MetricScalePenData

1. 0 2.0

Converts pen data points to one of the supported metric modes.

BOOL MetricScalePenData( HPENDATA hpndt, UINT wPndtNew )

Parameters

hpndt

Handle to a pen data object containing the points to be converted.

wPndtNew

Scaling metric to be used with the data, as listed here:

Constant	Description
PDTS_LOMETRIC	Each logical unit is mapped to 0.1 millimeter. Positive x is to the right; positive y is down.
PDTS_HIMETRIC	Each logical unit is mapped to 0.01 millimeter. Positive x is to the right; positive y is down.
PDTS_HIENGLISH	Each logical unit is mapped to 0.001 inch. Positive x is to the right; positive y is down. This is equivalent to PDTS_STANDARDSCALE.
PDTS_DISPLAY	This parameter scales the data, using DPtoTP. The pen data memory block is left in display coordinates.

Return Value

Returns TRUE if successful, or FALSE if hpndt is in a compressed state or if the data is not already in one of the metric modes such as PDTS_ARBITRARY.

Comments

The MetricScalePenData function 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 form the same mapping mode set in the Windows function SetMapMode.

MetricScalePenData allows an application to transform pen data to the mapping mode set for a device context. This ensures that ink rendered in the device context appears in the proper scale.

Note the following caveats about MetricScalePenData:

• Because of rounding errors, scaling is not precisely reversible between mapping modes. Rounding errors can also adversely affect recognition accuracy if the data is later given to a recognizer. The problem arises when transforming the standard ink scale of HIENGLISH to a scale of lower resolution, a transformation that loses some of the original data. The lost data cannot be recovered, even if the coordinates are converted back into HIENGLISH.

• The scaling is not perfect and results in numerous "off-by-one" discrepancies, visible when displaying the scaled data.

Strictly speaking, the PDTS_DISPLAY scaling type is not a metric scale. To use it, the current scale of the data must be in PDTS_STANDARDSCALE units.

The effect of this call is similar to that of using the TPtoDP function on the array of points. A recognizer may not accurately recognize the resulting data. As with the other scales, the PDTS_DISPLAY is set in the wPndts member of the pen data header. If data is in PDTS_DISPLAY scale, MetricScalePenData cannot be called to scale it back to the other metric scales. No overflow checks are made. Because of rounding errors, scaling conversion is not perfectly reversible. Recognizers must recognize points that have been scaled to PDTS_STANDARDSCALE (equivalent to PDTS_HIENGLISH).

See Also

OffsetPenData, ResizePenData, PDTS_

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