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    CanvasRenderingContext2D

    Le contexte de rendu 2D pour la surface de dessin d'un élément <canvas>. Pour obtenir cet objet, appelez getContext () sur un <canvas>, en fournissant "2d" comme argument:

    var canvas = document.getElementById('tutorial');
    var ctx = canvas.getContext('2d');
    

    Une fois que vous avez votre contexte de rendu 2D pour un canvas, vous pouvez dessiner dedans. Par exemple:

    ctx.fillStyle = "rgb(200,0,0)";  
    ctx.fillRect(10, 10, 55, 50);  
    

    Voir le tutoriel à propos des Canvas pour plus d'informations, d'exemples et de ressources.

    Method overview

    void arc(in float x, in float y, in float radius, in float startAngle, in float endAngle, in boolean anticlockwise Facultatif);
    void arcTo(in float x1, in float y1, in float x2, in float y2, in float radius);
    void beginPath();
    void bezierCurveTo(in float cp1x, in float cp1y, in float cp2x, in float cp2y, in float x, in float y);
    void clearRect(in float x, in float y, in float width, in float height);
    void clip();
    void closePath();
    ImageData createImageData(in float width, in float height);
    ImageData createImageData(Imagedata imagedata);
    nsIDOMCanvasGradient createLinearGradient(in float x0, in float y0, in float x1, in float y1);
    nsIDOMCanvasPattern createPattern(in nsIDOMHTMLElement image, in DOMString repetition);
    nsIDOMCanvasGradient createRadialGradient(in float x0, in float y0, in float r0, in float x1, in float y1, in float r1);
    void drawImage(in nsIDOMElement image, in float a1, in float a2, in float a3 Facultatif, in float a4 Facultatif, in float a5 Facultatif, in float a6 Facultatif, in float a7 Facultatif, in float a8 Facultatif);
    boolean drawCustomFocusRing(Element element);
    void drawSystemFocusRing(Element element);
    void fill();
    void fillRect(in float x, in float y, in float width, in float height);
    void fillText(in DOMString text, in float x, in float y, in float maxWidth Facultatif);
    ImageData getImageData(in float x, in float y, in float width, in float height);
    sequence <unrestricted double> getLineDash()
    boolean isPointInPath(in float x, in float y);
    boolean isPointInStroke(in float x, in float y);
    void lineTo(in float x, in float y);
    nsIDOMTextMetrics measureText(in DOMString text);
    void moveTo(in float x, in float y);
    void putImageData(in ImageData imagedata, in float dx, double dy, in float dirtyX Facultatif, in float dirtyY Facultatif, in float dirtyWidth Facultatif, in float dirtyHeight Facultatif);
    void quadraticCurveTo(in float cpx, in float cpy, in float x, in float y);
    void rect(in float x, in float y, in float width, in float height);
    void restore();
    void rotate(in float angle);
    void save();
    void scale(in float x, in float y);
    void scrollPathIntoView();
    void setLineDash(in sequence <unrestricted double> segments);
    void setTransform(in float m11, in float m12, in float m21, in float m22, in float dx, in float dy);
    void stroke();
    void strokeRect(in float x, in float y, in float w, in float h);
    void strokeText(in DOMString text, in float x, in float y, in float maxWidth Facultatif);
    void transform(in float m11, in float m12, in float m21, in float m22, in float dx, in float dy);
    void translate(in float x, in float y);

    Gecko-specific Method overview

    void asyncDrawXULElement(in nsIDOMXULElement elem, in float x, in float y, in float w, in float h, in DOMString bgColor, in unsigned long flags Facultatif);
    void drawWindow(in nsIDOMWindow window, in float x, in float y, in float w, in float h, in DOMString bgColor, in unsigned long flags Facultatif);
    void getFillStyle_multi(out DOMString str, out nsISupports iface, out long type); Native code only!
    void getImageData_explicit(in long x, in long y, in unsigned long width, in unsigned long height, [array, size_is(dataLen)] in octet dataPtr, in unsigned long dataLen); Native code only!
    void getStrokeStyle_multi(out DOMString str, out nsISupports iface, out long type); Native code only!
    void mozDrawText(in DOMString textToDraw); (unimplemented since Gecko 7.0)
    float mozMeasureText(in DOMString textToMeasure); (unimplemented since Gecko 7.0)
    void mozPathText(in DOMString textToPath); (unimplemented since Gecko 7.0)
    void mozTextAlongPath(in DOMString textToDraw, in boolean stroke); (unimplemented since Gecko 7.0)
    void putImageData_explicit(in long x, in long y, in unsigned long width, in unsigned long height, [array, size_is(dataLen)] in octet dataPtr, in unsigned long dataLen, in boolean hasDirtyRect, in long dirtyX, in long dirtyY, in long dirtyWidth, in long dirtyHeight); Native code only!
    void setFillStyle_multi(in DOMString str, in nsISupports iface); Native code only!
    void setStrokeStyle_multi(in DOMString str, in nsISupports iface); Native code only!

    WebKit-specific Method overview

    void clearShadow();
    void drawImageFromRect(in HTMLImageElement image, in float sx Facultatif, in float sy Facultatif, in float sw Facultatif, in float sh Facultatif, in float dx Facultatif, in float dy Facultatif, in float dw Facultatif, in float dh Facultatif, in DOMString compositeOperation Facultatif);
    void setAlpha();
    void setCompositeOperation(in DOMString compositeOperation);
    void setLineWidth(in float width);
    void setLineCap(in DOMString cap);
    void setLineJoin(in DOMString join);
    void setMiterLimit(in float limit);
    void setStrokeColor(in DOMString color, in float alpha Facultatif);
    void setStrokeColor(in float grayLevel, in float alpha Facultatif);
    void setStrokeColor(in float r, in float g, in float b, in float a);
    void setStrokeColor(in float c, in float m, in float y, in float k, in float a);
    void setFillColor(in DOMString color, in float alpha Facultatif);
    void setFillColor(in float grayLevel, in float alpha Facultatif);
    void setFillColor(in float r, in float g, in float b, in float a);
    void setFillColor(in float c, in float m, in float y, in float k, in float a);
    void setShadow(in float width, in float height, in float blur, in DOMString color Facultatif, in float alpha Facultatif);
    void setShadow(in float width, in float height, in float blur, in float grayLevel, in float alpha Facultatif);
    void setShadow(in float width, in float height, in float blur, in float r, in float g, in float b, in float a);
    void setShadow(in float width, in float height, in float blur, in float c, in float m, in float y, in float k, in float a);

    Attributes

    Attribute Type Description
    canvas HTMLCanvasElement Back-reference to the canvas element for which this context was created. Read only.
    fillStyle nsIVariant Color or style to use inside shapes. Default #000 (black).
    font DOMString Default value 10px sans-serif.
    globalAlpha float Alpha value that is applied to shapes and images before they are composited onto the canvas. Default 1.0 (opaque).
    globalCompositeOperation DOMString With globalAlpha applied this sets how shapes and images are drawn onto the existing bitmap. Possible values:
    • source-atop
    • source-in
    • source-out
    • source-over (default)
    • destination-atop
    • destination-in
    • destination-out
    • destination-over
    • lighter
    • darker
    • copy
    • xor
    lineCap DOMString Type of endings on the end of lines. Possible values: butt (default), round, square
    lineDashOffset float Specifies where to start a dasharray on a line.
    lineJoin DOMString Defines the type of corners where two lines meet. Possible values: round, bevel, miter (default)
    lineWidth float Width of lines. Default 1.0
    miterLimit float Default 10.
    shadowBlur float Specifies the blurring effect. Default 0
    shadowColor DOMString Color of the shadow. Default fully-transparent black.
    shadowOffsetX float Horizontal distance the shadow will be offset. Default 0.
    shadowOffsetY float Vertical distance the shadow will be offset. Default 0.
    strokeStyle nsIVariant Color or style to use for the lines around shapes. Default #000 (black).
    textAlign DOMString Possible values: start (default), end, left, right or center.
    textBaseline DOMString Possible values: top, hanging, middle, alphabetic (default), ideographic, bottom

    Gecko-specific attributes

    Attribute Type Description
    mozCurrentTransform jsval Sets or gets the current transformation matrix.
    mozCurrentTransformInverse jsval Sets or gets the current inversed transformation matrix.
    mozDash array of float An array which specifies the lengths of alternating dashes and gaps. (see bug 740284 for implementing the HTML5 spec version / unprefixing)
    mozDashOffset float Specifies where to start a dasharray on a line. (see bug 740284 for implementing the HTML5 spec version / unprefixing)
    mozFillRule DOMString The fill rule to use. This must be one of evenodd or nonzero (default).
    mozImageSmoothingEnabled boolean Image smoothing mode; if disabled, images will not be smoothed if scaled.
    mozTextStyle DOMString Deprecated in favor of the HTML5 font attribute described above.

    WebKit-specific attributes

    Attribute Type Description
    webkitLineDash array of float An array which specifies the lengths of alternating dashes and gaps. (expected to be unprefixed / updated to HTML5 spec as per WebKit bug 80674)
    webkitLineDashOffset float Specifies where to start a dasharray on a line. (expected to be unprefixed / updated to HTML5 spec as per WebKit bug 80674)

    Constants

    Gecko-specific constants/flags

    Constant Value Description
    DRAWWINDOW_DRAW_CARET 0x01 Show the caret if appropriate when drawing.
    DRAWWINDOW_DO_NOT_FLUSH 0x02 Do not flush pending layout notifications that could otherwise be batched up.
    DRAWWINDOW_DRAW_VIEW 0x04 Draw scrollbars and scroll the viewport if they are present.
    DRAWWINDOW_USE_WIDGET_LAYERS 0x08 Use the widget layer manager if available. This means hardware acceleration may be used, but it might actually be slower or lower quality than normal. It will, however, more accurately reflect the pixels rendered to the screen.
    DRAWWINDOW_ASYNC_DECODE_IMAGES 0x10 Do not synchronously decode images - draw what we have.

    Methods

    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).

    void arc(
      in float x,
      in float y,
      in float radius,
      in float startAngle,
      in float endAngle,
      in boolean anticlockwise [optional]
    );
    
    Parameters
    x
    The x axis of the coordinate for the arc's center
    y
    The y axis of the coordinate for the arc's center.
    radius
    The arc's radius
    startAngle
    The starting point, measured from the x axis, from which it will be drawn, expressed in radians.
    endAngle
    The end arc's angle to which it will be drawn, expressed in radians.
    anticlockwise Facultatif depuis Gecko 2.0
    true draws the arc anticlockwise (AKA counter-clockwise), otherwise in a clockwise direction.

    arcTo()

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

    void arcTo(
      in float x1,
      in float y1,
      in float x2,
      in float y2,
      in float radius
    );
    
    Parameters
    x1
    The x axis of the coordinate for the first control point.
    y1
    The y axis of the coordinate for the first control point.
    x2
    The x axis of the coordinate for the second control point.
    y2
    The y axis of the coordinate for the second control point.
    radius
    The arc's radius.

    beginPath()

    Starts a new path by resetting the list of sub-paths. Call this method when you want to create a new path.

    void beginPath();
    
    Parameters

    None.

    bezierCurveTo()

    void bezierCurveTo(
      in float cp1x,
      in float cp1y,
      in float cp2x,
      in float cp2y,
      in float x,
      in float y
    );
    
    Parameters
    cp1x
     
    cp1y
     
    cp2x
     
    cp2y
     
    x
     
    y
     

    clearRect()

    Sets all pixels in the rectangle defined by starting point (x, y) and size (width, height) to transparent black.

    void clearRect(
      in float x,
      in float y,
      in float width,
      in float height
    );
    
    Parameters
    x
    The x axis of the coordinate for the rectangle starting point.
    y
    The y axis of the coordinate for the rectangle starting point.
    width
    The rectangle's width.
    height
    The rectangle's height.

    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.

    void clip();
    
    Parameters

    None.

    closePath()

    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.

    void closePath();
    
    Parameters

    None.

    createImageData()

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

    ImageData createImageData(
      in float width,
      in float height
    );
    ImageData createImageData(
      ImageData imagedata
    );
    
    Parameters
    width
    The width to give the new ImageData object.
    height
    The height to give the new ImageData object.
    imagedata
    An existing ImageData object from which to copy the width and height. The image itself is not copied.
    Return value

    A new ImageData object with the specified width and height. The new object is filled with transparent black pixels.

    createLinearGradient()

    Creates a gradient along the line given by the coordinates represented by the parameters.

    nsIDOMCanvasGradient createLinearGradient(
      in float x0,
      in float y0,
      in float x1,
      in float y1
    );
    
    Parameters
    x0
    The x axis of the coordinate of the start point.
    y0
    The y axis of the coordinate of the start point.
    x1
    The x axis of the coordinate of the end point.
    y1
    The y axis of the coordinate of the end point.
    Return value

    nsIDOMCanvasGradient

    createPattern()

    nsIDOMCanvasPattern createPattern(
      in nsIDOMHTMLElement image,
      in DOMString repetition
    );
    
    Parameters
    image
    A DOM element to use as the source image for the pattern. This can be any element, although typically you'll use an Image or <canvas>.
    repetition
    A string representing the direction of repetition.
    Possible values:
    • repeat
    • repeat-x
    • repeat-y
    • no-repeat

     

    Return value

    A new DOM canvas pattern object for use in pattern-based operations.

    Exceptions thrown
    NS_ERROR_DOM_INVALID_STATE_ERR
    The specified <canvas> element for the image parameter is zero-sized (that is, one or both of its dimensions are 0 pixels).

    createRadialGradient()

    nsIDOMCanvasGradient createRadialGradient(
      in float x0,
      in float y0,
      in float r0,
      in float x1,
      in float y1,
      in float r1
    );
    
    Parameters
    x0
     
    y0
     
    r0
     
    x1
     
    y1
     
    r1
     
    Return value

    nsIDOMCanvasGradient

    drawCustomFocusRing()

    boolean drawCustomFocusRing(Element element);
    
    Parameters
    element
     
    Return value

    boolean

    drawImage()

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

    void drawImage(
      in nsIDOMElement image,
      in float dx,
      in float dy
    );
    
    void drawImage(
      in nsIDOMElement image,
      in float dx,
      in float dy,
      in float dw,
      in float dh
    );
    
    void drawImage(
      in nsIDOMElement image,
      in float sx,
      in float sy,
      in float sw,
      in float sh,
      in float dx, 
      in float dy,
      in float dw,
      in float dh
    );
    
    Parameters
    image
    An element to draw into the context; the specification permits any image element (that is, <img>, <canvas>, and <video>). Some browsers let you use any arbitrary element; Firefox doesn’t.
    dx
    The X coordinate in the destination canvas at which to place the top-left corner of the source image.
    dy
    The Y coordinate in the destination canvas at which to place the top-left corner of the source image.
    dw
    The width to draw the image in the destination canvas. This allows scaling of the drawn image. If not specified, the image is not scaled in width when drawn.
    dh
    The height to draw the image in the destination canvas. This allows scaling of the drawn image. If not specified, the image is not scaled in height when drawn.
    sx
    The X coordinate of the top left corner of the sub-rectangle of the source image to draw into the destination context.
    sy
    The Y coordinate of the top left corner of the sub-rectangle of the source image to draw into the destination context.
    sw
    The width of the sub-rectangle of the source image to draw into the destination context. If not specified, the entire rectangle from the coordinates specified by sx and sy to the bottom-right corner of the image is used. If you specify a negative value, the image is flipped horizontally when drawn.
    sh
    The height of the sub-rectangle of the source image to draw into the destination context. If you specify a negative value, the image is flipped vertically when drawn.

    The diagram below illustrates the meanings of the various parameters.

    Exceptions thrown
    INDEX_SIZE_ERR
    If the canvas or source rectangle width or height is zero.
    INVALID_STATE_ERR
    The image has no image data.
    TYPE_MISMATCH_ERR
    The specified source element isn't supported. This is not thrown by Firefox, since any element may be used as a source image.
    Compatibility notes
    • Prior to Gecko 7.0 (Firefox 7.0 / Thunderbird 7.0 / SeaMonkey 2.4), Firefox threw an exception if any of the coordinate values was non-finite or zero. As per the specification, this no longer happens.
    • Support for flipping the image by using negative values for sw and sh was added in Gecko 5.0 (Firefox 5.0 / Thunderbird 5.0 / SeaMonkey 2.2).
    • Gecko 9.0 (Firefox 9.0 / Thunderbird 9.0 / SeaMonkey 2.6) now correctly supports CORS for drawing images across domains without tainting the canvas.
    • Gecko 11.0 (Firefox 11.0 / Thunderbird 11.0 / SeaMonkey 2.8) now allows SVG-as-an-image to be drawn into a canvas without tainting the canvas.

    drawSystemFocusRing()

    void drawSystemFocusRing(Element element);
    
    Parameters
    element
     

    fill()

    Fills the subpaths with the current fill style.

    void fill();
    
    Parameters

    None.

    fillRect()

    Draws a filled rectangle at (x, y) position whose size is determined by width and height.

    void fillRect(
      in float x,
      in float y,
      in float width,
      in float height
    );
    
    Parameters
    x
    The x axis of the coordinate for the rectangle starting point.
    y
    The y axis of the coordinate for the rectangle starting point.
    width
    The rectangle's width.
    height
    The rectangle's height.

    fillText()

    void fillText(
      in DOMString text,
      in float x,
      in float y,
      in float maxWidth [optional]
    );
    
    Parameters
    text
     
    x
     
    y
     
    maxWidth Facultatif
     

    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.

    ImageData getImageData(   
      in double sx, 
      in double sy, 
      in double sw, 
      in double sh
    );
    
    Parameters
    sx
    The x axis of the coordinate for the rectangle startpoint from which the ImageData will be extracted.
    sy
    The x axis of the coordinate for the rectangle endpoint from which the ImageData will be extracted.
    sw
    The width of the rectangle from which the ImageData will be extracted.
    sh
    The height of the rectangle from which the ImageData will be extracted.
    Return value

    Returns an ImageData object containing the image data for the given rectangle of the canvas.

    getLineDash()

    Returns a dash list array containing an even number of non-negative numbers.

    sequence getLineDash(   
    );
    
    Parameters

    None.

    Return value

    Returns a dash list array containing an even number of non-negative numbers.

    isPointInPath()

    Reports whether or not the specified point is contained in the current path.

    boolean isPointInPath(
      in float x,
      in float y
    );
    
    Parameters
    x
    The X coordinate of the point to check.
    y
    The Y coordinate of the point to check.
    Return value

    true if the specified point is contained in the current path, otherwise false.

    Compatibility notes
    • Prior to Gecko 7.0 (Firefox 7.0 / Thunderbird 7.0 / SeaMonkey 2.4), this method incorrectly failed to multiply the specified point's coordinates by the current transformation matrix before comparing it to the path. Now this method works correctly even if the context is rotated, scaled, or otherwise transformed.

    isPointInStroke()

    Reports whether or not the specified point is inside the area contained by the stroking of a path.

    boolean isPointInStroke(
      in float x,
      in float y
    );
    
    Parameters
    x
    The X coordinate of the point to check.
    y
    The Y coordinate of the point to check.
    Return value

    true if the point is inside the area contained by the stroking of a path, otherwise false.

    lineTo()

    Connects the last point in the subpath to the x, y coordinates with a straight line.

    void lineTo(
      in float x,
      in float y
    );
    
    Parameters
    x
    The x axis of the coordinate for the end of the line.
    y
    The y axis of the coordinate for the end of the line.

    measureText()

    nsIDOMTextMetrics measureText(
      in DOMString text
    );
    
    Parameters
    text
     
    Return value

    nsIDOMTextMetrics (see whatwg spec)

    moveTo()

    Moves the starting point of a new subpath to the (x, y) coordinates.

    void moveTo(
      in float x,
      in float y
    );
    
    Parameters
    x
    The x axis of the point.
    y
    The y axis of the point.

    putImageData()

    void putImageData(
      in ImageData imagedata,
      in long dx,
      in long dy,
      in long dirtyX, [optional]
      in long dirtyY, [optional]
      in long dirtyWidth, [optional]
      in long dirtyHeight [optional]
    );
    
    Parameters

    imageData

         An imageData object containing the array of pixel values.

    dx
    Position offset in the target canvas context of the rectangle to be painted, relative to the rectangle in the origin image data.
    dy
    Position offset in the target canvas context of the rectangle to be painted, relative to the rectangle in the origin image data.
    dirtyX Facultatif
    Position of the top left point of the rectangle to be painted, in the origin image data. Defaults to the top left of the whole image data.
    dirtyY Facultatif
    Position of the top left point of the rectangle to be painted, in the origin image data. Defaults to the top left of the whole image data.
    dirtyWidth Facultatif
    Width of the rectangle to be painted, in the origin image data. Defaults to the width of the image data.
    dirtyHeight Facultatif
    Height of the rectangle to be painted, in the origin image data. Defaults to the height of the image data.

    To understand what this algorithm performs, here is an implementation on top of fillRect().

    function putImageData(ctx, imageData, dx, dy,
        dirtyX, dirtyY, dirtyWidth, dirtyHeight) {
      var data = imageData.data;
      var height = imageData.height;
      var width = imageData.width;
      dirtyX = dirtyX || 0;
      dirtyY = dirtyY || 0;
      dirtyWidth = dirtyWidth !== undefined? dirtyWidth: width;
      dirtyHeight = dirtyHeight !== undefined? dirtyHeight: height;
      var limitBottom = dirtyY + dirtyHeight;
      var limitRight = dirtyX + dirtyWidth;
      for (var y = dirtyY; y < limitBottom; y++) {
        for (var x = dirtyX; x < limitRight; x++) {
          var pos = y * width + x;
          ctx.fillStyle = 'rgba(' + data[pos*4+0]
                            + ',' + data[pos*4+1]
                            + ',' + data[pos*4+2]
                            + ',' + (data[pos*4+3]/255) + ')';
          ctx.fillRect(x + dx, y + dy, 1, 1);
        }
      }
    }
    Compatibility notes
    • Starting in Gecko 10.0 (Firefox 10.0 / Thunderbird 10.0 / SeaMonkey 2.7), non-finite values to any of these parameters cause the call to putImageData() to be silently ignored, rather than throwing an exception.

    quadraticCurveTo()

    void quadraticCurveTo(
      in float cpx,
      in float cpy,
      in float x,
      in float y
    );
    
    Parameters
    cpx
     
    cpy
     
    x
     
    y
     

    rect()

    void rect(
      in float x,
      in float y,
      in float w,
      in float h
    );
    
    Parameters
    x
     
    y
     
    w
     
    h
     

    restore()

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

    void restore();
    
    Parameters

    None.

    rotate()

    void rotate(
      in float angle
    );
    
    Parameters
    angle
     

    save()

    Saves the current drawing style state using a stack so you can revert any change you make to it using restore().

    void save();
    
    Parameters

    None.

    scale()

    void scale(
      in float x,
      in float y
    );
    
    Parameters
    x
     
    y
     

    scrollPathIntoView()

    void scrollPathIntoView();
    
    Parameters

    None.

    setLineDash()

    void setLineDash(
      sequence segments
    );
    
    Parameters
    segments
    An even number of non-negative numbers specifying a dash list.

    setTransform()

    void setTransform(
      in float m11,
      in float m12,
      in float m21,
      in float m22,
      in float dx,
      in float dy
    );
    
    Parameters
    m11
     
    m12
     
    m21
     
    m22
     
    dx
     
    dy
     

    stroke()

    Strokes the subpaths with the current stroke style.

    void stroke();
    
    Parameters

    None.

    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.

    void strokeRect(
      in float x,
      in float y,
      in float w,
      in float h
    );
    
    Parameters
    x
    The x axis for the starting point of the rectangle.
    y
    The y axis for the starting point of the rectangle.
    w
    The rectangle's width.
    h
    The rectangle's height.

    strokeText()

    void strokeText(
      in DOMString text,
      in float x,
      in float y,
      in float maxWidth [optional]
    );
    
    Parameters
    text
     
    x
     
    y
     
    maxWidth Facultatif
     

    transform()

    void transform(
      in float m11,
      in float m12,
      in float m21,
      in float m22,
      in float dx,
      in float dy
    );
    
    Parameters
    m11
     
    m12
     
    m21
     
    m22
     
    dx
     
    dy
     

    translate()

    Moves the origin point of the context to (x, y).

    void translate(
      in float x,
      in float y
    );
    
    Parameters
    x
    The x axis for the point to be considered as the origin.
    y
    The y axis for the point to be considered as the origin.

    Gecko-specific methods

    Requires Gecko 2.0 (Firefox 4 / Thunderbird 3.3 / SeaMonkey 2.1)

    asyncDrawXULElement()

    void asyncDrawXULElement(
      in nsIDOMXULElement elem,
      in float x,
      in float y,
      in float w,
      in float h,
      in DOMString bgColor,
      in unsigned long flags [optional]
    );
    
    Parameters
    elem
     
    x
     
    y
     
    w
     
    h
     
    bgColor
     
    flags Facultatif
     

    drawWindow()

    This API cannot currently be used by Web content. It is chrome only.

    Renders a region of a window into the canvas. The contents of the window's viewport are rendered, ignoring viewport clipping and scrolling.

    Of course, the rendering obeys the current scale(), transform(), and globalAlpha values.

    Hints: If 'rgba(0,0,0,0)' is used for the background color, the drawing will be transparent wherever the window is transparent. Top-level browsed documents are usually not transparent because the user's background-color preference is applied, but IFRAMEs are transparent if the page doesn't set a background. If an opaque color is used for the background color, rendering will be faster because we won't have to compute the window's transparency.

    void drawWindow(
      in nsIDOMWindow window,
      in float x,
      in float y,
      in float w,
      in float h,
      in DOMString bgColor,
      in unsigned long flags [optional]
    );
    
    Parameters
    window
     
    x
     
    y
     
    w
     
    h
    Specify the area of the window to render, in CSS pixels.
    bgColor
    The canvas is filled with this color before we render the window into it. This color may be transparent/translucent. It is given as a CSS color string (for example, rgb() or rgba()).
    flags Facultatif
    Used to better control the drawWindow call. Flags can be ORed together. See the section on Gecko-specific constants above.

    Native code only!

    getFillStyle_multi

    Introduced in Gecko 2.0 (Firefox 4 / Thunderbird 3.3 / SeaMonkey 2.1).

    void getFillStyle_multi(
      out DOMString str,
      out nsISupports iface,
      out long type
    );
    
    Parameters
    str
     
    iface
     
    type
     

    Native code only!

    getImageData_explicit

    Introduced in Gecko 2.0 (Firefox 4 / Thunderbird 3.3 / SeaMonkey 2.1).

    void getImageData_explicit(
      in long x,
      in long y,
      in unsigned long width,
      in unsigned long height,
      [array, size_is(dataLen)] in octet dataPtr,
      in unsigned long dataLen
    );
    
    Parameters
    x
     
    y
     
    width
     
    height
     
    dataPtr
     
    dataLen
     

    Native code only!

    getStrokeStyle_multi

    Introduced in Gecko 2.0 (Firefox 4 / Thunderbird 3.3 / SeaMonkey 2.1).

    void getStrokeStyle_multi(
      out DOMString str,
      out nsISupports iface,
      out long type
    );
    
    Parameters
    str
     
    iface
     
    type
     

    Non implémenté

    mozDrawText()

    This method was introduced in Gecko 1.9 and is unimplemented starting with Gecko 7.0.

    void mozDrawText(
      in DOMString textToDraw
    );
    
    Parameters
    textToDraw
     

    Non implémenté

    mozMeasureText()

    This method was introduced in Gecko 1.9 and is unimplemented starting with Gecko 7.0.

    float mozMeasureText(
      in DOMString textToMeasure
    );
    
    Parameters
    textToMeasure
     
    Return value

     

    Non implémenté

    mozPathText()

    This method was introduced in Gecko 1.9 and is unimplemented starting with Gecko 7.0.

    void mozPathText(
      in DOMString textToPath
    );
    
    Parameters
    textToPath
     

    Non implémenté

    mozTextAlongPath()

    This method was introduced in Gecko 1.9 and is unimplemented starting with Gecko 7.0.

    void mozTextAlongPath(
      in DOMString textToDraw,
      in boolean stroke
    );
    
    Parameters
    textToDraw
     
    stroke
     

    Native code only!

    setFillStyle_multi

    Introduced in Gecko 2.0 (Firefox 4 / Thunderbird 3.3 / SeaMonkey 2.1).

    void setFillStyle_multi(
      in DOMString str,
      in nsISupports iface
    );
    
    Parameters
    str
     
    iface
     

    Native code only!

    setStrokeStyle_multi

    Introduced in Gecko 2.0 (Firefox 4 / Thunderbird 3.3 / SeaMonkey 2.1).

    void setStrokeStyle_multi(
      in DOMString str,
      in nsISupports iface
    );
    
    Parameters
    str
     
    iface
     

    WebKit-specific methods

    clearShadow()

    void clearShadow();
    
    Parameters

    None.

    drawImageFromRect()

    void drawImageFromRect(
      in HTMLImageElement image,
      in [Optional] float sx,
      in [Optional] float sy,
      in [Optional] float sw,
      in [Optional] float sh,
      in [Optional] float dx, 
      in [Optional] float dy,
      in [Optional] float dw,
      in [Optional] float dh,
      in [Optional] DOMString compositeOperation
    );
    

    setAlpha()

    void setAlpha(
      in float alpha
    );
    

    setCompositeOperation()

    void setCompositeOperation(
      in DOMString compositeOperation
    );
    

    setLineWidth()

    void setLineWidth(
      in float width
    );
    

    setLineCap()

    void setLineCap(
      in DOMString cap
    );
    

    setLineJoin()

    void setLineJoin(
      in DOMString join
    );
    

    setMiterLimit()

    void setMiterLimit(
      in float limit
    );
    

    setStrokeColor()

    void setStrokeColor(in DOMString color, in [Optional] float alpha);
    void setStrokeColor(in float grayLevel, in [Optional] float alpha);
    void setStrokeColor(in float r, in float g, in float b, in float a);
    void setStrokeColor(in float c, in float m, in float y, in float k, in float a);
    

    setFillColor()

    void setFillColor(in DOMString color, in [Optional] float alpha);
    void setFillColor(in float grayLevel, in [Optional] float alpha);
    void setFillColor(in float r, in float g, in float b, in float a);
    void setFillColor(in float c, in float m, in float y, in float k, in float a);
    

    setShadow()

    void setShadow(in float width, in float height, in float blur, in [Optional] DOMString color, in [Optional] float alpha);
    void setShadow(in float width, in float height, in float blur, in float grayLevel, in [Optional] float alpha);
    void setShadow(in float width, in float height, in float blur, in float r, in float g, in float b, in float a);
    void setShadow(in float width, in float height, in float blur, in float c, in float m, in float y, in float k, in float a);
    

    Browser compatibility

    Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
    Methods
    arc() ? (Oui) ? ? ?
    arcTo() ? (Oui) ? ? ?
    beginPath() ? (Oui) ? ? ?
    bezierCurveTo() ? (Oui) ? ? ?
    clearRect() ? (Oui) ? ? ?
    clip() ? (Oui) ? ? ?
    closePath() ? (Oui) ? ? ?
    createImageData() ? 3.5 (1.9.1) ? ? ?
    createLinearGradient() ? (Oui) ? ? ?
    createPattern() ? (Oui) ? ? ?
    createRadialGradient() ? (Oui) ? ? ?
    drawImage() ? (Oui) ? ? ?
    drawCustomFocusRing() ? Non implémenté (voir bug 540456) ? ? ?
    drawSystemFocusRing() ? Non implémenté (voir bug 540456) ? ? ?
    fill() ? (Oui) ? ? ?
    fillRect() ? (Oui) ? ? ?
    fillText() ? 3.5 (1.9.1) ? ? ?
    getImageData() ? (Oui) ? ? ?
    isPointInPath() ? (Oui) ? ? ?
    isPointInStroke() ? 19.0 (19.0) ? ? ?
    lineTo() ? (Oui) ? ? ?
    measureText() ? 3.5 (1.9.1) ? ? ?
    moveTo() ? (Oui) ? ? ?
    putImageData() ? (Oui) ? ? ?
    quadraticCurveTo() ? (Oui) ? ? ?
    rect() ? (Oui) ? ? ?
    restore() ? (Oui) ? ? ?
    rotate() ? (Oui) ? ? ?
    save() ? (Oui) ? ? ?
    scale() ? (Oui) ? ? ?
    scrollPathIntoView() ? (Oui) ? ? ?
    setTransform() ? 3.0 (1.9.0) ? ? ?
    stroke() ? (Oui) ? ? ?
    strokeRect() ? (Oui) ? ? ?
    strokeText() ? 3.5 (1.9.1) ? ? ?
    transform() ? 3.0 (1.9.0) ? ? ?
    translate() ? (Oui) ? ? ?
    Attributes
    canvas (Oui) (Oui) (Oui) (Oui) (Oui)
    fillstyle (Oui) (Oui) (Oui) (Oui) (Oui)
    font (Oui) (Oui) (Oui) (Oui) (Oui)
    globalAlpha (Oui) (Oui) (Oui) (Oui) (Oui)
    globalCompositeOperation (Oui) (Oui) (Oui) (Oui) (Oui)
    lineCap (Oui) (Oui) (Oui) (Oui) (Oui)
    lineJoin (Oui) (Oui) (Oui) (Oui) (Oui)
    lineWidth (Oui) (Oui) (Oui) (Oui) (Oui)
    miterLimit (Oui) (Oui) (Oui) (Oui) (Oui)
    shadowBlur (Oui) (Oui) (Oui) (Oui) (Oui)
    shadowColor (Oui) (Oui) (Oui) (Oui) (Oui)
    shadowOffsetX (Oui) (Oui) (Oui) (Oui) (Oui)
    shadowOffsetY (Oui) (Oui) (Oui) (Oui) (Oui)
    strokeStyle (Oui) (Oui) (Oui) (Oui) (Oui)
    textAlign (Oui) (Oui) (Oui) (Oui) (Oui)
    textBaseline (Oui) (Oui) (Oui) (Oui) (Oui)
    Feature Android Firefox Mobile (Gecko) IE Phone Opera Mobile Safari Mobile
    Methods
    arc() ? ? ? ? ?
    arcTo() ? ? ? ? ?
    beginPath() ? ? ? ? ?
    bezierCurveTo() ? ? ? ? ?
    clearRect() ? ? ? ? ?
    clip() ? ? ? ? ?
    closePath() ? ? ? ? ?
    createImageData() ? ? ? ? ?
    createLinearGradient() ? ? ? ? ?
    createPattern() ? ? ? ? ?
    createRadialGradient() ? ? ? ? ?
    drawImage() ? ? ? ? ?
    drawCustomFocusRing() ? ? ? ? ?
    drawSystemFocusRing() ? ? ? ? ?
    fill() ? ? ? ? ?
    fillRect() ? ? ? ? ?
    fillText() ? ? ? ? ?
    getImageData() ? ? ? ? ?
    isPointInPath() ? ? ? ? ?
    isPointInStroke() ? ? ? ? ?
    lineTo() ? ? ? ? ?
    measureText() ? ? ? ? ?
    moveTo() ? ? ? ? ?
    putImageData() ? ? ? ? ?
    quadraticCurveTo() ? ? ? ? ?
    rect() ? ? ? ? ?
    restore() ? ? ? ? ?
    rotate() ? ? ? ? ?
    save() ? ? ? ? ?
    scale() ? ? ? ? ?
    scrollPathIntoView() ? ? ? ? ?
    setTransform() ? ? ? ? ?
    stroke() ? ? ? ? ?
    strokeRect() ? ? ? ? ?
    strokeText() ? ? ? ? ?
    transform() ? ? ? ? ?
    translate() ? ? ? ? ?
    Attributes
    canvas ? ? ? ? ?
    fillstyle ? ? ? ? ?
    font ? ? ? ? ?
    globalAlpha ? ? ? ? ?
    globalCompositeOperation ? ? ? ? ?
    lineCap ? ? ? ? ?
    lineJoin ? ? ? ? ?
    lineWidth ? ? ? ? ?
    miterLimit ? ? ? ? ?
    shadowBlur ? ? ? ? ?
    shadowColor ? ? ? ? ?
    shadowOffsetX ? ? ? ? ?
    shadowOffsetY ? ? ? ? ?
    strokeStyle ? ? ? ? ?
    textAlign ? ? ? ? ?
    textBaseline ? ? ? ? ?

    Notes

    Gecko

    Please add a summary to this article.
    1.0
    29.0.1
    Introduced
    Gecko 1.8
    Inherits from: nsISupports Last changed in Gecko 7.0 (Firefox 7.0 / Thunderbird 7.0 / SeaMonkey 2.4)

    Note: Starting in Gecko 2.0, the following corrections were made to various behaviors in order to improve compliance with the HTML5 specification:

    • Specifying a negative radius when calling arc() now correctly throws an INDEX_SIZE_ERR exception.
    • Specifying non-finite values when calling createLinearGradient() and createRadialGradient() now throws NOT_SUPPORTED_ERR instead of SYNTAX_ERR.
    • Setting miterLimit to a negative value no longer throws an exception; instead, it properly ignores non-positive values.
    • Setting lineWidth to a negative value no longer throws an exception; instead, it properly ignores non-positive values.

    Note: Starting in Gecko 5.0, the following corrections were made to various behaviors in order to improve compliance with the HTML5 specification:

    • getImageData() now correctly accepts rectangles that extend beyond the bounds of the canvas; pixels outside the canvas are returned as transparent black.
    • drawImage() and createImageData() now handle negative arguments in accordance with the specification, by flipping the rectangle around the appropriate axis.
    • Specifying non-finite values when calling createImageData() now properly throws a NOT_SUPPORTED_ERR exception.
    • createImageData() and getImageData() now correctly return at least one pixel's worth of image data if a rectangle smaller than one pixel is specified.
    • Specifying a negative radius when calling createRadialGradient() now correctly throws INDEX_SIZE_ERR.
    • Specifying a null or undefined image when calling createPattern() or drawImage() now correctly throws a TYPE_MISMATCH_ERR exception.
    • Specifying invalid values for globalAlpha no longer throws a SYNTAX_ERR exception; these are now correctly silently ignored.
    • Specifying invalid values when calling translate(), transform(), rect(), clearRect(), fillRect(), strokeRect(), lineTo(), moveTo(), quadraticCurveTo(), or arc() no longer throws an exception; these calls are now correctly silently ignored.
    • Setting the value of shadowOffsetX, shadowOffsetY, or shadowBlur to an invalid value is now silently ignored.
    • Setting the value of rotate or scale to an invalid value is now silently ignored.

    Specification

    Étiquettes et contributeurs liés au document

    Contributors to this page: Halfman, Y0kaze, vdrac
    Dernière mise à jour par : Halfman,