Introduce Anchor class

It derives from Group class and uses same rendering.
Plus if `href` attribute specified - adds link with bounding box.
Requires usage of scale and page height values -
otherwise created link area does not match drawn text

Author: linev

src/nodes/anchor.ts

@@ -0,0 +1,19 @@
+import { Group } from './group'
+import { Context } from '../context/context'
+import { getAttribute } from '../utils/node'
+
+export class Anchor extends Group {
+  protected async renderCore(context: Context): Promise<void> {
+    await super.renderCore(context)
+
+    const href = getAttribute(this.element, context.styleSheets, 'href')
+    if (href) {
+      const box = this.getBoundingBox(context)
+      const scale = context.pdf.internal.scaleFactor
+      const ph = context.pdf.internal.pageSize.getHeight()
+
+      context.pdf.link(scale*(box[0] * context.transform.sx + context.transform.tx),
+                       ph - scale*(box[1] * context.transform.sy + context.transform.ty), scale*box[2], scale*box[3], { url: href })
+    }
+  }
+}

src/parse.ts

@@ -17,6 +17,7 @@ import { RadialGradient } from './nodes/radialgradient'
 import { Polyline } from './nodes/polyline'
 import { Svg } from './nodes/svg'
 import { Group } from './nodes/group'
+import { Anchor } from './nodes/anchor'
 import cssesc from 'cssesc'
 import { ClipPath } from './nodes/clippath'
 import { Symbol } from './nodes/symbol'
@@ -29,6 +30,8 @@ export function parse(node: Element, idMap?: { [id: string]: SvgNode }): SvgNode
 
   switch (node.tagName.toLowerCase()) {
     case 'a':
+      svgnode = new Anchor(node, children)
+      break
     case 'g':
       svgnode = new Group(node, children)
       break