On 10/6/11 6:37 PM, "Robert O'Callahan" <robert@ocallahan.org> wrote:
For normal desktop printing, we guarantee that 1in is one physical inch. It's very useful to have units that are guaranteed to map to given physical dimensions on paper, and also guaranteed to give a good viewing size on all kinds of screen devices.
I don’t see evidence of the guarantee that one CSS inch is one physical inch when printing. I tested this last week on the Mac browsers I had at hand, and found only one (Firefox) that printed inches that measured out on paper. Safari printed slightly larger, Opera printed slightly smaller, and Chrome didn’t even try (it appeared to use the screen zoom level).
I don’t think this is relevant to the current discussion – the CSS 2.1 spec certainly says that print should make one CSS inch equal one physical inch. I just don’t see current browsers all adhering to this requirement.
Alan