Dynamically increase textview size according to maxScreenRatio

[KashishGoel]

PR is based on the suggestions in GitHawkApp/GitHawk#1613

Additions

• ability to set max ratio of screen to use for message view
• ability to set maxHeight of message view
• works well for devices with a hardware keyboard attached

Tested On

• Devices: iPhone 7,8
• Simulators: iPhone 5s, X

[KashishGoel]

One comment: the available screen is calculated as the screen available without the software keyboard. I'm on the fence about changing it to the available screen after keyboard height is factored in.

The reason this matters is because if you consider a screen size of 640 and set the available screen ratio to 0.3. You have 192 screen space available for the message view. But when the keyboard is up you take away the height effectively making it < 0 so the maxLines overrides this value. @rnystrom

[rnystrom]

Is there a way to make this behavior optional? I want to make sure that if someone wants an explicit max height, that's always used. Would that be setting the maxScreenRatio to 1?

[rnystrom]

Are these used?

[KashishGoel]

Whoops, forgot to delete. Thanks for the catch.

[rnystrom]

Wo! What is this syntax? Haha

[KashishGoel]

it checks if maxScreenRatio is within the range 0-1. If it isn't we default to 0 since we never want the message view frame to be bigger than our view frame. ~= is used for pattern matching

[rnystrom]

Isn't this using the kb height now w/ the offset? I agree that we shouldn't account for this at all. If anything, it should be optional.

[KashishGoel]

gotcha, will add this as another customization option

[KashishGoel]

We could add explicit height as its own customization. Something like
public var maxMessageViewHeight

This would override both LineHeight and ScreenRatio.

The purpose of screen ratio is to optimize for different screen sizes, so instead of setting one maxValue for each screen (e.g. 150) we can change the amount depending on how much space the screen has.

Currently, the behavior of screenRatio is optional because we initialize it to 0 by default and maxLinesHeight is used instead because it is initialized to 4 by default.

[KashishGoel]

@rnystrom added your suggestion of allowing them to set a maxHeight. So now the message view height is set to the minimum of the max line height, max height (cgfloat) and max screen ratio which is defaulted to be set to 1.

The only caveat with this is if you want to set a custom maxHeight that is larger than 4 * line height (4 is our default line count) we need to ensure the user sets line count to 0. Similar to how we set UILabel.numberOfLines to 0 to allow it to grow.