Make collages resolution independent

[salutis]

This should make Elm more usable on modern systems with high-resolution screens. Tested with Retina MacBook Pro 15".
Related discussion: https://groups.google.com/forum/#!topic/elm-discuss/pq1KS8XgFiQ

[Apanatshka]

I took a look at the support for devicePixelRatio on MDN which in turn refers to PPK. I would suggest that you use a local variable and default the value to 1 if window.devicePixelRatio doesn't exist:

devicePixelRatio = window.devicePixelRatio || 1;

And please note that MDN says this property doesn't get updated if the browser is moved between screens with different device pixel ratios.

[Apanatshka]

I took a look at the support for devicePixelRatio on MDN which in turn refers to PPK. I would suggest that you use a local variable and default the value to 1 if window.devicePixelRatio doesn't exist:

devicePixelRatio = window.devicePixelRatio || 1;

And please note that MDN says this property doesn't get updated if the browser is moved between screens with different device pixel ratios.

[evancz]

Great, thank you so much! :D

I think there is one place that needs to know about the new initial scale though. Specifically when dealing with an Element inserted with toForm. I believe there's something like createTransform that needs its initial configuration updated.

[evancz]

Great, thank you so much! :D

I think there is one place that needs to know about the new initial scale though. Specifically when dealing with an Element inserted with toForm. I believe there's something like createTransform that needs its initial configuration updated.

[evancz]

Is there an event that triggers when windew.devicePixelRatio changes?

There is already a mechanism to do a redraw asynchronously (for images), so I assume that could be reused?

[evancz]

Is there an event that triggers when windew.devicePixelRatio changes?

There is already a mechanism to do a redraw asynchronously (for images), so I assume that could be reused?

[salutis]

MDN says: There are no callbacks or events to listen to when this value changes (for example, if you drag the window between displays with different densities).

[salutis]

MDN says: There are no callbacks or events to listen to when this value changes (for example, if you drag the window between displays with different densities).

[evancz]

Oh, I guess the toForm stuff should work the same, maybe I was wrong about that! Do you mind testing toForm thing to see if it is the right size?

Hmm, is there a recommended behavior for apps that need to cross from screen to screen? I assume going low to high is not a big deal, but is the reverse true?

Also, if the dimensions of the canvas are set initially, but then the scaling is done on a per-render bases, is it possible for them to get out of sync with each other?

[evancz]

Oh, I guess the toForm stuff should work the same, maybe I was wrong about that! Do you mind testing toForm thing to see if it is the right size?

Hmm, is there a recommended behavior for apps that need to cross from screen to screen? I assume going low to high is not a big deal, but is the reverse true?

Also, if the dimensions of the canvas are set initially, but then the scaling is done on a per-render bases, is it possible for them to get out of sync with each other?

[salutis]

@evancz, I've just tried to embed Clock using toForm like this:
collage 400 400 [(toForm (collage 400 400 ...
... and it works as expected. Is that what you saying?

[salutis]

@evancz, I've just tried to embed Clock using toForm like this:
collage 400 400 [(toForm (collage 400 400 ...
... and it works as expected. Is that what you saying?

[evancz]

Yeah, I was worried it might show up half size or something. Another example would be adding toForm (image 20 20 "http://elm-lang.org/yogi.jpg") and see if it comes out 20x20.

[evancz]

Yeah, I was worried it might show up half size or something. Another example would be adding toForm (image 20 20 "http://elm-lang.org/yogi.jpg") and see if it comes out 20x20.

[evancz]

Does the question about crossing from a normal monitor to a hi-DPI monitor make sense?

[evancz]

Does the question about crossing from a normal monitor to a hi-DPI monitor make sense?

[salutis]

@evancz No issues. This:
collage 400 400 [toForm (image 20 20 "http://elm-lang.org/yogi.jpg")]
... draws exactly the same output as with http://elm-lang.org/try.

[salutis]

@evancz No issues. This:
collage 400 400 [toForm (image 20 20 "http://elm-lang.org/yogi.jpg")]
... draws exactly the same output as with http://elm-lang.org/try.

[evancz]

Ah, I have read through the code all in one go and my concern is not realized there. Transferring from lo to hi should be no problem. Thanks a ton for working on this @salutis!

[evancz]

Ah, I have read through the code all in one go and my concern is not realized there. Transferring from lo to hi should be no problem. Thanks a ton for working on this @salutis!

[salutis]

My pleasure, @evancz!

[salutis]

My pleasure, @evancz!