Monkeybread Software - DynaPDF Manual

DynaPDF Manual - Page 645

Function Reference

Page 645 of 874

TSetFont

The TSetFont callback function activates a font in the graphics state. The following variables of the

graphics state must be set when the callback function is executed:

m_GState.ActiveFont = Font;

m_GState.FontSize

= FontSize;

m_GState.FontType

= Type;

m_GState.SpaceWidth = (float)(fntGetSpaceWidth(Font, FontSize) * 0.5);

The space width is required to construct text lines. It is usually best to use the half space width to

determine whether a space must be inserted at a specific position because many PDF fonts do not

contain a space character and the function fntGetSpaceWidth() returns just a default width in this

case (the function name is GetSpaceWidth() in C#, Delphi, and VB .Net).

The space width is measured in text space like the member Advance of a kerning record. However,

the distance between two text records is measured in user space! So, the space width must be

transformed to user space before it can be compared with the distance between two text records. See

the description of the TShowTextArrayW callback function for further information.

TRestoreGraphicState

As the name of the function suggests the graphics state must be restored when the callback function

is executed. The graphics state stack is a LIFO (last in first out) data structure that stores copies of

the graphics state. The last element from the graphics state stack must be popped and the values

must be copied to the current graphics state.

It is guaranteed that this function is not executed without a preceeding TSaveGraphicState call.

Invalid restore graphics state operators are trated as an error. The parser breaks processing when it

encounters such an error.

The return value of the function must be zero. Any other return value breaks processing.

TSaveGraphicState

As the name suggests the current graphics state must be saved when the callback function is

executed. As already described at TRestoreGraphiState the graphics state stack is a LIFO (last in first

out) data structure that stores copies of the graphics state. The application must create a copy of the

current graphics state and push it onto the graphics state stack.

It is not guaranteed that all saved graphics states will be restored until the page was fully parsed.

The application must make sure that remaining copies of the graphics state will be released before

parsing the next page or terminating the application.

The return value of the function must be zero. Any other return value breaks processing.

TShowTextArrayA

This is the preferred callback function to develop text search algorithms. See also Sub string

coordinates for further information. The function returns the source strings which can be converted