# CanvasRenderingContext2D

The CanvasRenderingContext2D interface is used for drawing rectangles, text, images and other objects onto the canvas element. It provides the 2D rendering context for the drawing surface of a `<canvas>` element.

To get an object of this interface, call `getContext()` on a `<canvas> element`, supplying "2d" as the argument:

```var canvas = document.getElementById('myCanvas'); // in your HTML this element appears as <canvas id="myCanvas"></canvas>
var ctx = canvas.getContext('2d');
```

Once you have the 2D rendering context for a canvas, you can draw within it. For example:

```ctx.fillStyle = 'rgb(200,0,0)'; // sets the color to fill in the rectangle with
ctx.fillRect(10, 10, 55, 50);   // draws the rectangle at position 10, 10 with a width of 55 and a height of 50
```

See the properties and methods in the sidebar and below. The canvas tutorial has more information, examples, and resources as well.

## Drawing rectangles

There are three methods that immediately draw rectangles to the bitmap.

`CanvasRenderingContext2D.clearRect()`
Sets all pixels in the rectangle defined by starting point (x, y) and size (width, height) to transparent black, erasing any previously drawn content.
`CanvasRenderingContext2D.fillRect()`
Draws a filled rectangle at (x, y) position whose size is determined by width and height.
`CanvasRenderingContext2D.strokeRect()`
Paints a rectangle which has a starting point at (x, y) and has a w width and an h height onto the canvas, using the current stroke style.

## Drawing text

The following methods are provided for drawing text. See also the `TextMetrics` object for text properties.

`CanvasRenderingContext2D.fillText()`
Draws (fills) a given text at the given (x,y) position.
`CanvasRenderingContext2D.strokeText()`
Draws (strokes) a given text at the given (x, y) position.
`CanvasRenderingContext2D.measureText()`
Returns a `TextMetrics` object.

## Line styles

The following methods and properties control how lines are drawn.

`CanvasRenderingContext2D.lineWidth`
Width of lines. Default `1.0`
`CanvasRenderingContext2D.lineCap`
Type of endings on the end of lines. Possible values: `butt` (default), `round`, `square`.
`CanvasRenderingContext2D.lineJoin`
Defines the type of corners where two lines meet. Possible values: `round`, `bevel`, `miter` (default).
`CanvasRenderingContext2D.miterLimit`
Miter limit ratio. Default `10`.
`CanvasRenderingContext2D.getLineDash()`
Returns the current line dash pattern array containing an even number of non-negative numbers.
`CanvasRenderingContext2D.setLineDash()`
Sets the current line dash pattern.
`CanvasRenderingContext2D.lineDashOffset`
Specifies where to start a dash array on a line.

## Text styles

The following properties control how text is laid out.

`CanvasRenderingContext2D.font`
Font setting. Default value `10px sans-serif`.
`CanvasRenderingContext2D.textAlign`
Text alignment setting. Possible values: `start` (default), `end`, `left`, `right` or `center`.
`CanvasRenderingContext2D.textBaseline`
Baseline alignment setting. Possible values: `top`, `hanging`, `middle`, `alphabetic` (default), `ideographic`, `bottom`.
`CanvasRenderingContext2D.direction`
Directionality. Possible values: `ltr, rtl`, `inherit` (default).

## Fill and stroke styles

Fill styling is used for colors and styles inside shapes and stroke styling is used for the lines around shapes.

`CanvasRenderingContext2D.fillStyle`
Color or style to use inside shapes. Default `#000` (black).
`CanvasRenderingContext2D.strokeStyle`
Color or style to use for the lines around shapes. Default `#000` (black).

`CanvasRenderingContext2D.createLinearGradient()`
Creates a linear gradient along the line given by the coordinates represented by the parameters.
`CanvasRenderingContext2D.createRadialGradient()`
Creates a radial gradient given by the coordinates of the two circles represented by the parameters.
`CanvasRenderingContext2D.createPattern()`
Creates a pattern using the specified image (a `CanvasImageSource`). It repeats the source in the directions specified by the repetition argument. This method returns a `CanvasPattern`.

`CanvasRenderingContext2D.shadowBlur`
Specifies the blurring effect. Default `0`
`CanvasRenderingContext2D.shadowColor`
Color of the shadow. Default fully-transparent black.
`CanvasRenderingContext2D.shadowOffsetX`
Horizontal distance the shadow will be offset. Default 0.
`CanvasRenderingContext2D.shadowOffsetY`
Vertical distance the shadow will be offset. Default 0.

## Paths

The following methods can be used to manipulate paths of objects.

`CanvasRenderingContext2D.beginPath()`
Starts a new path by emptying the list of sub-paths. Call this method when you want to create a new path.
`CanvasRenderingContext2D.closePath()`
Causes the point of the pen to move back to the start of the current sub-path. It tries to draw a straight line from the current point to the start. If the shape has already been closed or has only one point, this function does nothing.
`CanvasRenderingContext2D.moveTo()`
Moves the starting point of a new sub-path to the (x, y) coordinates.
`CanvasRenderingContext2D.lineTo()`
Connects the last point in the subpath to the `x, y` coordinates with a straight line.
`CanvasRenderingContext2D.bezierCurveTo()`
Adds a cubic Bézier curve to the path. It requires three points. The first two points are control points and the third one is the end point. The starting point is the last point in the current path, which can be changed using `moveTo()` before creating the Bézier curve.
`CanvasRenderingContext2D.quadraticCurveTo()`
`CanvasRenderingContext2D.arc()`
Adds an arc to the path which is centered at (x, y) position with radius r starting at startAngle and ending at endAngle going in the given direction by anticlockwise (defaulting to clockwise).
`CanvasRenderingContext2D.arcTo()`
Adds an arc to the path with the given control points and radius, connected to the previous point by a straight line.
`CanvasRenderingContext2D.ellipse()`
Adds an ellipse to the path which is centered at (x, y) position with the radii radiusX and radiusY starting at startAngle and ending at endAngle going in the given direction by anticlockwise (defaulting to clockwise).
`CanvasRenderingContext2D.rect()`
Creates a path for a rectangle at position (x, y) with a size that is determined by width and height.

## Drawing paths

`CanvasRenderingContext2D.fill()`
Fills the subpaths with the current fill style.
`CanvasRenderingContext2D.stroke()`
Strokes the subpaths with the current stroke style.
`CanvasRenderingContext2D.drawFocusIfNeeded()`
If a given element is focused, this method draws a focus ring around the current path.
`CanvasRenderingContext2D.scrollPathIntoView()`
Scrolls the current path or a given path into the view.
`CanvasRenderingContext2D.clip()`
Creates a clipping path from the current sub-paths. Everything drawn after `clip()` is called appears inside the clipping path only. For an example, see Clipping paths in the Canvas tutorial.
`CanvasRenderingContext2D.isPointInPath()`
Reports whether or not the specified point is contained in the current path.
`CanvasRenderingContext2D.isPointInStroke()`
Reports whether or not the specified point is inside the area contained by the stroking of a path.

## Transformations

Objects in the `CanvasRenderingContext2D` rendering context have a current transformation matrix and methods to manipulate it. The transformation matrix is applied when creating the current default path, painting text, shapes and `Path2D` objects. The methods listed below remain for historical and compatibility reasons as `SVGMatrix` objects are used in most parts of the API nowadays and will be used in the future instead.

`CanvasRenderingContext2D.currentTransform`
Current transformation matrix (`SVGMatrix` object).
`CanvasRenderingContext2D.rotate()`
Adds a rotation to the transformation matrix. The angle argument represents a clockwise rotation angle and is expressed in radians.
`CanvasRenderingContext2D.scale()`
Adds a scaling transformation to the canvas units by x horizontally and by y vertically.
`CanvasRenderingContext2D.translate()`
Adds a translation transformation by moving the canvas and its origin x horzontally and y vertically on the grid.
`CanvasRenderingContext2D.transform()`
Multiplies the current transformation matrix with the matrix described by its arguments.
`CanvasRenderingContext2D.setTransform()`
Resets the current transform to the identity matrix, and then invokes the `transform()` method with the same arguments.
`CanvasRenderingContext2D.resetTransform()`
Resets the current transform by the identity matrix.

## Compositing

`CanvasRenderingContext2D.globalAlpha`
Alpha value that is applied to shapes and images before they are composited onto the canvas. Default `1.0` (opaque).
`CanvasRenderingContext2D.globalCompositeOperation`
With `globalAlpha` applied this sets how shapes and images are drawn onto the existing bitmap.

## Drawing images

`CanvasRenderingContext2D.drawImage()`
Draws the specified image. This method is available in multiple formats, providing a great deal of flexibility in its use.

## Pixel manipulation

See also the `ImageData` object.

`CanvasRenderingContext2D.createImageData()`
Creates a new, blank `ImageData` object with the specified dimensions. All of the pixels in the new object are transparent black.
`CanvasRenderingContext2D.getImageData()`
Returns an `ImageData` object representing the underlying pixel data for the area of the canvas denoted by the rectangle which starts at (sx, sy) and has an sw width and sh height.
`CanvasRenderingContext2D.putImageData()`
Paints data from the given `ImageData` object onto the bitmap. If a dirty rectangle is provided, only the pixels from that rectangle are painted.

## Image smoothing

`CanvasRenderingContext2D.imageSmoothingEnabled`
Image smoothing mode; if disabled, images will not be smoothed if scaled.
`CanvasRenderingContext2D.imageSmoothingQuality`
Allows you to set the quality of image smoothing.

## The canvas state

The `CanvasRenderingContext2D` rendering context contains a variety of drawing style states (attributes for line styles, fill styles, shadow styles, text styles). The following methods help you to work with that state:

`CanvasRenderingContext2D.save()`
Saves the current drawing style state using a stack so you can revert any change you make to it using `restore()`.
`CanvasRenderingContext2D.restore()`
Restores the drawing style state to the last element on the 'state stack' saved by `save()`.
`CanvasRenderingContext2D.canvas`
A read-only back-reference to the `HTMLCanvasElement`. Might be `null` if it is not associated with a `<canvas>` element.

## Hit regions

`CanvasRenderingContext2D.addHitRegion()`
Adds a hit region to the canvas.
`CanvasRenderingContext2D.removeHitRegion()`
Removes the hit region with the specified `id` from the canvas.
`CanvasRenderingContext2D.clearHitRegions()`
Removes all hit regions from the canvas.

## Experimental APIs

`CanvasRenderingContext2D.filter`
Applys a CSS and SVG filter to the Canvas, e.g. to change the brightness or blur the canvas.

## Non-standard APIs

Most of these APIs are deprecated and were removed shortly after Chrome 36.

`CanvasRenderingContext2D.clearShadow()`
Removes all shadow settings like `CanvasRenderingContext2D.shadowColor` and `CanvasRenderingContext2D.shadowBlur`.
`CanvasRenderingContext2D.drawImageFromRect()`
This is redundant with an equivalent overload of `drawImage`.
`CanvasRenderingContext2D.setAlpha()`
Use `CanvasRenderingContext2D.globalAlpha` instead.
`CanvasRenderingContext2D.setCompositeOperation()`
Use `CanvasRenderingContext2D.globalCompositeOperation` instead.
`CanvasRenderingContext2D.setLineWidth()`
Use `CanvasRenderingContext2D.lineWidth` instead.
`CanvasRenderingContext2D.setLineJoin()`
Use `CanvasRenderingContext2D.lineJoin` instead.
`CanvasRenderingContext2D.setLineCap()`
Use `CanvasRenderingContext2D.lineCap` instead.
`CanvasRenderingContext2D.setMiterLimit()`
Use `CanvasRenderingContext2D.miterLimit` instead.
`CanvasRenderingContext2D.setStrokeColor()`
Use `CanvasRenderingContext2D.strokeStyle` instead.
`CanvasRenderingContext2D.setFillColor()`
Use `CanvasRenderingContext2D.fillStyle` instead.
`CanvasRenderingContext2D.setShadow()`
Use `CanvasRenderingContext2D.shadowColor` and `CanvasRenderingContext2D.shadowBlur` instead.
`CanvasRenderingContext2D.webkitLineDash`
Use `CanvasRenderingContext2D.getLineDash()` and `CanvasRenderingContext2D.setLineDash()` instead.
`CanvasRenderingContext2D.webkitLineDashOffset`
Use `CanvasRenderingContext2D.lineDashOffset` instead.
`CanvasRenderingContext2D.webkitImageSmoothingEnabled`
Use `CanvasRenderingContext2D.imageSmoothingEnabled` instead.
`CanvasRenderingContext2D.isContextLost()`
Inspired by the same `WebGLRenderingContext` method it returns `true` if the Canvas context has been lost, or `false` if not.

### WebKit only

`CanvasRenderingContext2D.webkitBackingStorePixelRatio`
The backing store size in relation to the canvas element. See High DPI Canvas.
`CanvasRenderingContext2D.webkitGetImageDataHD`
Intended for HD backing stores, but removed from canvas specifications.
`CanvasRenderingContext2D.webkitPutImageDataHD`
Intended for HD backing stores, but removed from canvas specifications.

### Gecko only

#### Prefixed APIs

`CanvasRenderingContext2D.mozCurrentTransform`
Sets or gets the current transformation matrix, see `CanvasRenderingContext2D.currentTransform`
`CanvasRenderingContext2D.mozCurrentTransformInverse`
Sets or gets the current inversed transformation matrix.
`CanvasRenderingContext2D.mozImageSmoothingEnabled`
See `CanvasRenderingContext2D.imageSmoothingEnabled`.
`CanvasRenderingContext2D.mozTextStyle`
Introduced in in Gecko 1.9, deprecated in favor of the `CanvasRenderingContext2D.font` property.
`CanvasRenderingContext2D.mozDrawText()`
This method was introduced in Gecko 1.9 and is removed starting with Gecko 7.0. Use `CanvasRenderingContext2D.strokeText()` or `CanvasRenderingContext2D.fillText()` instead.
`CanvasRenderingContext2D.mozMeasureText()`
This method was introduced in Gecko 1.9 and is unimplemented starting with Gecko 7.0. Use `CanvasRenderingContext2D.measureText()` instead.
`CanvasRenderingContext2D.mozPathText()`
This method was introduced in Gecko 1.9 and is removed starting with Gecko 7.0.
`CanvasRenderingContext2D.mozTextAlongPath()`
This method was introduced in Gecko 1.9 and is removed starting with Gecko 7.0.

#### Internal APIs (chrome-context only)

`CanvasRenderingContext2D.drawWindow()`
Renders a region of a window into the `canvas`. The contents of the window's viewport are rendered, ignoring viewport clipping and scrolling.
`CanvasRenderingContext2D.demote()`
This causes a context that is currently using a hardware-accelerated backend to fallback to a software one. All state should be preserved.

### Internet Explorer

`CanvasRenderingContext2D.msFillRule`
The fill rule to use. This must be one of `evenodd` or `nonzero` (default).

## Specifications

Specification Status Comment
HTML Living Standard
The definition of 'CanvasRenderingContext2D' in that specification.
Living Standard

## Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support1 Yes1.5992
`canvas` Yes Yes Yes Yes Yes Yes
`currentTransform` Yes1 Yes No2 No No No3
`direction` Yes1 ? No No No Yes
`fillStyle` Yes Yes Yes Yes Yes Yes
`filter`52 ?

49

35 — 484

No No No
`font` Yes Yes3.59 Yes Yes
`globalAlpha` Yes Yes Yes Yes Yes Yes
`globalCompositeOperation` Yes Yes Yes Yes Yes Yes
`imageSmoothingEnabled`

30

Yes — 30

Yes

51

Yes — 51

Yes ? ?
`imageSmoothingQuality`54 ? No ?41 Yes
`lineCap` Yes Yes Yes Yes Yes Yes
`lineDashOffset` Yes Yes

27

75

11 Yes Yes
`lineJoin` Yes Yes Yes Yes Yes Yes
`lineWidth` Yes Yes Yes Yes Yes Yes
`miterLimit` Yes Yes Yes Yes Yes Yes
`shadowBlur` Yes Yes Yes Yes Yes Yes
`shadowColor` Yes Yes Yes Yes Yes Yes
`shadowOffsetX` Yes Yes Yes Yes Yes Yes
`shadowOffsetY` Yes Yes Yes Yes Yes Yes
`strokeStyle` Yes Yes Yes Yes Yes Yes
`textAlign` Yes Yes3.5 Yes Yes Yes
`textBaseline` Yes Yes3.59 Yes Yes
`addHitRegion` Yes1 ?306 No No No
`arc` Yes Yes Yes Yes Yes Yes
`arcTo` Yes Yes Yes Yes Yes Yes
`beginPath` Yes Yes Yes Yes Yes Yes
`bezierCurveTo` Yes Yes Yes Yes Yes Yes
`clearHitRegions` Yes1 ?387 No No No
`clearRect` Yes Yes Yes Yes Yes Yes
`clip` Yes Yes Yes Yes Yes Yes
`closePath` Yes Yes Yes Yes Yes Yes
`createImageData` Yes Yes Yes Yes Yes Yes
`createLinearGradient` Yes Yes Yes Yes Yes Yes
`createPattern` Yes Yes Yes Yes Yes Yes
`createRadialGradient` Yes Yes Yes Yes Yes Yes
`drawFocusIfNeeded` Yes ?

32

298

289

No Yes Yes
`drawImage` Yes Yes Yes Yes Yes Yes
`drawWidgetAsOnScreen` No No41 No No No
`drawWindow` No No Yes No No No
`ellipse`311348 No189
`fill` Yes Yes Yes Yes Yes Yes
`fillRect` Yes Yes Yes Yes Yes Yes
`fillText` Yes Yes3.59 Yes Yes
`getImageData` Yes Yes

Yes

510

Yes Yes Yes
`getLineDash` Yes Yes2711 Yes Yes
`isPointInPath` Yes Yes Yes Yes Yes Yes
`isPointInStroke` Yes Yes Yes Yes Yes Yes
`lineTo` Yes Yes Yes Yes Yes Yes
`measureText` Yes Yes Yes9 Yes Yes
`moveTo` Yes Yes Yes Yes Yes Yes
`putImageData` Yes Yes Yes Yes Yes Yes
`quadraticCurveTo` Yes Yes Yes Yes Yes Yes
`rect` Yes Yes Yes Yes Yes Yes
`removeHitRegion` Yes1 ?306 Yes Yes Yes
`resetTransform`31 ?36 No No No
`restore` Yes Yes Yes Yes Yes Yes
`rotate` Yes Yes Yes Yes Yes Yes
`save` Yes Yes Yes Yes Yes Yes
`scale` Yes Yes Yes Yes Yes Yes
`scrollPathIntoView` Yes1 ? No No Yes No
`setLineDash` Yes Yes2711 Yes Yes
`setTransform` Yes Yes Yes Yes Yes Yes
`stroke` Yes Yes Yes Yes Yes Yes
`strokeRect` Yes Yes Yes Yes Yes Yes
`strokeText` Yes Yes3.59 Yes Yes
`transform` Yes Yes Yes Yes Yes Yes
`translate` Yes Yes Yes Yes Yes Yes
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support Yes Yes Yes ? ? ? ?
`canvas` Yes Yes Yes Yes Yes Yes ?
`currentTransform` No No Yes No No No ?
`direction` Yes Yes ? No No Yes ?
`fillStyle` Yes Yes Yes Yes Yes Yes ?
`filter`5252 ?

49

35 — 484

No No ?
`font` Yes Yes Yes4 Yes Yes ?
`globalAlpha` Yes Yes Yes Yes Yes Yes ?
`globalCompositeOperation` Yes Yes Yes Yes Yes Yes ?
`imageSmoothingEnabled`30 ? Yes

51

Yes — 51

? ? ?
`imageSmoothingQuality`5454 ? No41 Yes ?
`lineCap` Yes Yes Yes Yes Yes Yes ?
`lineDashOffset` Yes Yes Yes

27

75

Yes Yes ?
`lineJoin` Yes Yes Yes Yes Yes Yes ?
`lineWidth` Yes Yes Yes Yes Yes Yes ?
`miterLimit` Yes Yes Yes Yes Yes Yes ?
`shadowBlur` Yes Yes Yes Yes Yes Yes ?
`shadowColor` Yes Yes Yes Yes Yes Yes ?
`shadowOffsetX` Yes Yes Yes Yes Yes Yes ?
`shadowOffsetY` Yes Yes Yes Yes Yes Yes ?
`strokeStyle` Yes Yes Yes Yes Yes Yes ?
`textAlign` Yes Yes Yes4 Yes Yes ?
`textBaseline` Yes Yes Yes4 Yes Yes ?
`addHitRegion` No No ?306 No No ?
`arc` Yes Yes Yes Yes Yes Yes ?
`arcTo` Yes Yes Yes Yes Yes Yes ?
`beginPath` Yes Yes Yes Yes Yes Yes ?
`bezierCurveTo` Yes Yes Yes Yes Yes Yes ?
`clearHitRegions` No No ?387 No No ?
`clearRect` Yes Yes Yes Yes Yes Yes ?
`clip` Yes Yes Yes Yes Yes Yes ?
`closePath` Yes Yes Yes Yes Yes Yes ?
`createImageData` Yes Yes Yes Yes Yes Yes ?
`createLinearGradient` Yes Yes Yes Yes Yes Yes ?
`createPattern` Yes Yes Yes Yes Yes Yes ?
`createRadialGradient` Yes Yes Yes Yes Yes Yes ?
`drawFocusIfNeeded` Yes Yes ?

32

298

289

Yes Yes ?
`drawImage` Yes Yes Yes Yes Yes Yes ?
`drawWidgetAsOnScreen` No No No41 No No ?
`drawWindow` No No No Yes No No ?
`ellipse` No Yes Yes Yes No Yes ?
`fill` Yes Yes Yes Yes Yes Yes ?
`fillRect` Yes Yes Yes Yes Yes Yes ?
`fillText` Yes Yes Yes4 Yes Yes ?
`getImageData` Yes Yes Yes

Yes

510

Yes Yes ?
`getLineDash` Yes Yes Yes27 Yes Yes ?
`isPointInPath` Yes Yes Yes Yes Yes Yes ?
`isPointInStroke` Yes Yes Yes Yes Yes Yes ?
`lineTo` Yes Yes Yes Yes Yes Yes ?
`measureText` Yes Yes Yes Yes Yes Yes ?
`moveTo` Yes Yes Yes Yes Yes Yes ?
`putImageData` Yes Yes Yes Yes Yes Yes ?
`quadraticCurveTo` Yes Yes Yes Yes Yes Yes ?
`rect` Yes Yes Yes Yes Yes Yes ?
`removeHitRegion` No No ?306 Yes Yes ?
`resetTransform` No No ?36 No No ?
`restore` Yes Yes Yes Yes Yes Yes ?
`rotate` Yes Yes Yes Yes Yes Yes ?
`save` Yes Yes Yes Yes Yes Yes ?
`scale` Yes Yes Yes Yes Yes Yes ?
`scrollPathIntoView` Yes Yes ? No No No ?
`setLineDash` Yes Yes Yes No Yes Yes ?
`setTransform` Yes Yes Yes Yes Yes Yes ?
`stroke` Yes Yes Yes Yes Yes Yes ?
`strokeRect` Yes Yes Yes Yes Yes Yes ?
`strokeText` Yes Yes Yes Yes Yes Yes ?
`transform` Yes Yes Yes Yes Yes Yes ?
`translate` Yes Yes Yes Yes Yes Yes ?

1. This feature is behind the `ExperimentalCanvasFeatures` preference. To change preferences in Chrome, visit chrome://flags.

2. See bug (928150). Firefox also supports the experimental and prefixed properties mozCurrentTransform and mozCurrentTransformInverse which set or get the current (inverse) transformation matrix.

3. See webkitbug(174278).

4. From version 35 until version 48 (exclusive): this feature is behind the `canvas.filters.enabled` preference (needs to be set to `true`). To change preferences in Firefox, visit about:config.

5. Supported as `mozDashOffset`.

6. From version 30: this feature is behind the `canvas.hitregions.enabled` preference. To change preferences in Firefox, visit about:config.

7. From version 38: this feature is behind the `canvas.hitregions.enabled` preference. To change preferences in Firefox, visit about:config.

8. From version 29: this feature is behind the `canvas.focusring.enabled` preference. To change preferences in Firefox, visit about:config.

9. Supported as `drawSystemFocusRing`.

10. `getImageData` now correctly accepts rectangles that extend beyond the bounds of the canvas; pixels outside the canvas are returned as transparent black and now also returns at least one pixel's worth of image data if a rectangle smaller than one pixel is specified.