Fast, frictionless iOS animations
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README.md

Walt for RubyMotion

Tired of verbose animation chains in iOS?

With Walt, you can make this:

Walt animation

Using this:

@view = UIView.alloc.initWithFrame(....)

Walt.animate(
  assets: [{
    id: "logo",
    position: [100, 0],
    size: [110, 40],
    url: "http://bit.ly/S98Ta5"
  }],
  animations: [{
    duration: 2,
    operations: [{
      move: "logo",
      to: 150,
      axis: :y
    }],
    after: {
      duration: 2,
      operations: [{
        rotate: "logo",
        to: 360
      }]
    }
  }],
  in: @view
)

Installation

First install the Walt gem:

gem install walt

Add Walt to your Gemfile or require it in your Rakefile:

gem 'walt'
require 'walt'

If you're going to use the image-URL loading component of Walt, add AFNetworking to your pods:

app.pods do
  pod "AFNetworking"
end

Usage

Walt is organized around assets, animations, and operations. Each animation is a collection of operations occuring at the same time and configuration.

Assets

Walt supports arbitrary UIViews as assets, and can also build some types of views from hashes. Constructor hashes include:

# Uses an existing `UIView`
{ id: "my_id", view: UIView.alloc.initWithFrame(...) }

# Creates a new `UIView`
# All Walt::Assets support these options:
# :position, :size, :view, :content_mode, :clips_to_bounds, :background_color
{ id: "my_id", size: [100,100], background_color: "0088cc" }

# Creates a new `UILabel`; also supports:
# :text_color, :background_color, :number_of_lines, :font, :text_alignment
{ id: "my_id", text: "Hello World" }

# Creates a new `UIImageView`
# No animations will start until all
#   remotely-loaded assets have loaded
{ id: "my_id", url: "http://imgur.com/hello.png" }

Operations

Walt comes with a few nifty operations, and adding your own is easy.

Move

  {
    move: "my_id",
    from: [10, 10],
    to: [50, 50]
  }
  {
    move: "my_id",
    from: 0,
    to: 100,
    axis: :y # also supports :x
  }

Rotate

  {
    rotate: "my_id",
    from: 20, # in degrees
    to: 50
  }

Fade

  {
    fade: "my_id",
    from: 1.0,
    to: 0.2
  }

Scale

  {
    scale: "my_id",
    from: 1.0,
    to: 1.3
  }

Adding your own

Create a subclass of Walt::Operation::Base with a name of the form ____Operation (i.e. FancyOperation). In your class, implement def setup(view, animation) and def finalize(view, animation). Then, you can use a hash of the form {fancy: "my_id"} to use that operation.

Example:

module Walt
  module Operation
    class FancyOperation < Base

    # run before animation starts
    def setup(view, animation)
      ...
    end

    # make changes to animate
    def finalize(view, animation)
      ...
    end
  end
end

Walt.animate(...
  {
    fancy: "my_id"
  }
)

Animations

Animations control the timing and configuration of operations. They support :delay and :duration settings which affect timing, and a :options setting which you can pass a list of UIViewAnimationOptions for that animation.

Animations can be chained using an animation's :after property, which takes another animation hash.

# Also applies to Walt.animate
{
  delay: 0.3,
  duration: 2.2,
  options: [:curve_ease_in, :begin_from_current_state],
  operations: [...],
  after: {
    delay: 1.0,
    duration: 1.0,
    ...
  }
}

Contact

Clay Allsopp (http://clayallsopp.com)

License

Walt is available under the MIT license. See the LICENSE file for more info.