I am currently using the QGIS C++ libraries to display a map. I am new to QGIS, and wantd to know what the difference between map and layer coordinates is? From what I understand, map gives the coordinates as per the CRS of the canvas. Is that correct?
Yes, map is the canvas, while layer is the individual layer.
And from the API Docs:
transformation from screen coordinates to map coordinates
transformation from screen coordinates to layer's coordinates