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Displaying Pen Data
The Pen API provides four functions for displaying the pen data contained in
an HPENDATA object. An additional function, CreatePenDataRegion, determines the screen area necessary to display the pen data. This enables
an application to determine the screen area affected by a gesture.
The following table describes the API drawing functions:
Function
| Description
| DrawPenData
| Draws pen data in the specified device context using the Windows GDI Polyline function. The ink width and color specified in the PENDATAHEADER structure have no effect on how DrawPenData renders the ink.
The rendering of the ink data produced by DrawPenData generally does not exactly match the rendering produced by the display driver
when the data was first collected. An application that requires an exact
replication of the original ink rendering should call the RedisplayPenData function.
| DrawPenDataEx
| Draws pen data in its original color or in a given device context. This
function is an enhanced version of DrawPenData. Besides basic drawing capabilities, DrawPenDataEx can control the speed at which the data is rendered, a process called
animation. This function can also draw a selected subset of strokes or the points
within a stroke, rather than the entire pen data.
DrawPenDataEx can display a set of sequential strokes with a single call. Drawing
nonsequential strokes  say, the second, fifth, and eighth strokes of the pen data requires separate calls to DrawPenDataEx for each stroke.
| DrawPenDataFmt
| A macro function that simplifies calls to DrawPenDataEx by specifying:
- Rendering ink data in original ink attributes and speed (no animation).
- Entire data set is drawn (no stroke subsets).
- Each stroke is drawn with the color and width specified in the stroke header.
| RedisplayPenData
| Draws pen data ink that exactly matches the original rendering. RedisplayPenData displays pen data with a square GDI pen brush for maximum drawing speed. When
displaying wide lines of ink, this optimization can cause the ends of abutting
lines to appear "blocky."
| CreatePenDataRegion
| Returns a region of the screen required to show the contents of an HPENDATA object. Another call to the GDI function GetRgnBox returns the bounding rectangle that holds the region. (See also the
description of GetPenDataAttributes, which can return the bounding rectangle for the entire set of pen data.) The
application should call the Windows function DestroyObject to free the region when finished.
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