#### new Layer(width, height)

Abstract ordered drawing surface. Each Layer contains a canvas element and
provides simple drawing instructions for drawing to that canvas element,
however unlike the canvas element itself, drawing operations on a Layer are
guaranteed to run in order, even if such an operation must wait for an image
to load before completing.

##### Parameters:

Name | Type | Description |
---|---|---|

`width` |
Number | The width of the Layer, in pixels. The canvas element backing this Layer will be given this width. |

`height` |
Number | The height of the Layer, in pixels. The canvas element backing this Layer will be given this height. |

### Classes

### Members

#### (static) ATOP

Channel mask for the composite operation "atop".

#### (static) IN

Channel mask for the composite operation "in".
Beware that WebKit-based browsers may leave the contents of the destionation
layer where the source layer is transparent, despite the definition of this
operation.

#### (static) OUT

Channel mask for the composite operation "out".
Beware that WebKit-based browsers may leave the contents of the destionation
layer where the source layer is transparent, despite the definition of this
operation.

#### (static) OVER

Channel mask for the composite operation "over".

#### (static) PLUS

Channel mask for the composite operation "plus".

#### (static) RATOP

Channel mask for the composite operation "ratop".
Beware that WebKit-based browsers may leave the contents of the destionation
layer where the source layer is transparent, despite the definition of this
operation.

#### (static) RIN

Channel mask for the composite operation "rin".
Beware that WebKit-based browsers may leave the contents of the destionation
layer where the source layer is transparent, despite the definition of this
operation.

#### (static) ROUT

Channel mask for the composite operation "rout".

#### (static) ROVER

Channel mask for the composite operation "rover".

#### (static) SRC

Channel mask for the composite operation "src".
Beware that WebKit-based browsers may leave the contents of the destionation
layer where the source layer is transparent, despite the definition of this
operation.

#### (static) XOR

Channel mask for the composite operation "xor".

#### autosize :Boolean

Set to true if this Layer should resize itself to accomodate the
dimensions of any drawing operation, and false (the default) otherwise.
Note that setting this property takes effect immediately, and thus may
take effect on operations that were started in the past but have not
yet completed. If you wish the setting of this flag to only modify
future operations, you will need to make the setting of this flag an
operation with sync().

##### Type:

- Boolean

##### Example

```
// Set autosize to true for all future operations
layer.sync(function() {
layer.autosize = true;
});
```

#### height :Number

The current height of this layer.

##### Type:

- Number

#### width :Number

The current width of this layer.

##### Type:

- Number

### Methods

#### arc(x, y, radius, startAngle, endAngle, negative)

Add the specified arc to the current path.

##### Parameters:

Name | Type | Description |
---|---|---|

`x` |
Number | The X coordinate of the center of the circle which will contain the arc. |

`y` |
Number | The Y coordinate of the center of the circle which will contain the arc. |

`radius` |
Number | The radius of the circle. |

`startAngle` |
Number | The starting angle of the arc, in radians. |

`endAngle` |
Number | The ending angle of the arc, in radians. |

`negative` |
Boolean | Whether the arc should be drawn in order of decreasing angle. |

#### clip()

Clip all future drawing operations by the current path. The current path
is implicitly closed. The current path can continue to be reused
for other operations (such as fillColor()) but a new path will be started
once a path drawing operation (path() or rect()) is used.

#### close()

Closes the current path by connecting the end point with the start
point (if any) with a straight line.

#### copy(srcLayer, srcx, srcy, srcw, srch, x, y)

Copy a rectangle of image data from one Layer to this Layer. This
operation will copy exactly the image data that will be drawn once all
operations of the source Layer that were pending at the time this
function was called are complete. This operation will not alter the
size of the source Layer even if its autosize property is set to true.

##### Parameters:

Name | Type | Description |
---|---|---|

`srcLayer` |
Guacamole.Layer | The Layer to copy image data from. |

`srcx` |
Number | The X coordinate of the upper-left corner of the rectangle within the source Layer's coordinate space to copy data from. |

`srcy` |
Number | The Y coordinate of the upper-left corner of the rectangle within the source Layer's coordinate space to copy data from. |

`srcw` |
Number | The width of the rectangle within the source Layer's coordinate space to copy data from. |

`srch` |
Number | The height of the rectangle within the source Layer's coordinate space to copy data from. |

`x` |
Number | The destination X coordinate. |

`y` |
Number | The destination Y coordinate. |

#### curveTo(cp1x, cp1y, cp2x, cp2y, x, y)

Starts a new path at the specified point.

##### Parameters:

Name | Type | Description |
---|---|---|

`cp1x` |
Number | The X coordinate of the first control point. |

`cp1y` |
Number | The Y coordinate of the first control point. |

`cp2x` |
Number | The X coordinate of the second control point. |

`cp2y` |
Number | The Y coordinate of the second control point. |

`x` |
Number | The X coordinate of the endpoint of the curve. |

`y` |
Number | The Y coordinate of the endpoint of the curve. |

#### drawImage(x, y, image)

Draws the specified image at the given coordinates. The image specified
must already be loaded.

##### Parameters:

Name | Type | Description |
---|---|---|

`x` |
Number | The destination X coordinate. |

`y` |
Number | The destination Y coordinate. |

`image` |
Image | The image to draw. Note that this is an Image object - not a URL. |

#### fillColor(r, g, b, a)

Fills the current path with the specified color. The current path
is implicitly closed. The current path can continue to be reused
for other operations (such as clip()) but a new path will be started
once a path drawing operation (path() or rect()) is used.

##### Parameters:

Name | Type | Description |
---|---|---|

`r` |
Number | The red component of the color to fill. |

`g` |
Number | The green component of the color to fill. |

`b` |
Number | The blue component of the color to fill. |

`a` |
Number | The alpha component of the color to fill. |

#### fillLayer(srcLayer)

Fills the current path with the image within the specified layer. The
image data will be tiled infinitely within the stroke. The current path
is implicitly closed. The current path can continue to be reused
for other operations (such as clip()) but a new path will be started
once a path drawing operation (path() or rect()) is used.

##### Parameters:

Name | Type | Description |
---|---|---|

`srcLayer` |
Guacamole.Layer | The layer to use as a repeating pattern within the fill. |

#### getCanvas() → {HTMLCanvasElement}

Returns the canvas element backing this Layer. Note that the dimensions
of the canvas may not exactly match those of the Layer, as resizing a
canvas while maintaining its state is an expensive operation.

##### Returns:

The canvas element backing this Layer.

- Type
- HTMLCanvasElement

#### lineTo(x, y)

Add the specified line to the current path.

##### Parameters:

Name | Type | Description |
---|---|---|

`x` |
Number | The X coordinate of the endpoint of the line to draw. |

`y` |
Number | The Y coordinate of the endpoint of the line to draw. |

#### moveTo(x, y)

Starts a new path at the specified point.

##### Parameters:

Name | Type | Description |
---|---|---|

`x` |
Number | The X coordinate of the point to draw. |

`y` |
Number | The Y coordinate of the point to draw. |

#### pop()

Pop layer state off stack.

#### push()

Push current layer state onto stack.

#### put(srcLayer, srcx, srcy, srcw, srch, x, y)

Put a rectangle of image data from one Layer to this Layer directly
without performing any alpha blending. Simply copy the data.

##### Parameters:

Name | Type | Description |
---|---|---|

`srcLayer` |
Guacamole.Layer | The Layer to copy image data from. |

`srcx` |
Number | The X coordinate of the upper-left corner of the rectangle within the source Layer's coordinate space to copy data from. |

`srcy` |
Number | The Y coordinate of the upper-left corner of the rectangle within the source Layer's coordinate space to copy data from. |

`srcw` |
Number | The width of the rectangle within the source Layer's coordinate space to copy data from. |

`srch` |
Number | The height of the rectangle within the source Layer's coordinate space to copy data from. |

`x` |
Number | The destination X coordinate. |

`y` |
Number | The destination Y coordinate. |

#### rect(x, y, w, h)

Add the specified rectangle to the current path.

##### Parameters:

Name | Type | Description |
---|---|---|

`x` |
Number | The X coordinate of the upper-left corner of the rectangle to draw. |

`y` |
Number | The Y coordinate of the upper-left corner of the rectangle to draw. |

`w` |
Number | The width of the rectangle to draw. |

`h` |
Number | The height of the rectangle to draw. |

#### reset()

Reset the layer, clearing the stack, the current path, and any transform
matrix.

#### resize(newWidth, newHeight)

Changes the size of this Layer to the given width and height. Resizing
is only attempted if the new size provided is actually different from
the current size.

##### Parameters:

Name | Type | Description |
---|---|---|

`newWidth` |
Number | The new width to assign to this Layer. |

`newHeight` |
Number | The new height to assign to this Layer. |

#### setChannelMask(mask)

Sets the channel mask for future operations on this Layer.
The channel mask is a Guacamole-specific compositing operation identifier
with a single bit representing each of four channels (in order): source
image where destination transparent, source where destination opaque,
destination where source transparent, and destination where source
opaque.

##### Parameters:

Name | Type | Description |
---|---|---|

`mask` |
Number | The channel mask for future operations on this Layer. |

#### setMiterLimit(limit)

Sets the miter limit for stroke operations using the miter join. This
limit is the maximum ratio of the size of the miter join to the stroke
width. If this ratio is exceeded, the miter will not be drawn for that
joint of the path.

##### Parameters:

Name | Type | Description |
---|---|---|

`limit` |
Number | The miter limit for stroke operations using the miter join. |

#### setTransform(a, b, c, d, e, f)

Sets the given affine transform (defined with six values from the
transform's matrix).

##### Parameters:

Name | Type | Description |
---|---|---|

`a` |
Number | The first value in the affine transform's matrix. |

`b` |
Number | The second value in the affine transform's matrix. |

`c` |
Number | The third value in the affine transform's matrix. |

`d` |
Number | The fourth value in the affine transform's matrix. |

`e` |
Number | The fifth value in the affine transform's matrix. |

`f` |
Number | The sixth value in the affine transform's matrix. |

#### strokeColor(cap, join, thickness, r, g, b, a)

Stroke the current path with the specified color. The current path
is implicitly closed. The current path can continue to be reused
for other operations (such as clip()) but a new path will be started
once a path drawing operation (path() or rect()) is used.

##### Parameters:

Name | Type | Description |
---|---|---|

`cap` |
String | The line cap style. Can be "round", "square", or "butt". |

`join` |
String | The line join style. Can be "round", "bevel", or "miter". |

`thickness` |
Number | The line thickness in pixels. |

`r` |
Number | The red component of the color to fill. |

`g` |
Number | The green component of the color to fill. |

`b` |
Number | The blue component of the color to fill. |

`a` |
Number | The alpha component of the color to fill. |

#### strokeLayer(cap, join, thickness, srcLayer)

Stroke the current path with the image within the specified layer. The
image data will be tiled infinitely within the stroke. The current path
is implicitly closed. The current path can continue to be reused
for other operations (such as clip()) but a new path will be started
once a path drawing operation (path() or rect()) is used.

##### Parameters:

Name | Type | Description |
---|---|---|

`cap` |
String | The line cap style. Can be "round", "square", or "butt". |

`join` |
String | The line join style. Can be "round", "bevel", or "miter". |

`thickness` |
Number | The line thickness in pixels. |

`srcLayer` |
Guacamole.Layer | The layer to use as a repeating pattern within the stroke. |

#### toCanvas() → {HTMLCanvasElement}

Returns a new canvas element containing the same image as this Layer.
Unlike getCanvas(), the canvas element returned is guaranteed to have
the exact same dimensions as the Layer.

##### Returns:

A new canvas element containing a copy of the image content this
Layer.

- Type
- HTMLCanvasElement

#### transfer(srcLayer, srcx, srcy, srcw, srch, x, y, transferFunction)

Transfer a rectangle of image data from one Layer to this Layer using the
specified transfer function.

##### Parameters:

Name | Type | Description |
---|---|---|

`srcLayer` |
Guacamole.Layer | The Layer to copy image data from. |

`srcx` |
Number | The X coordinate of the upper-left corner of the rectangle within the source Layer's coordinate space to copy data from. |

`srcy` |
Number | The Y coordinate of the upper-left corner of the rectangle within the source Layer's coordinate space to copy data from. |

`srcw` |
Number | The width of the rectangle within the source Layer's coordinate space to copy data from. |

`srch` |
Number | The height of the rectangle within the source Layer's coordinate space to copy data from. |

`x` |
Number | The destination X coordinate. |

`y` |
Number | The destination Y coordinate. |

`transferFunction` |
function | The transfer function to use to transfer data from source to destination. |

#### transform(a, b, c, d, e, f)

Applies the given affine transform (defined with six values from the
transform's matrix).

##### Parameters:

Name | Type | Description |
---|---|---|

`a` |
Number | The first value in the affine transform's matrix. |

`b` |
Number | The second value in the affine transform's matrix. |

`c` |
Number | The third value in the affine transform's matrix. |

`d` |
Number | The fourth value in the affine transform's matrix. |

`e` |
Number | The fifth value in the affine transform's matrix. |

`f` |
Number | The sixth value in the affine transform's matrix. |