Font size and line height preferences

[dangoor]

Breaking this out into a separate issue to be resolved before Themes can land.

As @TomMalbran suggested in the themes pull request:

The font settings should be merged with the Increase/Decrease Font Size commands. I am thinking that we should make the fontSizeStyle view state a preference to store the font size and add a new preferences for the line height and the font family. But to make things simpler, the font size preference should just be a number which is then interpreted as the size of the font in px, and the line height should also be a number (float) which is then interpreted as the line height in ems. All these preference will be added in ViewCommandsHandlers so that we can use the same functions to update the style when the preferences change.

Since we don't have an UI for the preferences I am not sure if we should keep the UI used with the themes or just don't use any UI at the moment.

I don't mind keeping the [Themes] dialog. But when saving, it should only change the preferences values and the code in View Commands Manger can deal with the preference change.

cc @MiguelCastillo

[MiguelCastillo]

Awesome, I really like that we are doing this. It cleans up the code in themes real nicely and will fit real nicely with potential future fonts plugin I have been thinking about :)

Can we expose this stuff as a set of API functions? Maybe:

1. setFontSize
2. setFontType/setFontFamily
3. setLineHeight
4. setFontWeight

[lkcampbell]

@dangoor, we have an event for font size change but not for font face changes. CodeMirror does not have this functionality either. If users will be able to change fonts in multiple ways, I need events so I can adjust my Column Ruler extension appropriately. Thanks.

[dangoor]

@lkcampbell Agreed. I think one point of this issue is to ensure that all of this is handled consistently, and you're right about the need for events here.

[MiguelCastillo]

@lkcampbell could the ruler depend on units like em?

[lkcampbell]

@MiguelCastillo, whatever units you guys provide is fine with me. I just need to know when it happens :).

[MiguelCastillo]

@lkcampbell Ah gotcha! That seems manageable :)

[TomMalbran]

If we have set APIs, we should have gets. Then the Theme shouldn't need to store the values internally, it can just call the APIs when it will display the UI or require them for some other reason.

An alternative is to just use the Preferences, but I think that proper APIs will look cleaner.

[MiguelCastillo]

@TomMalbran Exactly why I am all for the API. ;-) This is also looking to the future a bit... Brackets should have its own awesome UI for managing fonts, and this API will definitely facilitate that.

It is still very easy to integrate if we want to use the view states.

[lkcampbell]

@MiguelCastillo, actually, to answer your question better (after some more thought), the ruler only grabs calculated values from font elements, so, no matter what units you are using I will always be dealing with pixels.

[dangoor]

@MiguelCastillo @lkcampbell @TomMalbran Do any of you want to take a stab at adding this API? I can help with the conversion from the current view state.

[lkcampbell]

I can work on it unless someone else wants to try it, particularly @TomMalbran since, of the three of us, he probably knows the font code the best.

[TomMalbran]

You can take it if you want. I am not sure how soon I could get to it. I
can review your PR and help you with what you need.