aseprite/data/scripts/layer.lua

-- ase -- allegro-sprite-editor: the ultimate sprites factory
-- Copyright (C) 2001-2005 by David A. Capello

-- internal routine
local function count_layers(layer)
  local count

  if layer.parent.type == GFXOBJ_SPRITE then
    count = 0
  else
    count = 1
  end

  if layer_is_set(layer) then
    local it = layer.layers
    while it do
      count = count + count_layers(it)
      it = it.next
    end
  end

  return count
end

-- const char *GetUniqueLayerName()
function GetUniqueLayerName()
  local sprite = current_sprite
  if sprite then
    return _("Layer") .. " " .. count_layers(sprite.set)
  else
    return nil
  end
end

-- Layer *NewLayer(const char *name, int x, int y, int w, int h)
-- creates a new layer with the "name" in the current sprite(in the
-- current frame) with the specified position and size(if w=h=0 the
-- routine will use the sprite dimension)
function NewLayer(name, x, y, w, h)
  local sprite = current_sprite
  local layer = nil
  local image, frame, index

  if sprite and name then
    if not w or w == 0 then w = sprite.w end
    if not h or h == 0 then h = sprite.h end
 
    -- new image
    image = image_new(sprite.imgtype, w, h)
    if not image then
      return nil
    end

    -- new layer
    layer = layer_new(sprite.imgtype)
    if not layer then
      image_free(image)
      return nil
    end

    -- clear with mask color
    image_clear(image, 0)

    -- configure layer name and blend mode
    layer_set_name(layer, name)
    layer_set_blend_mode(layer, BLEND_MODE_NORMAL)

    -- add image in the layer stock
    index = stock_add_image(layer.stock, image)

    -- create a new frame in the current frpos
    frame = frame_new(sprite.frpos, index)
    frame_set_position(frame, x, y)

    -- add frame
    layer_add_frame(layer, frame)

    -- undo stuff
    if undo_is_enabled(sprite.undo) then
      undo_open(sprite.undo)
      undo_add_layer(sprite.undo, sprite.set, layer)
      undo_set_layer(sprite.undo, sprite)
      undo_close(sprite.undo)
    end

    -- add the layer in the sprite set
    layer_add_layer(sprite.set, layer)

    -- select the new layer
    sprite_set_layer(sprite, layer)
  end

  return layer
end

-- Layer *NewLayerSet(const char *name)
-- creates a new layer set with the "name" in the current sprite
function NewLayerSet(name)
  local sprite = current_sprite
  local layer = nil

  if sprite and name then
    -- new layer
    layer = layer_set_new()
    if not layer then
      return nil
    end

    -- configure layer name and blend mode
    layer_set_name(layer, name)

    -- add the layer in the sprite set
    layer_add_layer(sprite.set, layer)

    -- select the new layer
    sprite_set_layer(sprite, layer)
  end

  return layer
end

-- removes the current selected layer
function RemoveLayer()
  local sprite = current_sprite
  if sprite and sprite.layer then
    local layer = sprite.layer
    local parent = layer.parent
    local layer_select

    -- select: previous layer, or next layer, or parent(if it is not
    -- the main layer of sprite set)
    if layer.prev then
      layer_select = layer.prev
    elseif layer.next then
      layer_select = layer.next
    elseif parent != sprite.set then
      layer_select = parent
    else
      layer_select = nil
    end

    -- undo stuff
    if undo_is_enabled(sprite.undo) then
      undo_open(sprite.undo)
      undo_set_layer(sprite.undo, sprite)
      undo_remove_layer(sprite.undo, layer)
      undo_close(sprite.undo)
    end

    -- select other layer
    sprite_set_layer(sprite, layer_select)

    -- remove the layer
    layer_remove_layer(parent, layer)

    -- destroy the layer
    layer_free(layer)
  end
end

function GUI_RemoveLayer()
  if current_sprite then
    RemoveLayer()
    GUI_Refresh(current_sprite)
  end
end