Class: RbSDL2::RWObject::ReadCallback

Inherits:
FFI::Function
  • Object
show all
Defined in:
lib/rb_sdl2/rw_ops/rw_object.rb

Instance Method Summary collapse

Constructor Details

#initialize ⇒ ReadCallback

Returns a new instance of ReadCallback.



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# File 'lib/rb_sdl2/rw_ops/rw_object.rb', line 21

def initialize
  # size_t (* read) (struct RWops * context, void *ptr, size_t size, size_t maxnum);
  super(:size_t, [:pointer, :pointer, :size_t, :size_t]) do |_context, ptr, size, max_num|
    num = size * max_num
    str = yield(num)
    next 0 if str.nil? # EOF
    len = str.size
    if len > num # 要求より多い文字数を返している。obj.read が壊れている。
      raise RbSDL2Error, "The return value of read method is corrupted"
    end
    ptr.write_bytes(str, 0, len)
    len / size
  rescue => e
    raise e if $DEBUG
    Error.last_error_message = e.message
    0
  end
end