Images and Bitmap Data

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Images and Bitmap Data

• 2533CIT - Week 13

Coridyn Fitzgerald-Hood
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Images

• Working with images and bitmap data is an
  important part of flash programming.

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Loading External Images

• Flash allows us to load external Images and Flash
  movies (compiled swfs) using the MovieClipLoader
  class.
• The MovieClipLoader class is the class-based
  equivalent to the MovieClip.loadMovie() and
  MovieClip.loadMovieNum() functions.

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MovieClipLoader

• Using the MovieClipLoader has quite a few
  benefits
• The MovieClipLoader instance is reusable,
• It supports event handling,
• Notifies us when the data has loaded and after it
  is initialised (for MovieClips).
• Provides an easy interface for monitoring the
  status of a MovieClip/image download.

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MovieClipLoader

• The MovieClipLoader is designed to allow you to
  load external graphical content into a particular
  MovieClip instance in your existing Flash movie.
• The use of the MovieClipLoader class follows a
  standard pattern
• Instantiate the MovieClipLoader instance.
• Set event handling functions.
• Initiate load.
• Respond to events.

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MovieClipLoader Example

• See MCLExample in content.

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MovieClipLoader

• An important thing to take note of with the
  loadMovie function of the MovieClipLoader class
  is that the loaded content replaces the MovieClip
  instance passed as the second parameter.
• The loaded content will be accessible through the
  given reference, but the original content will be
  unavailable.
• The loaded content also inherits the rotation,
  scaling and translation properties of the
  original MovieClip.

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Loading Images

• It is important to remember that images loaded
  with the MovieClipLoader will also replace the
  existing content in the MovieClip target.
• This is more important to remember for image
  content because images cannot be manipulated with
  actionscript code.
• This is important enough for repetition
• Images cannot be accessed or manipulated through
  Actionscript code.

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Loading Images

• To work with dynamically loaded image data we
  must perform a simple trick.
• Load the image data into a child of the intended
  MovieClip target.
• Once the image data has been loaded, treat the
  parent MovieClip as the image itself. This allows
  us to scale, rotate and translate the image on
  the screen.

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Loading Images (Incorrect)

• Loading Image content into a MovieClip instance.
• Before
• After

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Loading Images (Correct)

• Before
• After

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Bitmap Data
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BitmapData Class

• Flash 8 introduced the ability to directly access
  and manipulate bitmap image data.
• This ability has been used to great effect in
  many Flash applications e.g. textured 3D
  renderers
• (and to much lesser effect in others e.g.
  Puzzle Application).
• Either way it is a useful and interesting class.

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BitmapData - General Use

• Instantiate the BitmapData class.
• Attach the BitmapData instance to a MovieClip
  instance.
• Manipulate the BitmapData instance drawing
  directly to the bitmap data or running filters on
  the existing data.
• Draw the BitmapData to the stage.

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BitmapData.draw()

• The draw function lets us draw bitmap data
  directly from one source onto the current
  BitmapData instance.
• This is very useful for drawing the current
  representation of a MovieClip or other BitmapData
  instance.

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BitmapData example

• See FlashPaint in content.

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BitmapData.loadBitmap()

• Use the loadBitmap() function to load an image
  from the library onto the stage.
• The loadBitmap function was used in the Puzzle
  application to draw the initial puzzle image
  before being split into the puzzle pieces.

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BitmapData.copyPixels()

• Use the copyPixels function to quickly copy
  bitmap information from one BitmapData instance
  to another.
• You can copy information from the same BitmapData
  instance if required.

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loadBitmap, copyPixels Example

• See Puzzle in content.