Support full-screen cards

[nalbion]

The main purpose of this PR is to allow cards to be full-screen without the odd behaviour mentioned in #55.

In order to achieve this I've had to make a number of changes:

• Transform is used to translate and scale the card instead of Align and SizedBox
• Switching from SizedBox means that text on the card is resized instead of moved to different lines when the card size animates.
• Cards behind the front card are scaled in perspective, so you can have unlimited cards in your stack without cards at the back suddenly becoming larger
• Instead of specifying a minimum height/width, you can specify a scaling factor.
• card[0] is the front card - it removes a lot of complexity from the code
• the rotation angle depends on whether you started dragging the top or bottom half of the card. The card stays pinned under your finger and the far end drags behind.

[maheshj01]

Any Reason why we are not sending the current card Index being swiped in the call back?

[nalbion]

yes, because index = 0 is now the front card. You don't need to track _currentFront - the code becomes a lot simpler.

[maheshj01]

but on the client-side how do we track which card was swiped?

[nalbion]

it's always card[0]

[maheshj01]

So how do we handle a case e.g ,
I have a set of 5 cards and I would like to show some text associated with each card.
so basically there will be a

List<String> ['A','B','C','D','E'];

so in order to show a appropriate text with each card we will need the index of the card being swiped.

Let me know If I am wrong or missing anything :)

[nalbion]

I could have left the index argument in, but it would be 0 every single time.

[maheshj01]

So is it like if I have List mapped to cards.on each swipe complete callback I should remove the first element of this list.
And then the first element of the resulting list will be associated with the current card?

[maheshj01]

Sorry for asking too many questions

[nalbion]

yes, the top/first card gets special treatment - it's the only one that can be swiped, and then it's removed from the list

[maheshj01]

thanks for the explanation

[xxJeevesxx]

Do we know if this will get reviewed and closed?

[maheshj01]

cc: @ShaunRain