/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
var Guacamole = Guacamole || {};
/**
* 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.
*
* @constructor
*
* @param {!number} width
* The width of the Layer, in pixels. The canvas element backing this Layer
* will be given this width.
*
* @param {!number} height
* The height of the Layer, in pixels. The canvas element backing this
* Layer will be given this height.
*/
Guacamole.Layer = function(width, height) {
/**
* Reference to this Layer.
*
* @private
* @type {!Guacamole.Layer}
*/
var layer = this;
/**
* The number of pixels the width or height of a layer must change before
* the underlying canvas is resized. The underlying canvas will be kept at
* dimensions which are integer multiples of this factor.
*
* @private
* @constant
* @type {!number}
*/
var CANVAS_SIZE_FACTOR = 64;
/**
* The canvas element backing this Layer.
*
* @private
* @type {!HTMLCanvasElement}
*/
var canvas = document.createElement("canvas");
/**
* The 2D display context of the canvas element backing this Layer.
*
* @private
* @type {!CanvasRenderingContext2D}
*/
var context = canvas.getContext("2d");
context.save();
/**
* Whether the layer has not yet been drawn to. Once any draw operation
* which affects the underlying canvas is invoked, this flag will be set to
* false.
*
* @private
* @type {!boolean}
*/
var empty = true;
/**
* Whether a new path should be started with the next path drawing
* operations.
*
* @private
* @type {!boolean}
*/
var pathClosed = true;
/**
* The number of states on the state stack.
*
* Note that there will ALWAYS be one element on the stack, but that
* element is not exposed. It is only used to reset the layer to its
* initial state.
*
* @private
* @type {!number}
*/
var stackSize = 0;
/**
* Map of all Guacamole channel masks to HTML5 canvas composite operation
* names. Not all channel mask combinations are currently implemented.
*
* @private
* @type {!Object.<number, string>}
*/
var compositeOperation = {
/* 0x0 NOT IMPLEMENTED */
0x1: "destination-in",
0x2: "destination-out",
/* 0x3 NOT IMPLEMENTED */
0x4: "source-in",
/* 0x5 NOT IMPLEMENTED */
0x6: "source-atop",
/* 0x7 NOT IMPLEMENTED */
0x8: "source-out",
0x9: "destination-atop",
0xA: "xor",
0xB: "destination-over",
0xC: "copy",
/* 0xD NOT IMPLEMENTED */
0xE: "source-over",
0xF: "lighter"
};
/**
* Resizes the canvas element backing this Layer. This function should only
* be used internally.
*
* @private
* @param {number} [newWidth=0]
* The new width to assign to this Layer.
*
* @param {number} [newHeight=0]
* The new height to assign to this Layer.
*/
var resize = function resize(newWidth, newHeight) {
// Default size to zero
newWidth = newWidth || 0;
newHeight = newHeight || 0;
// Calculate new dimensions of internal canvas
var canvasWidth = Math.ceil(newWidth / CANVAS_SIZE_FACTOR) * CANVAS_SIZE_FACTOR;
var canvasHeight = Math.ceil(newHeight / CANVAS_SIZE_FACTOR) * CANVAS_SIZE_FACTOR;
// Resize only if canvas dimensions are actually changing
if (canvas.width !== canvasWidth || canvas.height !== canvasHeight) {
// Copy old data only if relevant and non-empty
var oldData = null;
if (!empty && canvas.width !== 0 && canvas.height !== 0) {
// Create canvas and context for holding old data
oldData = document.createElement("canvas");
oldData.width = Math.min(layer.width, newWidth);
oldData.height = Math.min(layer.height, newHeight);
var oldDataContext = oldData.getContext("2d");
// Copy image data from current
oldDataContext.drawImage(canvas,
0, 0, oldData.width, oldData.height,
0, 0, oldData.width, oldData.height);
}
// Preserve composite operation
var oldCompositeOperation = context.globalCompositeOperation;
// Resize canvas
canvas.width = canvasWidth;
canvas.height = canvasHeight;
// Redraw old data, if any
if (oldData)
context.drawImage(oldData,
0, 0, oldData.width, oldData.height,
0, 0, oldData.width, oldData.height);
// Restore composite operation
context.globalCompositeOperation = oldCompositeOperation;
// Acknowledge reset of stack (happens on resize of canvas)
stackSize = 0;
context.save();
}
// If the canvas size is not changing, manually force state reset
else
layer.reset();
// Assign new layer dimensions
layer.width = newWidth;
layer.height = newHeight;
};
/**
* Given the X and Y coordinates of the upper-left corner of a rectangle
* and the rectangle's width and height, resize the backing canvas element
* as necessary to ensure that the rectangle fits within the canvas
* element's coordinate space. This function will only make the canvas
* larger. If the rectangle already fits within the canvas element's
* coordinate space, the canvas is left unchanged.
*
* @private
* @param {!number} x
* The X coordinate of the upper-left corner of the rectangle to fit.
*
* @param {!number} y
* The Y coordinate of the upper-left corner of the rectangle to fit.
*
* @param {!number} w
* The width of the rectangle to fit.
*
* @param {!number} h
* The height of the rectangle to fit.
*/
function fitRect(x, y, w, h) {
// Calculate bounds
var opBoundX = w + x;
var opBoundY = h + y;
// Determine max width
var resizeWidth;
if (opBoundX > layer.width)
resizeWidth = opBoundX;
else
resizeWidth = layer.width;
// Determine max height
var resizeHeight;
if (opBoundY > layer.height)
resizeHeight = opBoundY;
else
resizeHeight = layer.height;
// Resize if necessary
layer.resize(resizeWidth, resizeHeight);
}
/**
* Set to true if this Layer should resize itself to accommodate 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().
*
* @example
* // Set autosize to true for all future operations
* layer.sync(function() {
* layer.autosize = true;
* });
*
* @type {!boolean}
* @default false
*/
this.autosize = false;
/**
* The current width of this layer.
*
* @type {!number}
*/
this.width = width;
/**
* The current height of this layer.
*
* @type {!number}
*/
this.height = height;
/**
* 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 {!HTMLCanvasElement}
* The canvas element backing this Layer.
*/
this.getCanvas = function getCanvas() {
return canvas;
};
/**
* 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 {!HTMLCanvasElement}
* A new canvas element containing a copy of the image content this
* Layer.
*/
this.toCanvas = function toCanvas() {
// Create new canvas having same dimensions
var canvas = document.createElement('canvas');
canvas.width = layer.width;
canvas.height = layer.height;
// Copy image contents to new canvas
var context = canvas.getContext('2d');
context.drawImage(layer.getCanvas(), 0, 0);
return canvas;
};
/**
* 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.
*
* @param {!number} newWidth
* The new width to assign to this Layer.
*
* @param {!number} newHeight
* The new height to assign to this Layer.
*/
this.resize = function(newWidth, newHeight) {
if (newWidth !== layer.width || newHeight !== layer.height)
resize(newWidth, newHeight);
};
/**
* Draws the specified image at the given coordinates. The image specified
* must already be loaded.
*
* @param {!number} x
* The destination X coordinate.
*
* @param {!number} y
* The destination Y coordinate.
*
* @param {!CanvasImageSource} image
* The image to draw. Note that this is not a URL.
*/
this.drawImage = function(x, y, image) {
if (layer.autosize) fitRect(x, y, image.width, image.height);
context.drawImage(image, x, y);
empty = false;
};
/**
* Transfer a rectangle of image data from one Layer to this Layer using the
* specified transfer function.
*
* @param {!Guacamole.Layer} srcLayer
* The Layer to copy image data from.
*
* @param {!number} srcx
* The X coordinate of the upper-left corner of the rectangle within
* the source Layer's coordinate space to copy data from.
*
* @param {!number} srcy
* The Y coordinate of the upper-left corner of the rectangle within
* the source Layer's coordinate space to copy data from.
*
* @param {!number} srcw
* The width of the rectangle within the source Layer's coordinate
* space to copy data from.
*
* @param {!number} srch
* The height of the rectangle within the source Layer's coordinate
* space to copy data from.
*
* @param {!number} x
* The destination X coordinate.
*
* @param {!number} y
* The destination Y coordinate.
*
* @param {!function} transferFunction
* The transfer function to use to transfer data from source to
* destination.
*/
this.transfer = function(srcLayer, srcx, srcy, srcw, srch, x, y, transferFunction) {
var srcCanvas = srcLayer.getCanvas();
// If entire rectangle outside source canvas, stop
if (srcx >= srcCanvas.width || srcy >= srcCanvas.height) return;
// Otherwise, clip rectangle to area
if (srcx + srcw > srcCanvas.width)
srcw = srcCanvas.width - srcx;
if (srcy + srch > srcCanvas.height)
srch = srcCanvas.height - srcy;
// Stop if nothing to draw.
if (srcw === 0 || srch === 0) return;
if (layer.autosize) fitRect(x, y, srcw, srch);
// Get image data from src and dst
var src = srcLayer.getCanvas().getContext("2d").getImageData(srcx, srcy, srcw, srch);
var dst = context.getImageData(x , y, srcw, srch);
// Apply transfer for each pixel
for (var i=0; i<srcw*srch*4; i+=4) {
// Get source pixel environment
var src_pixel = new Guacamole.Layer.Pixel(
src.data[i],
src.data[i+1],
src.data[i+2],
src.data[i+3]
);
// Get destination pixel environment
var dst_pixel = new Guacamole.Layer.Pixel(
dst.data[i],
dst.data[i+1],
dst.data[i+2],
dst.data[i+3]
);
// Apply transfer function
transferFunction(src_pixel, dst_pixel);
// Save pixel data
dst.data[i ] = dst_pixel.red;
dst.data[i+1] = dst_pixel.green;
dst.data[i+2] = dst_pixel.blue;
dst.data[i+3] = dst_pixel.alpha;
}
// Draw image data
context.putImageData(dst, x, y);
empty = false;
};
/**
* Put a rectangle of image data from one Layer to this Layer directly
* without performing any alpha blending. Simply copy the data.
*
* @param {!Guacamole.Layer} srcLayer
* The Layer to copy image data from.
*
* @param {!number} srcx
* The X coordinate of the upper-left corner of the rectangle within
* the source Layer's coordinate space to copy data from.
*
* @param {!number} srcy
* The Y coordinate of the upper-left corner of the rectangle within
* the source Layer's coordinate space to copy data from.
*
* @param {!number} srcw
* The width of the rectangle within the source Layer's coordinate
* space to copy data from.
*
* @param {!number} srch
* The height of the rectangle within the source Layer's coordinate
* space to copy data from.
*
* @param {!number} x
* The destination X coordinate.
*
* @param {!number} y
* The destination Y coordinate.
*/
this.put = function(srcLayer, srcx, srcy, srcw, srch, x, y) {
var srcCanvas = srcLayer.getCanvas();
// If entire rectangle outside source canvas, stop
if (srcx >= srcCanvas.width || srcy >= srcCanvas.height) return;
// Otherwise, clip rectangle to area
if (srcx + srcw > srcCanvas.width)
srcw = srcCanvas.width - srcx;
if (srcy + srch > srcCanvas.height)
srch = srcCanvas.height - srcy;
// Stop if nothing to draw.
if (srcw === 0 || srch === 0) return;
if (layer.autosize) fitRect(x, y, srcw, srch);
// Get image data from src and dst
var src = srcLayer.getCanvas().getContext("2d").getImageData(srcx, srcy, srcw, srch);
context.putImageData(src, x, y);
empty = false;
};
/**
* 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.
*
* @param {!Guacamole.Layer} srcLayer
* The Layer to copy image data from.
*
* @param {!number} srcx
* The X coordinate of the upper-left corner of the rectangle within
* the source Layer's coordinate space to copy data from.
*
* @param {!number} srcy
* The Y coordinate of the upper-left corner of the rectangle within
* the source Layer's coordinate space to copy data from.
*
* @param {!number} srcw
* The width of the rectangle within the source Layer's coordinate
* space to copy data from.
*
* @param {!number} srch
* The height of the rectangle within the source Layer's coordinate
* space to copy data from.
*
* @param {!number} x
* The destination X coordinate.
*
* @param {!number} y
* The destination Y coordinate.
*/
this.copy = function(srcLayer, srcx, srcy, srcw, srch, x, y) {
var srcCanvas = srcLayer.getCanvas();
// If entire rectangle outside source canvas, stop
if (srcx >= srcCanvas.width || srcy >= srcCanvas.height) return;
// Otherwise, clip rectangle to area
if (srcx + srcw > srcCanvas.width)
srcw = srcCanvas.width - srcx;
if (srcy + srch > srcCanvas.height)
srch = srcCanvas.height - srcy;
// Stop if nothing to draw.
if (srcw === 0 || srch === 0) return;
if (layer.autosize) fitRect(x, y, srcw, srch);
context.drawImage(srcCanvas, srcx, srcy, srcw, srch, x, y, srcw, srch);
empty = false;
};
/**
* Starts a new path at the specified point.
*
* @param {!number} x
* The X coordinate of the point to draw.
*
* @param {!number} y
* The Y coordinate of the point to draw.
*/
this.moveTo = function(x, y) {
// Start a new path if current path is closed
if (pathClosed) {
context.beginPath();
pathClosed = false;
}
if (layer.autosize) fitRect(x, y, 0, 0);
context.moveTo(x, y);
};
/**
* Add the specified line to the current path.
*
* @param {!number} x
* The X coordinate of the endpoint of the line to draw.
*
* @param {!number} y
* The Y coordinate of the endpoint of the line to draw.
*/
this.lineTo = function(x, y) {
// Start a new path if current path is closed
if (pathClosed) {
context.beginPath();
pathClosed = false;
}
if (layer.autosize) fitRect(x, y, 0, 0);
context.lineTo(x, y);
};
/**
* Add the specified arc to the current path.
*
* @param {!number} x
* The X coordinate of the center of the circle which will contain the
* arc.
*
* @param {!number} y
* The Y coordinate of the center of the circle which will contain the
* arc.
*
* @param {!number} radius
* The radius of the circle.
*
* @param {!number} startAngle
* The starting angle of the arc, in radians.
*
* @param {!number} endAngle
* The ending angle of the arc, in radians.
*
* @param {!boolean} negative
* Whether the arc should be drawn in order of decreasing angle.
*/
this.arc = function(x, y, radius, startAngle, endAngle, negative) {
// Start a new path if current path is closed
if (pathClosed) {
context.beginPath();
pathClosed = false;
}
if (layer.autosize) fitRect(x, y, 0, 0);
context.arc(x, y, radius, startAngle, endAngle, negative);
};
/**
* Starts a new path at the specified point.
*
* @param {!number} cp1x
* The X coordinate of the first control point.
*
* @param {!number} cp1y
* The Y coordinate of the first control point.
*
* @param {!number} cp2x
* The X coordinate of the second control point.
*
* @param {!number} cp2y
* The Y coordinate of the second control point.
*
* @param {!number} x
* The X coordinate of the endpoint of the curve.
*
* @param {!number} y
* The Y coordinate of the endpoint of the curve.
*/
this.curveTo = function(cp1x, cp1y, cp2x, cp2y, x, y) {
// Start a new path if current path is closed
if (pathClosed) {
context.beginPath();
pathClosed = false;
}
if (layer.autosize) fitRect(x, y, 0, 0);
context.bezierCurveTo(cp1x, cp1y, cp2x, cp2y, x, y);
};
/**
* Closes the current path by connecting the end point with the start
* point (if any) with a straight line.
*/
this.close = function() {
context.closePath();
pathClosed = true;
};
/**
* Add the specified rectangle to the current path.
*
* @param {!number} x
* The X coordinate of the upper-left corner of the rectangle to draw.
*
* @param {!number} y
* The Y coordinate of the upper-left corner of the rectangle to draw.
*
* @param {!number} w
* The width of the rectangle to draw.
*
* @param {!number} h
* The height of the rectangle to draw.
*/
this.rect = function(x, y, w, h) {
// Start a new path if current path is closed
if (pathClosed) {
context.beginPath();
pathClosed = false;
}
if (layer.autosize) fitRect(x, y, w, h);
context.rect(x, y, w, h);
};
/**
* 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.
*/
this.clip = function() {
// Set new clipping region
context.clip();
// Path now implicitly closed
pathClosed = true;
};
/**
* 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.
*
* @param {!string} cap
* The line cap style. Can be "round", "square", or "butt".
*
* @param {!string} join
* The line join style. Can be "round", "bevel", or "miter".
*
* @param {!number} thickness
* The line thickness in pixels.
*
* @param {!number} r
* The red component of the color to fill.
*
* @param {!number} g
* The green component of the color to fill.
*
* @param {!number} b
* The blue component of the color to fill.
*
* @param {!number} a
* The alpha component of the color to fill.
*/
this.strokeColor = function(cap, join, thickness, r, g, b, a) {
// Stroke with color
context.lineCap = cap;
context.lineJoin = join;
context.lineWidth = thickness;
context.strokeStyle = "rgba(" + r + "," + g + "," + b + "," + a/255.0 + ")";
context.stroke();
empty = false;
// Path now implicitly closed
pathClosed = true;
};
/**
* 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.
*
* @param {!number} r
* The red component of the color to fill.
*
* @param {!number} g
* The green component of the color to fill.
*
* @param {!number} b
* The blue component of the color to fill.
*
* @param {!number} a
* The alpha component of the color to fill.
*/
this.fillColor = function(r, g, b, a) {
// Fill with color
context.fillStyle = "rgba(" + r + "," + g + "," + b + "," + a/255.0 + ")";
context.fill();
empty = false;
// Path now implicitly closed
pathClosed = true;
};
/**
* 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.
*
* @param {!string} cap
* The line cap style. Can be "round", "square", or "butt".
*
* @param {!string} join
* The line join style. Can be "round", "bevel", or "miter".
*
* @param {!number} thickness
* The line thickness in pixels.
*
* @param {!Guacamole.Layer} srcLayer
* The layer to use as a repeating pattern within the stroke.
*/
this.strokeLayer = function(cap, join, thickness, srcLayer) {
// Stroke with image data
context.lineCap = cap;
context.lineJoin = join;
context.lineWidth = thickness;
context.strokeStyle = context.createPattern(
srcLayer.getCanvas(),
"repeat"
);
context.stroke();
empty = false;
// Path now implicitly closed
pathClosed = true;
};
/**
* 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.
*
* @param {!Guacamole.Layer} srcLayer
* The layer to use as a repeating pattern within the fill.
*/
this.fillLayer = function(srcLayer) {
// Fill with image data
context.fillStyle = context.createPattern(
srcLayer.getCanvas(),
"repeat"
);
context.fill();
empty = false;
// Path now implicitly closed
pathClosed = true;
};
/**
* Push current layer state onto stack.
*/
this.push = function() {
// Save current state onto stack
context.save();
stackSize++;
};
/**
* Pop layer state off stack.
*/
this.pop = function() {
// Restore current state from stack
if (stackSize > 0) {
context.restore();
stackSize--;
}
};
/**
* Reset the layer, clearing the stack, the current path, and any transform
* matrix.
*/
this.reset = function() {
// Clear stack
while (stackSize > 0) {
context.restore();
stackSize--;
}
// Restore to initial state
context.restore();
context.save();
// Clear path
context.beginPath();
pathClosed = false;
};
/**
* Sets the given affine transform (defined with six values from the
* transform's matrix).
*
* @param {!number} a
* The first value in the affine transform's matrix.
*
* @param {!number} b
* The second value in the affine transform's matrix.
*
* @param {!number} c
* The third value in the affine transform's matrix.
*
* @param {!number} d
* The fourth value in the affine transform's matrix.
*
* @param {!number} e
* The fifth value in the affine transform's matrix.
*
* @param {!number} f
* The sixth value in the affine transform's matrix.
*/
this.setTransform = function(a, b, c, d, e, f) {
context.setTransform(
a, b, c,
d, e, f
/*0, 0, 1*/
);
};
/**
* Applies the given affine transform (defined with six values from the
* transform's matrix).
*
* @param {!number} a
* The first value in the affine transform's matrix.
*
* @param {!number} b
* The second value in the affine transform's matrix.
*
* @param {!number} c
* The third value in the affine transform's matrix.
*
* @param {!number} d
* The fourth value in the affine transform's matrix.
*
* @param {!number} e
* The fifth value in the affine transform's matrix.
*
* @param {!number} f
* The sixth value in the affine transform's matrix.
*/
this.transform = function(a, b, c, d, e, f) {
context.transform(
a, b, c,
d, e, f
/*0, 0, 1*/
);
};
/**
* 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.
*
* @param {!number} mask
* The channel mask for future operations on this Layer.
*/
this.setChannelMask = function(mask) {
context.globalCompositeOperation = compositeOperation[mask];
};
/**
* 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.
*
* @param {!number} limit
* The miter limit for stroke operations using the miter join.
*/
this.setMiterLimit = function(limit) {
context.miterLimit = limit;
};
// Initialize canvas dimensions
resize(width, height);
// Explicitly render canvas below other elements in the layer (such as
// child layers). Chrome and others may fail to render layers properly
// without this.
canvas.style.zIndex = -1;
};
/**
* Channel mask for the composite operation "rout".
*
* @type {!number}
*/
Guacamole.Layer.ROUT = 0x2;
/**
* Channel mask for the composite operation "atop".
*
* @type {!number}
*/
Guacamole.Layer.ATOP = 0x6;
/**
* Channel mask for the composite operation "xor".
*
* @type {!number}
*/
Guacamole.Layer.XOR = 0xA;
/**
* Channel mask for the composite operation "rover".
*
* @type {!number}
*/
Guacamole.Layer.ROVER = 0xB;
/**
* Channel mask for the composite operation "over".
*
* @type {!number}
*/
Guacamole.Layer.OVER = 0xE;
/**
* Channel mask for the composite operation "plus".
*
* @type {!number}
*/
Guacamole.Layer.PLUS = 0xF;
/**
* Channel mask for the composite operation "rin".
* Beware that WebKit-based browsers may leave the contents of the destination
* layer where the source layer is transparent, despite the definition of this
* operation.
*
* @type {!number}
*/
Guacamole.Layer.RIN = 0x1;
/**
* Channel mask for the composite operation "in".
* Beware that WebKit-based browsers may leave the contents of the destination
* layer where the source layer is transparent, despite the definition of this
* operation.
*
* @type {!number}
*/
Guacamole.Layer.IN = 0x4;
/**
* Channel mask for the composite operation "out".
* Beware that WebKit-based browsers may leave the contents of the destination
* layer where the source layer is transparent, despite the definition of this
* operation.
*
* @type {!number}
*/
Guacamole.Layer.OUT = 0x8;
/**
* Channel mask for the composite operation "ratop".
* Beware that WebKit-based browsers may leave the contents of the destination
* layer where the source layer is transparent, despite the definition of this
* operation.
*
* @type {!number}
*/
Guacamole.Layer.RATOP = 0x9;
/**
* Channel mask for the composite operation "src".
* Beware that WebKit-based browsers may leave the contents of the destination
* layer where the source layer is transparent, despite the definition of this
* operation.
*
* @type {!number}
*/
Guacamole.Layer.SRC = 0xC;
/**
* Represents a single pixel of image data. All components have a minimum value
* of 0 and a maximum value of 255.
*
* @constructor
*
* @param {!number} r
* The red component of this pixel.
*
* @param {!number} g
* The green component of this pixel.
*
* @param {!number} b
* The blue component of this pixel.
*
* @param {!number} a
* The alpha component of this pixel.
*/
Guacamole.Layer.Pixel = function(r, g, b, a) {
/**
* The red component of this pixel, where 0 is the minimum value,
* and 255 is the maximum.
*
* @type {!number}
*/
this.red = r;
/**
* The green component of this pixel, where 0 is the minimum value,
* and 255 is the maximum.
*
* @type {!number}
*/
this.green = g;
/**
* The blue component of this pixel, where 0 is the minimum value,
* and 255 is the maximum.
*
* @type {!number}
*/
this.blue = b;
/**
* The alpha component of this pixel, where 0 is the minimum value,
* and 255 is the maximum.
*
* @type {!number}
*/
this.alpha = a;
};