to draw on `GdkSurface
CairoContext.cairoCreate
cairo.context.Context cairoCreate()Retrieves a Cairo context to be used to draw on the [gdk.surface.Surface] of context.
A call to [gdk.draw_context.DrawContext.beginFrame] with this context must have been done or this function will return null.
The returned context is guaranteed to be valid until [gdk.draw_context.DrawContext.endFrame] is called.
Returns
a Cairo context