scrawl-canvas

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class="source" href="styles.html"> ./source/mixin/styles.js </a> <a class="source" href="tween.html"> ./source/mixin/tween.js </a> </div> </div> </li> </ul> <ul class="sections"> <li id="section-1"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-1">§</a> </div> <h1 id="asset-mixin">Asset mixin</h1> <p>The asset factories - <a href="../factory/imageAsset.html">ImageAsset</a>, <a href="../factory/spriteAsset.html">SpriteAsset</a>, and <a href="../factory/videoAsset.html">VideoAsset</a> - are wrappers around images and videos which can either be pulled from the current document (DOM-based assets) or fetched from the server using an URL address.</p> <ul> <li>Assets are used (consumed) by Picture entitys and Pattern styles.</li> <li>This mixin adds functionality common to all three factories to them as part of their initialization.</li> <li>The mixin is also used by the <a href="../factory/cell.html">Cell</a> factory, as <canvas> elements can be used by Picture entitys and Pattern styles as their image sources.</li> </ul> </div> </li> <li id="section-2"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-2">§</a> </div> <p>Assets can be loaded into scrawl using dedicated import and create functions:</p> <ul> <li><code>scrawl.importImage</code></li> <li><code>scrawl.importDomImage</code></li> <li><code>scrawl.importDomVideo</code></li> <li><code>scrawl.importVideo</code></li> <li><code>scrawl.importMediaStream</code></li> <li><code>scrawl.importSprite</code></li> <li><code>scrawl.createImageFromCell</code></li> <li><code>scrawl.createImageFromGroup</code></li> <li><code>scrawl.createImageFromEntity</code></li> </ul> <p>Assets will also be created when Picture entitys or Pattern styles are defined using a ‘scrawl.make’ function (<code>makePicture</code>, <code>makePattern</code>), or updated with the <code>set</code> function, where the <em>imageSource</em>, <em>videoSource</em> or <em>spriteSource</em> key in the argument object has been set to a valid URL path string.</p> <p>Be aware that <strong>loading assets takes time!</strong> </p> <ul> <li>Performing a single render operation immediately after defining or updating a Picture entity or Pattern style will almost certainly fail to render the expected image/sprite/video in the canvas. </li> <li>The load functionality is asynchronous (using Promises). </li> <li>To display the resulting images in the canvas, it needs to be running an animation object (for instance, <strong>scrawl.makeRender</strong>) so that updates appear as soon as they have loaded, as part of the animation’s Display cycle functionality.</li> </ul> </div> </li> <li id="section-3"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-3">§</a> </div> <h4 id="imports">Imports</h4> </div> <div class="content"><div class='highlight'><pre><span class="hljs-keyword">import</span> { mergeOver, pushUnique, λ<span class="hljs-literal">null</span>, Ωempty } <span class="hljs-keyword">from</span> <span class="hljs-string">'../core/utilities.js'</span>;</pre></div></div> </li> <li id="section-4"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-4">§</a> </div> <h4 id="export-function">Export function</h4> </div> <div class="content"><div class='highlight'><pre><span class="hljs-keyword">export</span> <span class="hljs-keyword">default</span> <span class="hljs-keyword">function</span> (<span class="hljs-params">P = Ωempty</span>) {</pre></div></div> </li> <li id="section-5"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-5">§</a> </div> <h4 id="shared-attributes">Shared attributes</h4> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">let</span> defaultAttributes = {</pre></div></div> </li> <li id="section-6"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-6">§</a> </div> <p><strong>sourceLoaded</strong> - A flag to indicate that the source image or video has completed sufficient loading (or streaming) to be usefully consumed by Picture entitys and Pattern styles.</p> <ul> <li><strong>Note that this flag cannot be directly or indirectly set.</strong> The asset wrapper’s functionality will handle the checking of load progress, and notify its subscribers that the load has completed as-and-when required.</li> </ul> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-attr">sourceLoaded</span>: <span class="hljs-literal">false</span>,</pre></div></div> </li> <li id="section-7"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-7">§</a> </div> <p><strong>source</strong> - A handle to the DOM element supplying the image - either an <img>, <video> or <canvas> element.</p> <ul> <li>Note that the <em><strong>Web Canvas API does not support</strong></em> using the <picture> element as a legitimate image source. </li> <li>However most browsers allow the <img> element to use <strong>srcset</strong> and <strong>sizes</strong> attributes, which will give them the same type of functionality as picture elements - for example to determine the most appropriately sized image file for the browser/device’s viewport dimensions.</li> <li>Asset wrappers will detect, and handle actions required, if/when a browser decides to download a new image file, to update the <img> element with a more detailed image, for instance when the browser viewport changes its dimensions, or a device is rotated from portrait to landscape viewing.</li> <li>The web Canvas API claims that <strong>SVG</strong> images can be used as legitimate image sources for the canvas element. To make this happen, the SVG file needs to be set as the src attribute of an <img> element, and the resulting image will be entirely static, and rasterized! </li> <li>For this reason, we don’t recommend trying to use SVG files for canvas image sources; instead, the SVG can be included in a Scrawl-canvas display by adding it - as an <svg> element - to a Scrawl-canvas stack (see Demo DOM-003 for an example of this approach).</li> <li><img> elements using an animated GIF as their src are not supported.</li> <li><em><strong>Be aware that this attribute cannot be directly or indirectly set.</strong></em> Scrawl-canvas will update it as part of its asset loading and wrapper creation functionality.</li> </ul> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-attr">source</span>: <span class="hljs-literal">null</span>,</pre></div></div> </li> <li id="section-8"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-8">§</a> </div> <p><strong>subscribers</strong> - An Array containing the Picture entity and Pattern style Objects, who wish to use the asset as their source. </p> <ul> <li>Pictures and Patterns may subscribe to a maximum of ONE asset at any given time, though they may set/update that asset subscription to a different asset whenever required (which involves unsubscribing their existing asset).</li> <li><em><strong>Note that the contents of this Array cannot be directly or indirectly set.</strong></em> Picture entitys and Pattern styles will subscribe and unsubscribe to an asset as part of their source acquisition functionality (via the asset wrapper’s <strong>subscribe</strong> and <strong>unsubscribe</strong> functions).</li> </ul> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-attr">subscribers</span>: <span class="hljs-literal">null</span>, }; P.<span class="hljs-property">defs</span> = <span class="hljs-title function_">mergeOver</span>(P.<span class="hljs-property">defs</span>, defaultAttributes);</pre></div></div> </li> <li id="section-9"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-9">§</a> </div> <h4 id="packet-management">Packet management</h4> <p>Assets do not include their source images (or videos!) in their packet output. They do include the String name values of each of their subscribers.</p> </div> <div class="content"><div class='highlight'><pre> P.<span class="hljs-property">packetExclusions</span> = <span class="hljs-title function_">pushUnique</span>(P.<span class="hljs-property">packetExclusions</span>, [<span class="hljs-string">'sourceLoaded'</span>, <span class="hljs-string">'source'</span>, <span class="hljs-string">'subscribers'</span>]); P.<span class="hljs-property">finalizePacketOut</span> = <span class="hljs-keyword">function</span> (<span class="hljs-params">copy, items</span>) { <span class="hljs-keyword">if</span> (<span class="hljs-variable language_">this</span>.<span class="hljs-property">subscribers</span> && <span class="hljs-variable language_">this</span>.<span class="hljs-property">subscribers</span>.<span class="hljs-property">length</span>) { copy.<span class="hljs-property">subscribers</span> = <span class="hljs-variable language_">this</span>.<span class="hljs-property">subscribers</span>.<span class="hljs-title function_">map</span>(<span class="hljs-function"><span class="hljs-params">sub</span> =></span> sub.<span class="hljs-property">name</span>); } <span class="hljs-keyword">return</span> copy; };</pre></div></div> </li> <li id="section-10"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-10">§</a> </div> <h4 id="clone-management">Clone management</h4> <p>No additional clone functionality defined here</p> </div> </li> <li id="section-11"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-11">§</a> </div> <h4 id="kill-management">Kill management</h4> </div> <div class="content"><div class='highlight'><pre> P.<span class="hljs-property">kill</span> = <span class="hljs-keyword">function</span> (<span class="hljs-params">removeDomEntity = <span class="hljs-literal">false</span></span>) { <span class="hljs-keyword">if</span> (removeDomEntity && <span class="hljs-variable language_">this</span>.<span class="hljs-property">source</span>) <span class="hljs-variable language_">this</span>.<span class="hljs-property">source</span>.<span class="hljs-title function_">remove</span>(); <span class="hljs-keyword">return</span> <span class="hljs-variable language_">this</span>.<span class="hljs-title function_">deregister</span>(); };</pre></div></div> </li> <li id="section-12"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-12">§</a> </div> <h4 id="get-set-deltaset">Get, Set, deltaSet</h4> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">let</span> G = P.<span class="hljs-property">getters</span>, S = P.<span class="hljs-property">setters</span>, D = P.<span class="hljs-property">deltaSetters</span>;</pre></div></div> </li> <li id="section-13"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-13">§</a> </div> <p><strong>source</strong> - imageAsset.js and videoAsset.js overwrite this function, thus only put here so cell.js also gains the function - which I don’t think it will ever need as cells ARE their own source.</p> </div> <div class="content"><div class='highlight'><pre> S.<span class="hljs-property">source</span> = <span class="hljs-keyword">function</span> (<span class="hljs-params">item</span>) { <span class="hljs-keyword">if</span> (item) {</pre></div></div> </li> <li id="section-14"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-14">§</a> </div> <p>No action required for Canvas objects as they don’t have a source; they ARE the source!</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">if</span> (<span class="hljs-variable language_">this</span>.<span class="hljs-property">sourceLoaded</span>) <span class="hljs-variable language_">this</span>.<span class="hljs-title function_">notifySubscribers</span>(); } };</pre></div></div> </li> <li id="section-15"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-15">§</a> </div> <p><strong>subscribers</strong> - we disable the ability to set the subscribers Array directly. Picture entitys and Pattern styles will manage their subscription to the asset using their subscribe() and unsubscribe() functions.</p> </div> <div class="content"><div class='highlight'><pre> S.<span class="hljs-property">subscribers</span> = λ<span class="hljs-literal">null</span>;</pre></div></div> </li> <li id="section-16"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-16">§</a> </div> <h4 id="prototype-functions">Prototype functions</h4> </div> </li> <li id="section-17"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-17">§</a> </div> <p><code>assetConstructor</code> - Common actions required by <strong>imageAsset</strong>, <strong>spriteAsset</strong>, and <strong>videoAsset</strong> factories as part if their instance constructor work.</p> </div> <div class="content"><div class='highlight'><pre> P.<span class="hljs-property">assetConstructor</span> = <span class="hljs-keyword">function</span> (<span class="hljs-params">items</span>) { <span class="hljs-variable language_">this</span>.<span class="hljs-title function_">makeName</span>(items.<span class="hljs-property">name</span>); <span class="hljs-variable language_">this</span>.<span class="hljs-title function_">register</span>(); <span class="hljs-variable language_">this</span>.<span class="hljs-property">subscribers</span> = []; <span class="hljs-variable language_">this</span>.<span class="hljs-title function_">set</span>(<span class="hljs-variable language_">this</span>.<span class="hljs-property">defs</span>); <span class="hljs-variable language_">this</span>.<span class="hljs-title function_">set</span>(items); <span class="hljs-keyword">if</span> (items.<span class="hljs-property">subscribe</span>) <span class="hljs-variable language_">this</span>.<span class="hljs-property">subscribers</span>.<span class="hljs-title function_">push</span>(items.<span class="hljs-property">subscribe</span>); <span class="hljs-keyword">return</span> <span class="hljs-variable language_">this</span>; };</pre></div></div> </li> <li id="section-18"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-18">§</a> </div> <h5 id="subscribe-and-unsubscribe-to-an-asset">Subscribe and unsubscribe to an asset</h5> <p><code>subscribe</code></p> </div> <div class="content"><div class='highlight'><pre> P.<span class="hljs-property">subscribe</span> = <span class="hljs-keyword">function</span> (<span class="hljs-params">sub</span>) { <span class="hljs-keyword">if</span> (sub && sub.<span class="hljs-property">name</span>) { <span class="hljs-keyword">let</span> name = sub.<span class="hljs-property">name</span>; <span class="hljs-keyword">if</span> (<span class="hljs-variable language_">this</span>.<span class="hljs-property">subscribers</span>.<span class="hljs-title function_">every</span>(<span class="hljs-function"><span class="hljs-params">item</span> =></span> item.<span class="hljs-property">name</span> !== name)) <span class="hljs-variable language_">this</span>.<span class="hljs-title function_">subscribeAction</span>(sub); } };</pre></div></div> </li> <li id="section-19"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-19">§</a> </div> <p><code>subscribeAction</code> - separated out because cells handle things differently (they ARE the source)</p> </div> <div class="content"><div class='highlight'><pre> P.<span class="hljs-property">subscribeAction</span> = <span class="hljs-keyword">function</span> (<span class="hljs-params">sub</span>) { <span class="hljs-keyword">if</span> (sub) { <span class="hljs-variable language_">this</span>.<span class="hljs-property">subscribers</span>.<span class="hljs-title function_">push</span>(sub); sub.<span class="hljs-property">asset</span> = <span class="hljs-variable language_">this</span>; sub.<span class="hljs-property">source</span> = <span class="hljs-variable language_">this</span>.<span class="hljs-property">source</span>; <span class="hljs-variable language_">this</span>.<span class="hljs-title function_">notifySubscriber</span>(sub); } };</pre></div></div> </li> <li id="section-20"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-20">§</a> </div> <p><code>unsubscribe</code></p> </div> <div class="content"><div class='highlight'><pre> P.<span class="hljs-property">unsubscribe</span> = <span class="hljs-keyword">function</span> (<span class="hljs-params">sub</span>) { <span class="hljs-keyword">if</span> (sub && sub.<span class="hljs-property">name</span>) { <span class="hljs-keyword">let</span> name = sub.<span class="hljs-property">name</span>, index = <span class="hljs-variable language_">this</span>.<span class="hljs-property">subscribers</span>.<span class="hljs-title function_">findIndex</span>(<span class="hljs-function"><span class="hljs-params">item</span> =></span> item.<span class="hljs-property">name</span> === name); <span class="hljs-keyword">if</span> (index >= <span class="hljs-number">0</span>) { sub.<span class="hljs-property">source</span> = <span class="hljs-literal">null</span>; sub.<span class="hljs-property">asset</span> = <span class="hljs-literal">null</span>; sub.<span class="hljs-property">sourceNaturalHeight</span> = <span class="hljs-number">0</span>; sub.<span class="hljs-property">sourceNaturalWidth</span> = <span class="hljs-number">0</span>; sub.<span class="hljs-property">sourceLoaded</span> = <span class="hljs-literal">false</span>; <span class="hljs-variable language_">this</span>.<span class="hljs-property">subscribers</span>.<span class="hljs-title function_">splice</span>(index, <span class="hljs-number">1</span>) } } };</pre></div></div> </li> <li id="section-21"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-21">§</a> </div> <p><code>notifySubscribers</code>, <code>notifySubscriber</code> - Subscriber notification in the asset factories will happen when something changes with the image. Changes vary across the different types of asset:</p> <ul> <li><strong>imageAsset</strong> - needs to update its subscribers when an image completes loading - or, for <img> sources with srcset (and sizes) attributes, when the image completes a reload of its source data.</li> <li><strong>spriteAsset</strong> - will also update its subscribers each time it moves to a new sprite image frame, if the sprite is being animated</li> <li><strong>videoAsset</strong> - will update its subscribers for every RAF tick while the video is playing, or if the video is halted and seeks to a different time in the video play stream.</li> <li><strong>noiseAsset</strong> - will update its subscribers when any of its attributes changes (Note: factory/noiseAsset.js overwrites these functions).</li> <li><strong>reactionDiffusionAsset</strong> - will update its subscribers when any of its attributes changes (Note: factory/reactionDiffusionAsset.js overwrites these functions).</li> </ul> <p>All notifications are push; the notification is achieved by setting various attributes and flags in each subscriber.</p> </div> <div class="content"><div class='highlight'><pre> P.<span class="hljs-property">notifySubscribers</span> = <span class="hljs-keyword">function</span> (<span class="hljs-params"></span>) { <span class="hljs-variable language_">this</span>.<span class="hljs-property">subscribers</span>.<span class="hljs-title function_">forEach</span>(<span class="hljs-function"><span class="hljs-params">sub</span> =></span> <span class="hljs-variable language_">this</span>.<span class="hljs-title function_">notifySubscriber</span>(sub), <span class="hljs-variable language_">this</span>); }; P.<span class="hljs-property">notifySubscriber</span> = <span class="hljs-keyword">function</span> (<span class="hljs-params">sub</span>) { sub.<span class="hljs-property">sourceNaturalWidth</span> = <span class="hljs-variable language_">this</span>.<span class="hljs-property">sourceNaturalWidth</span>; sub.<span class="hljs-property">sourceNaturalHeight</span> = <span class="hljs-variable language_">this</span>.<span class="hljs-property">sourceNaturalHeight</span>; sub.<span class="hljs-property">sourceLoaded</span> = <span class="hljs-variable language_">this</span>.<span class="hljs-property">sourceLoaded</span>; sub.<span class="hljs-property">source</span> = <span class="hljs-variable language_">this</span>.<span class="hljs-property">source</span>; sub.<span class="hljs-property">dirtyImage</span> = <span class="hljs-literal">true</span>; sub.<span class="hljs-property">dirtyCopyStart</span> = <span class="hljs-literal">true</span>; sub.<span class="hljs-property">dirtyCopyDimensions</span> = <span class="hljs-literal">true</span>; sub.<span class="hljs-property">dirtyImageSubscribers</span> = <span class="hljs-literal">true</span>; sub.<span class="hljs-property">dirtyFilterIdentifier</span> = <span class="hljs-literal">true</span>; };</pre></div></div> </li> <li id="section-22"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-22">§</a> </div> <p>Return the prototype</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">return</span> P; };</pre></div></div> </li> </ul> </div> </body> </html>