that was automatically exposed from the OS. I'm a bit surprised that they had to explicitly make some of those capabilities available to third party developers.
Score: 12 Votes (Like | Disagree)
cocky jeremy Avatar
21 months ago
I mean... duh?
Score: 6 Votes (Like | Disagree)
cmaier Avatar
21 months ago

I would have expected that was automatically exposed from the OS. I'm a bit surprised that they had to explicitly make some of those capabilities available to third party developers.

It is, if you use the appropriate control. But developer’s may want to integrate it into their own canvas or controls. In which case it is harder to expose it since things you do in your own code can interfere with the ability of the pen code to get the cycles it needs from the GPU and CPU.
Score: 4 Votes (Like | Disagree)
nexusrule Avatar
21 months ago

How nice of Apple. You would think they would limit functionality improvements to their own apps.

I think you don’t know how development works. When you start creating code you can’t always abstract it in a way that’s usable by third party devs through an API. What Federighi meant is right now the code that allow for that part of delay reduction is split between different of Apple software technologies. To be made safely accessible to others devs it needs to be abstracted, made indipendent, because private frameworks can’t be exposed for security reasons. You build these frameworks after you have the working feature, it’s simply impossible to abstract a solution that doesn’t exist. And this sort of work can require a massive rewrite of some parts of the relevant underlying technologies, and it requires time.
Score: 4 Votes (Like | Disagree)
NickName99 Avatar
21 months ago
I love that he gets into such detail. That’s interesting about the 4ms improvement they got using something they apparently can’t expose as a public method without some risk.

Now I’m curious about “mid-frame event processing”, but googling it hasn’t immediately got me anything.
Score: 4 Votes (Like | Disagree)
Cayden Avatar
21 months ago

I love that he gets into such detail. That’s interesting about the 4ms improvement they got using something they apparently can’t expose as a public method without some risk.

Now I’m curious about “mid-frame event processing”, but googling it hasn’t immediately got me anything.

Now I’m not sure so take this with a grain of salt, but as an engineer I’m inclined to believe “mid-frame event processing” means they are updating some pixel information (likely just the pixels associated with the pencil) in between frame updates in which all pixel information is updated and displayed. In other words, in between hardware detections of the pencil location, software would update where it presicts the pencil to be on the next update, and it can start looking for the pencil there instead of looking arbitrarily, mean the location can (usually) be found quicker. What I’m not sure about is if these pixels are actually being updated mid-frame or if the processing is simply keeping this information stored until the next frame is ready to update. I can’t see how the pixels could be updated mid-frame unless they had an individual refresh rate, so I’m inclined to believe the second case. If it’s the second case, it would make sense why Apple doesn’t want to give developers access to this, as this could quickly lead to timing errors between the software and hardware interrupts, such that it would only work within Apple’s framework and not an arbitrary code framework.
Score: 3 Votes (Like | Disagree)

Top Stories

iphone 5s black slate

Images of Unreleased iPhone 5s in Black and Slate Shared Online

Sunday January 17, 2021 9:47 am PST by
Twitter user @DongleBookPro has today shared images of a prototype iPhone 5s in an unreleased Black and Slate color. The iPhone 5s was launched in September 2013. The device featured Touch ID, a 64-bit processor, and a True Tone LED flash for the first time. Other new features included a five-element lens with an f/2.2 aperture, a 15 percent larger camera sensor, Burst Mode, and Slo-Mo...
iP12 charge airpods feature 2

Hidden iPhone 12 Hardware Feature Could Still be Unlocked

Thursday January 14, 2021 2:51 am PST by
All iPhone 12 and iPhone 12 Pro models purportedly have a hidden reverse wireless charging feature, according to an FCC filing. The feature has not yet been activated, but could yet be unlocked for an upcoming Apple accessory. The FCC filing suggests that iPhone 12 models contain the hardware for Wireless Power Transfer (WPT) to accessories: In addition to being able to be charged by a...
Top Stories 43 Feature

Top Stories: MacBook Pro, iMac, Mac Pro, and iPhone Rumors, Best of CES 2021

Saturday January 16, 2021 6:00 am PST by
This week was sure a busy one in the Apple world, with a flurry of announcements out of CES early in the week followed by a rash of Mac- and iPhone-related rumors later in the week. The new rumors this week included details on updated MacBook Pro, iMac, and Mac Pro models, as well as a few other tidbits, so make sure to read on below to get caught up! Kuo: New MacBook Pro Models to...
macbook pro flexgate

Apple Extends 13-Inch MacBook Pro Backlight Repair Program

Sunday January 17, 2021 10:31 am PST by
Apple this week extended its worldwide 13-inch MacBook Pro Display Backlight Service Program, authorizing coverage for eligible notebooks for up to five years after the original purchase date or up to three years after the start date of the program, whichever is longer. The previous cutoff was four years after the original purchase date. Apple launched the program on May 21, 2019 after...
foldable iPhone concept feature

Apple Testing In-Display Fingerprint Sensor for iPhone 13, Foldable iPhone Also in the Works

Friday January 15, 2021 1:46 pm PST by
Apple has started "early work" on an iPhone that has a foldable display, according to a new report from Bloomberg's Mark Gurman. Though testing of a foldable iPhone has begun, Apple has not committed to releasing a device that has a foldable display. Development has not yet expanded beyond a display and Apple does not have full foldable iPhone prototypes in its labs. Like foldable...
google maps detailed street level e1611052089473

Google Maps Gains Enhanced Street-Level Detail in Four Major Cities

Tuesday January 19, 2021 2:34 am PST by
Google Maps has quietly been updated to include significantly more detailed street-level information in a handful of key cities around the world. Upon zooming in, Google's maps for Central London, Tokyo, San Francisco, and New York now benefit from shapes and widths that match the scale of roads more accurately. Meanwhile, enhanced graphical representations of sidewalks, crosswalks,...
16inchmacbookpromain

Kuo: New MacBook Pro Models to Feature Flat-Edged Design, MagSafe, No Touch Bar and More Ports

Thursday January 14, 2021 9:32 pm PST by
Apple is working on two new MacBook Pro models that will feature significant design changes, well-respected Apple analyst Ming-Chi Kuo said today in a note to investors that was obtained by MacRumors. According to Kuo, Apple is developing two models in 14 and 16-inch size options. The new MacBook Pro machines will feature a flat-edged design, which Kuo describes as "similar to the iPhone 12" ...
macbook pro screensaver table

Some M1 Macs Affected By Fast User Switching Screensaver Bug

Monday January 18, 2021 1:57 am PST by
A growing number of user reports online suggest some of Apple's M1 Mac models are susceptible to a Fast User Switching bug that spontaneously activates the screensaver and leaves the user unable to dismiss it. In macOS Big Sur, Fast User Switching allows users to quickly switch between user accounts without having to completely log out. Based on posts in the MacRumors forums, Apple...
iphone x camera close

iOS 14.4 Will Introduce Warning on iPhones With Non-Genuine Cameras

Thursday January 14, 2021 8:07 am PST by
In the second beta of iOS 14.4 seeded to developers and public testers this week, MacRumors contributor Steve Moser has discovered code indicating that Apple will be introducing a new warning on iPhones that have had their camera repaired or replaced with aftermarket components rather than genuine Apple components. "Unable to verify this iPhone has a genuine Apple camera," the message will...
apple fitness plus burn bar

Fitness+ Subscribers Now Have Nearly 300 Workouts to Choose From

Monday January 18, 2021 3:24 am PST by
Apple on Monday added over two dozen new video workout sessions to Fitness+, continuing a recent trend of building out the catalog of its fledgling subscription service on a weekly basis. Fitness+ launched December 14, 2020, and is designed to help Apple Watch owners keep fit through a series of guided workouts that are available across multiple workout categories. As you follow along with...