Chapter 4. Immediate Mode Imaging Model

IN THIS CHAPTER

• Push Imaging Model

• Pixel Storage and Conversion

• Immediate Mode Imaging Model

Before discussing the immediate mode imaging model, it is important to understand the older, push imaging model. It is from the limitations of this model that the immediate mode model was created, just as the limitations of the immediate mode model led to the creation of the Java advanced imaging (JAI) API discussed in Chapter 6, “Java Advanced Imaging.” But just as the limitations of one model led to the creation of another, each model is built on the functionality of the one before, so understanding the push model is important to understanding the immediate mode model just as understanding the immediate mode model is important to understanding JAI.

As a quick introduction, both the push imaging model and the immediate mode imaging model are part of the Java Advanced Windowing Toolkit (AWT) package, although at one time the immediate mode model was part of a separate Java 2D package. (The Java 2D package has since been incorporated into the AWT package.) In the push imaging model, the image data isn't introduced into the imaging pipeline until it is needed; at which time an object called an ImageProducer starts pushing the data into this pipeline. On the other end of this pipeline is an ImageConsumer that must wait for the data to get pushed to it. In contrast, the immediate mode imaging model makes the image data available in memory immediately after each step in the imaging pipeline.