Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

feat: use exponential increase for srcset widths #224

Merged
merged 7 commits into from
Nov 26, 2018
Merged

feat: use exponential increase for srcset widths #224

Show file tree
Hide file tree
Changes from 6 commits
Commits
Show all changes
7 commits
Select commit Hold shift + click to select a range
bdf80bb
feat: use exponential increase for srcset widths
frederickfogerty Nov 15, 2018
c81e810
Merge branch 'master' into fred/use-exponential-srcset-widths
frederickfogerty Nov 20, 2018
53a7c8b
test: add more srcset width tests
frederickfogerty Nov 22, 2018
a69f38b
fix: remove fallback src from srcset
frederickfogerty Nov 22, 2018
620cf9f
Merge branch 'fred/use-exponential-srcset-widths' of https://github.c…
frederickfogerty Nov 22, 2018
f1d3a11
Merge branch 'master' into fred/use-exponential-srcset-widths
frederickfogerty Nov 22, 2018
e1c47ea
Merge branch 'master' into fred/use-exponential-srcset-widths
frederickfogerty Nov 26, 2018
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
3 changes: 1 addition & 2 deletions src/react-imgix.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -121,8 +121,7 @@ function buildSrc({
const url = constructUrl(rawSrc, urlParams);
return `${url} ${targetWidth}w`;
};
const addFallbackSrc = srcSet => srcSet.concat(src);
srcSet = addFallbackSrc(targetWidths.map(buildSrcSetPair)).join(", ");
srcSet = targetWidths.map(buildSrcSetPair).join(", ");

if (showARWarning && config.warnings.invalidARFormat) {
console.warn(
Expand Down
106 changes: 11 additions & 95 deletions src/targetWidths.js
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,102 +1,18 @@
// Taken from https://github.com/imgix/imgix.js/blob/eff194416a0efc9f0c528eb070466cd474ae0bf5/src/targetWidths.js

function uniq(arr) {
var n = {},
r = [],
i;

for (i = 0; i < arr.length; i++) {
if (!n[arr[i]]) {
n[arr[i]] = true;
r.push(arr[i]);
}
}

return r;
}

const MINIMUM_SCREEN_WIDTH = 100;
const MAXIMUM_SCREEN_WIDTH = 2560;
const MAX_DPR = 2;
const SCREEN_STEP = 100;

// Screen data from http://gs.statcounter.com/screen-resolution-stats/mobile/worldwide

// With these resolutions we cover 80% of mobile devices
// prettier-ignore
const MOBILE_RESOLUTIONS = [320, 360, 375, 414, 480, 540, 640, 720, 1080]

// With these resolutions we cover 90% of tablets
// prettier-ignore
const TABLET_RESOLUTIONS = [600, 768, 800, 962, 1024, 1280];

// With these resolutions we cover 80% of desktops
// prettier-ignore
const DESKTOP_RESOLUTIONS = [1024, 1280, 1366, 1440, 1536, 1600, 1680, 1820, 1920]

// Bootstrap breakpoints
const BOOTSTRAP_SM = { cssWidth: 576, dpr: 1 };
const BOOTSTRAP_SM_2X = { cssWidth: 576, dpr: 2 };
const BOOTSTRAP_MD = { cssWidth: 720, dpr: 1 };
const BOOTSTRAP_MD_2X = { cssWidth: 720, dpr: 2 };
const BOOTSTRAP_LG = { cssWidth: 940, dpr: 1 };
const BOOTSTRAP_LG_2X = { cssWidth: 940, dpr: 2 };
const BOOTSTRAP_XL = { cssWidth: 1140, dpr: 1 };
const BOOTSTRAP_XL_2X = { cssWidth: 1140, dpr: 2 };

const BOOTSTRAP_BREAKS = [
BOOTSTRAP_SM,
BOOTSTRAP_SM_2X,
BOOTSTRAP_MD,
BOOTSTRAP_MD_2X,
BOOTSTRAP_LG,
BOOTSTRAP_LG_2X,
BOOTSTRAP_XL,
BOOTSTRAP_XL_2X
];

function deviceWidths() {
const widths = [
...MOBILE_RESOLUTIONS,
...TABLET_RESOLUTIONS,
...DESKTOP_RESOLUTIONS,
...BOOTSTRAP_BREAKS.map(device => device.cssWidth * device.dpr)
];
return widths;
}
function targetWidths() {
const resolutions = [];
let prev = 100;
const INCREMENT_PERCENTAGE = 8;
const MAX_SIZE = 8192;

// Generates an array of physical screen widths to represent
// the different potential viewport sizes.
//
// We step by `SCREEN_STEP` to give some sanity to the amount
// of widths we output.
//
// The upper bound is the widest known screen on the planet.
// @return {Array} An array of {Fixnum} instances
function screenWidths(maxWidth) {
const widths = [];
const ensureEven = n => 2 * Math.round(n / 2);

for (let i = MINIMUM_SCREEN_WIDTH; i < maxWidth; i += SCREEN_STEP) {
widths.push(i);
resolutions.push(prev);
while (prev <= MAX_SIZE) {
prev *= 1 + (INCREMENT_PERCENTAGE / 100) * 2;
resolutions.push(ensureEven(prev));
}
widths.push(maxWidth);

return widths;
}

// Return the widths to generate given the input `sizes`
// attribute.
//
// @return {Array} An array of {Fixnum} instances representing the unique `srcset` URLs to generate.
function targetWidths() {
const minPxWidthRequired = SCREEN_STEP;
const maxPxWidthRequired = MAXIMUM_SCREEN_WIDTH * MAX_DPR;
const _screenWidths = screenWidths(maxPxWidthRequired);
const allWidths = deviceWidths().concat(_screenWidths);

return uniq(allWidths).sort(function(x, y) {
return x - y;
});
return resolutions;
}

export default targetWidths();
66 changes: 57 additions & 9 deletions test/unit/react-imgix.test.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@ import ReactDOM from "react-dom";
import { shallow as enzymeShallow, mount } from "enzyme";
import PropTypes from "prop-types";
import { shallowUntilTarget } from "../helpers";
import targetWidths from "targetWidths";

import Imgix, {
__ReactImgixImpl,
Expand Down Expand Up @@ -71,15 +72,62 @@ describe("When in default mode", () => {
const sut = shallow(<Imgix src={src} sizes="100vw" />);
expect(sut.type()).toBe("img");
});
it("the rendered element should have a srcSet set correctly", async () => {
const sut = shallow(<Imgix src={src} sizes="100vw" />);
const srcSet = sut.props().srcSet;
expect(srcSet).not.toBeUndefined();
expect(srcSet.split(", ")[0].split(" ")).toHaveLength(2);
const aSrcFromSrcSet = srcSet.split(", ")[0].split(" ")[0];
expect(aSrcFromSrcSet).toContain(src);
const aWidthFromSrcSet = srcSet.split(", ")[0].split(" ")[1];
expect(aWidthFromSrcSet).toMatch(/^\d+w$/);
describe("srcset", () => {
it("the rendered element should have a srcSet set correctly", async () => {
const sut = shallow(<Imgix src={src} sizes="100vw" />);
const srcset = sut.props().srcSet;
expect(srcset).not.toBeUndefined();
expect(srcset.split(", ")[0].split(" ")).toHaveLength(2);
const aSrcFromSrcSet = srcset.split(", ")[0].split(" ")[0];
expect(aSrcFromSrcSet).toContain(src);
const aWidthFromSrcSet = srcset.split(", ")[0].split(" ")[1];
expect(aWidthFromSrcSet).toMatch(/^\d+w$/);
});
it("returns the expected number of `url widthDescriptor` pairs", function() {
const sut = shallow(<Imgix src={src} sizes="100vw" />);
const srcset = sut.props().srcSet;

expect(srcset.split(",").length).toEqual(targetWidths.length);
});

it("should not exceed the bounds of [100, 8192]", () => {
const sut = shallow(<Imgix src={src} sizes="100vw" />);
const srcset = sut.props().srcSet;

const srcsetWidths = srcset
.split(", ")
.map(srcset => srcset.split(" ")[1])
.map(width => width.slice(0, -1))
.map(Number.parseFloat);

const min = Math.min(...srcsetWidths);
const max = Math.max(...srcsetWidths);

expect(min).not.toBeLessThan(100);
expect(min).not.toBeGreaterThan(8192);
});

// 18% used to allow +-1% for rounding
it("should not increase more than 18% every iteration", () => {
const INCREMENT_ALLOWED = 0.18;

const sut = shallow(<Imgix src={src} sizes="100vw" />);
const srcset = sut.props().srcSet;

const srcsetWidths = srcset
.split(", ")
.map(srcset => srcset.split(" ")[1])
.map(width => width.slice(0, -1))
.map(Number.parseFloat);

let prev = srcsetWidths[0];

for (let index = 1; index < srcsetWidths.length; index++) {
const element = srcsetWidths[index];
expect(element / prev).toBeLessThan(1 + INCREMENT_ALLOWED);
prev = element;
}
});
});
});

Expand Down