Express animations for an element

All SVG element functions in omsvg (the svg_*() functions) are animatable through their anims argument. The anims() function should be used with that argument should we want to express animations for the element. Within the anims() function call, we can insert a list of formulas that incorporate calls to any of the anim_*() functions (e.g., anim_position(), anim_rotation(), etc.), and, have keyframe times as part of the formula.

anims(...)

Arguments

...	One or more animations that included the use of anim_*() functions, expressed as two-sided formulas. The LHS provides the keyframe time (in units of seconds) and the RHS is the associated anim_*() call.

Value

A tibble of animation directives.

Details

A useful template to use for an anims() call within an svg_*() function is:

anims = anims(
  <time_i> ~ <anim_fn>(...),
  ...,
  <time_n> ~ <anim_fn>(...)
  )

We can also use multiple calls to anim_*() functions for each distinct keyframe time by placing those calls in a list:

anims = anims(
  <time_i> ~ list(
    <anim_fn_x>(...),
    <anim_fn_y>(...)
    ),
  ...,
  <time_n> ~ list(
    <anim_fn_x>(...),
    <anim_fn_y>(...)
    )
  )

Examples

# Basic animation of an element's
# position (moving to a new `x` and
# `y` position)
svg_1 <-
  SVG(width = 300, height = 300) %>%
  svg_rect(
    x = 50, y = 50,
    width = 50, height = 50,
    attrs = svg_attrs_pres(
      stroke = "magenta",
      fill = "lightblue"
    ),
    anims = anims(
      2.0 ~ anim_position(x = 100, y = 50)
    )
  )

# We can define multiple animations
# for a single element: put them in a
# `list()`; the `easing_fn` function for
# both `anim_*()` function is no longer
# linear but now eases in and out
svg_2 <-
  SVG(width = 300, height = 300) %>%
  svg_rect(
    x = 50, y = 50,
    width = 50, height = 50,
    attrs = svg_attrs_pres(
      stroke = "black",
      fill = "yellow"
    ),
    anims = anims(
      0.5 ~ list(
        anim_position(x = 50, y = 50, easing_fn = ease_in_out()),
        anim_rotation(0, easing_fn = ease_in_out())
      ),
      2.0 ~ list(
        anim_position(x = 200, y = 50, easing_fn = ease_in_out()),
        anim_rotation(90, easing_fn = ease_in_out())
      )
    )
  )

# The initial state of the element
# can be used in any `anim_*()`
# function with `initial = TRUE`
svg_3 <-
  SVG(width = 300, height = 300) %>%
  svg_rect(
    x = 50, y = 50,
    width = 50, height = 50,
    attrs = svg_attrs_pres(
      stroke = "black",
      fill = "yellow"
    ),
    anims = anims(
      1.0 ~ list(
        anim_position(initial = TRUE),
        anim_rotation(initial = TRUE)
      ),
      3.0 ~ list(
        anim_position(x = 200, y = 50),
        anim_rotation(90)
      ),
      5.0 ~ list(
        anim_position(initial = TRUE),
        anim_rotation(initial = TRUE)
      )
    )
  )