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-- If all parameteres, besides the image, are nil, this is equivalent to image:Clone.
-- If any parameter is not nil, then the value is used instead of the one from the source image.
-- If a parameter is a function, then the function is called, passing the source
-- image as parameter, to obtain the substituion value.
function im.ImageCreateBased(image, width, height, color_space, data_type)
-- default values are those of the source image
width = width or image:Width()
height = height or image:Height()
color_space = color_space or image:ColorSpace()
data_type = data_type or image:DataType()
-- callback to calculate parameters based on source image
if type(width) == "function" then width = width(image) end
if type(height) == "function" then height = height(image) end
if type(color_space) == "function" then color_space = color_space(image) end
if type(data_type) == "function" then data_type = data_type(image) end
-- create a new image
new_image = im.ImageCreate(width, height, color_space, data_type)
image:CopyAttributes(new_image)
if (image:HasAlpha()) then new_image:AddAlpha() end
return new_image
end
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