Keyboard and Ink Input with WPF - Ink Input

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The stylus used on Tablet PCs and other ink-enabled systems has its own set of events. Table 4-3 shows the ink input events offered by user interface elements.

Table 4-3. Stylus and ink events

Event	Routing	Meaning
GotStylusCapture	Bubble	Element captured stylus.
LostStylusCapture	Bubble	Element lost stylus capture.
PreviewStylusButtonDown, StylusButtonDown	Tunnel, Bubble	Stylus button pressed while over element.
PreviewStylusButtonUp, StylusButtonUp	Tunnel, Bubble	Stylus button released while over element.
PreviewStylusDown, StylusDown	Tunnel, Bubble	Stylus touched screen while over element.
PreviewStylusUp, StylusUp	Tunnel, Bubble	Stylus left screen while over element.
StylusEnter	Direct	Stylus moved into element.
StylusLeave	Direct	Stylus left element.
PreviewStylusInRange, StylusInRange	Tunnel, Bubble	Stylus moved close enough to screen to be detected.
PreviewStylusOutOfRange, StylusOutOfRange	Tunnel, Bubble	Stylus moved out of detection range.
PreviewStylusMove, StylusMove	Tunnel, Bubble	Stylus moved while over element.
PreviewStylusInAirMove, StylusInAirMove	Tunnel, Bubble	Stylus moved while over element but not in contact with screen.
PreviewStylusSystemGesture, StylusSystemGesture	Tunnel, Bubble	Stylus performed a gesture.
PreviewTextInput, TextInput	Tunnel, Bubble	Element received text input.

TheStylusclass provides a staticCapturemethod that works exactly the same as theMouse.Capturemethod described earlier. It also offersCaptured andDirectlyOverproperties that do the same for the stylus as the matching properties of theMouseclass do for the mouse.

There is an alternative way of dealing with stylus input. Instead of handling all of these low-level events yourself, you can use WPF’s high-level ink handling element,InkCanvas. Example 4-14 shows how little is required to add an ink input area to a WPF application.

Example 4-14. InkCanvas

<InkCanvas />

TheInkCanvas accepts free-form ink input. Figure 4-3 shows the InkCanvasin action. (It also demonstrates that I should probably stick to using the keyboard.)InkCanvasmakes all of the ink input available to your program through itsStrokes property. It is possible to connect this data to the handwriting recognition APIs in Windows, but that is beyond the scope of this book.

Figure 4-3.  InkCanvas

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