Add a highlighted region.
PDFRegionHandle pdfAddRegion(PDFViewerHandle viewer, int page, double x0, double y0, double x1, double y1, COLORREF color, COLORREF selectColor, int selectable, char *label)
The XpdfViewer library can display a set of highlighted regions on the currently open PDF file. Once a highlighted region is created, the user can manipulate it by selecting it (clicking on it) and then moving its edges to resize it. As far as the XpdfViewer library is concerned, highlighted regions are simply rectangles drawn in some specified color. You can use regions for various purposes, e.g., allowing the user to mark parts of a PDF file to be extracted later.

This function adds a new highlighted region. The arguments are:

The pdfAddRegion function returns a handle that can be passed to the other region-related functions.
int page; double x0, y0, x1, y1; PDFRegionHandle region; /* user requested that the current selection be highlighted */ if (pdfGetCurrentSelection2(viewer, &page, &x0, &y0, &x1, &y1)) { region = pdfAddRegion(viewer, page, x0, y0, x1, y1, RGB(0,0,255), RGB(255,0,0), 1, NULL); }