Unexpected: calibre 3.0 high-dpi support looks weird

Katsunami · 06-19-2017, 07:35 AM

Hi

It seems high-dpi support was requested often, but I have never missed it. Actually, it even looks/looked like as if Calibre 2.x has always had it; at least since the move to Qt5. I never used calibre's Qt4 versions on a high-dpi screen.

It never looked blurry on my high-dpi laptop screen. It's always looked perfect. (1920x1080 @ 15.6 inch, set at 150%, effectively displaying 1280x720; I'm unable to read 1.25x and 1.0x settings.)

So, I wondered what high-dpi support for calibre 3.0 would add.

For me, it does nothing, except to make the interface positively huge, with *a lot* of white space, especially in the tag browser. It even becomes very hard to work with the program, as all dialogs are huge. I've disabled high-dpi support, and now calibre 3.0 looks the same as 2.85.1 again. (And no, it isn't blurry, as far as I can see.)

So, to be honest, I don't really understand what calibre's high-dpi support does add. For me, it's been there all along

Any thoughts? Maybe there's a bug somewhere?

JSWolf · 06-19-2017, 07:38 AM

Calibre never looked blurry or off in any way on my 2560 x 1440 desktop monitor. I never did see a need for high-DPI support as it wasn't a problem.

kovidgoyal · 06-19-2017, 08:28 AM

You dont actually have a high DPI screen, so...

The main thing that high DPI support does is make the icons and other graphics look sharp on an actual high dpi screen. At 1.5 you wont notice anything. Try it in on an actual high dpi screen with a factor of 2.0 sometime.

JSWolf · 06-19-2017, 08:30 AM

Quote:

Originally Posted by kovidgoyal

You dont actually have a high DPI screen, so...

The main thing that high DPI support does is make the icons and other graphics look sharp on an actual high dpi screen. At 1.5 you wont notice anything. Try it in on an actual high dpi screen with a factor of 2.0 sometime.

Should try Calibre on my 4K TV? That's as high as I can go.

pclewis · 06-19-2017, 09:02 AM

On my 2560X1600 laptop it is significantly better. So much so that I sent in another donation. I have used Calibre for many years. It keeps getting better. Keep it up.

Phil

Katsunami · 06-19-2017, 09:24 AM

Quote:

Originally Posted by kovidgoyal

You dont actually have a high DPI screen, so...

The main thing that high DPI support does is make the icons and other graphics look sharp on an actual high dpi screen. At 1.5 you wont notice anything. Try it in on an actual high dpi screen with a factor of 2.0 sometime.

That's a 141 dpi screen. It's either impossible or very uncomfortable to read anything with the scaling set to 1.0, even for people with normal (non-poor) eyesight. I know a few people who can use a laptop as such, but they have 120%+ vision compared to normal, which is quite rare.

Maybe it's just me, but I consider everything above 96 dpi a high-dpi screen. I don't know if Windows 10 or the Creator's Update changed anything, but AFAIK, Windows can't even go higher than 2.0x. (On my laptop it already stops at 1.75x.)

What high-dpi support also does, is make sure that letters aren't blurry. Calibre never had blurry letters at a setting of 1.5x, whereas Scrivener, which claims to have high-dpi support does. If I disable the high-dpi support in the compatibility options of Scrivener and then set a larger font in the program, everything is not blurry, but the user interface is super-tiny.

So what it high-dpi in your opinion; 200 dpi? 300? Even more? I could have bought my laptop with a 3200x1800 screen, but that would have been unusable with most software I use.

kovidgoyal · 06-19-2017, 10:02 AM

I really dont want to get into a pissing contest about what is high DPI. If you dont like what high DPI scaling does on your setup, turn it off, that is why I provided the option.

Katsunami · 06-19-2017, 11:50 AM

I understand that. I'm not trying to convince you that my laptop screen is high-dpi or anything. I only have the feeling that calibre (Qt5) already provides some high-dpi scaling out of the box. Maybe the new option scales calibre on its own, but on top of the default 1.5x provided by the OS (and possibly, Qt), which would explain why the interface is so large after enabling high-dpi support.

kovidgoyal · 06-19-2017, 12:13 PM

DPI scaling is complicated. There are two basic components two it. Text and vector images are the first. Raster images are the second.

On windows, the OS can decide to either handle the scaling itself or let the application do it. If the application indicates it can do it, windows usually lets it do it itself. calibre has always indicated that it can do it, because of the two components, it has always been able to draw text correctly. This is because font sizes in calibre are specified in pts which are an absolute unit and resolution independent.

However, while text sizes are in pts, UI element sizes and images sizes are in pixels, which are resolution dependent, inthe sense that the actual physical space they take up on the monitor depends on the monitor resolution. The "perfect" way to solve high DPI issues is to go through all the UI code and convert everything everywhere to use resolution independent sizes, however, for something of calibre's size that is impossible. So Qt, as of version 5.6 provides a "hack". This hack works like high DPI support on macOS and all browsers. Basically, the pixel no longer means a physical pixel on the screen, but is instead a virtual unit scaled by the DPI scaling factor.

So now, text is still sized in pts but the rest of the UI is sized in virtual pixels. The idea being that the virtual pixel based sizes should more closesly correspond to the text sizes.

Now, you have been running at 1.5 DPI which means that, in calibre, you were in effect increasing the text size relative to the rest of the UI elements, in calibre 2.x

In calibre 3.x, with scaling turned on, that is no longer the case. UI elements are also scaled by 1.5. This will look weird to you because you are used to the UI with relatively large text and small padding around it. All the saved dialog sizes on your sytem will now be too large because the pixel is now 1.5 times larger than it was.

So if you were happy with how calibre looked in 2.x your best bet is to just turn off high dpi scaling and be on your merry way. However, if you have a high resolution enough monitor/sharp enough eyesight/nitpicky enough personality that slightly pixelated images and ratio of text sizes to UI element sizes being off bothered you, then you will like the scaling.

kovidgoyal · 06-19-2017, 12:24 PM

I should add, that calibre changes only happen for people who were previously running at a scaling factor of something other than 100% in the OS. If you were at 100% in the OS previously, calibre 3 will continue to look just like it did before.

Katsunami · 06-19-2017, 12:30 PM

Thanks for the clarification. That explains why I have a very small font size set in calibre (8 points), which still looks as big as about the 10 or 11 points I set on my previous laptop.

So yes, I'm used to a 'normal' calibre GUI, with somewhat larger text than normal; if programs have their own font settings, this is the case for all other software I use as well. Actually, in most cases, I don't need a larger GUI; only slightly larger text. And thus, on Windows 10, I set a scaling factor of 1.5x, to obtain the GUI size and text I'm used to (with most software), and add a little bit of extra text size.

So in calibre, the GUI is already fine for me, and its own high-dpi text scaling provides the somewhat larger text.

06-19-2017, 07:35 AM	#1
Katsunami Grand Sorcerer Posts: 6,111 Karma: 34000001 Join Date: Mar 2008 Device: KPW1, KA1	Unexpected: calibre 3.0 high-dpi support looks weird Hi It seems high-dpi support was requested often, but I have never missed it. Actually, it even looks/looked like as if Calibre 2.x has always had it; at least since the move to Qt5. I never used calibre's Qt4 versions on a high-dpi screen. It never looked blurry on my high-dpi laptop screen. It's always looked perfect. (1920x1080 @ 15.6 inch, set at 150%, effectively displaying 1280x720; I'm unable to read 1.25x and 1.0x settings.) So, I wondered what high-dpi support for calibre 3.0 would add. For me, it does nothing, except to make the interface positively huge, with a lot of white space, especially in the tag browser. It even becomes very hard to work with the program, as all dialogs are huge. I've disabled high-dpi support, and now calibre 3.0 looks the same as 2.85.1 again. (And no, it isn't blurry, as far as I can see.) So, to be honest, I don't really understand what calibre's high-dpi support does add. For me, it's been there all along Any thoughts? Maybe there's a bug somewhere? Last edited by Katsunami; 06-19-2017 at 07:41 AM.

06-19-2017, 09:02 AM	#5
pclewis Enthusiast Posts: 32 Karma: 14644 Join Date: Jan 2007 Location: Texas Device: Kobo Aura One	Much better On my 2560X1600 laptop it is significantly better. So much so that I sent in another donation. I have used Calibre for many years. It keeps getting better. Keep it up. Phil

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06-19-2017, 07:38 AM	#2
JSWolf Resident Curmudgeon Posts: 73,957 Karma: 128903250 Join Date: Nov 2006 Location: Roslindale, Massachusetts Device: Kobo Libra 2, Kobo Aura H2O, PRS-650, PRS-T1, nook STR, PW3	Calibre never looked blurry or off in any way on my 2560 x 1440 desktop monitor. I never did see a need for high-DPI support as it wasn't a problem.

06-19-2017, 08:28 AM	#3
kovidgoyal creator of calibre Posts: 43,850 Karma: 22666666 Join Date: Oct 2006 Location: Mumbai, India Device: Various	You dont actually have a high DPI screen, so... The main thing that high DPI support does is make the icons and other graphics look sharp on an actual high dpi screen. At 1.5 you wont notice anything. Try it in on an actual high dpi screen with a factor of 2.0 sometime.

06-19-2017, 10:02 AM	#7
kovidgoyal creator of calibre Posts: 43,850 Karma: 22666666 Join Date: Oct 2006 Location: Mumbai, India Device: Various	I really dont want to get into a pissing contest about what is high DPI. If you dont like what high DPI scaling does on your setup, turn it off, that is why I provided the option.

06-19-2017, 11:50 AM	#8
Katsunami Grand Sorcerer Posts: 6,111 Karma: 34000001 Join Date: Mar 2008 Device: KPW1, KA1	I understand that. I'm not trying to convince you that my laptop screen is high-dpi or anything. I only have the feeling that calibre (Qt5) already provides some high-dpi scaling out of the box. Maybe the new option scales calibre on its own, but on top of the default 1.5x provided by the OS (and possibly, Qt), which would explain why the interface is so large after enabling high-dpi support.

06-19-2017, 12:13 PM	#9
kovidgoyal creator of calibre Posts: 43,850 Karma: 22666666 Join Date: Oct 2006 Location: Mumbai, India Device: Various	DPI scaling is complicated. There are two basic components two it. Text and vector images are the first. Raster images are the second. On windows, the OS can decide to either handle the scaling itself or let the application do it. If the application indicates it can do it, windows usually lets it do it itself. calibre has always indicated that it can do it, because of the two components, it has always been able to draw text correctly. This is because font sizes in calibre are specified in pts which are an absolute unit and resolution independent. However, while text sizes are in pts, UI element sizes and images sizes are in pixels, which are resolution dependent, inthe sense that the actual physical space they take up on the monitor depends on the monitor resolution. The "perfect" way to solve high DPI issues is to go through all the UI code and convert everything everywhere to use resolution independent sizes, however, for something of calibre's size that is impossible. So Qt, as of version 5.6 provides a "hack". This hack works like high DPI support on macOS and all browsers. Basically, the pixel no longer means a physical pixel on the screen, but is instead a virtual unit scaled by the DPI scaling factor. So now, text is still sized in pts but the rest of the UI is sized in virtual pixels. The idea being that the virtual pixel based sizes should more closesly correspond to the text sizes. Now, you have been running at 1.5 DPI which means that, in calibre, you were in effect increasing the text size relative to the rest of the UI elements, in calibre 2.x In calibre 3.x, with scaling turned on, that is no longer the case. UI elements are also scaled by 1.5. This will look weird to you because you are used to the UI with relatively large text and small padding around it. All the saved dialog sizes on your sytem will now be too large because the pixel is now 1.5 times larger than it was. So if you were happy with how calibre looked in 2.x your best bet is to just turn off high dpi scaling and be on your merry way. However, if you have a high resolution enough monitor/sharp enough eyesight/nitpicky enough personality that slightly pixelated images and ratio of text sizes to UI element sizes being off bothered you, then you will like the scaling.

06-19-2017, 12:24 PM	#10
kovidgoyal creator of calibre Posts: 43,850 Karma: 22666666 Join Date: Oct 2006 Location: Mumbai, India Device: Various	I should add, that calibre changes only happen for people who were previously running at a scaling factor of something other than 100% in the OS. If you were at 100% in the OS previously, calibre 3 will continue to look just like it did before.

06-19-2017, 12:30 PM	#11
Katsunami Grand Sorcerer Posts: 6,111 Karma: 34000001 Join Date: Mar 2008 Device: KPW1, KA1	Thanks for the clarification. That explains why I have a very small font size set in calibre (8 points), which still looks as big as about the 10 or 11 points I set on my previous laptop. So yes, I'm used to a 'normal' calibre GUI, with somewhat larger text than normal; if programs have their own font settings, this is the case for all other software I use as well. Actually, in most cases, I don't need a larger GUI; only slightly larger text. And thus, on Windows 10, I set a scaling factor of 1.5x, to obtain the GUI size and text I'm used to (with most software), and add a little bit of extra text size. So in calibre, the GUI is already fine for me, and its own high-dpi text scaling provides the somewhat larger text.

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