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Fix Fill options for non Fixed width options #2018
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Fix Fill options for non Fixed width options #2018
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I think that the current design is probably working as intended (I didn't write it) but maybe we should talk about whether or not that intention is correct? Basically: currently, if the size of the image widget is not explicitly constrained, then we size it to be exactly the same as the underlying image. For me, a "fill strategy" is only really relevant in a situation where we are fitting an image into a rectangle with different dimensions; if the image and the target dimensions match exactly, then all fill strategies should perform equally? Another way to think about this: fill strategy is a function of the dimensions of the widget, but it should not influence the dimensions of the widget. In this current implementation, the size of the widget changes (often dramatically) based on the selected fill strategy. I'm not sure this is desirable. In any case, I'm just trying to express my current understanding, it is very possible that I'm overlooking something and I'd be happy to discuss further! |
So if the The issue i had is that if i just want the image to fill up the space available to the widget, I cant, I can explicitly set the size of the widget but if i just want to have a widget that take up the available space the widget could fill i have to write my own widget.
I was thinking of it of how the image fills the space available to the widget. This change will never ask for more than In my original PR i included a example were one of the images expanded to fill the width #557 as seen I am just trying to get back to a place were you can do that will at least one of the options. BTW major kudos to every one who has worked on the example since the current one is much better, and is really nice with all the options and things. If this is ok I can ether add the svg layout to this PR or have a second as especially for that widget it make a lot of sense for it to fill up. |
The image explicitly doesnt scale up to the max size it can take, because if you put the image in a so
However I dont think the current code takes the |
Im happy to help but i don't really get what my responsibly/roll as a widget author is with regard to layout. This PR is my best gues but if you can give me a more detailed spec of what the layout function should do i can update it accordingly.
I don't know how flex works but dose it not pass a semi sensible My use case is, buttons at the top that control a simulation and then a gif/image as a output. and I want the image/output to just fill the rest of the window. |
There are a couple cases
This is what the code currently does, and I am not exactly sure what case you want to change and how. It also seems that your code doesnt retain aspect ratio. |
Ok so:
All just work if you have And if you want:
Then you want AFAICT the only time the aspect ratio is not fixed is when using The reason that I made this PR is that this widget used to behave like https://api.flutter.dev/flutter/painting/BoxFit-class.html and now it dose not so i thought that was a bug that I can help fix. This PR dose cater for your use cases, see above. But it also caters for use cases where the user wants to let the image be scaled up but not to a fixed amount. This is my use case and the image widget has regressed for my use case. If you just dont want to support this use case then I can close the PR. |
What do you mean? To what do you want it to be scaled? to the width of the flex? That should already be possible, thats what it should currently do. (assuming the flex's width is fixed, and you have a column flex. height otherwise.) |
I just want the image to scale up to the size of the window. The image example demonstrates it perfectly, untick the 2 constraints. and select something like
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druid/src/widget/image.rs
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if bc.is_width_bounded() { | ||
width = width.min(max.width); | ||
} | ||
if bc.is_height_bounded() { | ||
height = height.min(max.height); | ||
} |
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I think the strategy to use affine_to_fill
is probably good. However this doesnt take into account when both sides are unbounded.
In my if else chain the first 2 should remain the same, since this takes into account being inside unbounded parents. This code should only apply if its bounded on both sides, since affine_to_fill
is not made for unbounded constraints. In the last case where all sides are unbounded it should use the bc.constrain(self.image_data.size())
code (Which could be simplified to self.image_data.size()
since bc is unbounded).
The reason the code is the way it is now, is so that we dont return an infinite size when unbounded in either direction. Since your code doesnt take into account being unbounded on either side we still need these safeguards using a different implementation.
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Since your code doesnt take into account being unbounded on either side we still need these safeguards using a different implementation.
But this code never returns a unbounded result. and some of the fill strategies call for more than the image. So letting affine_to_fill
determine the result dose all the work you are asking for when you want it and other things for the other fill strategies.
self.fill.affine_to_fill(max, image_size)
takes the max size the widget may be to not change the window size, this gives it a max
to work with. then it also knows the original image size, image_size
. so for no scale
or scale down
the max it asks for the smallest of original image or the space available.
affine_to_fill
is doing the guarding its self in the non-constrained
case and most of the constrained cases, only for a few edge cases do the two if's every have to do anything.
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I was looking at this code and realised I can simplify it without changing the behaviour of the demo at all. Also by having less branching it makes it simpler for the cpu so might be a tiny tiny bit faster.
I have added some comments that might make it easer to under stand as well.
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But this code never returns a unbounded result
It does, when the constraints are unbounded the resulting size of the image could be infinitely big. Since there are no checks for this this infinity will traverse it's way through the calculations into the final size.
or the space available.
that's the problem, the space available could be infinite in either direction.
druid/src/widget/image.rs
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@@ -190,19 +190,22 @@ impl<T: Data> Widget<T> for Image { | |||
bc.debug_check("Image"); | |||
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// If either the width or height is constrained calculate a value so that the image fits |
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Use the fillstrat to determine the size of the image so that the the image will fit perfectly using this filstrat. If it is unconstrained by both width and height take the size of the image.
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The problem is that some of the fill strats do take the size of the image but other strategies do not so your alternative is self contradicting.
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oh I see, I mean the size of the underlying image data.
I made some comments, I think I understand the problem now. Thanks for your comments. Your patch indeed fixes the problems outlined by you, but it doesnt keep working in the problems outlined by me. So I suggested some changes so that it will keep working in cases I had problems with when I changed the code. |
@JAicewizard and @cmyr i really don't understand "However this doesnt take into account when both sides are unbounded." or "Since your code doesnt take into account being unbounded on either side we still need these safeguards using a different implementation." Here are two screen shots of the PR with If I am still miss understanding can you please give me details of how to recreate the issue? |
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This is because the examples constrains the image within the window. If you dont do that by using something scroll able it will give errors. You can check if the given bounds are constrained using See #1189 for fix and issue. (the one where I changed the code to what it is now) |
That makes sense, thanks for explaining the case. yes i can see that the original didnt do a good job in that case but this new code will work according to the flutter guidance in that case AFAICT. I don't know what flutter dose in that use case with the fill strategy but the new code should behave sensibly for But the fill strategies I think its a shame to rule out a hole class of UI because some of the fill strats dont' make sense in that use case. If the image gets too far out of AR or toooo big then we could clip them? Now I finally under stand your use case, i might be able think of something else.. |
This is what i meant by
I have not seen a case were bc.max() did not give a non integer or non sensible value. Even when non contained it still gives sensible values most of the time. it would be easy to check @cmyr / @JAicewizard are there any other |
Okay, I wrote a thing here but I think it's actually not the most useful response. Instead, I want to just point to the flutter docs for Some things to note:
Anyway: my basic position would be to emulate what flutter is doing, as closely as possible. Without adding a new widget, this means:
What is important here is that we separate the applying of the constraints from the determination of the widget size. It is not the responsibility of the image widget to choose a size, outside of ensuring that it satisfies the input constraints. If you need to do fancier things to grow or shrink your widget in a given scenario, you should be accomplishing that with some other layout widget. |
Now I understand the case were you can have infinite bc.max() I think i have caught this edge case and do something sensible for it in the latest version of this PR. But i had not understood the subtlety of flutter and druids layout so while this now restores the old functionality while also addressing the infinite edge case I'm not sure that the original behaviour was right. But @cmyr how would you ever get the image to be big? even if it was in a layout widget the current code in master would always just return the image's max? would a layout widget just ignore the image widget and force the image bigger? what are the rules for the images layout function in that case? dose one of the examples cover something like this? even with a completely different widget? |
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Thinking about this a bit more. Its worth noting that the code in master dose |
The parent layout widget would only influence the child by modifying the constraints. For instance if you had received constraints that were (0,0) (500,500) you could output 'tight' constraints that were (500,500), (500,500). This is achievable by built in widgets, and if you needed more complicated conditional logic you could have a custom container widget that implements it. I definitely agree that the original (and all subsequent!) impls of the image widget, in druid, have had incomplete implementations of the layout fn. I think the best approach is to step back and try to just think this through systematically, instead of trying to achieve some specific set of layout objectives. |
I don't understand this. Are the responsibilities of the layout fn documented some were, the trait docs were a bit light IIRC.. edit: eg: the layout returns a size , wich i understand to be (x,y) not (x,y) (x,y) |
Sorry, I was composing that on my phone and I wasn't done, I guess it posted it after some timeout? Not sure. The way that a parent widget influences a child's layout is by modifying the For a good overview of how this works, check out the flutter docs for |
You dont have to, your code works perfectly fine when everything is constrained and we can use it in that case. The only case it doesnt cover is when either sidie (or both ofc) is unconstrained. This is what my code handles, so you can combine them as I described in my review.
Could you maybe explain a bit more? The I think the widget should chose a size it will actually use, aka not take more space than actually needed. And this being an image widget I would also say that it is usefull to take the maximum size we will end up using (with accordance to the fillstrat). |
let mut max_width = bc.max().width; | ||
let mut max_height = bc.max().height; | ||
let mut fill_strat = self.fill; | ||
if max_width == f64::INFINITY && max_height == f64::INFINITY { |
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Please use bc.is_xxx_bounded
.
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These detect times when it would note be safe to use the max so they work quite differently. ah yes
fill_strat = match fill_strat { | ||
FillStrat::FitWidth if max_width == f64::INFINITY => FillStrat::Contain, | ||
FillStrat::FitHeight if max_height == f64::INFINITY => FillStrat::Contain, | ||
FillStrat::Cover | FillStrat::Fill => FillStrat::Contain, | ||
_ => fill_strat, | ||
} |
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This effectively the same code as I had, but much more convoluted. It is more clear to use the already existing code in this case (and the if statement on line 200-205 as well). Maybe it would be nice to have a match on (bool,bool)
for the boundness of each axis and have clean fast code for each case.
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I don't believe this does behave very much like your code out side of the options that fall back to Contain.
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Ah yes I see I missed 2 cases.
@cmyr If i understand correctly fishrockz@a123167 would be much more idiomatic of fluter. BUT it will cause issues with the srollbar/srollbox with some fill options in paint (paint will crash as @JAicewizard points out). Am I right in thinking that flutter would error out at the layout stage in this case? https://flutter.dev/docs/testing/common-errors#vertical-viewport-was-given-unbounded-height this seems to imply that flutter just refuses to layout a widget if something silly was going to happen? Our layout dose not provide a option to return a error so I'm not sure what to do with that case, I presume you dont want the layout to panic? I can detect the issue at paint time and paint a big error message instead of crashing? I think the most pragmatic option is to do the min/max thing but with some logic to detect |
if the input constraints are not bounded, the image widget should ignore It is very possible in druid to produce a layout that is not meaningful/is poorly formed, like when you |
Right but AFAICT the reason that @JAicewizard updated this widget last was that druid was not if layout returns the minimal box constraint which in that case would be fixed width but inf height, then at paint we detect the inf and just paint everything red or just return early without doing anything to the context? Would we log some errors in the paint function or the layout function? do you have a example of this? |
Also expanding on the If FillSrat is I don't really understand flutter enough to know what the write answer is. Also in general: If I'm only ever going to paint some of the screen because I have |
What's the status of this PR? Are we still moving foward with it @fishrockz? If so, then please rebase on |
Excellent, having this rebased will help me test the code too. I'll read through the earlier messages here tomorrow to better understand the history of concerns. |
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@xStrom i have rebased to master If you check out master and run But if you checkout this branch and run It seems cmyr wanted the flutter behaviour than rather than ether of our behaviours. I did try to get closer to the flutter behaviour, i even have another non pushed branch trying to get there but without a working flutter system to test ageist i was struggling to understand exactly what flutter did. |
Hi, long time since I last contributed but I have been making a little GUI for something I was working on and notice that the image demo's filling seemed broken.
I have not go my head round the layout function so any feed back on how this should work would be appreciated :)