image: constrain axes to domain, apply defaults whenever an image is present

[antoinerg]

Following #4307 (comment), this PR adds a smart default layout to constrain x and y axes to the domain if there is an image present.

The notion of a "smart default layout" is changed slightly in this PR for image. Now, the layout defaults will be applied to a subplot's axes whenever an image is present in the subplot. Adding a scatter on top will not affect the defaults. This is clearly tested in a very explicit (and probably redundant) series of jasmine tests.

[etpinard]

I think we need to reset to null as we're in a loop:

var axNames = ['xaxis', 'yaxis']

for(var i = 0; i < axNames.length; i++) {
  var dflt;
  if(axNames[i] === 'xaxis') {
    dflt = 'NEW DEFAULT';
  }
  console.log(dflt)
}

prints NEW DEFAULT twice, whereas

var axNames = ['xaxis', 'yaxis']

for(var i = 0; i < axNames.length; i++) {
  var dflt = null;
  if(axNames[i] === 'xaxis') {
    dflt = 'NEW DEFAULT';
  }
  console.log(dflt)
}

print NEW DEFAULT and then null.

[antoinerg]

You're right but setting it to null will prevent var constrain = coerce('constrain', constrainDflt); from getting the default value. This can be seen in the previous commit d1eca2c for which test-image fails. Any suggestion/simple fix for this?

[antoinerg]

Setting it to undefined make the tests pass but the linter complains :\

[antoinerg]

The following pass all the tests (including linter). Would that be 👌 ?

        var scaleanchorDflt;
        if(axLetter === 'y' && !axLayoutIn.hasOwnProperty('scaleanchor') && axHasImage[axName]) {
            scaleanchorDflt = axLayoutOut.anchor;
        } else {scaleanchorDflt = undefined;}

        var constrainDflt;
        if(!axLayoutIn.hasOwnProperty('constrain') && axHasImage[axName]) {
            constrainDflt = 'domain';
        } else {constrainDflt = undefined;}

[etpinard]

What about:

        var scaleanchorDflt = undefined;
        if(axLetter === 'y' && !axLayoutIn.hasOwnProperty('scaleanchor') && axHasImage[axName]) {
            scaleanchorDflt = axLayoutOut.anchor;
        }

        var constrainDflt = undefined;
        if(!axLayoutIn.hasOwnProperty('constrain') && axHasImage[axName]) {
            constrainDflt = 'domain';
        }

??

[antoinerg]

[etpinard]

Ha that's annoying. Your latest is fine 👍

[antoinerg]

Done in 29cf98f

[etpinard]

by latest I mean:

        var scaleanchorDflt;
        if(axLetter === 'y' && !axLayoutIn.hasOwnProperty('scaleanchor') && axHasImage[axName]) {
            scaleanchorDflt = axLayoutOut.anchor;
        } else {
            scaleanchorDflt = undefined;
        }

        var constrainDflt;
        if(!axLayoutIn.hasOwnProperty('constrain') && axHasImage[axName]) {
            constrainDflt = 'domain';
        } else {
            constrainDflt = undefined;
        }

[etpinard]

Awesome - 💃 let's get this in #4307