On Sat, 23 Sep 2023 06:00:40 GMT, John Hendrikx <jhendr...@openjdk.org> wrote:
>> Some observations on the paper class:
>>
>> /**
>> * Specifies the North American legal size, 8.5 inches by 14 inches.
>> */
>> public static final Paper LEGAL = new Paper("Legal", 8.4, 14, INCH);
>>
>>
>> The comment and actual size contradict each other. 8.4 inches would not
>> result in an integer number of points (604.8) and looking up the legal paper
>> size confirms it should be 8.5 inches
>>
>> /**
>> * Specifies the Monarch envelope size, 3.87 inch by 7.5 inch.
>> */
>> public static final Paper MONARCH_ENVELOPE = new Paper("Monarch
>> Envelope", 3.87, 7.5, INCH);
>>
>> This seems incorrect, the size is 3-7/8” x 7-1/2”, which would be `3.875` x
>> `7.5` -- the difference in this case is small enough that it will be rounded
>> to the same value in points.
>
> About the rounding; all these values are fixed values and could have been
> entered in points as constants directly.
>
> Also realize that all papers measured in inches can be expressed exactly in
> points (after the above errors are fixed) so no rounding is needed for those
> at all; the same is not true for the papers specified in millimeters.
>
> Since the papers in inches never should need any rounding, the rounding can
> therefore be removed for those. If there is a worry that the multiplication
> (* 72) may cause floating point errors, then I suggest to specify all papers
> in points immediately, like this:
>
> new Paper("Letter", 8.5 * 72, 11 * 72, POINT);
>
> As for the papers specified in millimeters, these can't be expressed in whole
> points, as a millimeter is equivalent to `2,83465` points. Rounding them to
> points will require some guess work to find out what the actual size in
> millimeters was, for example, when it says 3 points it must have been 1 mm,
> while 1, 2, 4 or 5 points has no direct mm equivalent.
It is also very odd that `Paper` would expose the name (like `A4`), but not the
unit (`MM`) and the exact sizes for those. Representing these in a UI
therefore becomes terribly complicated; if I want to show the user, I can show
them the name, but then when I want to display its size, I have to show it in
points (a useless measurement, for users, for both papers specific in inches
and mm).
-------------
PR Review Comment: https://git.openjdk.org/jfx/pull/1244#discussion_r1334928528
