kdu_region_compositor::map_region

This function attempts to map the region found, on entry, in the region argument to the high resolution grid of some codestream. The function first finds the uppermost codestream whose contents are visible within the supplied region. If none is found, the function returns false. It one is found, its index is written to component_idx and the region is mapped onto that codestream's high resolution canvas and returned via region. Note that the region supplied on entry is expressed within the same coordinate system as that supplied to set_buffer_surface, while the region returned on exit is expressed on the codestream's high resolution canvas, after undoing the effects of rotation, flipping and scaling. The returned region is offset so that its location is expressed relative to the upper left hand corner of the image region on the codestream canvas, which is not necessarily the canvas origin.

codestream_idx [int &]

region [kdu_dims &]