std.typeset.fromScaledPoints

Physical Length values with the Pt, Mm, Cm, or In marker provide toScaledPoints returning int. One point is 65,536 scaled points. The result is the exact stored signed 64-bit count.

The scaledPoints member is absent from every Length type. Calling that removed member is rejected with TPZ5006. Length<Em> has no toScaledPoints member and must resolve to a physical length first.

fromScaledPoints accepts every int from -9223372036854775808 through 9223372036854775807 inclusive. It returns Length<Pt> with that exact scaled-point count. Zero and negative inputs are valid. Construction performs no rounding and has no value-dependent failure.

fromMilliPoints interprets its int argument as thousandths of a point. Its scaled-point result is roundEven of the exact rational input times 8192 divided by 125.

fromMilliPoints accepts -140737488355328000 through 140737488355327999 inclusive. An input outside that range stops with runtime diagnostic TPZ4004. It does not return Result, wrap, saturate, or clamp.

Length<Pt>.toMilliPoints returns roundEven of the exact stored count times 125 divided by 8192. Every representable point length has a representable int result.

roundEven selects the nearest integer and chooses the even integer at an exact tie. Positive and negative ties follow the same rule. Range checking applies to the final rounded value. Intermediate arithmetic must preserve the exact rational value.

A count of 4096 scaled points converts to 62 millipoints. A count of 12288 converts to 188. Their negatives convert to -62 and -188. One millipoint constructs 66 scaled points and negative one constructs -66.

Millipoint conversion can lose scaled-point precision. A conversion to millipoints and back need not recover the original length. The maximum point length converts to 140737488355328000 millipoints, which exceeds the fromMilliPoints input range.

The constructors require int arguments. A float or Length argument is rejected with TPZ5001. Physical conversions and scalar arithmetic do not provide an implicit integer constructor.

A constructor evaluates its argument once before checking the result range. A receiver conversion evaluates its receiver once. These operations perform no I/O or mutation and read no font or paragraph state.

A fromMilliPoints overflow is reported at the public constructor call. Earlier argument effects remain visible and later expressions do not execute.