scrawl-canvas

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class="sswrap "> <a class="ss" href="#section-1">§</a> </div> <h1 id="demo-canvas-052">Demo Canvas 052</h1> <p>Create and use a RawAsset object to modify an image asset</p> </div> </li> <li id="section-2"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-2">§</a> </div> <p><a href="../../demo/canvas-052.html">Run code</a></p> </div> <div class="content"><div class='highlight'><pre><span class="hljs-keyword">import</span> * <span class="hljs-keyword">as</span> scrawl <span class="hljs-keyword">from</span> <span class="hljs-string">'../source/scrawl.js'</span> <span class="hljs-keyword">import</span> { reportSpeed, addImageDragAndDrop } <span class="hljs-keyword">from</span> <span class="hljs-string">'./utilities.js'</span>;</pre></div></div> </li> <li id="section-3"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-3">§</a> </div> <h4 id="scene-setup">Scene setup</h4> </div> <div class="content"><div class='highlight'><pre><span class="hljs-keyword">let</span> canvas = scrawl.<span class="hljs-property">library</span>.<span class="hljs-property">artefact</span>.<span class="hljs-property">mycanvas</span>;</pre></div></div> </li> <li id="section-4"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-4">§</a> </div> <p>Magic numbers</p> </div> <div class="content"><div class='highlight'><pre><span class="hljs-keyword">const</span> dimension = <span class="hljs-number">600</span>;</pre></div></div> </li> <li id="section-5"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-5">§</a> </div> <p>Import image from DOM, and create Picture entity using it</p> </div> <div class="content"><div class='highlight'><pre>scrawl.<span class="hljs-title function_">importDomImage</span>(<span class="hljs-string">'.flowers'</span>);</pre></div></div> </li> <li id="section-6"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-6">§</a> </div> <p>We need a background image to act as the template on which we will draw</p> </div> <div class="content"><div class='highlight'><pre><span class="hljs-keyword">const</span> backgroundImage = scrawl.<span class="hljs-title function_">makePicture</span>({ <span class="hljs-attr">name</span>: <span class="hljs-string">'background'</span>, <span class="hljs-attr">asset</span>: <span class="hljs-string">'iris'</span>, <span class="hljs-attr">dimensions</span>: [dimension, dimension], <span class="hljs-attr">copyDimensions</span>: [<span class="hljs-string">'100%'</span>, <span class="hljs-string">'100%'</span>], <span class="hljs-attr">method</span>: <span class="hljs-string">'none'</span>, });</pre></div></div> </li> <li id="section-7"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-7">§</a> </div> <p>We will use Perlin noise to determine brush stroke length and direction</p> </div> <div class="content"><div class='highlight'><pre><span class="hljs-keyword">let</span> noiseAsset = scrawl.<span class="hljs-title function_">makeNoiseAsset</span>({ <span class="hljs-attr">name</span>: <span class="hljs-string">'my-noise-generator'</span>, <span class="hljs-attr">width</span>: dimension, <span class="hljs-attr">height</span>: dimension, <span class="hljs-attr">noiseEngine</span>: <span class="hljs-string">'improved-perlin'</span>, <span class="hljs-attr">scale</span>: <span class="hljs-number">80</span>, });</pre></div></div> </li> <li id="section-8"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-8">§</a> </div> <p>We’ll code up the painting effect in a RawAsset, which can then be used by Picture entitys, Pattern styles, and filters</p> </div> <div class="content"><div class='highlight'><pre><span class="hljs-keyword">let</span> impressionistAsset = scrawl.<span class="hljs-title function_">makeRawAsset</span>({ <span class="hljs-attr">name</span>: <span class="hljs-string">'pretend-van-gogh'</span>, <span class="hljs-attr">userAttributes</span>: [{</pre></div></div> </li> <li id="section-9"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-9">§</a> </div> <p><strong>lineWidth</strong>, <strong>lineLengthMultiplier</strong>, <strong>lineLengthStart</strong>, <strong>linesToAdd</strong>, <strong>lineBlend</strong>, <strong>lineOpacity</strong> - some brush attributes that we’ll allow the user to modify in real time.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-attr">key</span>: <span class="hljs-string">'lineWidth'</span>, <span class="hljs-attr">defaultValue</span>: <span class="hljs-number">4</span>, },{ <span class="hljs-attr">key</span>: <span class="hljs-string">'lineLengthMultiplier'</span>, <span class="hljs-attr">defaultValue</span>: <span class="hljs-number">20</span>, },{ <span class="hljs-attr">key</span>: <span class="hljs-string">'lineLengthStart'</span>, <span class="hljs-attr">defaultValue</span>: <span class="hljs-number">5</span>, },{ <span class="hljs-attr">key</span>: <span class="hljs-string">'linesToAdd'</span>, <span class="hljs-attr">defaultValue</span>: <span class="hljs-number">50</span>, },{ <span class="hljs-attr">key</span>: <span class="hljs-string">'lineBlend'</span>, <span class="hljs-attr">defaultValue</span>: <span class="hljs-string">'source-over'</span>, },{ <span class="hljs-attr">key</span>: <span class="hljs-string">'lineOpacity'</span>, <span class="hljs-attr">defaultValue</span>: <span class="hljs-number">1</span>, },{</pre></div></div> </li> <li id="section-10"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-10">§</a> </div> <p><strong>offsetX</strong>, <strong>offsetY</strong>, <strong>rotationMultiplier</strong>, <strong>rotationStart</strong> - some additional brush rotation attributes.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-attr">key</span>: <span class="hljs-string">'offsetX'</span>, <span class="hljs-attr">defaultValue</span>: <span class="hljs-number">0</span>, },{ <span class="hljs-attr">key</span>: <span class="hljs-string">'offsetY'</span>, <span class="hljs-attr">defaultValue</span>: <span class="hljs-number">0</span>, },{ <span class="hljs-attr">key</span>: <span class="hljs-string">'rotationMultiplier'</span>, <span class="hljs-attr">defaultValue</span>: <span class="hljs-number">90</span>, },{ <span class="hljs-attr">key</span>: <span class="hljs-string">'rotationStart'</span>, <span class="hljs-attr">defaultValue</span>: <span class="hljs-number">0</span>, },{</pre></div></div> </li> <li id="section-11"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-11">§</a> </div> <p><strong>canvasWidth</strong>, <strong>canvasHeight</strong> - make the RawAsset’s dimensions the same as our canvas base Cell’s dimensions</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-attr">key</span>: <span class="hljs-string">'canvasWidth'</span>, <span class="hljs-attr">defaultValue</span>: dimension, },{ <span class="hljs-attr">key</span>: <span class="hljs-string">'canvasHeight'</span>, <span class="hljs-attr">defaultValue</span>: dimension, },{</pre></div></div> </li> <li id="section-12"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-12">§</a> </div> <p><strong>background</strong> - a handle to our background Picture entity, from which we will be extracting color values</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-attr">key</span>: <span class="hljs-string">'background'</span>, <span class="hljs-attr">defaultValue</span>: <span class="hljs-literal">false</span>, <span class="hljs-attr">setter</span>: <span class="hljs-keyword">function</span> (<span class="hljs-params">item</span>) { <span class="hljs-variable language_">this</span>.<span class="hljs-property">background</span> = item; <span class="hljs-variable language_">this</span>.<span class="hljs-property">dirtyBackground</span> = <span class="hljs-literal">true</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>noise</strong> - a handle to our Noise asset, from which we will be extracting brushstroke direction and length data</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-attr">key</span>: <span class="hljs-string">'noise'</span>, <span class="hljs-attr">defaultValue</span>: <span class="hljs-literal">false</span>, <span class="hljs-attr">setter</span>: <span class="hljs-keyword">function</span> (<span class="hljs-params">item</span>) { <span class="hljs-variable language_">this</span>.<span class="hljs-property">noise</span> = item; <span class="hljs-variable language_">this</span>.<span class="hljs-property">dirtyData</span> = <span class="hljs-literal">true</span>; }, },{</pre></div></div> </li> <li id="section-14"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-14">§</a> </div> <p><strong>trigger</strong> - we update the RawAsset at the start of each Display cycle by setting its <code>trigger</code> attribute. </p> <ul> <li>It’s at this point that we fill the RawAsset canvas with the background image, if required</li> </ul> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-attr">key</span>: <span class="hljs-string">'trigger'</span>, <span class="hljs-attr">defaultValue</span>: <span class="hljs-literal">false</span>, <span class="hljs-attr">setter</span>: <span class="hljs-keyword">function</span> (<span class="hljs-params">item</span>) { <span class="hljs-keyword">if</span> (<span class="hljs-variable language_">this</span>.<span class="hljs-property">dirtyBackground</span>) { <span class="hljs-variable language_">this</span>.<span class="hljs-property">dirtyBackground</span> = <span class="hljs-literal">false</span>;</pre></div></div> </li> <li id="section-15"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-15">§</a> </div> <p>@ts-expect-error</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">const</span> { element, engine, canvasWidth, canvasHeight, background } = <span class="hljs-variable language_">this</span>; element.<span class="hljs-property">width</span> = canvasWidth; element.<span class="hljs-property">height</span> = canvasHeight; <span class="hljs-keyword">const</span> { source, copyArray, pasteArray } = background; <span class="hljs-keyword">if</span> (source && copyArray && pasteArray ) {</pre></div></div> </li> <li id="section-16"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-16">§</a> </div> <p>Strictly speaking, copyArray and pasteArray are Picture entity internal data structures but that doesn’t stop us using them here.</p> <ul> <li>TODO: consider whether the RawAsset object should be using a Cell wrapper rather than a raw <canvas> element </li> <li>if we did it that way, then we would be able to simpleStamp the Picture entity onto the canvas</li> <li>the reason why we’re NOT doing it that way at the moment is to keep RawAsset canvases out of the SC library</li> </ul> </div> <div class="content"><div class='highlight'><pre> engine.<span class="hljs-title function_">drawImage</span>(background.<span class="hljs-property">source</span>, ...background.<span class="hljs-property">copyArray</span>, ...background.<span class="hljs-property">pasteArray</span>); <span class="hljs-variable language_">this</span>.<span class="hljs-property">backgroundData</span> = engine.<span class="hljs-title function_">getImageData</span>(<span class="hljs-number">0</span>, <span class="hljs-number">0</span>, dimension, dimension); <span class="hljs-variable language_">this</span>.<span class="hljs-property">dirtyData</span> = <span class="hljs-literal">true</span>; } <span class="hljs-keyword">else</span> <span class="hljs-variable language_">this</span>.<span class="hljs-property">dirtyBackground</span> = <span class="hljs-literal">true</span>; } <span class="hljs-keyword">else</span> <span class="hljs-variable language_">this</span>.<span class="hljs-property">dirtyData</span> = <span class="hljs-literal">true</span>; }, }],</pre></div></div> </li> <li id="section-17"> <div class="annotation"> <div class="sswrap "> <a class="ss" href="#section-17">§</a> </div> <p><code>assetWrapper</code> is the same as <code>this</code> when function is declared with the function keyword</p> <ul> <li>We clear the RawAsset’s canvas, then draw the updated Voronoi web onto it</li> </ul> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-attr">updateSource</span>: <span class="hljs-keyword">function</span> (<span class="hljs-params">assetWrapper</span>) { <span class="hljs-keyword">const</span> { engine, noise, backgroundData, lineWidth, lineLengthMultiplier, lineLengthStart, linesToAdd, lineBlend, lineOpacity, offsetX, offsetY, rotationMultiplier, rotationStart } = assetWrapper; <span class="hljs-keyword">if</span> (noise && backgroundData) { <span class="hljs-keyword">const</span> { data, width, height } = backgroundData; <span class="hljs-keyword">const</span> { noiseValues } = noise; <span class="hljs-keyword">if</span> (noiseValues) { engine.<span class="hljs-property">lineWidth</span> = lineWidth; engine.<span class="hljs-property">lineCap</span> = <span class="hljs-string">'round'</span>; engine.<span class="hljs-property">globalCompositeOperation</span> = lineBlend; engine.<span class="hljs-property">globalAlpha</span> = lineOpacity; <span class="hljs-keyword">let</span> x, y, pos, len, rx, ry, dx, dy, roll, r, g, b, a; <span class="hljs-keyword">const</span> coord = scrawl.<span class="hljs-title function_">requestCo