feat(icon): expose 'inner-html' and 'svg' as shadow parts

Also
- add usage examples to index.html
- update icon readme

Author: Juarrow

src/components/icon/icon.tsx

@@ -12,6 +12,7 @@ export class Icon {
   private io?: IntersectionObserver;
   private iconName: string | null = null;
   private inheritedAttributes: { [k: string]: any } = {};
+  private svgContentInjected: boolean = false;
 
   @Element() el!: HTMLElement;
 
@@ -80,7 +81,7 @@ export class Icon {
    * @default true
    */
   @Prop() sanitize = true;
-  
+
   componentWillLoad() {
     this.inheritedAttributes = inheritAttributes(this.el, ['aria-label']);
   }
@@ -122,13 +123,43 @@ export class Icon {
       cb();
     }
   }
-  
+
   private hasAriaHidden = () => {
     const { el } = this;
-    
+
     return el.hasAttribute('aria-hidden') && el.getAttribute('aria-hidden') === 'true';
   }
 
+  private createSvgElement(): SVGElement | null {
+    if (this.svgContent) {
+      const template = document.createElement("template");
+      template.innerHTML = this.svgContent;
+
+      // Extract the first element from the template.
+      // It should be our <svg>.
+      const node = template.content.firstChild;
+      if (node) {
+        if (node.nodeType === Node.ELEMENT_NODE && (node as Element).tagName === 'svg') {
+          const svg = node as SVGElement;
+
+          // Add the shadow part
+          svg.setAttribute('part', 'svg');
+
+          return svg;
+        }
+      }
+    }
+
+    return null;
+  }
+
+  private injectSvgElement(svgElement: SVGElement) {
+    const el = (this.el.shadowRoot as ShadowRoot).querySelector('.icon-inner')
+    if (el) {
+      el.appendChild(svgElement);
+    }
+  }
+
   @Watch('name')
   @Watch('src')
   @Watch('icon')
@@ -186,13 +217,29 @@ export class Icon {
         {...inheritedAttributes}
       >
         {Build.isBrowser && this.svgContent ? (
-          <div class="icon-inner" innerHTML={this.svgContent}></div>
+          <div class="icon-inner" part="icon-inner" >
+          </div>
         ) : (
           <div class="icon-inner"></div>
         )}
       </Host>
     );
   }
+
+  componentDidRender() {
+    /**
+     * If it has not been done already, create & inject the <SVG> element
+     * into `div.icon-inner`.
+     */
+    if (!this.svgContentInjected) {
+      const svgElement = this.createSvgElement();
+      if (svgElement) {
+        this.injectSvgElement(svgElement);
+
+        this.svgContentInjected = true;
+      }
+    }
+  }
 }
 
 const getIonMode = () =>
@@ -201,8 +248,8 @@ const getIonMode = () =>
 const createColorClasses = (color: string | undefined) => {
   return color
     ? {
-        'ion-color': true,
-        [`ion-color-${color}`]: true,
-      }
+      'ion-color': true,
+      [`ion-color-${color}`]: true,
+    }
     : null;
 };

src/components/icon/readme.md

@@ -22,6 +22,14 @@
 | `src`      | `src`      | Specifies the exact `src` of an SVG file to use.                                                                                                                                              | `string \| undefined`  | `undefined`    |
 
 
+## Shadow Parts
+
+| Part           | Description |
+| -------------- | ----------- |
+| `"icon-inner"` | The container that wraps the SVG element |
+| `"svg"` | The svg element |
+
+
 ----------------------------------------------
 
 *Built with [StencilJS](https://stenciljs.com/)*

src/index.html

@@ -130,6 +130,10 @@ <h2>Sanitized (shouldn't show)</h2>
     <h2>Not Sanitized (should show)</h2>
     <ion-icon sanitize="false" src="./assets/no-sanitize.svg"></ion-icon>
 
+    <h2>Accessing ::part()'s</h2>
+    <ion-icon id="part-svg" src="./assets/bug_report.svg"></ion-icon>
+    <ion-icon id="part-icon-inner" src="./assets/chat.svg"></ion-icon>
+
     <p>
       <a href="./cheatsheet.html">Cheatsheet</a>
     </p>
@@ -156,6 +160,14 @@ <h2>Not Sanitized (should show)</h2>
         stroke: red;
         fill: blue;
       }
+
+      #part-svg::part(svg) {
+        fill: rebeccapurple;
+      }
+
+      #part-icon-inner::part(icon-inner) {
+        fill: aliceblue;
+      }
     </style>
   </body>
 </html>