Fitting a frame of a fixed shape into a picture of another, with bars on the sides or above and below.
A :picture scene that names its :frame — the shape the game's screen is shown at,
{320, 240} for a 320×200 VGA screen shown 4:3 — draws its screen into the rectangle
letterbox/3 gives, and the surface maps the pointer into that same rectangle, so a
game reads the pointer as a point of its own screen.
Cauldron2D.Fit.letterbox({400, 200}, 1.0, {320, 240})
#=> {66, 0, 267, 200}Summary
Functions
The rectangle {x, y, width, height} of a {width, height} picture, whose pixels are
aspect times as tall as they are wide, that shows a frame of shape frame as large
as it fits, centred.
The point of the frame under picture fraction {fx, fy} (as a :picture surface
reports the pointer), as fractions of the letterboxed frame, or nil outside it.
Functions
@spec letterbox({pos_integer(), pos_integer()}, number(), {number(), number()}) :: {non_neg_integer(), non_neg_integer(), pos_integer(), pos_integer()}
The rectangle {x, y, width, height} of a {width, height} picture, whose pixels are
aspect times as tall as they are wide, that shows a frame of shape frame as large
as it fits, centred.
@spec within( {number(), number()}, {pos_integer(), pos_integer()}, number(), {number(), number()} ) :: {float(), float()} | nil
The point of the frame under picture fraction {fx, fy} (as a :picture surface
reports the pointer), as fractions of the letterboxed frame, or nil outside it.