background-size

CSS background-size ์†์„ฑ์€ ์š”์†Œ ๋ฐฐ๊ฒฝ ์ด๋ฏธ์ง€์˜ ํฌ๊ธฐ๋ฅผ ์„ค์ •ํ•ฉ๋‹ˆ๋‹ค. ๊ทธ๋Œ€๋กœ ๋‘๊ฑฐ๋‚˜, ๋Š˜๋ฆฌ๊ณ  ์ค„์ด๊ฑฐ๋‚˜, ๊ณต๊ฐ„์— ๋งž์ถœ ์ˆ˜ ์žˆ์Šต๋‹ˆ๋‹ค.

๋ฐฐ๊ฒฝ ์ด๋ฏธ์ง€๋กœ ๋ฎ์ด์ง€ ์•Š์€ ๊ณต๊ฐ„์€ background-color ์†์„ฑ์œผ๋กœ ์ฑ„์›Œ์ง€๊ณ , ๋ฐฐ๊ฒฝ ์ด๋ฏธ์ง€์—์„œ ํˆฌ๋ช…ํ•˜๊ฑฐ๋‚˜ ๋ฐ˜ํˆฌ๋ช…ํ•œ ๋ถ€๋ถ„์„ ํ†ตํ•ด์„œ๋„ ๋ฐฐ๊ฒฝ์ƒ‰์ด ๋ณด์ž…๋‹ˆ๋‹ค.

๊ตฌ๋ฌธ

/* ํ‚ค์›Œ๋“œ ๊ฐ’ */
background-size: cover;
background-size: contain;

/* ๋‹จ์ผ ๊ฐ’ ๊ตฌ๋ฌธ */
/* ์ด๋ฏธ์ง€ ๋„ˆ๋น„ (๋†’์ด๋Š” 'auto'๊ฐ€ ๋จ) */
background-size: 50%;
background-size: 3.2em;
background-size: 12px;
background-size: auto;

/* ๋‘ ๊ฐœ ๊ฐ’ ๊ตฌ๋ฌธ */
/* ์ฒซ ๋ฒˆ์งธ ๊ฐ’: ์ด๋ฏธ์ง€ ๋„ˆ๋น„, ๋‘ ๋ฒˆ์งธ ๊ฐ’: ์ด๋ฏธ์ง€ ๋†’์ด */
background-size: 50% auto;
background-size: 3em 25%;
background-size: auto 6px;
background-size: auto auto;

/* ๋‹ค์ค‘ ๋ฐฐ๊ฒฝ */
background-size: auto, auto; /* `auto auto`์™€ ํ˜ผ๋™ํ•˜์ง€ ๋ง ๊ฒƒ */
background-size: 50%, 25%, 25%;
background-size: 6px, auto, contain;

/* ์ „์—ญ ๊ฐ’ */
background-size: inherit;
background-size: initial;
background-size: unset;

 background-size ์†์„ฑ์€ ๋‹ค์Œ ๋ฐฉ๋ฒ• ์ค‘ ํ•˜๋‚˜๋กœ ์ง€์ •ํ•  ์ˆ˜ ์žˆ์Šต๋‹ˆ๋‹ค. 

  • contain ๋˜๋Š” cover ํ‚ค์›Œ๋“œ ๊ฐ’ ์‚ฌ์šฉ.
  • ๋„ˆ๋น„ ๊ฐ’๋งŒ ์‚ฌ์šฉ. ๋†’์ด๋Š” ์ž๋™์œผ๋กœ auto๊ฐ€ ๋ฉ๋‹ˆ๋‹ค.
  • ๋„ˆ๋น„์™€ ๋†’์ด ๊ฐ’์„ ๋ชจ๋‘ ์‚ฌ์šฉ. ์ฒซ ๋ฒˆ์งธ ๊ฐ’์€ ๋„ˆ๋น„๋กœ, ๋‘ ๋ฒˆ์งธ ๊ฐ’์€ ๋†’์ด๋ฅผ ์„ค์ •ํ•ฉ๋‹ˆ๋‹ค. ๊ฐ ๊ฐ’์€ <length>, <percentage>, auto๋ฅผ ์‚ฌ์šฉํ•  ์ˆ˜ ์žˆ์Šต๋‹ˆ๋‹ค.

์—ฌ๋Ÿฌ ๋ฐฐ๊ฒฝ ์ด๋ฏธ์ง€์˜ ์‚ฌ์ด์ฆˆ๋ฅผ ์ง€์ •ํ•˜๋ ค๋ฉด ๊ฐ๊ฐ์˜ ๊ฐ’์„ ์‰ผํ‘œ๋กœ ๊ตฌ๋ถ„ํ•˜์„ธ์š”.

๊ฐ’

contain
์ด๋ฏธ์ง€๊ฐ€ ์ž˜๋ฆฌ๊ฑฐ๋‚˜ ์ฐŒ๊ทธ๋Ÿฌ์ง€์ง€ ์•Š๋Š” ํ•œ๋„ ๋‚ด์—์„œ ์ œ์ผ ํฌ๊ฒŒ ์„ค์ •.
cover
์ด๋ฏธ์ง€๊ฐ€ ์ฐŒ๊ทธ๋Ÿฌ์ง€์ง€ ์•Š๋Š” ํ•œ๋„ ๋‚ด์—์„œ ์ œ์ผ ํฌ๊ฒŒ ์„ค์ •. ์ด๋ฏธ์ง€์˜ ๊ฐ€๋กœ์„ธ๋กœ๋น„๊ฐ€ ์š”์†Œ์™€ ๋‹ค๋ฅด๋‹ค๋ฉด ์ด๋ฏธ์ง€๋ฅผ ์„ธ๋กœ ๋˜๋Š” ๊ฐ€๋กœ๋ฐฉํ–ฅ์œผ๋กœ ์ž˜๋ผ๋‚ด์–ด ๋นˆ ๊ณต๊ฐ„์ด ์ƒ๊ธฐ์ง€ ์•Š๋„๋ก ์„ค์ •ํ•ฉ๋‹ˆ๋‹ค.
auto
๋ฐฐ๊ฒฝ ์ด๋ฏธ์ง€์˜ ์›๋ณธ ํฌ๊ธฐ๋ฅผ ์œ ์ง€.
<length>
์›๋ณธ ํฌ๊ธฐ์˜ ๋„ˆ๋น„/๋†’์ด๋ฅผ ์ฃผ์–ด์ง„ ๊ฐ’์œผ๋กœ ๋Š˜๋ฆฌ๊ฑฐ๋‚˜ ์ค„์ž„. ์Œ์ˆ˜๋Š” ์œ ํšจํ•˜์ง€ ์•Š์Šต๋‹ˆ๋‹ค.
<percentage>
Stretches the image in the corresponding dimension to the specified percentage of the background positioning area. The background positioning area is determined by the value of background-origin (by default, the padding box). However, if the background's background-attachment value is fixed, the positioning area is instead the entire viewport. Negative values are not allowed.

์›๋ณธ ํฌ๊ธฐ์™€ ๋น„์œจ

The computation of values depends on the image's intrinsic dimensions (width and height) and intrinsic proportions (width-to-height ratio). These attributes are as follows:

  • A bitmap image (such as JPG) always has intrinsic dimensions and proportions.
  • A vector image (such as SVG) does not necessarily have intrinsic dimensions. If it has both horizontal and vertical intrinsic dimensions, it also has intrinsic proportions. If it has no dimensions or only one dimension, it may or may not have proportions.
  • CSS <gradient>s have no intrinsic dimensions or intrinsic proportions.
  • Background images created with the element() function use the intrinsic dimensions and proportions of the generating element.

Note: The behavior of <gradient>s changed in Gecko 8.0 (Firefox 8.0 / Thunderbird 8.0 / SeaMonkey 2.5). Before this, they were treated as images with no intrinsic dimensions, but with intrinsic proportions identical to that of the background positioning area.

Note: In Gecko, background images created using the element() function are currently treated as images with the dimensions of the element, or of the background positioning area if the element is SVG, with the corresponding intrinsic proportion. This is non-standard behavior.

Based on the intrinsic dimensions and proportions, the rendered size of the background image is computed as follows:

If both components of background-size are specified and are not auto:
The background image is rendered at the specified size.
If the background-size is contain or cover:
While preserving its intrinsic proportions, the image is rendered at the largest size contained within, or covering, the background positioning area. If the image has no intrinsic proportions, then it's rendered at the size of the background positioning area.
If the background-size is auto or auto auto:
  • If the image has both horizontal and vertical intrinsic dimensions, it's rendered at that size.
  • If the image has no intrinsic dimensions and has no intrinsic proportions, it's rendered at the size of the background positioning area.
  • If the image has no intrinsic dimensions but has intrinsic proportions, it's rendered as if contain had been specified instead.
  • If the image has only one intrinsic dimension and has intrinsic proportions, it's rendered at the size corresponding to that one dimension. The other dimension is computed using the specified dimension and the intrinsic proportions.
  • If the image has only one intrinsic dimension but has no intrinsic proportions, it's rendered using the specified dimension and the other dimension of the background positioning area.
Note: SVG images have a preserveAspectRatio attribute that defaults to the equivalent of contain. In Firefox 43, as opposed to Chrome 52, an explicit background-size causes preserveAspectRatio to be ignored.
If the background-size has one auto component and one non-auto component:
  • If the image has intrinsic proportions, it's stretched to the specified dimension. The unspecified dimension is computed using the specified dimension and the intrinsic proportions.
  • If the image has no intrinsic proportions, it's stretched to the specified dimension. The unspecified dimension is computed using the image's corresponding intrinsic dimension, if there is one. If there is no such intrinsic dimension, it becomes the corresponding dimension of the background positioning area.

Note: Background sizing for vector images that lack intrinsic dimensions or proportions is not yet fully implemented in all browsers. Be careful about relying on the behavior described above, and test in multiple browsers to be sure the results are acceptable.

ํ˜•์‹ ๊ตฌ๋ฌธ

<bg-size>#

where
<bg-size> = [ <length-percentage> | auto ]{1,2} | cover | contain

where
<length-percentage> = <length> | <percentage>

์˜ˆ์ œ

Please see Scaling background images for examples.

์ฐธ๊ณ 

If you use a <gradient> as the background and specify a background-size to go with it, it's best not to specify a size that uses a single auto component, or is specified using only a width value (for example, background-size: 50%). Rendering of <gradient>s in such cases changed in Firefox 8, and at present is generally inconsistent across browsers, which do not all implement rendering in full accordance with the CSS3 background-size specification and with the CSS3 Image Values gradient specification.

.gradient-example {
  width: 50px;
  height: 100px;
  background-image: linear-gradient(blue, red);

  /* Not safe to use */
  background-size: 25px;
  background-size: 50%;
  background-size: auto 50px;
  background-size: auto 50%;

  /* Safe to use */
  background-size: 25px 50px;
  background-size: 50% 50%;
}

Note that it's particularly not recommended to use a pixel dimension and an auto dimension with a <gradient>, because it's impossible to replicate rendering in versions of Firefox prior to 8, and in browsers not implementing Firefox 8's rendering, without knowing the exact size of the element whose background is being specified.

๋ช…์„ธ

Specification Status Comment
CSS Backgrounds and Borders Module Level 3
The definition of 'background-size' in that specification.
Candidate Recommendation Initial definition.

์ดˆ๊ธฐ๊ฐ’auto auto
์ ์šฉ๋Œ€์ƒall elements. It also applies to ::first-letter and ::first-line.
์ƒ์†no
Percentagesrelative to the background positioning area
Computed valueas specified, but with relative lengths converted into absolute lengths
Animation typerepeatable list of simple list of length, percentage, or calc

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