Quick Exporter for Aseprite that uses layer names to be smarter

Quick Vial Exporter.lua

----------------------------------------------------------------------
-- Author: Cory Beutler
-- License: MIT  (So you can't sue me... Otherwise go wild!)
-- 
-- Exports the current file using layer name prefixes to be smart.
-- The png and json files are always exported with all their data.
-- Texture png files will be auto-named <filename>.png
-- Json files will be auto-named <filename>.asejson
-- Layer name prefixes it recognizes:
--   _  Hide from all exports. Useful for guide and reference layers.
--   >  An extra export will be performed on this layer. This can be
--      placed on as many groups/layers as you want. Each will be
--      exported to its own files auto_named with suffixes based on
--      their group/layer path like so: <filename>[_<group>]_<layer>
-- Feel free to change the settings in 'export_current' below to match
-- your needs. It will affect ALL exports using this script.
-- Installing:
--   Easiest way is to zip it up and rename
--   from `.zip` to `.aseprite-extension`, then double click it. This
--   will trigger aseprite to launch and install.
----------------------------------------------------------------------

-- Utility Funcs --
local function starts_with(str, start)
    return str:sub(1, #start) == start
end
local function ends_with(str, ending)
    return ending == "" or str:sub(-#ending) == ending
end
local function trim_prefix(str, prefix)
    return (str:gsub( "^" .. prefix, ""))
end
local function trim_suffix(str, suffix)
    return (str:gsub( suffix .. "$", ""))
end


function init( plugin )
    if app.apiVersion == nil or app.apiVersion < 15 then
        app.alert("Plugin Minimum Requirement not met: Aseprite v1.2.30 or greater")
        return
    end
    
    plugin:newCommand{
        id = "monster-vial-com-godot-exporter",
        title = "Export for Godot",
        group = "file_save",
        onclick = godot_export
    }
end

function exit( plugin )
end


----
-- Save layer visibility and set based on name
-- input:
--   layers - aseprite layers array like from a sprite
-- output:
--   list of bools and lists representing all starting visibility values
----
function __push_visibility( layers )
    local saved_visibility = {}
    for i,layer in ipairs( layers ) do
        if starts_with( layer.name, "_" ) then
            table.insert(saved_visibility, i, layer.isVisible)
            layer.isVisible = false
        elseif layer.isGroup then
            table.insert(saved_visibility, i, __push_visibility( layer.layers ))
        else
            table.insert(saved_visibility, i, layer.isVisible)
            layer.isVisible = true
        end
    end
    return saved_visibility
end

----
-- Restore visibility
-- input:
--   layers - aseprite layers array like from a sprite
--   saved_visibility - the saved visibility results returned from __push_visibility
-- output:
--   void
----
function __restore_visibility( layers, saved_visibility )
    for i,layer in ipairs( layers ) do
        if starts_with( layer.name, "_" ) then
            layer.isVisible = saved_visibility[i]
        elseif layer.isGroup then
            __restore_visibility( layer.layers, saved_visibility[i] )
        else
            layer.isVisible = saved_visibility[i]
        end
    end
end


----
-- Export with settings best for godot.
-- input:
--   layer - optional. If provided, will export that layer to a file with [_group]_layer suffix
----
function __export_current( basename, layer )
    local layerSuffix = ""
    local askOverwrite = true
    if layer then
        askOverwrite = false
        -- sanitize the name and build suffix
        layerSuffix = (layerSuffix:gsub( "/", "_"))
        layerSuffix = (layerSuffix:gsub( "\\", "_"))
        layerSuffix = trim_prefix(layerSuffix, "_")
        layerSuffix = trim_prefix(layer, ">")
        layerSuffix = "_" .. layerSuffix
    end
    -- Currently, Aseprite doesn't translate slices for the extrude key, so we can't use it.
    if #app.activeSprite.slices > 0 then
        app.command.ExportSpriteSheet {
            ui=false,
            askOverwrite=askOverwrite,
            type=SpriteSheetType.PACKED,
            columns=0, rows=0,
            width=0, height=0,
            bestFit=true,
            -- texture:  '<basename>_<group>_<layer>.png'
            textureFilename=basename .. layerSuffix .. ".png",
            -- data:  '<basename>_<group>_<layer>.asejson'
            dataFilename=basename .. layerSuffix .. ".asejson",
            dataFormat=SpriteSheetDataFormat.JSON_HASH,
            borderPadding=0,
            shapePadding=0,
            innerPadding=0,
            trim=false,
            extrude=false,
            openGenerated=false,
            layer=layer,
            tag="",
            splitLayers=false,
            listLayers=false,
            listTags=true,
            listSlices=true
        }
    elseif #app.activeSprite.tags > 0 or #app.activeSprite.frames > 1 then
        app.command.ExportSpriteSheet {
            ui=false,
            askOverwrite=askOverwrite,
            type=SpriteSheetType.PACKED,
            columns=0, rows=0,
            width=0, height=0,
            bestFit=true,
            -- texture:  '<basename>_<group>_<layer>.png'
            textureFilename=basename .. layerSuffix .. ".png",
            -- data:  '<basename>_<group>_<layer>.asejson'
            dataFilename=basename .. layerSuffix .. ".asejson",
            dataFormat=SpriteSheetDataFormat.JSON_HASH,
            borderPadding=0,
            shapePadding=0,
            innerPadding=1,
            trim=false,
            extrude=true,
            openGenerated=false,
            layer=layer,
            tag="",
            splitLayers=false,
            listLayers=false,
            listTags=(#app.activeSprite.tags > 0),
            listSlices=false
        }
    else
        -- No frames, animations, or slices. Just one static image.
        app.command.ExportSpriteSheet {
            ui=false,
            askOverwrite=askOverwrite,
            type=SpriteSheetType.HORIZONTAL,
            columns=0, rows=0,
            width=0, height=0,
            bestFit=false,
            -- texture:  '<basename>_<group>_<layer>.png'
            textureFilename=basename .. layerSuffix .. ".png",
            -- data:  skipped
            dataFilename="",
            dataFormat=SpriteSheetDataFormat.JSON_HASH,
            borderPadding=0,
            shapePadding=0,
            innerPadding=0,
            trim=false,
            extrude=false,
            openGenerated=false,
            layer=layer,
            tag="",
            splitLayers=false,
            listLayers=false,
            listTags=false,
            listSlices=false
        }
    end
end

----
-- Scan layer names and do extra exports for '>' prefixed layers
-- input:
--   layer - optional. If provided, will export that layer to a file with [_group]_layer suffix
----
function __export_prefixed_layers( basename, layers, layer_path )
    layer_path = layer_path or ""
    for i,layer in ipairs( layers ) do
        if starts_with( layer.name, ">" ) then
            __export_current( basename, layer_path .. layer.name )
        end
        if layer.isGroup then
            __export_prefixed_layers( basename, layer.layers, layer_path .. layer.name )
        end
    end
end


function godot_export()
    local sprite = app.activeSprite
    if not sprite then
        app.alert("There is no sprite to export")
        return
    end
    local basename = sprite.filename
    if not basename then
        app.alert("Sprite is missing filename. Please save first.")
        return
    end

    -- Trim off the sprite's suffix --
    if ends_with( basename, ".ase") then
        basename = trim_suffix(basename, ".ase")
    elseif ends_with( basename, ".aseprite") then
        basename = trim_suffix(basename, ".aseprite")
    else
        app.alert("Unrecognized extension for this sprite file. Expected '.ase' or '.aseprite'")
        return
    end

    local saved_visibility = __push_visibility( sprite.layers )
    __export_current( basename )
    __export_prefixed_layers( basename, sprite.layers )
    __restore_visibility( sprite.layers, saved_visibility )

    app.refresh()
end