start of the @Frames macro (#338)

*@Frames macro with len and `stop`
* support for startof and endof (object or frame)

CHANGELOG.md

@@ -1,6 +1,7 @@
 # Javis.jl - Changelog
 
-## Unreleased 
+## Unreleased
+- added `@Frames` macro for full power mode of defining frames
 - bugfix in `@JLayer` when dimensions are not defined explicitly
 
 ## v0.6.1 (7th of August 2021)

examples/follow_path.jl

@@ -39,8 +39,11 @@ Background(1:220, ground)
 
 # let the points appear one by one
 objects = [
-    Object(frame_start:200, (args...) -> circle(O, 10, :fill), points[i]) for
-    (frame_start, i) in zip(1:2:(2 * npoints), 1:npoints)
+    Object(
+        @Frames(i == 1 ? 1 : prev_start() + 2, stop = 200),
+        (args...) -> circle(O, 10, :fill),
+        points[i],
+    ) for i in 1:npoints
 ]
 
 # easiest to move canvas to draw at origin

src/Javis.jl

@@ -175,11 +175,7 @@ function preprocess_frames!(objects::Vector{<:AbstractObject})
         )
     end
 
-    if isempty(CURRENT_OBJECT)
-        push!(CURRENT_OBJECT, objects[1])
-    else
-        CURRENT_OBJECT[1] = objects[1]
-    end
+    set_current_object(objects[1])
     return frames
 end
 
@@ -322,8 +318,12 @@ function render(
         @error "Currently, only gif and mp4 creation is supported. Not a $ext."
     end
 
+    # check if livestream is used and livestream if that's the case
     _livestream(streamconfig, framerate, video.width, video.height, pathname)
 
+    # clear all CURRENT_* constants to not accidentally use a previous video when creating a new one
+    empty_CURRENT_constants()
+
     # even if liveview = false, show the rendered gif in the cell output
     if isdefined(Main, :IJulia) && Main.IJulia.inited
         display(MIME("text/html"), """<img src="$(pathname)">""")
@@ -694,6 +694,8 @@ export rev
 export scaleto
 export act!
 export anim_translate, anim_rotate, anim_rotate_around, anim_scale
+
+export @Frames, prev_start, prev_end, startof, endof
 export JBox, JCircle, JEllipse, JLine, JPoly, JRect, JStar, @JShape
 
 # custom override of luxor extensions

src/structs/Action.jl

@@ -24,6 +24,9 @@ mutable struct Action <: AbstractAction
     defs::Dict{Symbol,Any}
 end
 
+const CURRENT_ACTION = Array{Action,1}()
+const PREVIOUS_ACTION = Array{Action,1}()
+
 """
     Action([frames], [Animation], func::Function; keep=true)
 

src/structs/Frames.jl

@@ -11,6 +11,7 @@ mutable struct Frames{T}
 end
 
 Base.convert(::Type{Frames}, x) = Frames(nothing, x)
+Base.convert(::Type{Frames}, x::Frames) = x
 Base.convert(::Type{Frames}, x::UnitRange) = Frames(x, x)
 
 Base.copy(f::Frames) = Frames(f.frames, f.user)
@@ -65,7 +66,7 @@ function get_frames(parent, elem, frames::Symbol, last_frames::UnitRange; is_fir
 end
 
 """
-    get_frames(parent, elem, relative::RFrames, last_frames::UnitRang; is_first=falsee)
+    get_frames(parent, elem, relative::RFrames, last_frames::UnitRange; is_first=falsee)
 
 Return the frames based on a relative frames [`RFrames`](@ref) object and the `last_frames`.
 """
@@ -95,3 +96,99 @@ function get_frames(parent, elem, glob::GFrames, last_frames::UnitRange; is_firs
     end
     return glob.frames
 end
+
+"""
+    function get_frames(parent, elem, func_frames::Function, last_frames::UnitRange; is_first = false)
+
+Return the frames based on a specified function. The function `func_frames` is simply evaluated 
+"""
+function get_frames(
+    parent,
+    elem,
+    func_frames::Function,
+    last_frames::UnitRange;
+    is_first = false,
+)
+    return func_frames()
+end
+
+"""
+    prev_start()
+
+The start frame of the previous object or for an action the start frame of the parental object.
+Can be used to provide frame ranges like:
+```
+@Frames(prev_start(), 10)
+```
+"""
+function prev_start()
+    if CURRENT_OBJECT_ACTION_TYPE[1] == :Object
+        PREVIOUS_OBJECT[1].frames.frames[1]
+    else
+        PREVIOUS_ACTION[1].frames.frames[1]
+    end
+end
+
+"""
+    prev_end()
+
+The end frame of the previous object or for an action the end frame of the parental object.
+Can be used to provide frame ranges like:
+```
+@Frames(prev_end()-10, 10)
+```
+"""
+function prev_end()
+    if CURRENT_OBJECT_ACTION_TYPE[1] == :Object
+        PREVIOUS_OBJECT[1].frames.frames[end]
+    else
+        PREVIOUS_ACTION[1].frames.frames[end]
+    end
+end
+
+startof(oa::Union{AbstractAction,AbstractObject}) = oa.frames.frames[1]
+endof(oa::Union{AbstractAction,AbstractObject}) = oa.frames.frames[end]
+
+"""
+    @Frames(start, len)
+    @Frames(start, stop=)
+
+Can be used to define frames using functions like [`prev_start`](@ref) or [`prev_end`](@ref)
+
+# Example
+```
+red_circ = Object(1:90, (args...)->circ("red"))
+blue_circ = Object(@Frames(prev_start()+20, 70), (args...)->circ("blue"))
+blue_circ = Object(@Frames(prev_start()+20, stop=90), (args...)->circ("blue"))
+```
+is the same as
+```
+red_circ = Object(1:90, (args...)->circ("red"))
+blue_circ = Object(21:90, (args...)->circ("blue"))
+blue_circ = Object(41:90, (args...)->circ("blue"))
+```
+"""
+macro Frames(start, in_args...)
+    args = []
+    kwargs = Pair{Symbol,Any}[]
+    kwarg_symbols = Symbol[]
+    for el in in_args
+        if Meta.isexpr(el, :(=))
+            push!(kwargs, Pair(el.args...))
+            push!(kwarg_symbols, el.args[1])
+        else
+            push!(args, el)
+        end
+    end
+    stop_idx = findfirst(==(:stop), kwarg_symbols)
+    if stop_idx !== nothing
+        stop = kwargs[stop_idx][2]
+        return esc(quote
+            Javis.Frames(nothing, () -> ($start):($stop))
+        end)
+    elseif isempty(kwarg_symbols)
+        esc(quote
+            Javis.Frames(nothing, () -> ($start):($start + $(args[1]) - 1))
+        end)
+    end
+end

src/structs/Object.jl

@@ -31,9 +31,12 @@ end
 holds the current object in an array to be declared as a constant
 The current object can be accessed using CURRENT_OBJECT[1]
 """
-
 const CURRENT_OBJECT = Array{Object,1}()
 
+
+const PREVIOUS_OBJECT = Array{Object,1}()
+const CURRENT_OBJECT_ACTION_TYPE = Array{Symbol,1}()
+
 Object(func::Function, args...; kwargs...) = Object(:same, func, args...; kwargs...)
 
 Object(frames, func::Function; kwargs...) = Object(frames, func, O; kwargs...)

src/util.jl

@@ -19,6 +19,15 @@ function compute_frames!(
     is_first = true
     counter = 1
     for elem in elements
+        # update (CURRENT/PREVIOUS)_(OBJECT/ACTION) and CURRENT_OBJECT_ACTION_TYPE
+        if elem isa Object
+            set_current_object(elem)
+            empty!(CURRENT_ACTION)
+        elseif elem isa Action
+            set_current_action(elem)
+        end
+        set_current_action_type(elem)
+
         if last_frames === nothing && get_frames(elem) === nothing
             throw(ArgumentError("Frames need to be defined explicitly in the initial
                 Object/Background or Action."))
@@ -138,3 +147,107 @@ function get_polypoint_at(points, t; pdist = polydistances(points))
     )
     return overshootpoint
 end
+
+"""
+    set_previous_object(object::Object)
+
+Set the `object` as `PREVIOUS_OBJECT`
+"""
+function set_previous_object(object::Object)
+    if isempty(PREVIOUS_OBJECT)
+        push!(PREVIOUS_OBJECT, object)
+    else
+        PREVIOUS_OBJECT[1] = object
+    end
+end
+
+"""
+    set_previous_action(action::Action)
+
+Set the `action` as `PREVIOUS_ACTION`
+"""
+function set_previous_action(action::Action)
+    if isempty(PREVIOUS_ACTION)
+        push!(PREVIOUS_ACTION, action)
+    else
+        PREVIOUS_ACTION[1] = action
+    end
+end
+
+"""
+    set_current_object(object::Object)
+
+Set the `object` as `CURRENT_OBJECT` and update `PREVIOUS_OBJECT`/`PREVIOUS_ACTION`
+"""
+function set_current_object(object::Object)
+    update_previous_object_or_action()
+
+    if isempty(CURRENT_OBJECT)
+        push!(CURRENT_OBJECT, object)
+    else
+        CURRENT_OBJECT[1] = object
+    end
+end
+
+"""
+    set_current_action(action::Action)
+
+Set the `action` as `CURRENT_ACTION` and update `PREVIOUS_OBJECT`/`PREVIOUS_ACTION`
+"""
+function set_current_action(action::Action)
+    update_previous_object_or_action()
+
+    if isempty(CURRENT_ACTION)
+        push!(CURRENT_ACTION, action)
+    else
+        CURRENT_ACTION[1] = action
+    end
+end
+
+"""
+    update_previous_object_or_action() 
+
+Update the `PREVIOUS_OBJECT` or `PREVIOUS_ACTION` depending on whether the 
+last element was an object or an action. This is still saved in `CURRENT_OBJECT_ACTION_TYPE`.
+"""
+function update_previous_object_or_action()
+    if !isempty(CURRENT_OBJECT_ACTION_TYPE)
+        if CURRENT_OBJECT_ACTION_TYPE[1] == :Object
+            !isempty(CURRENT_OBJECT) && set_previous_object(CURRENT_OBJECT[1])
+        else
+            !isempty(CURRENT_ACTION) && set_previous_action(CURRENT_ACTION[1])
+        end
+    end
+end
+
+"""
+    set_current_action_type(t)
+
+Set `CURRENT_OBJECT_ACTION_TYPE` to `:Object` or `:Action` depending 
+on the type of `t`.
+"""
+function set_current_action_type(t)
+    type = :Object
+    if t isa AbstractAction
+        type = :Action
+    end
+    if isempty(CURRENT_OBJECT_ACTION_TYPE)
+        push!(CURRENT_OBJECT_ACTION_TYPE, type)
+    else
+        CURRENT_OBJECT_ACTION_TYPE[1] = type
+    end
+end
+
+"""
+    empty_CURRENT_constants()
+
+empty all `CURRENT_` constants like `CURRENT_OBJECT`
+"""
+function empty_CURRENT_constants()
+    empty!(CURRENT_VIDEO)
+    empty!(CURRENT_OBJECT)
+    empty!(CURRENT_ACTION)
+    empty!(PREVIOUS_OBJECT)
+    empty!(PREVIOUS_ACTION)
+    empty!(CURRENT_OBJECT_ACTION_TYPE)
+end

test/animations.jl

@@ -106,10 +106,12 @@ end
     red_ball = Object(RFrames(-24:0), (args...) -> circ(O, "red"), p1)
     act!(red_ball, Action(anim_rotate_around(from_rot, to_rot, O)))
 
-    blue_ball = Object(1:25, (args...) -> circ(O, "blue"), p2)
+    blue_ball = Object(@Frames(prev_start(), 25), (args...) -> circ(O, "blue"), p2)
     act!(blue_ball, Action(anim_rotate_around(to_rot, from_rot, red_ball)))
-    path_red =
-        Object(1:25, (video, args...) -> path!(path_of_red, get_position(red_ball), "red"))
+    path_red = Object(
+        @Frames(prev_start(), stop = prev_start() + 25 - 1),
+        (video, args...) -> path!(path_of_red, get_position(red_ball), "red"),
+    )
     path_blue =
         Object(:same, (video, args...) -> path!(path_of_blue, pos(blue_ball), "blue"))
     string = Object(1:25, (args...) -> rad(pos(red_ball), pos(blue_ball), "black"))
@@ -133,7 +135,7 @@ end
     video = Video(500, 500)
     back = Object(1:25, ground, in_global_layer = true)
     act!(back, Action(anim_rotate(π / 2, π / 2)))
-    act!(back, Action(1:1, anim_translate(Point(25, 25))))
+    act!(back, Action(@Frames(prev_start(), stop = 1), anim_translate(Point(25, 25))))
 
     Object(latex_title)
     red_ball = Object(RFrames(-24:0), (args...) -> circ_ret_trans(O, "red"), p1)
@@ -220,7 +222,7 @@ end
     p = Point(100, 0)
 
     Background(1:10, ground_black_on_white)
-    circ = Object((args...) -> circ_ret_trans(), p)
+    circ = Object(@Frames(1, stop = prev_end()), (args...) -> circ_ret_trans(), p)
     act!(circ, Action(anim_rotate_around(0.0, 2π, O)))
     Object((args...) -> line(Point(-200, 0), Point(-200, -10 * ang(circ)), :stroke))
 

test/unit.jl

@@ -268,6 +268,24 @@
         @test Javis.get_frames(objects[2]) == 31:50
         @test Javis.get_frames(objects[2].actions[1]) == 1:10
         @test Javis.get_frames(objects[2].actions[2]) == 11:20
+
+
+        demo = Video(500, 500)
+        back = Background(1:50, (args...) -> 1)
+        obj1 = Object(1:10, (args...) -> 1)
+        a1 = Action(1:10, anim_scale(1, 2))
+        a2 = Action(@Frames(startof(a1) + 5, 5), anim_scale(1, 2))
+        act!(obj1, a1)
+        act!(obj1, a2)
+        obj2 = Object(@Frames(prev_start(), 10), (args...) -> 1)
+        obj3 = Object(@Frames(startof(obj2) + 1, 10), (args...) -> 1)
+
+        Javis.preprocess_frames!(demo.objects)
+        @test Javis.get_frames(obj1) == 1:10
+        @test Javis.get_frames(obj2) == 1:10
+        @test Javis.get_frames(obj3) == 2:11
+        @test Javis.get_frames(obj1.actions[1]) == 1:10
+        @test Javis.get_frames(obj1.actions[2]) == 6:10
     end
 
     @testset "anim_" begin