Support for append css

Author: blocknotes

README.md

@@ -35,6 +35,23 @@ pdf.render_file('test.pdf')
 
 To check some examples with the PDF output see [examples](examples/) folder.
 
+Alternative form using _PrawnHtml::Instance_ to preserve the context:
+
+```rb
+require 'prawn-html'
+pdf = Prawn::Document.new(page_size: 'A4')
+phtml = PrawnHtml::Instance.new(pdf)
+css = <<~CSS
+  h1 { color: green }
+  i { color: red }
+CSS
+phtml.append(css: css)
+phtml.append(html: '<h1>Some <i>HTML</i> before</h1>')
+pdf.text 'Some Prawn text'
+phtml.append(html: '<h1>Some <i>HTML</i> after</h1>')
+pdf.render_file('test.pdf')
+```
+
 ## Supported tags & attributes
 
 HTML tags (using MDN definitions):

examples/instance.pdf

@@ -30,6 +30,13 @@ def process(html)
       renderer.flush
     end
 
+    # Parses CSS styles
+    #
+    # @param text_styles [String] The CSS styles to evaluate
+    def parse_styles(text_styles)
+      @raw_styles = text_styles.scan(REGEXP_STYLES).to_h
+    end
+
     private
 
     attr_reader :document, :ignore, :processing, :renderer, :styles
@@ -62,7 +69,7 @@ def init_element(node)
     end
 
     def process_styles(text_styles = nil)
-      @raw_styles = text_styles.scan(REGEXP_STYLES).to_h if text_styles
+      parse_styles(text_styles) if text_styles
       @raw_styles.each do |selector, rule|
         document.css(selector).each do |node|
           styles[node] = rule

lib/prawn_html/html_parser.rb

@@ -10,8 +10,9 @@ def initialize(pdf)
       @html_parser = PrawnHtml::HtmlParser.new(@renderer)
     end
 
-    def append(html:)
-      html_parser.process(html)
+    def append(css: nil, html: nil)
+      html_parser.parse_styles(css) if css
+      html_parser.process(html) if html
     end
   end
 end

lib/prawn_html/instance.rb

@@ -4,10 +4,14 @@
   it 'preserves the styles in the instance' do
     pdf = Prawn::Document.new(page_size: 'A4')
     phtml = PrawnHtml::Instance.new(pdf)
-    phtml.append(html: '<style>h1 { color: green }</style>')
-    phtml.append(html: '<h1>Some HTML before</h1>')
+    css = <<~CSS
+      h1 { color: green }
+      i { color: red }
+    CSS
+    phtml.append(css: css)
+    phtml.append(html: '<h1>Some <i>HTML</i> before</h1>')
     pdf.text 'Some Prawn text'
-    phtml.append(html: '<h1>Some HTML after</h1>')
+    phtml.append(html: '<h1>Some <i>HTML</i> after</h1>')
 
     output_file = File.expand_path('../../examples/instance.pdf', __dir__)
     pdf.render_file(output_file) unless File.exist?(output_file)

spec/features/instance_spec.rb

@@ -38,6 +38,14 @@
     end
   end
 
+  describe '#parse_styles' do
+    subject(:parse_styles) { html_parser.parse_styles(css) }
+
+    let(:css) { 'h1 { color: red }' }
+
+    it { is_expected.to eq('h1' => 'color: red') }
+  end
+
   describe '#process' do
     subject(:process) { html_parser.process(html) }