IXpsOMGeometryFigure::GetSegmentData method

项目
06/01/2017

Gets the segment data points for the geometry figure.

Syntax

HRESULT GetSegmentData(
  [in, out] UINT32 *dataCount,
  [in, out] FLOAT  *segmentData
);

Parameters

dataCount [in, out]
The size of the array referenced by the segmentData parameter.

If the method returns successfully, dataCount will contain the number of elements returned in the array that is referenced by segmentData.

If segmentData is set to NULL when the method is called, dataCount must be set to zero.

If a NULL pointer is returned in segmentData, dataCount will contain the required buffer size as the number of elements.
segmentData [in, out]
The address of an array that has the same number of elements as specified in dataCount. This value can be set to NULL if the caller requires that the method return only the required buffer size in dataCount.

If the array is large enough, this method copies the segment data points into the array and returns, in dataCount, the number of data points that are copied. If segmentData is set to NULL or references a buffer that is not large enough, a NULL pointer will be returned, no data will be copied, and dataCount will contain the required buffer size specified as the number of elements.

Return value

The method returns an HRESULT. Possible values include, but are not limited to, those in the table that follows. For information about XPS document API return values that are not listed in this table, see XPS Document Errors.

Return code	Description
S_OK	The method succeeded.
E_POINTER	dataCount is NULL.
ERROR_MORE_DATA	segmentData is NULL or references a buffer that is not large enough to receive the segment data. dataCount contains the required number of elements.

Remarks

To determine the required size of the segment data array before calling this method, call GetSegmentDataCount.

A geometry segment is described by the start point, the segment type, and additional parameters whose values are determined by the segment type. The coordinates for the start point of the first segment are a property of the geometry figure and are set by calling SetStartPoint. The start point of each subsequent segment is the end point of the preceding segment.

The values in the array returned in the segmentData parameter will correspond with the XPS_SEGMENT_TYPE values in the array returned by the GetSegmentTypes method in the segmentTypes parameter. To read the segment data values correctly, you will need to know the type of each segment in the geometry figure. For example, if the first line segment has a segment type value of XPS_SEGMENT_TYPE_LINE, the first two data values in the segmentData array will be the x and y coordinates of the end point of that segment; if the next segment has a segment type value of XPS_SEGMENT_TYPE_BEZIER, the next six values in the segmentData array will describe the characteristics of that segment; and so on for each line segment in the geometry figure.

The table that follows describes the specific set of data values that are returned for each segment type. For an example of how to access this data in a program, see the code example that follows.

Segment type	Required data values
XPS_SEGMENT_TYPE_LINE	Two data values: x-coordinate of the segment line's end point. y-coordinate of the segment line's end point.
XPS_SEGMENT_TYPE_ARC_LARGE_CLOCKWISE	Five data values: x-coordinate of the arc's end point. y-coordinate of the arc's end point. Length of the ellipse's radius along the x-axis. Length of the ellipse's radius along the y-axis. Rotation angle.
XPS_SEGMENT_TYPE_ARC_SMALL_CLOCKWISE	Five data values: x-coordinate of the arc's end point. y-coordinate of the arc's end point. Length of the ellipse's radius along the x-axis. Length of the ellipse's radius along the y-axis. Rotation angle.
XPS_SEGMENT_TYPE_ARC_LARGE_COUNTERCLOCKWISE	Five data values: x-coordinate of the arc's end point. y-coordinate of the arc's end point. Length of the ellipse's radius along the x-axis. Length of the ellipse's radius along the y-axis. Rotation angle.
XPS_SEGMENT_TYPE_ARC_SMALL_COUNTERCLOCKWISE	Five data values: x-coordinate of the arc's end point. y-coordinate of the arc's end point. Length of the ellipse's radius along the x-axis. Length of the ellipse's radius along the y-axis. Rotation angle.
XPS_SEGMENT_TYPE_BEZIER	Six data values: x-coordinate of the Bezier curve's first control point. y-coordinate of the Bezier curve's first control point. x-coordinate of the Bezier curve's second control point. y-coordinate of the Bezier curve's second control point. x-coordinate of the Bezier curve's end point. y-coordinate of the Bezier curve's end point.
XPS_SEGMENT_TYPE_QUADRATIC_BEZIER	Four data values: x-coordinate of the Quad Bezier curve's control point. y-coordinate of the Quad Bezier curve's control point. x-coordinate of the Quad Bezier curve's end point. y-coordinate of the Quad Bezier curve's end point.

The following code example accesses the different data points of each segment type in a geometry figure.

    // currentFigure is the pointer to an IXpsOMGeometryFigure
    // that contains the segment data to examine

    HRESULT             hr = S_OK;
    UINT32              numSegments = 0;
    UINT32              numSegmentDataPoints = 0;
    XPS_SEGMENT_TYPE    *segmentTypes = NULL;
    FLOAT               *segmentDataPoints = NULL;
    BOOL                *segmentStrokes = NULL;

    // get number of segments in this figure
    hr = currentFigure->GetSegmentCount (&numSegments);

    if (SUCCEEDED(hr))
    {
        // allocate array for segment data types
        segmentTypes = new (std::nothrow) XPS_SEGMENT_TYPE[numSegments];
        if (segmentTypes == NULL) { hr = E_OUTOFMEMORY; }
    }

    if (SUCCEEDED(hr))
    {
        // allocate array for segment strokes
        segmentStrokes = new (std::nothrow) BOOL[numSegments];
        if (segmentStrokes == NULL) { hr = E_OUTOFMEMORY; }
    }

    if (SUCCEEDED(hr))
    {
        // get array of segment data types
        hr = currentFigure->GetSegmentTypes (&numSegments, segmentTypes);
    }

    if (SUCCEEDED(hr))
    {
        // get size of segment data array
        hr = currentFigure->GetSegmentDataCount (&numSegmentDataPoints);
    }

    if (SUCCEEDED(hr))
    {
        // get array to hold segment data points
        segmentDataPoints = new (std::nothrow) FLOAT[numSegmentDataPoints];
        if (segmentDataPoints == NULL) { hr = E_OUTOFMEMORY; }
    }

    if (SUCCEEDED(hr))
    {
        // get segment data points
        hr = currentFigure->GetSegmentData (
            &numSegmentDataPoints, segmentDataPoints);
    }

    if (SUCCEEDED(hr))
    {
        // process segment data
        UINT32           thisSegment = 0;
        XPS_SEGMENT_TYPE *thisSegmentType = segmentTypes;
        XPS_SEGMENT_TYPE *lastSegmentType = NULL;
        FLOAT            *thisSegmentDataPoint = segmentDataPoints;
        FLOAT            *lastSegmentsDataPoint = NULL;

        // points to element just after valid array
        // valid pointers are < this value and  >= &segmentTypes[0]
        lastSegmentType = &segmentTypes[numSegments]; 
        // points to element just after valid array
        // valid pointers are < this value and >= &segmentDataPoints[0]
        lastSegmentsDataPoint = &segmentDataPoints[numSegmentDataPoints];

        // look at each segment that was returned
        while (thisSegment < numSegments)
        {
            if ((thisSegmentType >= lastSegmentType) || 
                (thisSegmentDataPoint >= lastSegmentsDataPoint))
            {
                // the array data is not correct.
                hr = E_UNEXPECTED;
                break; // out of loop
            } 
            else
            {
                // process the data based on the segment type
                switch (*thisSegmentType) 
                {
                    case    XPS_SEGMENT_TYPE_ARC_LARGE_CLOCKWISE:
                    case    XPS_SEGMENT_TYPE_ARC_LARGE_COUNTERCLOCKWISE:
                    case    XPS_SEGMENT_TYPE_ARC_SMALL_CLOCKWISE:
                    case    XPS_SEGMENT_TYPE_ARC_SMALL_COUNTERCLOCKWISE:
                        {
                        // 5 data points
                        FLOAT    arcEndPoint_x = *thisSegmentDataPoint++;
                        FLOAT    arcEndPoint_y = *thisSegmentDataPoint++;
                        FLOAT    radius_x = *thisSegmentDataPoint++;
                        FLOAT    radius_y = *thisSegmentDataPoint++;
                        FLOAT    angle = *thisSegmentDataPoint++;
                        // do something with these points
                        }
                        break;
                    case    XPS_SEGMENT_TYPE_BEZIER:
                        {
                        // 6 data points
                        FLOAT    controlPoint1_x = *thisSegmentDataPoint++;
                        FLOAT    controlPoint1_y = *thisSegmentDataPoint++;
                        FLOAT    controlPoint2_x = *thisSegmentDataPoint++;
                        FLOAT    controlPoint2_y = *thisSegmentDataPoint++;
                        FLOAT    endPoint_x = *thisSegmentDataPoint++;
                        FLOAT    endPoint_y = *thisSegmentDataPoint++;
                        // do something with these points
                        }
                        break;
                    case    XPS_SEGMENT_TYPE_LINE:
                        {
                        // 2 data points
                        FLOAT    endPoint_x = *thisSegmentDataPoint++;
                        FLOAT    endPoint_y = *thisSegmentDataPoint++;
                        // do something with these points
                        }
                        break;
                    case    XPS_SEGMENT_TYPE_QUADRATIC_BEZIER:
                        {
                        // 4 data points
                        FLOAT    controlPoint_x = *thisSegmentDataPoint++;
                        FLOAT    controlPoint_y = *thisSegmentDataPoint++;
                        FLOAT    endPoint_x = *thisSegmentDataPoint++;
                        FLOAT    endPoint_y = *thisSegmentDataPoint++;
                        // do something with these points
                        }
                        break;
                    default:
                        // unrecognized segment type
                        break;
                }
                // 
                thisSegment++;
                thisSegmentType++;
            }
        }
    }

    delete[] segmentTypes; segmentTypes = NULL;
    delete[] segmentStrokes; segmentStrokes = NULL;
    delete[] segmentDataPoints; segmentDataPoints = NULL;

Requirements

Minimum supported client	Windows 7, Windows Vista with SP2 and Platform Update for Windows Vista [desktop apps \| Windows Store apps]
Minimum supported server	Windows Server 2008 R2, Windows Server 2008 with SP2 and Platform Update for Windows Server 2008 [desktop apps \| Windows Store apps]
Header	Xpsobjectmodel.h
IDL	XpsObjectModel.idl

通过