Building Tablet PC Applications

Targeting and Hit-Testing Ink Strokes

In Chapter 2, we learned the importance of making it easy to select ink and manipulate it directly with the pen. Using the pen or mouse to target ink strokes to perform selection or another operation, such as erasing, is known as hit-testing.

Just as certain factors of human physiology must be taken into account when detecting tapping vs. dragging with the pen, we must also consider similar factors in the determination of whether ink has been targeted. The specific considerations depend on the kind of hit-testing being performed, so let’s take a look at the various forms of hit-testing that apply to ink.

Different Types of Hit-Testing

A user can perform three main types of targeting, resulting in three types ...