From 1109132f09d75da9a28b649c7677bb6ce07c40c0 Mon Sep 17 00:00:00 2001 From: Peter Bengtsson Date: Tue, 8 Dec 2020 14:41:45 -0500 Subject: initial commit --- .../createlineargradient/index.html | 114 ++++++ .../fa/web/api/canvasrenderingcontext2d/index.html | 424 +++++++++++++++++++++ 2 files changed, 538 insertions(+) create mode 100644 files/fa/web/api/canvasrenderingcontext2d/createlineargradient/index.html create mode 100644 files/fa/web/api/canvasrenderingcontext2d/index.html (limited to 'files/fa/web/api/canvasrenderingcontext2d') diff --git a/files/fa/web/api/canvasrenderingcontext2d/createlineargradient/index.html b/files/fa/web/api/canvasrenderingcontext2d/createlineargradient/index.html new file mode 100644 index 0000000000..d7a1e1bde6 --- /dev/null +++ b/files/fa/web/api/canvasrenderingcontext2d/createlineargradient/index.html @@ -0,0 +1,114 @@ +--- +title: CanvasRenderingContext2D.createLinearGradient() +slug: Web/API/CanvasRenderingContext2D/createLinearGradient +translation_of: Web/API/CanvasRenderingContext2D/createLinearGradient +--- +
{{APIRef}}
+ +

The CanvasRenderingContext2D.createLinearGradient() method of the Canvas 2D API creates a gradient along the line connecting two given coordinates.

+ +

+ +

This method returns a linear {{domxref("CanvasGradient")}}. To be applied to a shape, the gradient must first be assigned to the {{domxref("CanvasRenderingContext2D.fillStyle", "fillStyle")}} or {{domxref("CanvasRenderingContext2D.strokeStyle", "strokeStyle")}} properties.

+ +
+

Note: Gradient coordinates are global, i.e., relative to the current coordinate space. When applied to a shape, the coordinates are NOT relative to the shape's coordinates.

+
+ +

Syntax

+ +
CanvasGradient ctx.createLinearGradient(x0, y0, x1, y1);
+
+ +

The createLinearGradient() method is specified by four parameters defining the start and end points of the gradient line.

+ +

Parameters

+ +
+
x0
+
The x-axis coordinate of the start point.
+
y0
+
The y-axis coordinate of the start point.
+
x1
+
The x-axis coordinate of the end point.
+
y1
+
The y-axis coordinate of the end point.
+
+ +

Return value

+ +
+
{{domxref("CanvasGradient")}}
+
A linear CanvasGradient initialized with the specified line.
+
+ +

Examples

+ +

Filling a rectangle with a linear gradient

+ +

This example initializes a linear gradient using the createLinearGradient() method. Three color stops between the gradient's start and end points are then created. Finally, the gradient is assigned to the canvas context, and is rendered to a filled rectangle.

+ +

HTML

+ +
<canvas id="canvas"></canvas>
+
+ +

JavaScript

+ +
var canvas = document.getElementById('canvas');
+var ctx = canvas.getContext('2d');
+
+// Create a linear gradient
+// The start gradient point is at x=20, y=0
+// The end gradient point is at x=220, y=0
+var gradient = ctx.createLinearGradient(20,0, 220,0);
+
+// Add three color stops
+gradient.addColorStop(0, 'green');
+gradient.addColorStop(.5, 'cyan');
+gradient.addColorStop(1, 'green');
+
+// Set the fill style and draw a rectangle
+ctx.fillStyle = gradient;
+ctx.fillRect(20, 20, 200, 100);
+
+ +

Result

+ +

{{ EmbedLiveSample('Filling_a_rectangle_with_a_linear_gradient', 700, 180) }}

+ +

Specifications

+ + + + + + + + + + + + + + +
SpecificationStatusComment
{{SpecName('HTML WHATWG', "scripting.html#dom-context-2d-createlineargradient", "CanvasRenderingContext2D.createLinearGradient")}}{{Spec2('HTML WHATWG')}}
+ +

Browser compatibility

+ + + +

{{Compat("api.CanvasRenderingContext2D.createLinearGradient")}}

+ +

Gecko-specific notes

+ + + +

See also

+ + diff --git a/files/fa/web/api/canvasrenderingcontext2d/index.html b/files/fa/web/api/canvasrenderingcontext2d/index.html new file mode 100644 index 0000000000..3b9cc7021e --- /dev/null +++ b/files/fa/web/api/canvasrenderingcontext2d/index.html @@ -0,0 +1,424 @@ +--- +title: CanvasRenderingContext2D +slug: Web/API/CanvasRenderingContext2D +tags: + - API + - Canvas + - CanvasRenderingContext2D + - Games + - Graphics + - NeedsTranslation + - Reference + - TopicStub +translation_of: Web/API/CanvasRenderingContext2D +--- +
{{APIRef}}
+ +

The CanvasRenderingContext2D interface, part of the Canvas API, provides the 2D rendering context for the drawing surface of a {{HTMLElement("canvas")}} element. It is used for drawing shapes, text, images, and other objects.

+ +

See the interface's properties and methods in the sidebar and below. The Canvas tutorial has more explanation, examples, and resources, as well.

+ +

Basic example

+ +

To get a CanvasRenderingContext2D instance, you must first have an HTML <canvas> element to work with:

+ +
<canvas id="my-house" width="300" height="300"></canvas>
+ +

To get the canvas' 2D rendering context, call {{domxref("HTMLCanvasElement.getContext()", "getContext()")}} 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 width
+ctx.lineWidth = 10;
+
+// Wall
+ctx.strokeRect(75, 140, 150, 110);
+
+// Door
+ctx.fillRect(130, 190, 40, 60);
+
+// Roof
+ctx.beginPath();
+ctx.moveTo(50, 140);
+ctx.lineTo(150, 60);
+ctx.lineTo(250, 140);
+ctx.closePath();
+ctx.stroke();
+
+ +

The resulting drawing looks like this:

+ +

{{EmbedLiveSample("Basic_example", 700, 330)}}

+ +

Reference

+ +

Drawing rectangles

+ +

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

+ +
+
{{domxref("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.
+
{{domxref("CanvasRenderingContext2D.fillRect()")}}
+
Draws a filled rectangle at (x, y) position whose size is determined by width and height.
+
{{domxref("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 draw text. See also the {{domxref("TextMetrics")}} object for text properties.

+ +
+
{{domxref("CanvasRenderingContext2D.fillText()")}}
+
Draws (fills) a given text at the given (x, y) position.
+
{{domxref("CanvasRenderingContext2D.strokeText()")}}
+
Draws (strokes) a given text at the given (x, y) position.
+
{{domxref("CanvasRenderingContext2D.measureText()")}}
+
Returns a {{domxref("TextMetrics")}} object.
+
+ +

Line styles

+ +

The following methods and properties control how lines are drawn.

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

Text styles

+ +

The following properties control how text is laid out.

+ +
+
{{domxref("CanvasRenderingContext2D.font")}}
+
Font setting. Default value 10px sans-serif.
+
{{domxref("CanvasRenderingContext2D.textAlign")}}
+
Text alignment setting. Possible values: start (default), end, left, right, center.
+
{{domxref("CanvasRenderingContext2D.textBaseline")}}
+
Baseline alignment setting. Possible values: top, hanging, middle, alphabetic (default), ideographic, bottom.
+
{{domxref("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.

+ +
+
{{domxref("CanvasRenderingContext2D.fillStyle")}}
+
Color or style to use inside shapes. Default #000 (black).
+
{{domxref("CanvasRenderingContext2D.strokeStyle")}}
+
Color or style to use for the lines around shapes. Default #000 (black).
+
+ +

Gradients and patterns

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

Shadows

+ +
+
{{domxref("CanvasRenderingContext2D.shadowBlur")}}
+
Specifies the blurring effect. Default: 0
+
{{domxref("CanvasRenderingContext2D.shadowColor")}}
+
Color of the shadow. Default: fully-transparent black.
+
{{domxref("CanvasRenderingContext2D.shadowOffsetX")}}
+
Horizontal distance the shadow will be offset. Default: 0.
+
{{domxref("CanvasRenderingContext2D.shadowOffsetY")}}
+
Vertical distance the shadow will be offset. Default: 0.
+
+ +

Paths

+ +

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

+ +
+
{{domxref("CanvasRenderingContext2D.beginPath()")}}
+
Starts a new path by emptying the list of sub-paths. Call this method when you want to create a new path.
+
{{domxref("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.
+
{{domxref("CanvasRenderingContext2D.moveTo()")}}
+
Moves the starting point of a new sub-path to the (x, y) coordinates.
+
{{domxref("CanvasRenderingContext2D.lineTo()")}}
+
Connects the last point in the current sub-path to the specified (x, y) coordinates with a straight line.
+
{{domxref("CanvasRenderingContext2D.bezierCurveTo()")}}
+
Adds a cubic Bézier curve to the current path.
+
{{domxref("CanvasRenderingContext2D.quadraticCurveTo()")}}
+
Adds a quadratic Bézier curve to the current path.
+
{{domxref("CanvasRenderingContext2D.arc()")}}
+
Adds a circular arc to the current path.
+
{{domxref("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.
+
{{domxref("CanvasRenderingContext2D.ellipse()")}}
+
Adds an elliptical arc to the current path.
+
{{domxref("CanvasRenderingContext2D.rect()")}}
+
Creates a path for a rectangle at position (x, y) with a size that is determined by width and height.
+
+ +

Drawing paths

+ +
+
{{domxref("CanvasRenderingContext2D.fill()")}}
+
Fills the current sub-paths with the current fill style.
+
{{domxref("CanvasRenderingContext2D.stroke()")}}
+
Strokes the current sub-paths with the current stroke style.
+
{{domxref("CanvasRenderingContext2D.drawFocusIfNeeded()")}}
+
If a given element is focused, this method draws a focus ring around the current path.
+
{{domxref("CanvasRenderingContext2D.scrollPathIntoView()")}}
+
Scrolls the current path or a given path into the view.
+
{{domxref("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.
+
{{domxref("CanvasRenderingContext2D.isPointInPath()")}}
+
Reports whether or not the specified point is contained in the current path.
+
{{domxref("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 {{domxref("Path2D")}} objects. The methods listed below remain for historical and compatibility reasons as {{domxref("SVGMatrix")}} objects are used in most parts of the API nowadays and will be used in the future instead.

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

Compositing

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

Drawing images

+ +
+
{{domxref("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 {{domxref("ImageData")}} object.

+ +
+
{{domxref("CanvasRenderingContext2D.createImageData()")}}
+
Creates a new, blank {{domxref("ImageData")}} object with the specified dimensions. All of the pixels in the new object are transparent black.
+
{{domxref("CanvasRenderingContext2D.getImageData()")}}
+
Returns an {{domxref("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.
+
{{domxref("CanvasRenderingContext2D.putImageData()")}}
+
Paints data from the given {{domxref("ImageData")}} object onto the bitmap. If a dirty rectangle is provided, only the pixels from that rectangle are painted.
+
+ +

Image smoothing

+ +
+
{{domxref("CanvasRenderingContext2D.imageSmoothingEnabled")}} {{experimental_inline}}
+
Image smoothing mode; if disabled, images will not be smoothed if scaled.
+
+ +
+
{{domxref("CanvasRenderingContext2D.imageSmoothingQuality")}} {{experimental_inline}}
+
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:

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

Hit regions

+ +
+
{{domxref("CanvasRenderingContext2D.addHitRegion()")}} {{experimental_inline}}
+
Adds a hit region to the canvas.
+
{{domxref("CanvasRenderingContext2D.removeHitRegion()")}} {{experimental_inline}}
+
Removes the hit region with the specified id from the canvas.
+
{{domxref("CanvasRenderingContext2D.clearHitRegions()")}} {{experimental_inline}}
+
Removes all hit regions from the canvas.
+
+ +

Filters

+ +
+
{{experimental_inline}} {{domxref("CanvasRenderingContext2D.filter")}}
+
Applies a CSS or SVG filter to the canvas, e.g., to change its brightness or bluriness.
+
+ +

Non-standard APIs

+ + + +

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

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

WebKit only

+ +
+
{{non-standard_inline}} {{obsolete_inline}} CanvasRenderingContext2D.webkitBackingStorePixelRatio
+
The backing store size in relation to the canvas element. See High DPI Canvas.
+
{{non-standard_inline}} {{obsolete_inline}} CanvasRenderingContext2D.webkitGetImageDataHD
+
Intended for HD backing stores, but removed from canvas specifications.
+
{{non-standard_inline}} {{obsolete_inline}} CanvasRenderingContext2D.webkitPutImageDataHD
+
Intended for HD backing stores, but removed from canvas specifications.
+
+ +
+
+ +

Gecko only

+ +

Prefixed APIs

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

Internal APIs (chrome-context only)

+ +
+
{{non-standard_inline}} {{domxref("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.
+
{{non-standard_inline}} 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

+ +
+
{{non-standard_inline}} CanvasRenderingContext2D.msFillRule
+
The fill rule to use. This must be one of evenodd or nonzero (default).
+
+ +

Specifications

+ + + + + + + + + + + + + + +
SpecificationStatusComment
{{SpecName('HTML WHATWG', "#2dcontext", "CanvasRenderingContext2D")}}{{Spec2('HTML WHATWG')}}
+ +

Browser compatibility

+ +
+ + +

{{Compat("api.CanvasRenderingContext2D")}}

+
+ +

See also

+ + -- cgit v1.2.3-54-g00ecf