defmodule Image.Options.WarpPerspective do
@moduledoc """
Options and option validation for `Image.warp_perspective/4`.
"""
alias Vix.Vips.Image, as: Vimage
alias Image.Color
@typedoc """
Options for Image.warp_perspective/4.
"""
@type t :: [warp_perspective_option()]
@typedoc """
Options applicable to `Image.embed/4`.
"""
@type warp_perspective_option :: [
{:background, Color.t() | :average}
| {:extend_mode, extend_mode()}
]
@typedoc """
When extending the canvas the generated
pixels are determined by this option.
"""
@type extend_mode :: [
:black
| :white
| :copy
| :repeat
| :mirror
| :background
]
@doc """
Validate the options for `Image.warp_perspective/4`.
"""
@spec validate_options(Vimage.t(), Keyword.t()) ::
{:ok, Keyword.t()} | {:error, Image.error_message()}
def validate_options(image, options) when is_list(options) do
options = Keyword.merge(default_options(), options)
case Enum.reduce_while(options, options, &validate_option(&1, image, &2)) do
{:error, value} ->
{:error, value}
options ->
{:ok, options}
end
end
defp validate_option({:background, :average}, image, options) do
case Image.average(image) do
color when is_list(color) ->
options = Keyword.put(options, :background, color)
{:cont, options}
{:error, reason} ->
{:halt, {:error, "Could not get the image average: #{inspect(reason)}"}}
end
end
defp validate_option({:background, color} = option, _image, options) do
case Color.rgb_color(color) do
{:ok, hex: _hex, rgb: color} -> {:cont, Keyword.put(options, :background, color)}
{:ok, color} -> {:cont, Keyword.put(options, :backgrouond, color)}
_other -> {:halt, invalid_option(option)}
end
end
defp validate_option({:extend_mode, extend}, _image, options) do
case Image.ExtendMode.validate_extend(extend) do
{:ok, extend_mode} ->
options = Keyword.put(options, :extend_mode, extend_mode)
{:cont, options}
{:error, reason} ->
{:halt, {:error, reason}}
end
end
defp validate_option(option, _image, _options) do
{:halt, {:error, invalid_option(option)}}
end
defp invalid_option(option) do
"Invalid option or option value: #{inspect(option)}"
end
defp default_options do
[
extend_mode: :black,
background: :black
]
end
end