export_layers.lua

--[[

Description:
A script to save all different layers in different files.

Made by Gaspi.
   - Itch.io: https://gaspi.itch.io/
   - Twitter: @_Gaspi
Further Contributors:
    - Levy E ("StoneLabs")
    - David Höchtl ("DavidHoechtl")
    - Demonkiller8973
--]]

-- Import main.
local err = dofile("main.lua")
if err ~= 0 then return err end

-- Variable to keep track of the number of layers exported.
local n_layers = 0


-- Function to calculate the bounding box of the non-transparent pixels in a layer
local function calculateBoundingBox(layer)
    local minX, minY, maxX, maxY = nil, nil, nil, nil
    for _, cel in ipairs(layer.cels) do
        local image = cel.image
        local position = cel.position

        for y = 0, image.height - 1 do
            for x = 0, image.width - 1 do
                if image:getPixel(x, y) ~= 0 then -- Non-transparent pixel
                    local pixelX = position.x + x
                    local pixelY = position.y + y
                    if not minX or pixelX < minX then minX = pixelX end
                    if not minY or pixelY < minY then minY = pixelY end
                    if not maxX or pixelX > maxX then maxX = pixelX end
                    if not maxY or pixelY > maxY then maxY = pixelY end
                end
            end
        end
    end
    return Rectangle(minX, minY, maxX - minX + 1, maxY - minY + 1)
end

-- Exports every layer individually.
local function exportLayers(sprite, root_layer, filename, group_sep, data)
    for _, layer in ipairs(root_layer.layers) do
        local filename = filename
        if layer.isGroup then
            -- Recursive for groups.
            local previousVisibility = layer.isVisible
            layer.isVisible = true
            filename = filename:gsub("{layergroups}",
                                     layer.name .. group_sep .. "{layergroups}")
            exportLayers(sprite, layer, filename, group_sep, data)
            layer.isVisible = previousVisibility
        else
            -- Individual layer. Export it.
            layer.isVisible = true
            filename = filename:gsub("{layergroups}", "")
            filename = filename:gsub("{layername}", layer.name)
            os.execute("mkdir \"" .. Dirname(filename) .. "\"")
            if data.spritesheet then
                local sheettype=SpriteSheetType.HORIZONTAL
                if (data.tagsplit == "To Rows") then
                    sheettype=SpriteSheetType.ROWS
                elseif (data.tagsplit == "To Columns") then
                    sheettype=SpriteSheetType.COLUMNS
                end
                app.command.ExportSpriteSheet{
                    ui=false,
                    askOverwrite=false,
                    type=sheettype,
                    columns=0,
                    rows=0,
                    width=0,
                    height=0,
                    bestFit=false,
                    textureFilename=filename,
                    dataFilename="",
                    dataFormat=SpriteSheetDataFormat.JSON_HASH,
                    borderPadding=0,
                    shapePadding=0,
                    innerPadding=0,
                    trimSprite=data.trimSprite,
                    trim=data.trimCells,
                    trimByGrid=data.trimByGrid,
                    mergeDuplicates=data.mergeDuplicates,
                    extrude=false,
                    openGenerated=false,
                    layer="",
                    tag="",
                    splitLayers=false,
                    splitTags=(data.tagsplit ~= "No"),
                    listLayers=layer,
                    listTags=true,
                    listSlices=true,
                }
            elseif data.trim then -- Trim the layer
                local boundingRect = calculateBoundingBox(layer)
                -- make a selection on the active layer
                app.activeLayer = layer;
                sprite.selection = Selection(boundingRect);
                
                -- create a new sprite from that selection
                app.command.NewSpriteFromSelection()
                
                -- save it as png
                app.command.SaveFile {
                    ui=false,
                    filename=filename
                }
                app.command.CloseFile()
                
                app.activeSprite = layer.sprite  -- Set the active sprite to the current layer's sprite
                sprite.selection = Selection();
            else
                sprite:saveCopyAs(filename)
            end
            layer.isVisible = false
            n_layers = n_layers + 1
        end
    end
end

-- Open main dialog.
local dlg = Dialog("Export layers")
dlg:file{
    id = "directory",
    label = "Output directory:",
    filename = Sprite.filename,
    open = false
}
dlg:entry{
    id = "filename",
    label = "File name format:",
    text = "{layergroups}{layername}"
}
dlg:combobox{
    id = 'format',
    label = 'Export Format:',
    option = 'png',
    options = {'png', 'gif', 'jpg'}
}
dlg:combobox{
    id = 'group_sep',
    label = 'Group separator:',
    option = Sep,
    options = {Sep, '-', '_'}
}
dlg:slider{id = 'scale', label = 'Export Scale:', min = 1, max = 10, value = 1}
dlg:check{
    id = "spritesheet",
    label = "Export as spritesheet:",
    selected = false,
    onclick = function()
        -- Hide these options when spritesheet is checked.
        dlg:modify{
            id = "trim",
            visible = not dlg.data.spritesheet
        }
        -- Show these options when spritesheet is checked.
        dlg:modify{
            id = "trimSprite",
            visible = dlg.data.spritesheet
        }
        dlg:modify{
            id = "trimCells",
            visible = dlg.data.spritesheet
        }
        dlg:modify{
            id = "mergeDuplicates",
            visible = dlg.data.spritesheet
        }
        dlg:modify{
            id = "tagsplit",
            visible = dlg.data.spritesheet
        }
    end
}
dlg:check{
    id = "trim",
    label = "Trim:",
    selected = false
}
dlg:check{
    id = "trimSprite",
    label = "  Trim Sprite:",
    selected = false,
    visible = false,
    onclick = function()
        dlg:modify{
            id = "trimByGrid",
            visible = dlg.data.trimSprite or dlg.data.trimCells,
        }
    end
}
dlg:check{
    id = "trimCells",
    label = "  Trim Cells:",
    selected = false,
    visible = false,
    onclick = function()
        dlg:modify{
            id = "trimByGrid",
            visible = dlg.data.trimSprite or dlg.data.trimCells,
        }
    end
}
dlg:check{
    id = "trimByGrid",
    label = "  Trim Grid:",
    selected = false,
    visible = false
}
dlg:combobox{ -- Spritesheet export only option
    id = "tagsplit",
    label = "  Split Tags:",
    visible = false,
    option = 'No',
    options = {'No', 'To Rows', 'To Columns'}
}
dlg:check{ -- Spritesheet export only option
    id = "mergeDuplicates",
    label = "  Merge duplicates:",
    selected = false,
    visible = false
}
dlg:check{id = "save", label = "Save sprite:", selected = false}
dlg:button{id = "ok", text = "Export"}
dlg:button{id = "cancel", text = "Cancel"}
dlg:show()

if not dlg.data.ok then return 0 end

-- Get path and filename
local output_path = Dirname(dlg.data.directory)
local filename = dlg.data.filename .. "." .. dlg.data.format

if output_path == nil then
    local dlg = MsgDialog("Error", "No output directory was specified.")
    dlg:show()
    return 1
end

local group_sep = dlg.data.group_sep
filename = filename:gsub("{spritename}",
                         RemoveExtension(Basename(Sprite.filename)))
filename = filename:gsub("{groupseparator}", group_sep)

-- Finally, perform everything.
Sprite:resize(Sprite.width * dlg.data.scale, Sprite.height * dlg.data.scale)
local layers_visibility_data = HideLayers(Sprite)
exportLayers(Sprite, Sprite, output_path .. filename, group_sep, dlg.data)
RestoreLayersVisibility(Sprite, layers_visibility_data)
Sprite:resize(Sprite.width / dlg.data.scale, Sprite.height / dlg.data.scale)

-- Save the original file if specified
if dlg.data.save then Sprite:saveAs(dlg.data.directory) end

-- Success dialog.
local dlg = MsgDialog("Success!", "Exported " .. n_layers .. " layers.")
dlg:show()

return 0