So I've got an early version of card zoom working. Check it out:
The idea is that when you tap on a card, you'll be presented with a zoomed view with all the currently available options for that card as clickable list items, based on the current Input. For example, for the default pass priority input, the options will consist of all SpellAbility instances available to the card. For the attack input, the options would consist of declaring or removing as an attacker, as well as potentially other options for banding. The ability to offer multiple choices here will allow getting around the lack of a right-click trigger for certain things.
You may notice that more than one card is being displayed. I decided for usability to allow scrolling through all cards in order within the same zone as the originally tapped card. This way you can stay in zoomed view while quickly analyzing your hand or all your creatures on the field for example. For certain inputs, such as paying mana, the zoom view will stay open and auto-select the next card after selecting a mana ability for instance, allowing you to quick tap multiple mana sources. Also, for certain inputs, the zoom view will filter out cards that have no applicable options, such as cards without mana sources in the case of the mana payment input.
Note that due to space constraints, only the first option is displayed by default, however if there's more than option, the More button will become enabled and tapping it will cause all options to display by making them cover up part or all of the card display as needed. Tapping that button again (which will at that point have the caption "Less") will go back down to just one option. The Back button will hide the zoomed view as you'd expect, as will tapping the selected card a second time.
Eventually, I will display a card detail panel above the zoomed card images, with the ability to tap it to expand if it's cut off at all.
I'm curious to hear people's reaction to this. I know it will add more taps to gameplay as playing a land will require two taps instead of one click for instance, but I felt that without being able to view a legible version of a card or see card details, it'd be hard to make informed decisions about what to do anyway. Plus, single tap to zoom seems a necessary ease of use requirement when cards start off so small. That said, I'm open to suggestions if there's anything I can do to make this more user friendly.
Thanks.
-Dan