Fitting

Library to calculate with JS when background-size or object-fit is not available.

Install

npm install @iki-inc/fitting
# or
yarn add @iki-inc/fitting

Usage

import Fitting from '@iki-inc/fitting'

const res = Fitting.cover(
  { width: 100, height: 200 },
  { width: 150, height: 400 }
)

Methods

Fitting.cover(base, target[, options]): { width: number, height: number, x: numner, y: numner }

Same as background-size: cover.

Parameters

base
params: { width: number, height: number }

Base size.

target
params: { width: number, height: number }

Original size of the element to be changed.

options (Optional)
params: { scale?: number, scaleX?: number, scaleY?: number }

Scale option to extend the calculation of the original element.

If present at the same time of scale, scaleX and scaleY is scaleX or scaleY > scale
e.g.:
{ scale: 0.5 }
X scale = 0.5
Y scale = 0.5

{ scaleX: 0.5 }
X scale = 0.5 (scaleX)
Y scale = 1 (default)

{ scaleY: 0.5 }
X scale = 1 (default)
Y scale = 0.5 (scaleY)

{ scale: 2, scaleX: 0.5 }
X scale = 0.5 (scaleX)
Y scale = 2 (scale)

{ scale: 2, scaleY: 0.5 }
X scale = 2 (scale)
Y scale = 0.5 (scaleY)

Example

import Fitting from '@iki-inc/fitting'

console.log(
  Fitting.cover({ width: 800, height: 400 }, { width: 1000, height: 200 })
)
// -> width: 2000, height: 400, x: -600, y: 0

console.log(
  Fitting.cover(
    { width: 800, height: 400 },
    { width: 1000, height: 200 },
    { scale: 0.5 }
  )
)
// -> width: 1000, height: 200, x: -100, y: 100

Fitting.contain(base, target[, position, scale]): { width: number, height: number, x: number, y: number }

Same as background-size: contain.

Parameters

base
params: { width: number, height: number }

Base size.

target
params: { width: number, height: number }

Original size of the element to be changed.

position (Optional)
type: string (top left | top center | top right | middle left | center | middle right | bottom left | bottom center | bottom right)
default: top left

Position pattern as below.

-------------------------------------------
top left    |   top center   |    top right
middle left |     center     | middle right
bottom left |  bottom center | bottom right
-------------------------------------------

scale (Optional)
type: number
default: 1

Example

import Fitting from '@iki-inc/fitting'

console.log(
  Fitting.contain({ width: 800, height: 400 }, { width: 1000, height: 200 })
)
// -> { width: 800, height: 160, x: 0, y: 0 }

console.log(
  Fitting.contain(
    { width: 800, height: 400 },
    { width: 1000, height: 200 },
    'center',
    0.5
  )
)
// -> { width: 400, height: 80, x: 200, y: 160 }