Checkout FcPatternAddMatrix() behavior
Submitted by Behdad Esfahbod
Link to original bug (#479099)
Description
In pango_fc_font_map_new_font() we FcPatternAddMatrix() the ctm to the pattern, and later use that to initialize font_matrix in cairo backend.
First, ctm is not supposed to end up there in font matrix. We do something tricky to work around it (that is, divide by its scale factor).
Second, what if the pattern already has a matrix set? (for synthetic italic for example). Does FcPatternAddMatrix() multiply the matrices or do we have to fetch all matrix elements and apply them ourselves? We definitely don't do that right now.