Touch How to do Partial Refreshes

charleski · 06-17-2011, 10:16 PM

Ok, the partial screen refresh was a decent idea that just needs a bit of work. Speeding-up page-turns makes a lot of sense in some scenarios, but not in others, and it's pretty simple to modify the logic to account for this.

Let's look at the desired outcomes and work back from there:
1) When people are reading normally, they want the text to look as good as possible.
--> Perform a full screen refresh on forward page-turns that occur above a certain threshold. This threshold could, optimally, be related to the size of the font (a longer time for smaller fonts) and could be adjustable to allow for individual differences in reading speed.

2) When people are flipping through a book looking for a certain passage, they want the pages to turn as quickly as possible. This is something I do quite often. The slow speed of eInk page changes can become very annoying, and is something that is far easier in paper books. This is where you want to implement a speed-up in page-turning.
--> When page-turns occur below the threshold, only do a partial refresh. At some point you will need to perform a full refresh of the page, but that point can be varied (within limits) by the rate at which page-turns are requested. If you see a flurry of page-turns which suddenly ends, it's probably a good idea to perform a full page-refresh at that point since this implies the reader has found the section they wish to read (it's probably a good idea to display a banner announcing the refresh at this point).

3) Intermediate states: If the reader does a page-forward and then soon after does a page-back, then another page-forward, they're probably just making sure they caught the full sense of a sentence that has carried on from the previous page.
--> So do a partial refresh on the page-back and then a full refresh on the second page-forward.

These states can all be modified by a global refresh counter. But this should be modifiable by the user, so they can specify the number of partial refreshes they would tolerate for text that they're reading normally.

joshmosh · 06-18-2011, 12:53 AM

I honestly am fine if they add all this as options, but I think it complicates matters. I honestly believe that the full page refresh is fine and gives the best clarity which is the point of an ereader as you want crisp and clear text. Any partial refresh severely degrades the quality of the text.

Also, on the Kindle 3 the full page refreshes are VERY fast and they look fantastic. There is really no need for partial refreshes ever. It doesn't speed things up, it just looks prettier for the transition, but after that it looks bad as the text is less dark and crisp and you can see the old text faintly.

As I said, having options is great, but I personally don't think it comes down to speed.

06-17-2011, 10:16 PM	#1
charleski Wizard Posts: 1,196 Karma: 1281258 Join Date: Sep 2009 Device: PRS-505	How to do Partial Refreshes Ok, the partial screen refresh was a decent idea that just needs a bit of work. Speeding-up page-turns makes a lot of sense in some scenarios, but not in others, and it's pretty simple to modify the logic to account for this. Let's look at the desired outcomes and work back from there: 1) When people are reading normally, they want the text to look as good as possible. --> Perform a full screen refresh on forward page-turns that occur above a certain threshold. This threshold could, optimally, be related to the size of the font (a longer time for smaller fonts) and could be adjustable to allow for individual differences in reading speed. 2) When people are flipping through a book looking for a certain passage, they want the pages to turn as quickly as possible. This is something I do quite often. The slow speed of eInk page changes can become very annoying, and is something that is far easier in paper books. This is where you want to implement a speed-up in page-turning. --> When page-turns occur below the threshold, only do a partial refresh. At some point you will need to perform a full refresh of the page, but that point can be varied (within limits) by the rate at which page-turns are requested. If you see a flurry of page-turns which suddenly ends, it's probably a good idea to perform a full page-refresh at that point since this implies the reader has found the section they wish to read (it's probably a good idea to display a banner announcing the refresh at this point). 3) Intermediate states: If the reader does a page-forward and then soon after does a page-back, then another page-forward, they're probably just making sure they caught the full sense of a sentence that has carried on from the previous page. --> So do a partial refresh on the page-back and then a full refresh on the second page-forward. These states can all be modified by a global refresh counter. But this should be modifiable by the user, so they can specify the number of partial refreshes they would tolerate for text that they're reading normally.

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06-18-2011, 12:53 AM	#2
joshmosh Enthusiast Posts: 38 Karma: 12 Join Date: Jun 2011 Location: Canada Device: Kobo Glo, Kobo Touch	I honestly am fine if they add all this as options, but I think it complicates matters. I honestly believe that the full page refresh is fine and gives the best clarity which is the point of an ereader as you want crisp and clear text. Any partial refresh severely degrades the quality of the text. Also, on the Kindle 3 the full page refreshes are VERY fast and they look fantastic. There is really no need for partial refreshes ever. It doesn't speed things up, it just looks prettier for the transition, but after that it looks bad as the text is less dark and crisp and you can see the old text faintly. As I said, having options is great, but I personally don't think it comes down to speed.

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