Scaling Pen Data

The Pen API provides three functions to transform or scale pen data in an HPENDATA object. The related functions TPtoDP and DPtoTP do not operate explicitly on an HPENDATA object, but instead convert the resolution of an array of points.

Converts pen coordinates between metric and English standard measurements. Metric units are 0.1 and 0.01 millimeter; English standard units are 0.001 inch. These scaling metrics comply with the mapping modes set in the Windows function SetMapMode, described in the Windows Software Development Kit.
MetricScalePenData can also convert pen data to display resolution. See "Converting Data to Display Resolution" later in this chapter.
Offsets the coordinates in an HPENDATA object to make them relative to another origin. The function adds or subtracts offset values to or from the coordinate points. The offset values must use the same units as the pen data. Offsetting coordinates does not lose data. The process is completely reversible and does not reduce recognition accuracy.
Scales ink into arbitrarily sized rectangles. This function exhibits the same weakness as the other scaling functions. It preserves rectangle proportions, but rounding errors prevent the scaling process from being precisely reversible. However, enlarging the ink data generally does not adversely affect recognition accuracy for data later given to a recognizer.

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