Add chart component

CHANGELOG.md

@@ -9,6 +9,7 @@
 
 ## Unreleased
 
+* Add chart component ([PR #4301](https://github.com/alphagov/govuk_publishing_components/pull/4301))
 * Add inverse option for organisation logo ([PR #4284](https://github.com/alphagov/govuk_publishing_components/pull/4284))
 * New options for contents-list component ([PR #4305](https://github.com/alphagov/govuk_publishing_components/pull/4305))
 

Gemfile.lock

@@ -2,6 +2,7 @@ PATH
   remote: .
   specs:
     govuk_publishing_components (44.3.0)
+      chartkick
       govuk_app_config
       govuk_personalisation (>= 0.7.0)
       kramdown
@@ -103,6 +104,7 @@ GEM
       rack-test (>= 0.6.3)
       regexp_parser (>= 1.5, < 3.0)
       xpath (~> 3.2)
+    chartkick (5.1.0)
     coderay (1.1.3)
     concurrent-ruby (1.3.4)
     connection_pool (2.4.1)

app/assets/javascripts/govuk_publishing_components/components/chart.js

@@ -0,0 +1 @@
+//= require chartkick

app/assets/stylesheets/govuk_publishing_components/components/_chart.scss

@@ -0,0 +1,44 @@
+@import "govuk_publishing_components/individual_component_support";
+
+.gem-c-chart {
+  // slight hack to hide the table automatically added by the charts JS
+  // not needed as we already output the table manually in the component
+  svg + div:has(table) {
+    display: none;
+  }
+
+  .google-visualization-tooltip {
+    background-color: govuk-colour("black");
+    box-shadow: none;
+    border: 0;
+
+    span {
+      color: govuk-colour("white");
+      @include govuk-font($size: 16, $weight: bold);
+    }
+  }
+}
+
+.gem-c-chart__table-wrapper {
+  overflow: auto;
+}
+
+.gem-c-chart__table {
+  margin-top: govuk-spacing(3);
+
+  .govuk-table {
+    margin: 0;
+  }
+
+  .govuk-table .govuk-table__header {
+    text-align: center;
+  }
+
+  .govuk-table .govuk-table__cell {
+    text-align: center;
+  }
+}
+
+.gem-c-chart__accessibility-message {
+  @include govuk-visually-hidden;
+}

app/views/govuk_publishing_components/components/_chart.html.erb

@@ -0,0 +1,151 @@
+<%
+  add_gem_component_stylesheet("chart")
+  add_gem_component_stylesheet("table")
+  add_gem_component_stylesheet("details")
+  add_gem_component_stylesheet("heading")
+
+  chart_heading ||= nil
+  chart_heading_level ||= 2
+  table_direction ||= "horizontal"
+  h_axis_title ||= nil
+  v_axis_title ||= nil
+  rows ||= []
+  keys ||= []
+  chart_overview ||= nil
+  hide_legend ||= false
+  link ||= false
+
+  chart_id = "chart-id-#{SecureRandom.hex(4)}"
+  table_id = "table-id-#{SecureRandom.hex(4)}"
+
+  shared_helper = GovukPublishingComponents::Presenters::SharedHelper.new(local_assigns)
+  component_helper = GovukPublishingComponents::Presenters::ComponentWrapperHelper.new(local_assigns)
+  component_helper.add_class("gem-c-chart")
+  component_helper.add_class(shared_helper.get_margin_bottom)
+
+  require "chartkick"
+  Chartkick.options[:html] = '<div id="%{id}"><noscript><p class="govuk-body">Our charts are built using JavaScript but all the data is also available in the table below.</p></noscript></div>'
+  # config options are here: https://developers.google.com/chart/interactive/docs/gallery/linechart
+  font_16 = { color: '#000', fontName: 'GDS Transport', fontSize: '16', italic: false }
+  font_19 = { color: '#000', fontName: 'GDS Transport', fontSize: '19', italic: false }
+  legend = 'none'
+  legend = { position: 'top', textStyle: font_16 } unless hide_legend
+
+  chart_library_options = {
+    chartArea: { width: '80%', height: '60%' },
+    crosshair: { orientation: 'vertical', trigger: 'both', color: '#ccc' },
+    curveType: 'none',
+    legend: legend,
+    pointSize: 10,
+    height: 400,
+    tooltip: { isHtml: true },
+    hAxis: {
+      textStyle: font_16,
+      format: 'd MMM Y', # https://developers.google.com/chart/interactive/docs/reference#dateformatter
+      title: h_axis_title,
+      titleTextStyle: font_19,
+    },
+    vAxis: {
+      format: '#,###,###',
+      textStyle: font_16,
+      title: v_axis_title,
+      titleTextStyle: font_19,
+    },
+  }
+
+  if rows.length > 0 && keys.length > 0
+    chart_format_data = rows.map do |row|
+      {
+        name: row[:label],
+        linewidth: 10,
+        data: keys.zip(row[:values])
+      }
+    end
+  end
+%>
+<% if rows.length > 0 && keys.length > 0 %>
+  <%= javascript_include_tag "https://www.gstatic.com/charts/loader.js" %>
+  <%= tag.div(**component_helper.all_attributes) do %>
+    <% if chart_heading %>
+      <%= render "govuk_publishing_components/components/heading", {
+        text: chart_heading,
+        heading_level: chart_heading_level,
+        margin_bottom: 2,
+      } %>
+    <% end %>
+
+    <div class="gem-c-chart__chart" id="<%= chart_id %>">
+      <div class="gem-c-chart__accessibility-message">
+        <%= t("components.chart.accessibility_html", table_id: table_id) %>
+        <%= content_tag :span, chart_overview, class: "gem-c-chart__overview" if chart_overview %>
+      </div>
+      <%= line_chart(chart_format_data, library: chart_library_options) %>
+    </div>
+
+    <div class="gem-c-chart__table" id="<%= table_id %>">
+      <%= render("govuk_publishing_components/components/details",
+        title: t("components.chart.table_dropdown")
+      ) do %>
+        <div tabindex="0" class="gem-c-chart__table-wrapper">
+          <table class="govuk-table">
+            <% if table_direction == "horizontal" %>
+              <thead class="govuk-table__head">
+                <tr class="govuk-table__row">
+                  <td class="govuk-table__cell"></td>
+                  <% keys.each do |key| %>
+                    <th class="govuk-table__header scope="col">
+                      <%= key %>
+                    </th>
+                  <% end %>
+                </tr>
+              </thead>
+              <tbody class="govuk-table__body">
+                <% rows.each do |row| %>
+                  <tr class="govuk-table__row">
+                    <th class="govuk-table__header" scope="row"><%= row[:label]  %></th>
+                    <% row[:values].each do |value| %>
+                      <td class="govuk-table__cell govuk-table__cell--numeric">
+                        <%= number_with_delimiter value %>
+                      </td>
+                    <% end %>
+                  </tr>
+                <% end %>
+              </tbody>
+            <% else %>
+              <thead class="govuk-table__head">
+                <tr class="govuk-table__row">
+                  <td class="govuk-table__cell"></td>
+                  <% rows.each do |row| %>
+                    <th class="govuk-table__header govuk-table__header--stacked" scope="row">
+                      <%= row[:label] %>
+                    </th>
+                  <% end %>
+                </tr>
+              </thead>
+              <tbody class="govuk-table__body">
+                <% keys.each_with_index do |key, index| %>
+                  <tr>
+                    <th class="govuk-table__header scope="row">
+                      <%= key %>
+                    </th>
+                    <% rows.each do |row| %>
+                      <td class="govuk-table__cell govuk-table__cell--numeric">
+                        <%= number_with_delimiter row[:values][index] %>
+                      </td>
+                    <% end %>
+                  </tr>
+                <% end %>
+              </tbody>
+            <% end %>
+          </table>
+        </div>
+      <% end %>
+    </div>
+
+    <% if link %>
+      <p class="govuk-body">
+        <%= link_to "Download chart data", link,  class: "govuk-link" %>
+      </p>
+    <% end %>
+  <% end %>
+<% end %>