...which reveals that SpriteCanvasBase is not derived from XBitmapCanvas, so
split up BitmapCanvasBase (just XBitmap) and BitmapCanvasBase2 (plus
XBitmapCanvas) and make IntegerBitmapBase directly abstract over those two as
arguments.
Change-Id: Ieae87fe466bb9f1a861c8a95162ef25235ae5799
see https://gerrit.libreoffice.org/#/c/3367/
and Change-Id: I00c96fa77d04b33a6f8c8cd3490dfcd9bdc9e84a for details
Change-Id: I199a75bc4042af20817265d5ef85b1134a96ff5a