dear-image

DearImage

A class that represents a graphical image.

setup

npm

npm i dear-image

---

Install optionally to support Node.

npm i canvas

ES module

import DearImage from 'dear-image';

Node

let DearImage = require('dear-image');

browser

<script src="https://unpkg.com/dear-image"></script>

The module is globally available as DearImage.

members

static methods

.isDearImage(value)

Determines whether the passed value is an instance of DearImage.

argument	description
value	The value to be checked.

Returns true if the passed value is an instance of DearImage, false otherwise.

---

.from(value)

Creates a DearImage instance from the given value.

argument	description
value	The value to create from. Supported value types are ImageData, HTMLCanvasElement, OffscreenCanvas, HTMLImageElement and DearImage.

Returns the created DearImage instance.

let element = document.getElementById('my-image');
let image = DearImage.from(element);
document.body.appendChild(image.toHTMLCanvasElement());

---

.fromExcept(value)

Creates a DearImage instance from the given value if it's not one.

argument	description
value	The value to create from.

Returns the same or created DearImage instance.

let element = document.getElementById('my-image');
let image = DearImage.fromExcept(element);
let otherImage = DearImage.fromExcept(image);
console.log(otherImage === image); // => true

---

.loadFrom(value)

Asynchronously loads a DearImage instance from the given value.

argument	description
value	The value to load from. Supported value types are String, URL, Buffer, Blob, HTMLImageElement and everything the function .from supports.

Returns a promise that resolves to the created DearImage instance.

let url = '/path/to/image.jpg';
let image = await DearImage.loadFrom(url);
document.body.appendChild(image.toHTMLCanvasElement());

---

.loadFromExcept(value)

Asynchronously loads a DearImage instance from the given value if it's not one.

argument	description
value	The value to load from.

Returns a promise that resolves to the same or created DearImage instance.

let url = '/path/to/image.jpg';
let image = await DearImage.loadFrom(url);
let otherImage = await DearImage.loadFromExcept(image);
console.log(otherImage === image); // => true

---

.blank(sizeX = 0, sizeY = 0)

Creates a DearImage instance without content.

argument	description
sizeX	A number as the width of the image.
sizeY	A number as the height of the image.

Returns the created DearImage instance.

---

.loadFontFace(fontFace = {
  family: 'sans-serif',
  style: 'normal',
  variant: 'normal',
  weight: 'normal',
}, source)

argument	description
fontFace	Either a string as the font family or an object with the font face options.
fontFace.family	A string as the font family.
fontFace.style	A string as the font style.
fontFace.variant	A string as the font variant.
fontFace.weight	A number or a string as the font weight.
source	A string as the source path to load from.

Returns a promise.

---

.measureText(text, font = {
  family: 'sans-serif',
  size: 10,
  style: 'normal',
  variant: 'normal',
  weight: 'normal',
})

Creates a TextMetrics instance representing the dimensions of the drawn text.

argument	description
text	A string as the text.
font.family	A string as the font family.
font.size	A number as the font size.
font.style	A string as the font style.
font.variant	A string as the font variant.
font.weight	A number or a string as the font weight.

Returns the created TextMetrics instance.

---

.text(text, options = {
  fill: '#000',
  font: {
    family: 'sans-serif',
    size: 10,
    style: 'normal',
    variant: 'normal',
    weight: 'normal',
  },
  padding: 0.3,
})

Creates a DearImage instance with the drawn text.

argument	description
text	A string as the text.
options.fill	A string as the fill color.
options.font.family	A string as the font family.
options.font.size	A string as the font size.
options.font.style	A string as the font style.
options.font.variant	A string as the font variant.
options.font.weight	A number or a string as the font weight.
options.padding	A number as the space around the text. The value is relative to the font size.

Returns the created DearImage instance.

properties

.sizeX

The size of the image along the x-axis.

let image = DearImage.blank(300, 150);
console.log(image.sizeX); // => 300

---

.sizeY

The size of the image along the y-axis.

let image = DearImage.blank(300, 150);
console.log(image.sizeY); // => 150

methods

.resize(sizeX = this.sizeX, sizeY = this.sizeY)

Changes the size of the image.

argument	description
sizeX	A number as the new width of the image.
sizeY	A number as the new height of the image.

Returns the created DearImage instance.

let image = DearImage.from(source).resize(300, 150);

---

.resizeX(size = this.sizeY, proportionally = false)

Changes the width of the image.

argument	description
size	A number as the new width of the image.
proportionally	If true, the aspect ratio of the image is preserved.

Returns the created DearImage instance.

---

.resizeY(size = this.sizeX, proportionally = false)

Changes the height of the image.

argument	description
size	A number as the new height of the image.
proportionally	If true, the aspect ratio of the image is preserved.

Returns the created DearImage instance.

---

.crop(startX = 0, startY = 0, sizeX = this.sizeX, sizeY = this.sizeY)

Selects an area from the image.

argument	description
startX	A number as the horizontal offset of the area. A positive value indicates the offset from the left of the image. A negative value indicates the offset from the right of the image.
startY	A number as the vertical offset of the area. A positive value indicates the offset from the top of the image. A negative value indicates the offset from the bottom of the image.
sizeX	A number as the width of the area. A positive value selects an area from left to right. A negative value selects an area from right to left.
sizeY	A number as the height of the area. A positive value selects an area from top to bottom. A negative value selects an area from bottom to top.

Returns the created DearImage instance.

let image = DearImage.from(source).crop(100, -200, -50, 150);

---

.reframe(sizeX = this.sizeX, sizeY = this.sizeY, alignmentX = 'center', alignmentY = 'center')

Aligns the image inside an area.

argument	description
sizeX	A number as the width of the area.
sizeY	A number as the height of the area.
alignmentX	A number as the horizontal alignment of the image. Possible values are 'start', 'center' and 'end'.
alignmentY	A number as the vertical alignment of the image. Possible values are 'start', 'center' and 'end'.

Returns the created DearImage instance.

let image = DearImage.from(source).reframe(300, 150, 'start', 'end');

---

.rescale(scalingX = 1, scalingY = 1)

Changes the size of the image factorially.

argument	description
scalingX	A number as the scaling factor for the width.
scalingY	A number as the scaling factor for the height.

Returns the created DearImage instance.

let image = DearImage.from(source).rescale(3/2, 2/3);

---

.scale(scaling = 1)

Changes the size of the image factorially. The aspect ratio of the image is preserved.

argument	description
scaling	A number as the scaling factor.

Returns the created DearImage instance.

let image = DearImage.from(source).scale(3/2);

---

.scaleIn(sizeX = this.sizeX, sizeY = this.sizeY)

Scales the image inside an area. The aspect ratio of the image is preserved.

argument	description
sizeX	A number as the width of the area.
sizeY	A number as the height of the area.

Returns the created DearImage instance.

---

.scaleOut(sizeX = this.sizeX, sizeY = this.sizeY)

Scales the image outside an area. The aspect ratio of the image is preserved.

argument	description
sizeX	A number as the width of the area.
sizeY	A number as the height of the area.

Returns the created DearImage instance.

---

.scaleDownIn(sizeX = this.sizeX, sizeY = this.sizeY)

If necessary, scales the image down inside an area. The aspect ratio of the image is preserved.

argument	description
sizeX	A number as the width of the area.
sizeY	A number as the height of the area.

Returns the created DearImage instance.

---

.scaleDownOut(sizeX = this.sizeX, sizeY = this.sizeY)

If necessary, scales the image down outside an area. The aspect ratio of the image is preserved.

argument	description
sizeX	A number as the width of the area.
sizeY	A number as the height of the area.

Returns the created DearImage instance.

---

.scaleUpIn(sizeX = this.sizeX, sizeY = this.sizeY)

If necessary, scales the image up inside an area. The aspect ratio of the image is preserved.

argument	description
sizeX	A number as the width of the area.
sizeY	A number as the height of the area.

Returns the created DearImage instance.

---

.scaleUpOut(sizeX = this.sizeX, sizeY = this.sizeY)

If necessary, scales the image up outside an area. The aspect ratio of the image is preserved.

argument	description
sizeX	A number as the width of the area.
sizeY	A number as the height of the area.

Returns the created DearImage instance.

---

.flipX()

Flips the image horizontally.

Returns the created DearImage instance.

---

.flipY()

Flips the image vertically.

Returns the created DearImage instance.

---

.toDataURL(format, quality)

Creates a data URL string representing the content.

Returns the created data URL string.

---

.toImageData()

Creates an ImageData object representing the content.

Returns the created ImageData object.

---

.toBlob(format, quality)

browser only

Creates a Blob instance representing the content.

Returns the created Blob instance.

---

.toBuffer(format, quality)

node only

Creates a Buffer instance representing the content.

Returns the created Buffer instance.

---

.toHTMLCanvasElement()

browser only

Creates a HTMLCanvasElement instance representing the content.

Returns the created HTMLCanvasElement instance.

---

.toOffscreenCanvas()

browser only

Creates an OffscreenCanvas instance representing the content.

Returns the created OffscreenCanvas instance.

---

.toHTMLImageElement(format, quality)

browser only

Creates a HTMLImageElement instance representing the content.

Returns the created HTMLImageElement instance.

let image = DearImage.from(source);
let element = image.toHTMLImageElement('image/jpeg', 0.75);
element.style.border = '1px solid BlueViolet';
document.body.appendChild(element);

---

.saveToFileSystem(target, format, quality)

node only

Asynchronously saves the content to the file system.

argument	description
target	A string as the target path to save to.

Returns a promise.

let image = DearImage.from(source);
await image.saveToFileSystem('/path/to/image.jpg', 'image/jpeg', 0.75);

utils

.isURL(value)

Determines whether the passed value is an instance of URL or an URL string.

argument	description
value	The value to be checked.

Returns true if the passed value is an instance of URL or an URL string, false otherwise.

console.log(DearImage.utils.isURL('https://github.com/SeregPie/DearImage'));
// => true

console.log(DearImage.utils.isURL(new URL('/SeregPie/DearImage', 'https://github.com')));
// => true

console.log(DearImage.utils.isURL('/SeregPie/DearImage')));
// => true in browser and false in node

---

.isDataURL(value)

Determines whether the passed value is a data URL string.

argument	description
value	The value to be checked.

Returns true if the passed value is a data URL string, false otherwise.

console.log(DearImage.utils.isDataURL('data:image/png;base64,R0lGODdh'));
// => true

console.log(DearImage.utils.isDataURL('data:,')));
// => true

console.log(DearImage.utils.isDataURL('data:image/png;base64')));
// => false