feat(demo): nav:back element

demo/backend/advanced/community/elements/nav-back/_styles.xml.njk

@@ -0,0 +1,5 @@
+<style
+  id="text"
+  marginHorizontal="24"
+  marginBottom="16"
+/>

demo/backend/advanced/community/elements/nav-back/index.xml.njk

@@ -0,0 +1,26 @@
+---
+permalink: "/backend/advanced/community/nav-back/index.xml"
+tags: "Advanced/Community/Elements"
+hv_button_behavior: "back"
+hv_title: "Nav Back"
+---
+
+{% from 'macros/button/index.xml.njk' import button %}
+{% from 'macros/description/index.xml.njk' import description %}
+{% extends 'templates/scrollview.xml.njk' %}
+
+{% block content %}
+  {{ description('Tapping one of the buttons will render the same screen with a different navigation style. The control to navigate back will be dynamic, based on the navigation context.') }}
+  {% call button('Push') -%}
+    <behavior
+      action="push"
+      href="/hyperview/public/advanced/community/elements/nav-back/screen.xml"
+    />
+  {%- endcall %}
+  {% call button('New') -%}
+    <behavior
+      action="new"
+      href="/hyperview/public/advanced/community/elements/nav-back/screen.xml"
+    />
+  {%- endcall %}
+{% endblock %}

demo/backend/advanced/community/elements/nav-back/screen.xml.njk

@@ -0,0 +1,44 @@
+---
+permalink: "/backend/advanced/community/nav-back/screen.xml"
+hv_title: "Nav Back"
+---
+
+{% from 'macros/button/index.xml.njk' import button %}
+{% from 'macros/description/index.xml.njk' import description %}
+{% extends 'templates/base.xml.njk' %}
+
+{% block styles %}
+  {% include './_styles.xml.njk' %}
+{% endblock %}
+
+{% block body %}
+  <header style="header">
+    <nav:back xmlns:nav="https://hyperview.org/navigation">
+      <view
+        nav:role="close"
+        action="close"
+        href="#"
+        style="header-btn"
+      >
+        {% include 'icons/close.svg' %}
+      </view>
+      <view
+        nav:role="back"
+        action="back"
+        href="#"
+        style="header-btn"
+      >
+        {% include 'icons/back.svg' %}
+      </view>
+    </nav:back>
+    <text style="header-title">{{ hv_title }}</text>
+  </header>
+  <text style="text">
+    The button to navigate back to the previous screen will be rendered dynamically,
+    based on which kind of navigator the screen is currently loaded on. For regular screens
+    (added to the stack via "push" action), a back-arrow button will be rendered. For
+    modal screens (added to the stack via "new" action), a close button will be rendered.
+    Also (not demo'd here), if the screen is the first screen of the stack and there is no
+    place to navigate back to, no button will be rendered.
+  </text>
+{% endblock %}

demo/schema/hyperview.xsd

@@ -6,6 +6,7 @@
   xmlns:hv="https://hyperview.org/hyperview"
   xmlns:alert="https://hyperview.org/hyperview-alert"
   xmlns:filter="https://hyperview.org/filter"
+  xmlns:nav="https://hyperview.org/navigation"
   xmlns:scroll="https://hyperview.org/hyperview-scroll"
   xmlns:share="https://hyperview.org/share"
 >
@@ -85,6 +86,7 @@
 
       <!-- Hyperview demo extensions -->
       <xs:attributeGroup ref="filter:filterAttributes" />
+      <xs:attributeGroup ref="nav:navAttributes" />
       <xs:attributeGroup ref="share:shareAttributes" />
     </xs:attributeGroup>
 

demo/schema/navigation.xsd

@@ -3,6 +3,7 @@
   attributeFormDefault="qualified"
   elementFormDefault="qualified"
   targetNamespace="https://hyperview.org/navigation"
+  xmlns:nav="https://hyperview.org/navigation"
   xmlns:hv="https://hyperview.org/hyperview"
 >
   <xs:import
@@ -28,4 +29,20 @@
       <xs:attribute name="key" type="hv:KEY" form="unqualified" />
     </xs:complexType>
   </xs:element>
+  <xs:simpleType name="role">
+    <xs:restriction base="xs:string">
+      <xs:enumeration value="back" />
+      <xs:enumeration value="close" />
+    </xs:restriction>
+  </xs:simpleType>
+  <xs:element name="back">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:any minOccurs="0" maxOccurs="unbounded" />
+      </xs:sequence>
+    </xs:complexType>
+  </xs:element>
+  <xs:attributeGroup name="navAttributes">
+    <xs:attribute name="role" type="nav:role" />
+  </xs:attributeGroup>
 </xs:schema>

demo/src/Components/Filter/Filter.tsx

@@ -1,11 +1,7 @@
 import * as Logging from 'hyperview/src/services/logging';
 import type { HvComponentProps, LocalName } from 'hyperview';
-import Hyperview, {
-  Events,
-  LOCAL_NAME,
-  NODE_TYPE,
-  Namespaces,
-} from 'hyperview';
+import Hyperview, { Events, LOCAL_NAME, Namespaces } from 'hyperview';
+import { findElements } from '../../Helpers';
 import { useEffect } from 'react';
 
 type FormDataPart = {
@@ -18,30 +14,6 @@ declare class FormData {
 }
 const FILTER_NS = 'https://hyperview.org/filter';
 
-export const findElements = (node: Element, attributeNames: string[]) => {
-  if (node.nodeType !== NODE_TYPE.ELEMENT_NODE) {
-    return [];
-  }
-
-  if (
-    attributeNames.reduce(
-      (found, name) => found || !!node.getAttributeNS(FILTER_NS, name),
-      false,
-    )
-  ) {
-    return [node];
-  }
-
-  return (Array.from(node.childNodes) as Element[])
-    .filter((child: Node | null) => {
-      return child !== null && child.nodeType === NODE_TYPE.ELEMENT_NODE;
-    })
-    .reduce((elements: Element[], child: Element) => {
-      elements.push(...findElements(child, attributeNames));
-      return elements;
-    }, []);
-};
-
 const Filter = (props: HvComponentProps) => {
   const onEventDispatch = (eventName: string) => {
     const filterEvent =
@@ -74,7 +46,7 @@ const Filter = (props: HvComponentProps) => {
       : filterTerm;
 
     // Hide/show each element with filter terms or matching given regex. Modify attributes in-place
-    const filterElements: Element[] = findElements(props.element, [
+    const filterElements: Element[] = findElements(FILTER_NS, props.element, [
       'terms',
       'regex',
     ]);
@@ -101,22 +73,24 @@ const Filter = (props: HvComponentProps) => {
     props.onUpdate(null, 'swap', props.element, { newElement });
 
     // Set elements that need to render the filter term
-    findElements(newElement, ['role']).forEach((element: Element) => {
-      if (element.getAttributeNS(FILTER_NS, 'role') === 'filter-terms') {
-        if (
-          element.namespaceURI === Namespaces.HYPERVIEW &&
-          element.localName !== LOCAL_NAME.TEXT
-        ) {
-          Logging.error(
-            'Element with attribute `role="filter-terms"` should be a <text> element or a custom element',
-          );
-          return;
+    findElements(FILTER_NS, newElement, ['role']).forEach(
+      (element: Element) => {
+        if (element.getAttributeNS(FILTER_NS, 'role') === 'filter-terms') {
+          if (
+            element.namespaceURI === Namespaces.HYPERVIEW &&
+            element.localName !== LOCAL_NAME.TEXT
+          ) {
+            Logging.error(
+              'Element with attribute `role="filter-terms"` should be a <text> element or a custom element',
+            );
+            return;
+          }
+          const newRoleElement = element.cloneNode(true) as Element;
+          newRoleElement.textContent = filterTerm;
+          props.onUpdate(null, 'swap', element, { newElement: newRoleElement });
         }
-        const newRoleElement = element.cloneNode(true) as Element;
-        newRoleElement.textContent = filterTerm;
-        props.onUpdate(null, 'swap', element, { newElement: newRoleElement });
-      }
-    });
+      },
+    );
   };
 
   useEffect(() => {

demo/src/Components/NavBack/NavBack.tsx

@@ -0,0 +1,40 @@
+import type { HvComponentProps, LocalName } from 'hyperview';
+import Hyperview from 'hyperview';
+import { NavigationContext } from '@react-navigation/native';
+import { findElements } from '../../Helpers';
+import { useContext } from 'react';
+
+export const namespaceURI = 'https://hyperview.org/navigation';
+
+const NavBack = (props: HvComponentProps) => {
+  const ctx = useContext(NavigationContext);
+  const state = ctx?.getState();
+  const route = state?.routes[state.index];
+
+  // Screen is first on the stack? Don't render anything
+  if (state?.index === 0) {
+    return null;
+  }
+
+  const role = route?.name === 'modal' ? 'close' : 'back';
+  const [element] = findElements(namespaceURI, props.element, ['role']).filter(
+    el => {
+      return el.getAttributeNS(namespaceURI, 'role') === role;
+    },
+  );
+  if (!element) {
+    return null;
+  }
+  return (Hyperview.renderElement(
+    element,
+    props.stylesheets,
+    props.onUpdate,
+    props.options,
+  ) as unknown) as JSX.Element;
+};
+
+NavBack.namespaceURI = namespaceURI;
+NavBack.localName = 'back' as LocalName;
+NavBack.localNameAliases = [] as LocalName[];
+
+export { NavBack };

demo/src/Components/NavBack/index.ts

@@ -0,0 +1 @@
+export { NavBack } from './NavBack';

demo/src/Components/index.ts

@@ -6,6 +6,7 @@ import {
 import { BottomTabBar, BottomTabBarItem } from './BottomTabBar';
 import { Map, MapMarker } from './Map';
 import { Filter } from './Filter';
+import { NavBack } from './NavBack';
 import { ProgressBar } from './ProgressBar';
 import { ScrollOpacity } from './ScrollOpacity';
 import { Svg } from './Svg';
@@ -19,6 +20,7 @@ export default [
   Filter,
   Map,
   MapMarker,
+  NavBack,
   ProgressBar,
   ScrollOpacity,
   Svg,

demo/src/Helpers/misc.ts

@@ -1,3 +1,4 @@
+import { NODE_TYPE } from 'hyperview';
 import moment from 'moment';
 
 export const formatDate = (
@@ -21,3 +22,31 @@ export const fetchWrapper = (
     mode: 'cors',
   });
 };
+
+export const findElements = (
+  namespace: string,
+  node: Element,
+  attributeNames: string[],
+) => {
+  if (node.nodeType !== NODE_TYPE.ELEMENT_NODE) {
+    return [];
+  }
+
+  if (
+    attributeNames.reduce(
+      (found, name) => found || !!node.getAttributeNS(namespace, name),
+      false,
+    )
+  ) {
+    return [node];
+  }
+
+  return (Array.from(node.childNodes) as Element[])
+    .filter((child: Node | null) => {
+      return child !== null && child.nodeType === NODE_TYPE.ELEMENT_NODE;
+    })
+    .reduce((elements: Element[], child: Element) => {
+      elements.push(...findElements(namespace, child, attributeNames));
+      return elements;
+    }, []);
+};