The Updating and Rendering Pipeline

Figure 3 presents an illustration of the updating and rendering pipeline of the canvas. The steps are as follows:

1. The first step is to cause a state change in a canvas item, usually from direct manipulation through the user interface.

2. Identify the deltas, or the parts of the display that have actually changed. This is done in the ::update() method of canvas items.

3. Represent the deltas as a microtile array. Each microtile is a small rectangle that needs updating.

4. The microtile array is decomposed into bigger rectangles for more efficient redrawing.

5. Fifth and sixth, repeated for each rectangle from (4), canvas items are rendered in their normal stacking order, culling them against the bounding boxes defined in (4), and are displayed in the canvas window.

Figure 3: The updating and rendering process