Class: FreeImage::MemoryStream

Inherits:
FFI::AutoPointer
  • Object
show all
Defined in:
lib/free-image/sources/memory.rb

Overview

Wrapper for a FreeImage memory stream which allows images to be read and written to memory. Memory streams are usefule for storing images as blobs in a database or writing them to an to a Internet stream.

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(bytes = nil) ⇒ MemoryStream

Create a new memory stream.

Parameters

bytes

If specified, a binary encoded Ruby string that stores image data. FreeImage will treat the string as read-only. If not specified, a writable MemoryStream is created.



48
49
50
51
52
53
54
55
56
57
58
 
# File 'lib/free-image/sources/memory.rb', line 48

def initialize(bytes = nil)
  ptr = if bytes
    buf = FFI::MemoryPointer.from_string(bytes)
    FreeImage.FreeImage_OpenMemory(buf, bytes.bytesize)
  else
    FreeImage.FreeImage_OpenMemory(nil, 0)
  end
  FreeImage.check_last_error

  super(ptr)
end

Class Method Details

.release(ptr) ⇒ Object 



37
38
39
40
 
# File 'lib/free-image/sources/memory.rb', line 37

def self.release(ptr)
  FreeImage.FreeImage_CloseMemory(ptr)
  FreeImage.check_last_error
end

Instance Method Details

#bytes ⇒ Object

Returns the bytes of the memory stream.



79
80
81
82
83
84
85
86
87
88
89
90
 
# File 'lib/free-image/sources/memory.rb', line 79

def bytes
  size = FFI::Type::CHAR.size

  # Reset memory to start
  FreeImage.FreeImage_SeekMemory(self, 0, ::IO::SEEK_SET)
  FreeImage.check_last_error

  buffer = FFI::MemoryPointer.new(FFI::Type::CHAR, size * count)
  FreeImage.check_last_error
  size = FreeImage.FreeImage_ReadMemory(buffer, size, count, self)
  buffer.null? ? nil : buffer.read_string
end

#count ⇒ Object

Returns the size of the memory stream.



61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
 
# File 'lib/free-image/sources/memory.rb', line 61

def count
  # Store current position
  pos = FreeImage.FreeImage_TellMemory(self)
  FreeImage.check_last_error

  # Go to end of stream to get length
  FreeImage.FreeImage_SeekMemory(self, 0, ::IO::SEEK_END)
  FreeImage.check_last_error
  count = FreeImage.FreeImage_TellMemory(self)

  # Restore position
  FreeImage.FreeImage_SeekMemory(self, pos, ::IO::SEEK_SET)
  FreeImage.check_last_error

  count
end