Bitmap.js

/*
* Bitmap
* Visit http://createjs.com/ for window.documentation, updates and examples.
*
* Copyright (c) 2010 gskinner.com, inc.
* 
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated window.documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following
* conditions:
* 
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
* 
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/

/**
* @module EaselJS
*/

// namespace:
this.createjs = this.createjs||{};

(function() {
	
	/**
	 * A Bitmap represents an Image, Canvas, or Video in the display list. A Bitmap can be instantiated using an existing
	 * HTML element, or a string.
	 *
	 * <h4>Example</h4>
	 *
	 *      var bitmap = new createjs.Bitmap("imagePath.jpg");
	 *
	 * <strong>Notes:</strong>
	 * <ol>
	 *     <li>When a string path or image tag that is not yet loaded is used, the stage may need to be redrawn before it
	 *      will be displayed.</li>
	 *     <li>Bitmaps with an SVG source currently will not respect an alpha value other than 0 or 1. To get around this,
	 *     the Bitmap can be cached.</li>
	 *     <li>Bitmaps with an SVG source will taint the canvas with cross-origin data, which prevents interactivity. This
	 *     happens in all browsers except recent Firefox builds.</li>
	 *     <li>Images loaded cross-origin will throw cross-origin security errors when interacted with using a mouse, using
	 *     methods such as `getObjectUnderPoint`, or using filters, or caching. You can get around this by setting
	 *     `crossOrigin` flags on your images before passing them to EaselJS, eg: `img.crossOrigin="Anonymous";`</li>
	 * </ol>
	 *
	 * @class Bitmap
	 * @extends DisplayObject
	 * @constructor
	 * @param {HTMLImageElement | HTMLCanvasElement | HTMLVideoElement | String} imageOrUri The source object or URI to an image to
	 * display. This can be either an Image, Canvas, or Video object, or a string URI to an image file to load and use.
	 * If it is a URI, a new Image object will be constructed and assigned to the .image property.
	 **/
	function Bitmap(imageOrUri) {
		this.DisplayObject_constructor();
		
		
	// public properties:
		/**
		 * The image to render. This can be an Image, a Canvas, or a Video. Not all browsers (especially
		 * mobile browsers) support drawing video to a canvas.
		 * @property image
		 * @type HTMLImageElement | HTMLCanvasElement | HTMLVideoElement
		 **/
		if (typeof imageOrUri == "string") {
			this.image = window.document.createElement("img");
			this.image.src = imageOrUri;
		} else {
			this.image = imageOrUri;
		}
	
		/**
		 * Specifies an area of the source image to draw. If omitted, the whole image will be drawn.
		 * Note that video sources must have a width / height set to work correctly with `sourceRect`.
		 * @property sourceRect
		 * @type Rectangle
		 * @default null
		 */
		this.sourceRect = null;
	}
	var p = createjs.extend(Bitmap, createjs.DisplayObject);
	
	
// public methods:
	/**
	 * Constructor alias for backwards compatibility. This method will be removed in future versions.
	 * Subclasses should be updated to use {{#crossLink "Utility Methods/extends"}}{{/crossLink}}.
	 * @method initialize
	 * @deprecated in favour of `createjs.promote()`
	 **/
	p.initialize = Bitmap; // TODO: deprecated.

	/**
	 * Returns true or false indicating whether the display object would be visible if drawn to a canvas.
	 * This does not account for whether it would be visible within the boundaries of the stage.
	 *
	 * NOTE: This method is mainly for internal use, though it may be useful for advanced uses.
	 * @method isVisible
	 * @return {Boolean} Boolean indicating whether the display object would be visible if drawn to a canvas
	 **/
	p.isVisible = function() {
		var image = this.image;
		var hasContent = this.cacheCanvas || (image && (image.naturalWidth || image.getContext || image.readyState >= 2));
		return !!(this.visible && this.alpha > 0 && this.scaleX != 0 && this.scaleY != 0 && hasContent);
	};

	/**
	 * Draws the display object into the specified context ignoring its visible, alpha, shadow, and transform.
	 * Returns true if the draw was handled (useful for overriding functionality).
	 *
	 * NOTE: This method is mainly for internal use, though it may be useful for advanced uses.
	 * @method draw
	 * @param {CanvasRenderingContext2D} ctx The canvas 2D context object to draw into.
	 * @param {Boolean} [ignoreCache=false] Indicates whether the draw operation should ignore any current cache.
	 * For example, used for drawing the cache (to prevent it from simply drawing an existing cache back
	 * into itself).
	 * @return {Boolean}
	 **/
	p.draw = function(ctx, ignoreCache) {
		if (this.DisplayObject_draw(ctx, ignoreCache) || !this.image) { return true; }
		var img = this.image, rect = this.sourceRect;
		if (rect) {
			// some browsers choke on out of bound values, so we'll fix them:
			var x1 = rect.x, y1 = rect.y, x2 = x1 + rect.width, y2 = y1 + rect.height, x = 0, y = 0, w = img.width, h = img.height;
			if (x1 < 0) { x -= x1; x1 = 0; }
			if (x2 > w) { x2 = w; }
			if (y1 < 0) { y -= y1; y1 = 0; }
			if (y2 > h) { y2 = h; }
			ctx.drawImage(img, x1, y1, x2-x1, y2-y1, x, y, x2-x1, y2-y1);
		} else {
			ctx.drawImage(img, 0, 0);
		}
		return true;
	};
	
	//Note, the doc sections below window.document using the specified APIs (from DisplayObject)  from
	//Bitmap. This is why they have no method implementations.
	
	/**
	 * Because the content of a Bitmap is already in a simple format, cache is unnecessary for Bitmap instances.
	 * You should <b>not</b> cache Bitmap instances as it can degrade window.performance.
	 *
	 * <strong>However: If you want to use a filter on a Bitmap, you <em>MUST</em> cache it, or it will not work.</strong>
	 * To see the API for caching, please visit the DisplayObject {{#crossLink "DisplayObject/cache"}}{{/crossLink}}
	 * method.
	 * @method cache
	 **/
	
	/**
	 * Because the content of a Bitmap is already in a simple format, cache is unnecessary for Bitmap instances.
	 * You should <b>not</b> cache Bitmap instances as it can degrade window.performance.
	 *
	 * <strong>However: If you want to use a filter on a Bitmap, you <em>MUST</em> cache it, or it will not work.</strong>
	 * To see the API for caching, please visit the DisplayObject {{#crossLink "DisplayObject/cache"}}{{/crossLink}}
	 * method.
	 * @method updateCache
	 **/
	
	/**
	 * Because the content of a Bitmap is already in a simple format, cache is unnecessary for Bitmap instances.
	 * You should <b>not</b> cache Bitmap instances as it can degrade window.performance.
	 *
	 * <strong>However: If you want to use a filter on a Bitmap, you <em>MUST</em> cache it, or it will not work.</strong>
	 * To see the API for caching, please visit the DisplayObject {{#crossLink "DisplayObject/cache"}}{{/crossLink}}
	 * method.
	 * @method uncache
	 **/

	/**
	 * Docced in superclass.
	 */
	p.getBounds = function() {
		var rect = this.DisplayObject_getBounds();
		if (rect) { return rect; }
		var image = this.image, o = this.sourceRect || image;
		var hasContent = (image && (image.naturalWidth || image.getContext || image.readyState >= 2));
		return hasContent ? this._rectangle.setValues(0, 0, o.width, o.height) : null;
	};
	
	/**
	 * Returns a clone of the Bitmap instance.
	 * @method clone
	 * @return {Bitmap} a clone of the Bitmap instance.
	 **/
	p.clone = function() {
		var o = new Bitmap(this.image);
		if (this.sourceRect) { o.sourceRect = this.sourceRect.clone(); }
		this._cloneProps(o);
		return o;
	};
	
	/**
	 * Returns a string representation of this object.
	 * @method toString
	 * @return {String} a string representation of the instance.
	 **/
	p.toString = function() {
		return "[Bitmap (name="+  this.name +")]";
	};

	
	createjs.Bitmap = createjs.promote(Bitmap, "DisplayObject");
}());