To get aCanvasRenderingContext2D instance, you must first have an HTML<canvas> element to work with:

<canvas width="300" height="300"></canvas>

To get the canvas' 2D rendering context, callgetContext() on the<canvas> element, supplying'2d' as the argument:

const canvas = document.getElementById("my-house");const ctx = canvas.getContext("2d");

With the context in hand, you can draw anything you like. This code draws a house:

// Set line widthctx.lineWidth = 10;// Wallctx.strokeRect(75, 140, 150, 110);// Doorctx.fillRect(130, 190, 40, 60);// Roofctx.beginPath();ctx.moveTo(50, 140);ctx.lineTo(150, 60);ctx.lineTo(250, 140);ctx.closePath();ctx.stroke();

The resulting drawing looks like this:

CanvasRenderingContext2D.getContextAttributes()

Returns an object containing the context attributes used by the browser. Context attributes can be requested when usingHTMLCanvasElement.getContext() to create the 2D context.

CanvasRenderingContext2D.isContextLost()

Returnstrue if the rendering context was lost.

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

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 bywidth andheight.

CanvasRenderingContext2D.strokeRect()

Paints a rectangle which has a starting point at(x, y) and has aw width and anh height onto the canvas, using the current stroke style.

The following methods draw text. See also theTextMetrics 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 aTextMetrics object.

The following methods and properties control how lines are drawn.

CanvasRenderingContext2D.lineWidth

Width of lines. Default1.0.

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. Default10.

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.

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,center.

CanvasRenderingContext2D.textBaseline

Baseline alignment setting. Possible values:top,hanging,middle,alphabetic (default),ideographic,bottom.

CanvasRenderingContext2D.direction

Directionality. Possible values:ltr,rtl,inherit (default).

CanvasRenderingContext2D.letterSpacing

Letter spacing. Default:0px.

CanvasRenderingContext2D.fontKerning

Font kerning. Possible values:auto (default),normal,none.

CanvasRenderingContext2D.fontStretch

Font stretch. Possible values:ultra-condensed,extra-condensed,condensed,semi-condensed,normal (default),semi-expanded,expanded,extra-expanded,ultra-expanded.

CanvasRenderingContext2D.fontVariantCaps

Font variant caps. Possible values:normal (default),small-caps,all-small-caps,petite-caps,all-petite-caps,unicase,titling-caps.

CanvasRenderingContext2D.textRendering

Text rendering. Possible values:auto (default),optimizeSpeed,optimizeLegibility,geometricPrecision.

CanvasRenderingContext2D.wordSpacing

Word spacing. Default value:0px

CanvasRenderingContext2D.langExperimental

Gets or sets the language of the canvas drawing context.

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.createConicGradient()

Creates a conic gradient around a point given by coordinates represented by the parameters.

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. It repeats the source in the directions specified by the repetition argument. This method returns aCanvasPattern.

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.

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 current sub-path to the specified (x, y) coordinates with a straight line.

CanvasRenderingContext2D.bezierCurveTo()

Adds a cubic Bézier curve to the current path.

CanvasRenderingContext2D.quadraticCurveTo()

Adds a quadratic Bézier curve to the current path.

CanvasRenderingContext2D.arc()

Adds a circular arc to the current path.

CanvasRenderingContext2D.arcTo()

Adds an arc to the current path with the given control points and radius, connected to the previous point by a straight line.

CanvasRenderingContext2D.ellipse()

Adds an elliptical arc to the current path.

CanvasRenderingContext2D.rect()

Creates a path for a rectangle at position (x, y) with a size that is determined bywidth andheight.

CanvasRenderingContext2D.roundRect()

Creates a path for a rounded rectangle with a specified position, width, height, and corner radii.

CanvasRenderingContext2D.fill()

Fills the current sub-paths with the current fill style.

CanvasRenderingContext2D.stroke()

Strokes the current sub-paths with the current stroke style.

CanvasRenderingContext2D.drawFocusIfNeeded()

If a given element is focused, this method draws a focus ring around the current path.

CanvasRenderingContext2D.clip()

Creates a clipping path from the current sub-paths. Everything drawn afterclip() is called appears inside the clipping path only. For an example, seeClipping 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.

Objects in theCanvasRenderingContext2D 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 andPath2D objects. The methods listed below remain for historical and compatibility reasons asDOMMatrix objects are used in most parts of the API nowadays and will be used in the future instead.

CanvasRenderingContext2D.getTransform()

Retrieves the current transformation matrix being applied to the context.

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 horizontally 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 thetransform() method with the same arguments.

CanvasRenderingContext2D.resetTransform()

Resets the current transform by the identity matrix.

CanvasRenderingContext2D.globalAlpha

Alpha value that is applied to shapes and images before they are composited onto the canvas. Default1.0 (opaque).

CanvasRenderingContext2D.globalCompositeOperation

WithglobalAlpha applied this sets how shapes and images are drawn onto the existing bitmap.

CanvasRenderingContext2D.drawImage()

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

See also theImageData object.

CanvasRenderingContext2D.createImageData()

Creates a new, blankImageData object with the specified dimensions. All of the pixels in the new object are transparent black.

CanvasRenderingContext2D.getImageData()

Returns anImageData object representing the underlying pixel data for the area of the canvas denoted by the rectangle which starts at(sx, sy) and has answ width andsh height.

CanvasRenderingContext2D.putImageData()

Paints data from the givenImageData object onto the bitmap. If a dirty rectangle is provided, only the pixels from that rectangle are painted.

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.

TheCanvasRenderingContext2D 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 usingrestore().

CanvasRenderingContext2D.restore()

Restores the drawing style state to the last element on the 'state stack' saved bysave().

CanvasRenderingContext2D.canvas

A read-only back-reference to theHTMLCanvasElement. Might benull if it is not associated with a<canvas> element.

CanvasRenderingContext2D.getContextAttributes()

Returns an object containing the context attributes used by the browser. Context attributes can be requested when usingHTMLCanvasElement.getContext() to create the 2D context.

CanvasRenderingContext2D.reset()

Resets the rendering context, including the backing buffer, the drawing state stack, path, and styles.

CanvasRenderingContext2D.isContextLost()Experimental

Returnstrue if the rendering context was lost.

CanvasRenderingContext2D.filter

Applies a CSS or SVG filter to the canvas, e.g., to change its brightness or blurriness.

• HTMLCanvasElement
• <canvas>
• OffscreenCanvas