Dmitry Timoshkov : gdiplus: GdipMeasureString operates internally in pixels but in/ out rectangles are in device units.

[Vincent Povirk]

>> In cases where we need to convert a logical measurement to a device
>> measurement (maybe including in GdipTransformPoints) I think
>> units_to_pixels/pixels_to_units is appropriate, but it should really
>> take a Graphics object rather than a dpi (since the correct dpi cannot
>> be known without a Graphics object). And we need testing to decide
>> whether to account for the page scale in that calculation.
>
> The helpers are useful for a font object too, that's why they don't use
> graphics object as input.

Maybe for GdipGetFontHeightGivenDPI it's appropriate, but the other
uses in font.c are wrong and should be using the DPI from a Graphics
object.