Set the incremental update callback.
void pdfSetIncrementalUpdateCbk(PDFHandle pdf, void (*cbk)(void *data, PDFImageHeader *imgHdr, char *bits), void *cbkData)
This function sets a callback which is called periodically during rasterization to allow an intermediate version of the bitmap to be displayed to the user.

The imgHdr and bits arguments are similar to those used by pdfConvertPageToBitmap2 and pdfConvertRegionToBitmap2.

The incremental update callback is called frequently. The best approach is usually to display the bitmap only on every nth call, to avoid slowing things down too much.

NOTE: do not free the bits argument.

The incremental update callback is only available for the following functions:

int updateCounter; void incUpdateCbk(void *data, PDFImageHeader *imgHdr, char *bits) { ++updateCounter; if (updateCounter == 100) { /* imgHdr and bits are similar to the values returned by pdfConvertPageToBitmap2 -- they can be used to display the current status of the bitmap */ ... updateCounter = 0; } } pdfSetIncrementalUpdateCbk(pdf, &incUpdateCbk, data); updateCounter = 0; pdfConvertPageToBitmap2(pdf, ...);