Socket
Socket
Sign inDemoInstall

canvas

Package Overview
Dependencies
Maintainers
6
Versions
148
Alerts
File Explorer

Advanced tools

License
Socket logo

Install Socket

Detect and block malicious and high-risk dependencies

Install

canvas - npm Package Compare versions

Comparing version 2.0.0-alpha.18 to 2.0.1

50

CHANGELOG.md

@@ -8,25 +8,47 @@ # Changelog

2.0.0 (unreleased -- encompasses all alpha versions)
(Unreleased)
==================
### Changed
### Added
### Fixed
2.0.0
==================
**Upgrading from 1.x**
```js
// (1) The quality argument for canvas.createJPEGStream/canvas.jpegStream now
// (1) The Canvas constructor is no longer the default export from the module.
/* old: */
const Canvas = require('canvas')
const mycanvas = new Canvas(width, height)
/* new: */
const { createCanvas, Canvas } = require('canvas')
const mycanvas = createCanvas(width, height)
mycanvas instanceof Canvas // true
/* old: */
const Canvas = require('canvas')
const myimg = new Canvas.Image()
/* new: */
const { Image } = require('canvas')
const myimg = new Image()
// (2) The quality argument for canvas.createJPEGStream/canvas.jpegStream now
// goes from 0 to 1 instead of from 0 to 100:
canvas.createJPEGStream({quality: 50}) // old
canvas.createJPEGStream({quality: 0.5}) // new
canvas.createJPEGStream({ quality: 50 }) // old
canvas.createJPEGStream({ quality: 0.5 }) // new
// (2) The ZLIB compression level and PNG filter options for canvas.toBuffer are
// (3) The ZLIB compression level and PNG filter options for canvas.toBuffer are
// now named instead of positional arguments:
canvas.toBuffer(undefined, 3, canvas.PNG_FILTER_NONE) // old
canvas.toBuffer(undefined, {compressionLevel: 3, filters: canvas.PNG_FILTER_NONE}) // new
canvas.toBuffer(undefined, { compressionLevel: 3, filters: canvas.PNG_FILTER_NONE }) // new
// or specify the mime type explicitly:
canvas.toBuffer("image/png", {compressionLevel: 3, filters: canvas.PNG_FILTER_NONE}) // new
canvas.toBuffer('image/png', { compressionLevel: 3, filters: canvas.PNG_FILTER_NONE }) // new
// (3) #2 also applies for canvas.pngStream, although these arguments were not
// (4) #2 also applies for canvas.pngStream, although these arguments were not
// documented:
canvas.pngStream(3, canvas.PNG_FILTER_NONE) // old
canvas.pngStream({compressionLevel: 3, filters: canvas.PNG_FILTER_NONE}) // new
canvas.pngStream({ compressionLevel: 3, filters: canvas.PNG_FILTER_NONE }) // new
// (4) canvas.syncPNGStream() and canvas.syncJPEGStream() have been removed:
// (5) canvas.syncPNGStream() and canvas.syncJPEGStream() have been removed:
canvas.syncPNGStream() // old

@@ -39,2 +61,7 @@ canvas.createSyncPNGStream() // old

canvas.createJPEGStream() // new
// (6) Context2d.filter has been renamed to context2d.quality to avoid a
// conflict with the new standard 'filter' property.
context.filter = 'best' // old
context.quality = 'best' // new
```

@@ -55,2 +82,5 @@

on the incorrect types.
* Rename `context2d.filter` to `context2d.quality` to avoid a conflict with the
new standard 'filter' property. Note that the standard 'filter' property is
not yet implemented.

@@ -57,0 +87,0 @@ ### Fixed

3

package.json
{
"name": "canvas",
"description": "Canvas graphics API backed by Cairo",
"version": "2.0.0-alpha.18",
"version": "2.0.1",
"author": "TJ Holowaychuk <tj@learnboost.com>",

@@ -49,2 +49,3 @@ "main": "index.js",

"mocha": "^5.2.0",
"pixelmatch": "^4.0.2",
"standard": "^12.0.1"

@@ -51,0 +52,0 @@ },

566

Readme.md
# node-canvas
-----
## This is the documentation for version 2.0.0-alpha
Alpha versions of 2.0 can be installed using `npm install canvas@next`.
See the [changelog](https://github.com/Automattic/node-canvas/blob/master/CHANGELOG.md)
for a guide to upgrading from 1.x to 2.x.
**For version 1.x documentation, see [the v1.x branch](https://github.com/Automattic/node-canvas/tree/v1.x)**
-----
### Canvas graphics API backed by Cairo
[![Build Status](https://travis-ci.org/Automattic/node-canvas.svg?branch=master)](https://travis-ci.org/Automattic/node-canvas)
[![NPM version](https://badge.fury.io/js/canvas.svg)](http://badge.fury.io/js/canvas)
node-canvas is a [Cairo](http://cairographics.org/) backed Canvas implementation for [NodeJS](http://nodejs.org).
node-canvas is a [Cairo](http://cairographics.org/)-backed Canvas implementation for [Node.js](http://nodejs.org).
## Authors
- TJ Holowaychuk ([tj](http://github.com/tj))
- Nathan Rajlich ([TooTallNate](http://github.com/TooTallNate))
- Rod Vagg ([rvagg](http://github.com/rvagg))
- Juriy Zaytsev ([kangax](http://github.com/kangax))
## Installation

@@ -34,29 +14,26 @@

By default, binaries for macOS, Linux and Windows will be downloaded. If you want to build from source, use `npm install --build-from-source`.
By default, binaries for macOS, Linux and Windows will be downloaded. If you want to build from source, use `npm install --build-from-source` and see the **Compiling** section below.
Currently the minimum version of node required is __6.0.0__
The minimum version of Node.js required is **6.0.0**.
### Compiling
If you don't have a supported OS or processor architecture, or you use `--build-from-source`, the module will be compiled on your system. Unless previously installed you'll _need_ __Cairo__ and __Pango__. For system-specific installation view the [Wiki](https://github.com/Automattic/node-canvas/wiki/_pages).
If you don't have a supported OS or processor architecture, or you use `--build-from-source`, the module will be compiled on your system. This requires several dependencies, including Cairo and Pango.
You can quickly install the dependencies by using the command for your OS:
For detailed installation information, see the [wiki](https://github.com/Automattic/node-canvas/wiki/_pages). One-line installation instructions for common OSes are below. Note that libgif/giflib, librsvg and libjpeg are optional and only required if you need GIF, SVG and JPEG support, respectively.
OS | Command
----- | -----
OS X | Using [Homebrew](https://brew.sh/):<br/>`brew install pkg-config cairo pango libpng jpeg giflib`<br/><br/>Using [MacPorts](https://www.macports.org/):<br/>`port install pkgconfig cairo pango libpng jpeg giflib libsrvg`
Ubuntu | `sudo apt-get install libcairo2-dev libjpeg-dev libpango1.0-dev libgif-dev build-essential g++`
Fedora | `sudo yum install cairo cairo-devel cairomm-devel libjpeg-turbo-devel pango pango-devel pangomm pangomm-devel giflib-devel`
OS X | Using [Homebrew](https://brew.sh/):<br/>`brew install pkg-config cairo pango libpng jpeg giflib librsvg`
Ubuntu | `sudo apt-get install build-essential libcairo2-dev libpango1.0-dev libjpeg-dev libgif-dev librsvg2-dev`
Fedora | `sudo yum install gcc-c++ cairo-devel pango-devel libjpeg-turbo-devel giflib-devel`
Solaris | `pkgin install cairo pango pkg-config xproto renderproto kbproto xextproto`
OpenBSD | `doas pkg_add cairo pango png jpeg giflib`
Windows | [Instructions on our wiki](https://github.com/Automattic/node-canvas/wiki/Installation:-Windows)
Windows | See the [wiki](https://github.com/Automattic/node-canvas/wiki/Installation:-Windows)
Others | See the [wiki](https://github.com/Automattic/node-canvas/wiki)
**Mac OS X v10.11+:** If you have recently updated to Mac OS X v10.11+ and are experiencing trouble when compiling, run the following command: `xcode-select --install`. Read more about the problem [on Stack Overflow](http://stackoverflow.com/a/32929012/148072).
## Screencasts
## Quick Example
- [Introduction](http://screenr.com/CTk)
## Example
```javascript

@@ -88,23 +65,120 @@ const { createCanvas, loadImage } = require('canvas')

## Know issues
## Upgrading from 2.x
- CMYK images are not supported ([#1183](https://github.com/Automattic/node-canvas/issues/1183), [#425](https://github.com/Automattic/node-canvas/issues/425))
- `ctx.fillText` `maxWidth` is inconsistent ([#1088](https://github.com/Automattic/node-canvas/issues/1183), [#1088](https://github.com/Automattic/node-canvas/issues/425))
- Async `canvas.toBuffer` for PDF is not working ([#821](https://github.com/Automattic/node-canvas/issues/821))
See the [changelog](https://github.com/Automattic/node-canvas/blob/master/CHANGELOG.md) for a guide to upgrading from 1.x to 2.x.
[See all list of bugs](https://github.com/Automattic/node-canvas/issues?q=is%3Aissue+is%3Aopen+label%3ABug).
For version 1.x documentation, see [the v1.x branch](https://github.com/Automattic/node-canvas/tree/v1.x).
## Non-Standard APIs
## Documentation
node-canvas implements the [HTML Canvas API](https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API) as closely as possible.
(See [Compatibility Status](https://github.com/Automattic/node-canvas/wiki/Compatibility-Status)
for the current API compliance.) All non-standard APIs are documented below.
This project is an implementation of the Web Canvas API and implements that API as closely as possible. For API documentation, please visit [Mozilla Web Canvas API](https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API). (See [Compatibility Status](https://github.com/Automattic/node-canvas/wiki/Compatibility-Status) for the current API compliance.) All utility methods and non-standard APIs are documented below.
### Utility methods
* [createCanvas()](#createcanvas)
* [createImageData()](#createimagedata)
* [loadImage()](#loadimage)
* [registerFont()](#registerfont)
### Non-standard APIs
* [Image#src](#imagesrc)
* [Image#dataMode](#imagedatamode)
* [Canvas#toBuffer()](#canvastobuffer)
* [Canvas#createPNGStream()](#canvascreatepngstream)
* [Canvas#createJPEGStream()](#canvascreatejpegstream)
* [Canvas#createPDFStream()](#canvascreatepdfstream)
* [Canvas#toDataURL()](#canvastodataurl)
* [CanvasRenderingContext2D#patternQuality](#canvasrenderingcontext2dpatternquality)
* [CanvasRenderingContext2D#quality](#canvasrenderingcontext2dquality)
* [CanvasRenderingContext2D#textDrawingMode](#canvasrenderingcontext2dtextdrawingmode)
* [CanvasRenderingContext2D#globalCompositeOperator = 'saturate'](#canvasrenderingcontext2dglobalcompositeoperator--saturate)
* [CanvasRenderingContext2D#antialias](#canvasrenderingcontext2dantialias)
### createCanvas()
> ```ts
> createCanvas(width: number, height: number, type?: 'PDF'|'SVG') => Canvas
> ```
Creates a Canvas instance. This method works in both Node.js and Web browsers, where there is no Canvas constructor. (See `browser.js` for the implementation that runs in browsers.)
```js
const { createCanvas } = require('canvas')
const mycanvas = createCanvas(200, 200)
const myPDFcanvas = createCanvas(600, 800, 'pdf') // see "PDF Support" section
```
### createImageData()
> ```ts
> createImageData(width: number, height: number) => ImageData
> createImageData(data: Uint8ClampedArray, width: number, height?: number) => ImageData
> // for alternative pixel formats:
> createImageData(data: Uint16Array, width: number, height?: number) => ImageData
> ```
Creates an ImageData instance. This method works in both Node.js and Web browsers.
```js
const { createImageData } = require('canvas')
const width = 20, height = 20
const arraySize = width * height * 4
const mydata = createImageData(new Uint8ClampedArray(arraySize), width)
```
### loadImage()
> ```ts
> loadImage() => Promise<Image>
> ```
Convenience method for loading images. This method works in both Node.js and Web browsers.
```js
const { loadImage } = require('canvas')
const myimg = loadImage('http://server.com/image.png')
myimg.then(() => {
// do something with image
}).catch(err => {
console.log('oh no!', err)
})
// or with async/await:
const myimg = await loadImage('http://server.com/image.png')
// do something with image
```
### registerFont()
> ```ts
> registerFont(path: string, { family: string, weight?: string, style?: string }) => void
> ```
To use a font file that is not installed as a system font, use `registerFont()` to register the font with Canvas. *This must be done before the Canvas is created.*
```js
const { registerFont, createCanvas } = require('canvas')
registerFont('comicsans.ttf', { family: 'Comic Sans' })
const canvas = createCanvas(500, 500)
const ctx = canvas.getContext('2d')
ctx.font = '12px "Comic Sans"'
ctx.fillText('Everyone hates this font :(', 250, 10)
```
The second argument is an object with properties that resemble the CSS properties that are specified in `@font-face` rules. You must specify at least `family`. `weight`, and `style` are optional and default to `'normal'`.
### Image#src
As in browsers, `img.src` can be set to a `data:` URI or a remote URL. In addition,
node-canvas allows setting `src` to a local file path or to a `Buffer` instance.
> ```ts
> img.src: string|Buffer
> ```
As in browsers, `img.src` can be set to a `data:` URI or a remote URL. In addition, node-canvas allows setting `src` to a local file path or `Buffer` instance.
```javascript
const { Image } = require('canvas');
const { Image } = require('canvas')

@@ -135,63 +209,51 @@ // From a buffer:

*Note: In some cases, `img.src=` is currently synchronous. However, you should
always use `img.onload` and `img.onerror`, as we intend to make `img.src=` always
asynchronous as it is in browsers. See https://github.com/Automattic/node-canvas/issues/1007.*
*Note: In some cases, `img.src=` is currently synchronous. However, you should always use `img.onload` and `img.onerror`, as we intend to make `img.src=` always asynchronous as it is in browsers. See https://github.com/Automattic/node-canvas/issues/1007.*
### Image#dataMode
node-canvas adds `Image#dataMode` support, which can be used to opt-in to mime data tracking of images (currently only JPEGs).
> ```ts
> img.dataMode: number
> ```
When mime data is tracked, in PDF mode JPEGs can be embedded directly into the output, rather than being re-encoded into PNG. This can drastically reduce filesize, and speed up rendering.
Applies to JPEG images drawn to PDF canvases only.
Setting `img.dataMode = Image.MODE_MIME` or `Image.MODE_MIME|Image.MODE_IMAGE` enables MIME data tracking of images. When MIME data is tracked, PDF canvases can embed JPEGs directly into the output, rather than re-encoding into PNG. This can drastically reduce filesize and speed up rendering.
```javascript
const { Image } = require('canvas');
var img = new Image();
img.dataMode = Image.MODE_IMAGE; // Only image data tracked
img.dataMode = Image.MODE_MIME; // Only mime data tracked
img.dataMode = Image.MODE_MIME | Image.MODE_IMAGE; // Both are tracked
const { Image, createCanvas } = require('canvas')
const canvas = createCanvas(w, h, 'pdf')
const img = new Image()
img.dataMode = Image.MODE_IMAGE // Only image data tracked
img.dataMode = Image.MODE_MIME // Only mime data tracked
img.dataMode = Image.MODE_MIME | Image.MODE_IMAGE // Both are tracked
```
If image data is not tracked, and the Image is drawn to an image rather than a PDF canvas, the output will be junk. Enabling mime data tracking has no benefits (only a slow down) unless you are generating a PDF.
If working with a non-PDF canvas, image data *must* be tracked; otherwise the output will be junk.
Enabling mime data tracking has no benefits (only a slow down) unless you are generating a PDF.
### Canvas#toBuffer()
Creates a [`Buffer`](https://nodejs.org/api/buffer.html) object representing the
image contained in the canvas.
> ```ts
> canvas.toBuffer((err: Error|null, result: Buffer) => void, mimeType?: string, config?: any) => void
> canvas.toBuffer(mimeType?: string, config?: any) => Buffer
> ```
> `canvas.toBuffer((err: Error|null, result: Buffer) => void[, mimeType[, config]]) => void`
> `canvas.toBuffer([mimeType[, config]]) => Buffer`
Creates a [`Buffer`](https://nodejs.org/api/buffer.html) object representing the image contained in the canvas.
* **callback** If provided, the buffer will be provided in the callback instead
of being returned by the function. Invoked with an error as the first argument
if encoding failed, or the resulting buffer as the second argument if it
succeeded. Not supported for mimeType `raw` or for PDF or SVG canvases (there
is no async work to do in those cases).
* **mimeType** A string indicating the image format. Valid options are `image/png`,
`image/jpeg` (if node-canvas was built with JPEG support) and `raw` (unencoded
ARGB32 data in native-endian byte order, top-to-bottom). Defaults to
`image/png`. If the canvas is a PDF or SVG canvas, this argument is ignored
and a PDF or SVG is returned always.
* **callback** If provided, the buffer will be provided in the callback instead of being returned by the function. Invoked with an error as the first argument if encoding failed, or the resulting buffer as the second argument if it succeeded. Not supported for mimeType `raw` or for PDF or SVG canvases.
* **mimeType** A string indicating the image format. Valid options are `image/png`, `image/jpeg` (if node-canvas was built with JPEG support) and `raw` (unencoded ARGB32 data in native-endian byte order, top-to-bottom). Defaults to `image/png`. If the canvas is a PDF or SVG canvas, this argument is ignored and a PDF or SVG is returned always.
* **config**
* For `image/jpeg` an object specifying the quality (0 to 1), if progressive
compression should be used and/or if chroma subsampling should be used:
`{quality: 0.75, progressive: false, chromaSubsampling: true}`. All
properties are optional.
* For `image/png`, an object specifying the ZLIB compression level (between 0
and 9), the compression filter(s), the palette (indexed PNGs only), the
the background palette index (indexed PNGs only) and/or the resolution (ppi):
`{compressionLevel: 6, filters: canvas.PNG_ALL_FILTERS, palette: undefined, backgroundIndex: 0, resolution: undefined}`.
All properties are optional.
* For `image/jpeg` an object specifying the quality (0 to 1), if progressive compression should be used and/or if chroma subsampling should be used: `{quality: 0.75, progressive: false, chromaSubsampling: true}`. All properties are optional.
* For `image/png`, an object specifying the ZLIB compression level (between 0 and 9), the compression filter(s), the palette (indexed PNGs only), the the background palette index (indexed PNGs only) and/or the resolution (ppi): `{compressionLevel: 6, filters: canvas.PNG_ALL_FILTERS, palette: undefined, backgroundIndex: 0, resolution: undefined}`. All properties are optional.
Note that the PNG format encodes the resolution in pixels per meter, so if
you specify `96`, the file will encode 3780 ppm (~96.01 ppi). The resolution
is undefined by default to match common browser behavior.
Note that the PNG format encodes the resolution in pixels per meter, so if you specify `96`, the file will encode 3780 ppm (~96.01 ppi). The resolution is undefined by default to match common browser behavior.
**Return value**
If no callback is provided, a [`Buffer`](https://nodejs.org/api/buffer.html).
If a callback is provided, none.
If no callback is provided, a [`Buffer`](https://nodejs.org/api/buffer.html). If a callback is provided, none.
#### Examples
```javascript
```js
// Default: buf contains a PNG-encoded image

@@ -201,10 +263,10 @@ const buf = canvas.toBuffer()

// PNG-encoded, zlib compression level 3 for faster compression but bigger files, no filtering
const buf2 = canvas.toBuffer('image/png', {compressionLevel: 3, filters: canvas.PNG_FILTER_NONE})
const buf2 = canvas.toBuffer('image/png', { compressionLevel: 3, filters: canvas.PNG_FILTER_NONE })
// JPEG-encoded, 50% quality
const buf3 = canvas.toBuffer('image/jpeg', {quality: 0.5})
const buf3 = canvas.toBuffer('image/jpeg', { quality: 0.5 })
// Asynchronous PNG
canvas.toBuffer((err, buf) => {
if (err) throw err; // encoding failed
if (err) throw err // encoding failed
// buf is PNG-encoded image

@@ -214,9 +276,9 @@ })

canvas.toBuffer((err, buf) => {
if (err) throw err; // encoding failed
if (err) throw err // encoding failed
// buf is JPEG-encoded image at 95% quality
}, 'image/jpeg', {quality: 0.95})
}, 'image/jpeg', { quality: 0.95 })
// ARGB32 pixel values, native-endian
const buf4 = canvas.toBuffer('raw')
const {stride, width} = canvas
const { stride, width } = canvas
// In memory, this is `canvas.height * canvas.stride` bytes long.

@@ -233,14 +295,11 @@ // The top row of pixels, in ARGB order, left-to-right, is:

### Canvas#createPNGStream(options)
### Canvas#createPNGStream()
Creates a [`ReadableStream`](https://nodejs.org/api/stream.html#stream_class_stream_readable)
that emits PNG-encoded data.
> ```ts
> canvas.createPNGStream(config?: any) => ReadableStream
> ```
> `canvas.createPNGStream([config]) => ReadableStream`
Creates a [`ReadableStream`](https://nodejs.org/api/stream.html#stream_class_stream_readable) that emits PNG-encoded data.
* `config` An object specifying the ZLIB compression level (between 0 and 9),
the compression filter(s), the palette (indexed PNGs only) and/or the
background palette index (indexed PNGs only):
`{compressionLevel: 6, filters: canvas.PNG_ALL_FILTERS, palette: undefined, backgroundIndex: 0, resolution: undefined}`.
All properties are optional.
* `config` An object specifying the ZLIB compression level (between 0 and 9), the compression filter(s), the palette (indexed PNGs only) and/or the background palette index (indexed PNGs only): `{compressionLevel: 6, filters: canvas.PNG_ALL_FILTERS, palette: undefined, backgroundIndex: 0, resolution: undefined}`. All properties are optional.

@@ -275,14 +334,11 @@ #### Examples

Creates a [`createJPEGStream`](https://nodejs.org/api/stream.html#stream_class_stream_readable)
that emits JPEG-encoded data.
> ```ts
> canvas.createJPEGStream(config?: any) => ReadableStream
> ```
_Note: At the moment, `createJPEGStream()` is synchronous under the hood. That is, it
runs in the main thread, not in the libuv threadpool._
Creates a [`ReadableStream`](https://nodejs.org/api/stream.html#stream_class_stream_readable) that emits JPEG-encoded data.
> `canvas.createJPEGStream([config]) => ReadableStream`
*Note: At the moment, `createJPEGStream()` is synchronous under the hood. That is, it runs in the main thread, not in the libuv threadpool.*
* `config` an object specifying the quality (0 to 1), if progressive compression
should be used and/or if chroma subsampling should be used:
`{quality: 0.75, progressive: false, chromaSubsampling: true}`. All properties
are optional.
* `config` an object specifying the quality (0 to 1), if progressive compression should be used and/or if chroma subsampling should be used: `{quality: 0.75, progressive: false, chromaSubsampling: true}`. All properties are optional.

@@ -305,129 +361,109 @@ #### Examples

### Canvas#toDataURL() sync and async
### Canvas#createPDFStream()
The following syntax patterns are supported:
> ```ts
> canvas.createPDFStream(config?: any) => ReadableStream
> ```
```javascript
var dataUrl = canvas.toDataURL(); // defaults to PNG
var dataUrl = canvas.toDataURL('image/png');
canvas.toDataURL(function(err, png){ }); // defaults to PNG
canvas.toDataURL('image/png', function(err, png){ });
canvas.toDataURL('image/jpeg', function(err, jpeg){ }); // sync JPEG is not supported
canvas.toDataURL('image/jpeg', {opts...}, function(err, jpeg){ }); // see Canvas#createJPEGStream for valid options
canvas.toDataURL('image/jpeg', quality, function(err, jpeg){ }); // spec-following; quality from 0 to 1
```
Applies to PDF canvases only. Creates a [`ReadableStream`](https://nodejs.org/api/stream.html#stream_class_stream_readable) that emits the encoded PDF. `canvas.toBuffer()` also produces an encoded PDF, but `createPDFStream()` can be used to reduce memory usage.
### `registerFont` for bundled fonts
### Canvas#toDataURL()
It can be useful to use a custom font file if you are distributing code that uses node-canvas and a specific font. Or perhaps you are using it to do automated tests and you want the renderings to be the same across operating systems regardless of what fonts are installed.
This is a standard API, but several non-standard calls are supported. The full list of supported calls is:
To do that, you should use `registerFont()`.
```js
dataUrl = canvas.toDataURL() // defaults to PNG
dataUrl = canvas.toDataURL('image/png')
canvas.toDataURL((err, png) => { }) // defaults to PNG
canvas.toDataURL('image/png', (err, png) => { })
canvas.toDataURL('image/jpeg', (err, jpeg) => { }) // sync JPEG is not supported
canvas.toDataURL('image/jpeg', {...opts}, (err, jpeg) => { }) // see Canvas#createJPEGStream for valid options
canvas.toDataURL('image/jpeg', quality, (err, jpeg) => { }) // spec-following; quality from 0 to 1
```
**You need to call it before the Canvas is created**
### CanvasRenderingContext2D#patternQuality
```javascript
const { registerFont, createCanvas } = require('canvas');
registerFont('comicsans.ttf', {family: 'Comic Sans'});
> ```ts
> context.patternQuality: 'fast'|'good'|'best'|'nearest'|'bilinear'
> ```
var canvas = createCanvas(500, 500),
ctx = canvas.getContext('2d');
Defaults to `'good'`. Affects pattern (gradient, image, etc.) rendering quality.
ctx.font = '12px "Comic Sans"';
ctx.fillText('Everyone hates this font :(', 250, 10);
```
### CanvasRenderingContext2D#quality
The second argument is an object with properties that resemble the CSS properties that are specified in `@font-face` rules. You must specify at least `family`. `weight`, and `style` are optional (and default to "normal").
> ```ts
> context.quality: 'fast'|'good'|'best'|'nearest'|'bilinear'
> ```
### CanvasRenderingContext2D#patternQuality
Defaults to `'good'`. Like `patternQuality`, but applies to transformations affecting more than just patterns.
Given one of the values below will alter pattern (gradients, images, etc) render quality, defaults to _good_.
- fast
- good
- best
- nearest
- bilinear
### CanvasRenderingContext2D#textDrawingMode
Can be either `path` or `glyph`. Using `glyph` is much faster than `path` for drawing, and when using a PDF context will embed the text natively, so will be selectable and lower filesize. The downside is that cairo does not have any subpixel precision for `glyph`, so this will be noticeably lower quality for text positioning in cases such as rotated text. Also, strokeText in `glyph` will act the same as fillText, except using the stroke style for the fill.
> ```ts
> context.textDrawingMode: 'path'|'glyph'
> ```
Defaults to _path_.
Defaults to `'path'`. The effect depends on the canvas type:
This property is tracked as part of the canvas state in save/restore.
* **Standard (image)** `glyph` and `path` both result in rasterized text. Glyph mode is faster than `path`, but may result in lower-quality text, especially when rotated or translated.
### CanvasRenderingContext2D#filter
* **PDF** `glyph` will embed text instead of paths into the PDF. This is faster to encode, faster to open with PDF viewers, yields a smaller file size and makes the text selectable. The subset of the font needed to render the glyphs will be embedded in the PDF. This is usually the mode you want to use with PDF canvases.
Like `patternQuality`, but applies to transformations effecting more than just patterns. Defaults to _good_.
* **SVG** `glyph` does *not* cause `<text>` elements to be produced as one might expect ([cairo bug](https://gitlab.freedesktop.org/cairo/cairo/issues/253)). Rather, `glyph` will create a `<defs>` section with a `<symbol>` for each glyph, then those glyphs be reused via `<use>` elements. `path` mode creates a `<path>` element for each text string. `glyph` mode is faster and yields a smaller file size.
- fast
- good
- best
- nearest
- bilinear
In `glyph` mode, `ctx.strokeText()` and `ctx.fillText()` behave the same (aside from using the stroke and fill style, respectively).
### Global Composite Operations
This property is tracked as part of the canvas state in save/restore.
In addition to those specified and commonly implemented by browsers, the following have been added:
### CanvasRenderingContext2D#globalCompositeOperator = 'saturate'
- multiply
- screen
- overlay
- hard-light
- soft-light
- hsl-hue
- hsl-saturation
- hsl-color
- hsl-luminosity
In addition to all of the standard global composite operators defined by the Canvas specification, the ['saturate'](https://www.cairographics.org/operators/#saturate) operator is also available.
## Anti-Aliasing
### CanvasRenderingContext2D#antialias
Set anti-aliasing mode
> ```ts
> context.antialias: 'default'|'none'|'gray'|'subpixel'
> ```
- default
- none
- gray
- subpixel
Sets the anti-aliasing mode.
For example:
## PDF Output Support
```javascript
ctx.antialias = 'none';
```
node-canvas can create PDF documents instead of images. The canvas type must be set when creating the canvas as follows:
## PDF Support
Basic PDF support was added in 0.11.0. If you are building cairo from source, be sure to use `--enable-pdf=yes` for the PDF backend.
node-canvas must know that it is creating a PDF on initialization, using the "pdf" string:
```js
var canvas = createCanvas(200, 500, 'pdf');
const canvas = createCanvas(200, 500, 'pdf')
```
An additional method `.addPage()` is then available to create
multiple page PDFs:
An additional method `.addPage()` is then available to create multiple page PDFs:
```js
ctx.font = '22px Helvetica';
ctx.fillText('Hello World', 50, 80);
ctx.addPage();
// On first page
ctx.font = '22px Helvetica'
ctx.fillText('Hello World', 50, 80)
ctx.font = '22px Helvetica';
ctx.fillText('Hello World 2', 50, 80);
ctx.addPage();
ctx.addPage()
// Now on second page
ctx.font = '22px Helvetica'
ctx.fillText('Hello World 2', 50, 80)
ctx.font = '22px Helvetica';
ctx.fillText('Hello World 3', 50, 80);
ctx.addPage();
canvas.toBuffer() // returns a PDF file
canvas.createPDFStream() // returns a ReadableStream that emits a PDF
```
## SVG Support
See also:
Just like PDF support, make sure to install cairo with `--enable-svg=yes`.
You also need to tell node-canvas that it is working on SVG upon its initialization:
* [Image#dataMode](#imagedatamode) for embedding JPEGs in PDFs
* [Canvas#createPDFStream()](#canvascreatepdfstream) for creating PDF streams
* [CanvasRenderingContext2D#textDrawingMode](#canvasrenderingcontext2dtextdrawingmode)
for embedding text instead of paths
## SVG Output Support
node-canvas can create SVG documents instead of images. The canva type must be set when creating the canvas as follows:
```js
var canvas = createCanvas(200, 500, 'svg');
const canvas = createCanvas(200, 500, 'svg')
// Use the normal primitives.
fs.writeFileSync('out.svg', canvas.toBuffer());
fs.writeFileSync('out.svg', canvas.toBuffer())
```

@@ -437,5 +473,3 @@

If librsvg is available when node-canvas is installed, node-canvas can render
SVG images to your canvas context. This currently works by rasterizing the SVG
image (i.e. drawing an SVG image to an SVG canvas will not preserve the SVG data).
If librsvg is available when node-canvas is installed, node-canvas can render SVG images to your canvas context. This currently works by rasterizing the SVG image (i.e. drawing an SVG image to an SVG canvas will not preserve the SVG data).

@@ -451,108 +485,50 @@ ```js

node-canvas has experimental support for additional pixel formats, roughly
following the [Canvas color space proposal](https://github.com/WICG/canvas-color-space/blob/master/CanvasColorSpaceProposal.md).
node-canvas has experimental support for additional pixel formats, roughly following the [Canvas color space proposal](https://github.com/WICG/canvas-color-space/blob/master/CanvasColorSpaceProposal.md).
```js
var canvas = createCanvas(200, 200);
var ctx = canvas.getContext('2d', {pixelFormat: 'A8'});
const canvas = createCanvas(200, 200)
const ctx = canvas.getContext('2d', { pixelFormat: 'A8' })
```
By default, canvases are created in the `RGBA32` format, which corresponds to
the native HTML Canvas behavior. Each pixel is 32 bits. The JavaScript APIs
that involve pixel data (`getImageData`, `putImageData`) store the colors in
the order {red, green, blue, alpha} without alpha pre-multiplication. (The C++
API stores the colors in the order {alpha, red, green, blue} in native-[endian](https://en.wikipedia.org/wiki/Endianness)
ordering, with alpha pre-multiplication.)
By default, canvases are created in the `RGBA32` format, which corresponds to the native HTML Canvas behavior. Each pixel is 32 bits. The JavaScript APIs that involve pixel data (`getImageData`, `putImageData`) store the colors in the order {red, green, blue, alpha} without alpha pre-multiplication. (The C++ API stores the colors in the order {alpha, red, green, blue} in native-[endian](https://en.wikipedia.org/wiki/Endianness) ordering, with alpha pre-multiplication.)
These additional pixel formats have experimental support:
* `RGB24` Like `RGBA32`, but the 8 alpha bits are always opaque. This format is
always used if the `alpha` context attribute is set to false (i.e.
`canvas.getContext('2d', {alpha: false})`). This format can be faster than
`RGBA32` because transparency does not need to be calculated.
* `A8` Each pixel is 8 bits. This format can either be used for creating
grayscale images (treating each byte as an alpha value), or for creating
indexed PNGs (treating each byte as a palette index) (see [the example using
alpha values with `fillStyle`](examples/indexed-png-alpha.js) and [the
example using `imageData`](examples/indexed-png-image-data.js)).
* `RGB16_565` Each pixel is 16 bits, with red in the upper 5 bits, green in the
middle 6 bits, and blue in the lower 5 bits, in native platform endianness.
Some hardware devices and frame buffers use this format. Note that PNG does
not support this format; when creating a PNG, the image will be converted to
24-bit RGB. This format is thus suboptimal for generating PNGs.
`ImageData` instances for this mode use a `Uint16Array` instead of a `Uint8ClampedArray`.
* `A1` Each pixel is 1 bit, and pixels are packed together into 32-bit
quantities. The ordering of the bits matches the endianness of the
platform: on a little-endian machine, the first pixel is the least-
significant bit. This format can be used for creating single-color images.
*Support for this format is incomplete, see note below.*
* `RGB30` Each pixel is 30 bits, with red in the upper 10, green
in the middle 10, and blue in the lower 10. (Requires Cairo 1.12 or later.)
*Support for this format is incomplete, see note below.*
* `RGB24` Like `RGBA32`, but the 8 alpha bits are always opaque. This format is always used if the `alpha` context attribute is set to false (i.e. `canvas.getContext('2d', {alpha: false})`). This format can be faster than `RGBA32` because transparency does not need to be calculated.
* `A8` Each pixel is 8 bits. This format can either be used for creating grayscale images (treating each byte as an alpha value), or for creating indexed PNGs (treating each byte as a palette index) (see [the example using alpha values with `fillStyle`](examples/indexed-png-alpha.js) and [the example using `imageData`](examples/indexed-png-image-data.js)).
* `RGB16_565` Each pixel is 16 bits, with red in the upper 5 bits, green in the middle 6 bits, and blue in the lower 5 bits, in native platform endianness. Some hardware devices and frame buffers use this format. Note that PNG does not support this format; when creating a PNG, the image will be converted to 24-bit RGB. This format is thus suboptimal for generating PNGs. `ImageData` instances for this mode use a `Uint16Array` instead of a `Uint8ClampedArray`.
* `A1` Each pixel is 1 bit, and pixels are packed together into 32-bit quantities. The ordering of the bits matches the endianness of the
platform: on a little-endian machine, the first pixel is the least-significant bit. This format can be used for creating single-color images. *Support for this format is incomplete, see note below.*
* `RGB30` Each pixel is 30 bits, with red in the upper 10, green in the middle 10, and blue in the lower 10. (Requires Cairo 1.12 or later.) *Support for this format is incomplete, see note below.*
Notes and caveats:
* Using a non-default format can affect the behavior of APIs that involve pixel
data:
* Using a non-default format can affect the behavior of APIs that involve pixel data:
* `context2d.createImageData` The size of the array returned depends on the
number of bit per pixel for the underlying image data format, per the above
descriptions.
* `context2d.getImageData` The format of the array returned depends on the
underlying image mode, per the above descriptions. Be aware of platform
endianness, which can be determined using node.js's [`os.endianness()`](https://nodejs.org/api/os.html#os_os_endianness)
* `context2d.createImageData` The size of the array returned depends on the number of bit per pixel for the underlying image data format, per the above descriptions.
* `context2d.getImageData` The format of the array returned depends on the underlying image mode, per the above descriptions. Be aware of platform endianness, which can be determined using node.js's [`os.endianness()`](https://nodejs.org/api/os.html#os_os_endianness)
function.
* `context2d.putImageData` As above.
* `A1` and `RGB30` do not yet support `getImageData` or `putImageData`. Have a
use case and/or opinion on working with these formats? Open an issue and let
us know! (See #935.)
* `A1` and `RGB30` do not yet support `getImageData` or `putImageData`. Have a use case and/or opinion on working with these formats? Open an issue and let us know! (See #935.)
* `A1`, `A8`, `RGB30` and `RGB16_565` with shadow blurs may crash or not render
properly.
* `A1`, `A8`, `RGB30` and `RGB16_565` with shadow blurs may crash or not render properly.
* The `ImageData(width, height)` and `ImageData(Uint8ClampedArray, width)`
constructors assume 4 bytes per pixel. To create an `ImageData` instance with
a different number of bytes per pixel, use
`new ImageData(new Uint8ClampedArray(size), width, height)` or
`new ImageData(new Uint16ClampedArray(size), width, height)`.
* The `ImageData(width, height)` and `ImageData(Uint8ClampedArray, width)` constructors assume 4 bytes per pixel. To create an `ImageData` instance with a different number of bytes per pixel, use `new ImageData(new Uint8ClampedArray(size), width, height)` or `new ImageData(new Uint16ClampedArray(size), width, height)`.
## Benchmarks
Although node-canvas is extremely new, and we have not even begun optimization yet it is already quite fast. For benchmarks vs other node canvas implementations view this [gist](https://gist.github.com/664922), or update the submodules and run `$ make benchmark` yourself.
Benchmarks live in the `benchmarks` directory.
## Contribute
Want to contribute to node-canvas? patches for features, bug fixes, documentation, examples and others are certainly welcome. Take a look at the [issue queue](https://github.com/Automattic/node-canvas/issues) for existing issues.
## Examples
Examples are placed in _./examples_, be sure to check them out! most produce a png image of the same name, and others such as _live-clock.js_ launch an http server to be viewed in the browser.
Examples line in the `examples` directory. Most produce a png image of the same name, and others such as *live-clock.js* launch an HTTP server to be viewed in the browser.
## Documentation
## Original Authors
This project is an implementation of the Web Canvas API. For API documentation, please visit: [Mozilla Web Canvas API](https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API)
- TJ Holowaychuk ([tj](http://github.com/tj))
- Nathan Rajlich ([TooTallNate](http://github.com/TooTallNate))
- Rod Vagg ([rvagg](http://github.com/rvagg))
- Juriy Zaytsev ([kangax](http://github.com/kangax))
## Testing
If you have not previously, init git submodules:
$ git submodule update --init
Install the node modules:
$ npm install
Build node-canvas:
$ node-gyp rebuild
Unit tests:
$ make test
Visual tests:
$ make test-server
## License

@@ -566,19 +542,17 @@

Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
'Software'), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:
Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the 'Software'), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
the Software, and to permit persons to whom the Software is furnished to do so,
subject to the following conditions:
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
src/CanvasRenderingContext2d.cc

Sorry, the diff of this file is not supported yet

src/CanvasRenderingContext2d.h

Sorry, the diff of this file is not supported yet

SocketSocket SOC 2 Logo

Product

  • Package Alerts
  • Integrations
  • Docs
  • Pricing
  • FAQ
  • Roadmap
  • Changelog

About

Packages

npm

Go

Maven

PyPI

Rubygems

Stay in touch

Get open source security insights delivered straight into your inbox.

  • Terms
  • Privacy
  • Security

Made with ⚡️ by Socket Inc