Context.setFontSize

Sets the current font matrix to a scale by a factor of size, replacing any font matrix previously set with [cairo.context.Context.setFontSize] or [cairo.context.Context.setFontMatrix]. This results in a font size of size user space units. (More precisely, this matrix will result in the font's em-square being a size by size square in user space.)

If text is drawn without a call to [cairo.context.Context.setFontSize], (nor [cairo.context.Context.setFontMatrix] nor [cairo.context.Context.setScaledFont]), the default font size is 10.0.