• Dynamic Visual Content:
  • Visual content that changes over time
  • It has been given a variety of different names over the years including movies, videos, films, animations, and marquees
• Sampling Dynamic Visual Content:
  • Select a discrete set of points in time (called frames)
  • "Record" the action at each time

An Illustration

• Each frame is thought of as a coherent whole
• Each frame consists of static visual content
• Each frame can be either sampled or described (and is completely independent of the time-based sampling)

• Requirements:
  • The system must render a sequence of SimpleContent objects over time
• To Satisfy this Requirement we Need:
  • An object that manages the collection of SimpleContent objects
  • A process that controls the rendering of the objects in the sequence
  • A GUI component that presents the SimpleContent objects
• We Have Everything But:
  • An "enhanced" Visualization object to manage the collection of SimpleContent objects

• Alternative Ways to Add these Enhancements:
  • Add code to the Visualization and VisualizationView classes
  • Decorate the Visualization and VisualizationView classes
  • Specialize the Visualization and VisualizationView classes
• Which is Best?
  • You tell me

• An Obvious Approach to Control the Rendering:
  • Write a loop that calls each SimpleContent object's render() method
• The Problem:
  • No control over the amount of time each frame is visible

Controlling the Timing of the Rendering Process

Outline of a Screen Class

javaexamples/visual/dynamic/sampled/Screen.java (Fragment: skeleton)

Handling Metronome Ticks

javaexamples/visual/dynamic/sampled/Screen.java (Fragment: handleTick) javaexamples/visual/dynamic/sampled/Screen.java (Fragment: advanceFrame)

Modifying Behavior in the Parent Class

javaexamples/visual/dynamic/sampled/Screen.java (Fragment: iterator)

The Rendering Process

• A Problem:
  • Dynamic visual content has a tendency to "flicker" when pre-rendering, rendering, and post-rendering takes a "noticeable" abount of time
• A Solution:
  • Don't have the rendering engine write directly to the screen (i.e., video memory).
  • Have it write to a background image.

javaexamples/visual/VisualizationView.java (Fragment: doublebuffer1) javaexamples/visual/VisualizationView.java (Fragment: doublebuffer2) javaexamples/visual/VisualizationView.java (Fragment: doublebuffer3)

• In Java, all Swing components support double buffering
• The approach used is not suitable for our purposes
• Hence, we must use our own implementation and deactivate the default buffering

• Straight Cut:
  • Frame n+1 is rendered in its entirety immediately after frame n
• Transition:
  • An alternative way to "join" frames together

• Fade-In (or Fade-Up):
  • A progressive brightening
  • Most commonly, a "fade from black"
• Fade-Out (or Fade-To):
  • A progressive darkening
  • Most commonly, a "fade to black"

A Fade Class

javaexamples/visual/dynamic/sampled/Fade.java (Fragment: setDestinationPixels)

Pre-Rendering Phase

javaexamples/visual/dynamic/sampled/Fade.java (Fragment: preRendering)

Post-Rendering Phase

javaexamples/visual/dynamic/sampled/Fade.java (Fragment: postRendering)

• Dissolve:
  • Frame n fades out while framen+1 fades in
• The Most Common Dissolve:
  • A fade-in without an intermediate solid background

A Disolve Class

javaexamples/visual/dynamic/sampled/Dissolve.java

• Wipe:
  • A frame (or frames) is clipped to a series of (one or more) geometric shapes
• Common Wipes:
  • Rectangle Wipe, Circle Wipe, Star Wipe
  • Line Wipe
  • Quivering, Venetian Blind

A RectangleWipe Class

javaexamples/visual/dynamic/sampled/RectangleWipe.java (Fragment: calculateClip)

Pre-Rendering Phase

javaexamples/visual/dynamic/sampled/RectangleWipe.java (Fragment: preRendering)

Post-Rendering Phase

javaexamples/visual/dynamic/sampled/RectangleWipe.java (Fragment: postRendering)

A LineWipe Class

javaexamples/visual/dynamic/sampled/LineWipe.java (Fragment: calculateClip)

• Superimposition:
  • A description of visual content that is to be added to an existing frame
• Common Types:
  • "Text"
  • "Graphics"

An AbstractSuperimposition Class

javaexamples/visual/dynamic/sampled/AbstractSuperimposition.java

A TransformableContentSuperimposition Class

javaexamples/visual/dynamic/sampled/TransformableContentSuperimposition.java (Fragment: constructor) javaexamples/visual/dynamic/sampled/TransformableContentSuperimposition.java (Fragment: postRendering)

• Requirements:
  • The system must support transitions (other than straight cuts) between frames of sampled dynamic content
  • The system must support the superimposition of static visual content on one or more frames of sampled dynamic content
• Alternative Designs:
  • There are several to consider

Common Requirements

javaexamples/visual/dynamic/sampled/FrameOp.java

Abstract Implementation

javaexamples/visual/dynamic/sampled/AbstractFrameOp.java

The Screen Class

javaexamples/visual/dynamic/sampled/Screen.java (Fragment: transition1) javaexamples/visual/dynamic/sampled/Screen.java (Fragment: superimposition1) javaexamples/visual/dynamic/sampled/Screen.java (Fragment: transition3) javaexamples/visual/dynamic/sampled/Screen.java (Fragment: transition4) javaexamples/visual/dynamic/sampled/Screen.java (Fragment: superimposition3) javaexamples/visual/dynamic/sampled/Screen.java (Fragment: superimposition4)

The ScreenRenderer Class

javaexamples/visual/dynamic/sampled/ScreenRenderer.java (Fragment: preRendering) javaexamples/visual/dynamic/sampled/ScreenRenderer.java (Fragment: postRendering) javaexamples/visual/dynamic/sampled/ScreenRenderer.java (Fragment: render)