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guacamole-client/guacamole-common-js/src/main/resources/layer.js

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JavaScript

/*
* Guacamole - Clientless Remote Desktop
* Copyright (C) 2010 Michael Jumper
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
// Guacamole namespace
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
*/
var layer = this;
/**
* The canvas element backing this Layer.
* @private
*/
var display = document.createElement("canvas");
/**
* The 2D display context of the canvas element backing this Layer.
* @private
*/
var displayContext = display.getContext("2d");
displayContext.save();
/**
* The queue of all pending Tasks. Tasks will be run in order, with new
* tasks added at the end of the queue and old tasks removed from the
* front of the queue (FIFO).
* @private
*/
var tasks = new Array();
/**
* Map of all Guacamole channel masks to HTML5 canvas composite operation
* names. Not all channel mask combinations are currently implemented.
* @private
*/
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 without testing the
* new size. This function should only be used internally.
*
* @private
* @param {Number} newWidth The new width to assign to this Layer.
* @param {Number} newHeight The new height to assign to this Layer.
*/
function resize(newWidth, newHeight) {
// Only preserve old data if width/height are both non-zero
var oldData = null;
if (width != 0 && height != 0) {
// Create canvas and context for holding old data
oldData = document.createElement("canvas");
oldData.width = width;
oldData.height = height;
var oldDataContext = oldData.getContext("2d");
// Copy image data from current
oldDataContext.drawImage(display,
0, 0, width, height,
0, 0, width, height);
}
// Resize canvas
display.width = newWidth;
display.height = newHeight;
// Redraw old data, if any
if (oldData)
displayContext.drawImage(oldData,
0, 0, width, height,
0, 0, width, height);
width = newWidth;
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 the rectangle to fit.
* @param {Number} h The height of the 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 > width)
resizeWidth = opBoundX;
else
resizeWidth = width;
// Determine max height
var resizeHeight;
if (opBoundY > height)
resizeHeight = opBoundY;
else
resizeHeight = height;
// Resize if necessary
if (resizeWidth != width || resizeHeight != height)
resize(resizeWidth, resizeHeight);
}
/**
* A container for an task handler. Each operation which must be ordered
* is associated with a Task that goes into a task queue. Tasks in this
* queue are executed in order once their handlers are set, while Tasks
* without handlers block themselves and any following Tasks from running.
*
* @constructor
* @private
* @param {function} taskHandler The function to call when this task
* runs, if any.
*/
function Task(taskHandler) {
/**
* The handler this Task is associated with, if any.
*
* @type function
*/
this.handler = taskHandler;
}
/**
* If no tasks are pending or running, run the provided handler immediately,
* if any. Otherwise, schedule a task to run immediately after all currently
* running or pending tasks are complete.
*
* @private
* @param {function} handler The function to call when possible, if any.
* @returns {Task} The Task created and added to the queue for future
* running, if any, or null if the handler was run
* immediately and no Task needed to be created.
*/
function scheduleTask(handler) {
// If no pending tasks, just call (if available) and exit
if (layer.isReady() && handler != null) {
handler();
return null;
}
// If tasks are pending/executing, schedule a pending task
// and return a reference to it.
var task = new Task(handler);
tasks.push(task);
return task;
}
var tasksInProgress = false;
/**
* Run any Tasks which were pending but are now ready to run and are not
* blocked by other Tasks.
* @private
*/
function handlePendingTasks() {
if (tasksInProgress)
return;
tasksInProgress = true;
// Draw all pending tasks.
var task;
while ((task = tasks[0]) != null && task.handler) {
tasks.shift();
task.handler();
}
tasksInProgress = false;
}
/**
* 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().
*
* @example
* // Set autosize to true for all future operations
* layer.sync(function() {
* layer.autosize = true;
* });
*
* @type Boolean
* @default false
*/
this.autosize = false;
/**
* Returns the canvas element backing this Layer.
* @returns {Element} The canvas element backing this Layer.
*/
this.getCanvas = function() {
return display;
};
/**
* Returns whether this Layer is ready. A Layer is ready if it has no
* pending operations and no operations in-progress.
*
* @returns {Boolean} true if this Layer is ready, false otherwise.
*/
this.isReady = function() {
return tasks.length == 0;
};
/**
* 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) {
scheduleTask(function() {
if (newWidth != width || newHeight != 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 {Image} image The image to draw. Note that this is an Image
* object - not a URL.
*/
this.drawImage = function(x, y, image) {
scheduleTask(function() {
if (layer.autosize != 0) fitRect(x, y, image.width, image.height);
displayContext.drawImage(image, x, y);
});
};
/**
* Draws the image at the specified URL at the given coordinates. The image
* will be loaded automatically, and this and any future operations will
* wait for the image to finish loading.
*
* @param {Number} x The destination X coordinate.
* @param {Number} y The destination Y coordinate.
* @param {String} url The URL of the image to draw.
*/
this.draw = function(x, y, url) {
var task = scheduleTask(null);
var image = new Image();
image.onload = function() {
task.handler = function() {
if (layer.autosize != 0) fitRect(x, y, image.width, image.height);
displayContext.drawImage(image, x, y);
};
// As this task originally had no handler and may have blocked
// other tasks, handle any blocked tasks.
handlePendingTasks();
};
image.src = url;
};
/**
* Run an arbitrary function as soon as currently pending operations
* are complete.
*
* @param {function} handler The function to call once all currently
* pending operations are complete.
*/
this.sync = function(handler) {
scheduleTask(handler);
};
/**
* 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.copyRect = function(srcLayer, srcx, srcy, srcw, srch, x, y) {
function doCopyRect() {
if (layer.autosize != 0) fitRect(x, y, srcw, srch);
displayContext.drawImage(srcLayer.getCanvas(), srcx, srcy, srcw, srch, x, y, srcw, srch);
}
// If we ARE the source layer, no need to sync.
// Syncing would result in deadlock.
if (layer === srcLayer)
scheduleTask(doCopyRect);
// Otherwise synchronize copy operation with source layer
else {
var task = scheduleTask(null);
srcLayer.sync(function() {
task.handler = doCopyRect;
// As this task originally had no handler and may have blocked
// other tasks, handle any blocked tasks.
handlePendingTasks();
});
}
};
/**
* Clear the specified rectangle of image data.
*
* @param {Number} x The X coordinate of the upper-left corner of the
* rectangle to clear.
* @param {Number} y The Y coordinate of the upper-left corner of the
* rectangle to clear.
* @param {Number} w The width of the rectangle to clear.
* @param {Number} h The height of the rectangle to clear.
*/
this.clearRect = function(x, y, w, h) {
scheduleTask(function() {
if (layer.autosize != 0) fitRect(x, y, w, h);
displayContext.clearRect(x, y, w, h);
});
};
/**
* Fill the specified rectangle of image data with the specified color.
*
* @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.
* @param {Number} r The red component of the color of the rectangle.
* @param {Number} g The green component of the color of the rectangle.
* @param {Number} b The blue component of the color of the rectangle.
* @param {Number} a The alpha component of the color of the rectangle.
*/
this.drawRect = function(x, y, w, h, r, g, b, a) {
scheduleTask(function() {
if (layer.autosize != 0) fitRect(x, y, w, h);
displayContext.fillStyle = "rgba("
+ r + "," + g + "," + b + "," + a / 255 + ")";
displayContext.fillRect(x, y, w, h);
});
};
/**
* Clip all future drawing operations by the specified rectangle.
*
* @param {Number} x The X coordinate of the upper-left corner of the
* rectangle to use for the clipping region.
* @param {Number} y The Y coordinate of the upper-left corner of the
* rectangle to use for the clipping region.
* @param {Number} w The width of the rectangle to use for the clipping region.
* @param {Number} h The height of the rectangle to use for the clipping region.
*/
this.clipRect = function(x, y, w, h) {
scheduleTask(function() {
// Clear any current clipping region
displayContext.restore();
displayContext.save();
if (layer.autosize != 0) fitRect(x, y, w, h);
// Set new clipping region
displayContext.beginPath();
displayContext.rect(x, y, w, h);
displayContext.clip();
});
};
/**
* Provides the given filtering function with a writable snapshot of
* image data and the current width and height of the Layer.
*
* @param {function} filter A function which accepts an array of image
* data (as returned by the canvas element's
* display context's getImageData() function),
* the width of the Layer, and the height of the
* Layer as parameters, in that order. This
* function must accomplish its filtering by
* modifying the given image data array directly.
*/
this.filter = function(filter) {
scheduleTask(function() {
var imageData = displayContext.getImageData(0, 0, width, height);
filter(imageData.data, width, height);
displayContext.putImageData(imageData, 0, 0);
});
};
/**
* 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) {
scheduleTask(function() {
displayContext.globalCompositeOperation = compositeOperation[mask];
});
};
// Initialize canvas dimensions
display.width = width;
display.height = height;
};