Monkeybread Software - DynaPDF Manual

DynaPDF Manual - Page 644

Function Reference

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If a required CMap is absent the Decoded parameter of the TShowTextArrayW callback function is

set to false and the string should be ignored in this case because no meaningful values can be

returned.

Inside the Callback Functions

The following sub-clauses describe important operations which must be executed in the callback

functions to achieve correct results.

TBeginTemplate

This callback function is executed when a Form XObject in PDF terms is painted (we call this object

type template in DynaPDF). The parameter BBox specifies the template's bounding box or visible

area measured in form space. The required mapping from form space to user space is specified by

the Matrix parameter (see also Coordinate Spaces). The Matrix parameter is optional and can be set

to NULL. In the latter case, the form matrix is set to the identity matrix.

If the form matrix is present then it must be multiplied with the current transformation matrix of the

graphics state as follows:

// m_GState represents the current graphics state

if (Matrix)

{

m_GState.Matrix = MulMatrix(m_GState.Matrix, *Matrix);

}

The corresponding TEndTemplate callback function is executed if the contents of a template were

fully processed. The definition of this callback function is optional because no specific code is

required to be executed.

Return values:

•

0 indicates success and processing continues.

•

1 means that the template should be skipped.

•

Any other return value breaks processing.

TMulMatrix

The TMulMatrix callback function is executed if the current transformation matrix must be

multiplied with a new one. When using the function MulMatrix() the matrix must be multiplied

with the one of the graphics state as follows:

// m_GState represents the current graphics state

m_GState.Matrix = MulMatrix(m_GState.Matrix, *Matrix);

The parameter Matrix is always set; it is not required to check whether the parameter is set to NULL.