Monkeybread Software - DynaPDF Manual

DynaPDF Manual - Page 668

Function Reference

Page 668 of 860

Example:

Frame rectangle filled with an

Without the frame rectangle there

arbitrary color.

is no way to determine where the

page contents starts or ends.

Page area

Whether a frame rectangle should be drawn or not depends on the way how a page is rendered into

the destination window. If the viewer processes mainly simple PDF files then it is possible to render

pages simply on demand. The page can then directly be scaled into the destination image and in this

case it is usually best to draw the page into a frame rectangle.

However, scrolling and zooming becomes too slow when more complex pages must be rendered. To

achieve optimal processing speed as well as smoth and flicker free scrolling the viewer should

render the page into an image in the size of the scaled page format so that the finish image can be

scrolled. The background or the frame rectangle must be drawn by the viewer application in this

case.

To calculate the required image size in pixels the rendering engine provides helper functions to

access the page's bounding boxes as well as the page orientation fast as possible (see GetPageBBox()

and GetPageOrientation()).

The image size can be calculated as follows (C++):

UI32 w = 0, h = 0;

UI32 fw = 2540, fh = 1440; // Size of output rectangle in pixels

// Get a pointer of the page object to enable fast access to the page

// properties.

IPGE* pagePtr = pdfGetPageObject(m_PDF, pageNum);

// CalcPagePixelSize() returns the height of the image in this example.

// RenderPage() calculates the image size in the exact same way when

// called with the same parameters.

rasCalcPagePixelSize(pagePtr,psFitWidth,1.0f,fw,fh,rfDefault,&w,&h);