DrawPenData

0 2.0

Displays the pen data in an HPENDATA object as a trail of visible ink.

oid DrawPenData( HDC hdc, LPRECT lprect, HPENDATA hpndt )

Parameters
hdc

Handle to a device context. This parameter can also be the handle of a metafile.

lprect

Bounding rectangle of ink, in client coordinates. Can be NULL.

hpndt

Handle to a pen data object.

Return Value
This function does not return a value. If hpndt is NULL, DrawPenData does nothing.

Comments
DrawPenData draws the pen data in the specified device context using the GDI Polyline function. The current settings in the device context rather than the ink characteristics determine how the data is rendered. This means the ink width and color specified in the PENDATAHEADER structure have no effect on how DrawPenData renders the ink. To alter the display characteristics of the ink, an application must call the appropriate Windows GDI functions to set the GDI drawing pen (not to be confused with the real pen).

The application using DrawPenData must either scale the data points or set the mapping appropriately if lprect is NULL.

If lprect is not NULL, the points are scaled into lprect as the drawing is done. Internally, nondestructive calls to the SetViewportExtEx, SetViewPortOrg, SetWindowOrg, and SetWindowExtEx functions are used to render the pen data in the device context within the bounds of the provided rectangle. An application must compute the proper pen width (if it is other than 1) before calling this function with a valid lprect parameter to account for the scaling that occurs.

DrawPenData draws the ink in the rectangle relative to the upper-left corner of the window. It ignores any changes that have been made to the origin of the device context by previous calls to the SetWindowOrg or SetViewportOrgEx functions. If the origin has changed, the rectangle passed to DrawPenData must be offset by the appropriate amount.

If the ink is to be drawn with a width of greater than 1 pixel, the width of the currently selected pen must be set to achieve the desired result. The width must be set in client coordinates if a mapping mode is set in the device context. For example, if the mapping mode has been set to MM_HIENGLISH, the pen width must be set to a number appropriate for the desired width in MM_HIENGLISH units to preserve the proper scale of the ink. This scaling is only an issue when the ink width is greater than 1.

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. This discrepancy results because DrawPenData and the Polyline function use different algorithms to draw the data. The difference is an occasional "off by one" error that appears as a shifting of some pixels around the edges, depending on the rounding done by Polyline. An application that requires an exact replication of the original ink rendering should call the RedisplayPenData function.

The DrawPenDataEx function allows more control when drawing the contents of pen structures.

See Also
CreatePenData, DrawPenDataEx, DuplicatePenData, RedisplayPenData

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