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Old 12-17-2020, 12:51 PM   #1
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fbink image scaling question

Hi NiLuJe,
So I am printing small images using fbink, and they seem to be getting scaled in a manner I don't understand. For example:
fbink -i pic1.png -g halign=CENTER,w=775,y=690 -q'

No matter how small I make (pixel dimensions) the .png file, it seems to print at the same large size. w value remains unchanged What am I missing?

Thanks for the help!
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Old 12-17-2020, 01:22 PM   #2
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Because setting w *requests* scaling (it stands for width ^^).

Since I see an y flag right after, perhaps you meant to be using x here instead?

(When in doubt, enable verbose mode, it'll spout a *lot* of crap about what's happening and why ^^).
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Old 12-17-2020, 02:30 PM   #3
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ahhh - so w is not a scaling factor, it is an absolute width in pixels? Is there a scaling factor option in fbink, or a scaling factor in vertical pixels?

Last edited by handyguy; 12-17-2020 at 04:37 PM.
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Old 12-17-2020, 04:56 PM   #4
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The only thing that works with a plain factor is the fixed cell font rendering.

For images, scaling indeed works as "get me a wxh image out of whatever I'm feeding you". (Or a best fit for w; a best fit for h; a best fit for screen; there's a few magic values/combinations to achieve that, but the default is to keep the AR).

The assumption being that you know the screen size, you know the specific area you want to fill, so you don't really care about the source's size.

----

That said, it's entirely possible to request the image's dimensions without fully decoding it (for... most image formats, anyway), but that's not something that's currently exposed, even to API users.

I might revisit that later when I try my hands at a NanoSVG frontend, because knowing the optimal raster size for those *does* make sense, but it's highly unlikely to end up being exposed to the CLI tool, only to API users.

Last edited by NiLuJe; 12-17-2020 at 04:59 PM.
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Old 12-17-2020, 05:03 PM   #5
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When in doubt, read the giant wall of text that stands as documentation for the CLI-tool ^^. Here, specifically this section.

(I keep forgetting to add a real --help flag, mainly because the short -h is already taken for invert for... non-obvious reasons unless you've ever used eips on Kindle ;p. But it's currently displayed when no arguments are specified).

Or, the slightly less daunting and much better organized wall of text inlined in the API doc.
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Old 12-17-2020, 05:05 PM   #6
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Sidebar: it's not nearest neighbor scaling (it's Qt's smooth scaling algo), so choosing a "perfect" scaling factor won't help you much, FWIW .
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Old 12-17-2020, 07:01 PM   #7
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I should read the documentation once in awhile! Actually, I have copied the full fbink help text to a flat file for review purposes. I have changed the w parameter to h, and it does exactly what I want - any image displayed exactly at a specific height.
Thanks!

Last edited by handyguy; 12-18-2020 at 01:26 AM.
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