Added text that zooms vis font size changes,

lib/pixi/index.html

@@ -35,6 +35,7 @@ const index = new Index(itemTemplate, [
         ['DeepZoom', 'deepzoom.html'],
         ['DeepZoomImage', 'deepzoomimage.html'],
         ['Flippable', 'flippable.html'],
+        ['LabeledGraphics', 'labeledgraphics.html'],
         ['List', 'list.html'],
         ['Message', 'message.html'],
         ['Modal', 'modal.html'],

lib/pixi/labeledgraphics.html

@@ -23,23 +23,62 @@
     </p>
     <p><a href="../../doc/out/LabeledGraphics.html">JavaScript API</a></p>
     <p>Let's look at an example:</p><br />
-    <canvas id="canvas" class="interactive"></canvas>
+    <canvas id="canvas1" class="interactive"></canvas>
     <p>
         What you should see: A box with a label.
     </p>
     <script class="doctest">
 const app = new PIXIApp({
-    view: canvas,
+    view: canvas1,
     width: 900,
     height: 150
 }).setup().run()
 
 const labeledBox = new LabeledGraphics()
 labeledBox.ensureLabel('key', 'This is a label in a box', { justify: 'top'})
-labeledBox.beginFill(0x0000FF)
+labeledBox.beginFill(0x333333)
 labeledBox.drawRect(0, 0, 300, 100)
 labeledBox.endFill()
 
 app.scene.addChild(labeledBox)
     </script>
+    <h2>Zoomable Labels</h2>
+    <p>Labeled graphics can also be used to represent zoomable text columns in more complex layouts.
+        Use the mousewheel to zoom the following text column:
+    </p>
+
+    <canvas id="canvas2" class="interactive"></canvas>
+    <script class="doctest">
+const app2 = new PIXIApp({
+    view: canvas2,
+    width: 900,
+    height: 150
+}).setup().run()
+
+const loremIpsum = `Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. 
+At vero eos et accusam et justo duo dolores et ea rebum.`
+
+const column = new LabeledGraphics()
+const text = column.ensureLabel('key', loremIpsum, { maxWidth: 250, zoomFonts: true, justify: 'top', align: 'align'})
+column.beginFill(0x333333)
+column.drawRect(0, 0, 900, 150)
+column.endFill()
+
+column.interactive = true
+text.interactive = true
+text.getLocalBounds()
+
+text.on('zoom', (event) => {
+    let factor = 1.0 + event.wheelDelta / 1000
+    text.zoom(factor)
+})
+
+app2.view.addEventListener('mousewheel', (event) => {
+    text.emit('zoom', event)
+    event.preventDefault()
+})
+
+app2.scene.addChild(column)
+    </script>
+
 </body>

lib/pixi/labeledgraphics.js

@@ -130,6 +130,47 @@ export class Hypenate {
     }
 }
 
+class TextLabel extends PIXI.Text {
+
+    /**
+     *Creates an instance of TextLabel.
+     * @param {string} text - The string that you would like the text to display
+     * @param {object PIXI.TextStyle optional} style - The style parameters 
+     * @param {canvas} 
+     * @memberof TextLabel
+     */
+    constructor(text, style=null, canvas=null, { minZoom = 0.1, maxZoom = 10} = {}) {
+        super(text, style, canvas )
+        this.normFontSize = this.style.fontSize 
+        this.minZoom = minZoom
+        this.maxZoom = maxZoom
+    }
+
+    zoom(factor) {
+        let oldValue = parseFloat(this.style.fontSize) / this.normFontSize
+        let value = oldValue * factor
+        this.setZoom(value)
+    }
+
+    setZoom(value) {
+        let oldValue = parseFloat(this.style.fontSize) / this.normFontSize
+        if (value > this.maxZoom) {
+            value = this.maxZoom
+        }
+        if (value < this.minZoom) {
+            value = this.minZoom
+        }
+        if (value != oldValue) {
+            this.style.fontSize = Math.max(value * this.normFontSize, 1)
+        }
+    }
+
+    setZoomAndScale(scale) {
+        this.scale.set(1 / scale)
+        this.setZoom(scale)
+    }
+}
+
 /**
  * A specialization of the PIXI.Graphics class that allows to
  * resuse and place labels across different layout variants
@@ -151,7 +192,7 @@ export class LabeledGraphics extends PIXI.Graphics {
     }
 
     _createText(label, fontInfo) {
-        return new PIXI.Text(label, fontInfo)
+        return new TextLabel(label, fontInfo)
     }