add image loader option for more flexibility

README.md

@@ -65,6 +65,7 @@ Beside these options handled by Prawn / prawn-table, the following values may be
 * `[:list][:bullet][:margin]`: Margin before the bullet. Default is 10.
 * `[:list][:content][:margin]`: Margin between the bullet and the content. Default is 10.
 * `[:list][:placeholder][:too_large]`: If the list content does not fit into the current bounding box, this text/callable is rendered instead. Defaults to '[list content too large]'.
+* `[:image][:loader]`: A callable that accepts the `src` attribute as an argument an returns a value understood by Prawn's `image` method. Loads `http(s)` URLs and base64 encoded data URIs by default.
 * `[:image][:placeholder]`: If an image is not supported, this text/callable is rendered instead. Defaults to '[unsupported image]'.
 * `[:iframe][:placeholder]`: If the HTML contains IFrames, this text/callable is rendered instead.
 A callable gets the URL of the IFrame as an argument. Defaults to ignore iframes.
@@ -81,7 +82,7 @@ This gem parses the given HTML and layouts the following elements in a vertical
 
 All other elements are ignored, their content is added to the parent element. With a few exceptions, no CSS is processed. One exception is the `width` property of `img`, `td` and `th`, which may contain values in `cm`, `mm`, `px`, `pt`, `%` or `auto`.
 
-Images must be contained in the `src` attribute as base64 encoded data URIs. Prawn only supports `PNG` and `JPG`.
+If no explicit loader is given (see above), images are loaded from `http(s)` addresses are may be contained in the `src` attribute as base64 encoded data URIs. Prawn only supports `PNG` and `JPG`.
 
 
 ## Development

lib/prawn/markup/processor/headings.rb

@@ -34,16 +34,16 @@ def end_heading(level)
           add_cell_text_node(current_list_item, options)
         else
           add_current_text(options)
-          @margin_bottom = options[:margin_bottom]
+          put_bottom_margin(options[:margin_bottom])
         end
       end
 
       private
 
       def current_heading_margin_top(level)
         top_margin = heading_options(level)[:margin_top] || 0
-        margin = [top_margin, @margin_bottom || 0].max
-        @margin_bottom = nil
+        margin = [top_margin, @bottom_margin || 0].max
+        put_bottom_margin(nil)
         margin
       end
 

lib/prawn/markup/processor/images.rb

@@ -1,3 +1,5 @@
+require 'open-uri'
+
 module Prawn
   module Markup
     module Processor::Images
@@ -8,6 +10,7 @@ def self.prepended(base)
       end
 
       def start_img
+        add_current_text
         add_image_or_placeholder(current_attrs['src'])
       end
 
@@ -18,10 +21,9 @@ def start_iframe
 
       private
 
-      def add_image_or_placeholder(data)
-        img = image_properties(data)
+      def add_image_or_placeholder(src)
+        img = image_properties(src)
         if img
-          add_current_text
           add_image(img)
         else
           append_text("\n#{invalid_image_placeholder}\n")
@@ -33,24 +35,40 @@ def add_image(img)
         img[:width] = SizeConverter.new(pdf.bounds.width).parse(style_properties['width'])
         pdf.image(img.delete(:image), img)
         put_bottom_margin(text_margin_bottom)
+      rescue Prawn::Errors::UnsupportedImageType
+        append_text("\n#{invalid_image_placeholder}\n")
       end
 
-      def image_properties(data)
-        img = decode_base64_image(data)
+      def image_properties(src)
+        img = load_image(src)
         if img
           props = style_properties
           {
-            image: StringIO.new(img),
+            image: img,
             width: props['width'],
             position: convert_float_to_position(props['float'])
           }
         end
       end
 
-      def decode_base64_image(data)
-        match = data.match(/^data:(.*?);(.*?),(.*)$/)
+      def load_image(src)
+        if options[:image] && options[:image][:loader]
+          options[:image][:loader].call(src)
+        else
+          decode_base64_image(src) || load_remote_image(src)
+        end
+      end
+
+      def decode_base64_image(src)
+        match = src.match(/^data:(.*?);(.*?),(.*)$/)
         if match && ALLOWED_IMAGE_TYPES.include?(match[1])
-          Base64.decode64(match[3])
+          StringIO.new(Base64.decode64(match[3]))
+        end
+      end
+
+      def load_remote_image(src)
+        if src =~ %r{^https?:/}
+          URI.parse(src).open
         end
       end
 

spec/fixtures/showcase.html

@@ -21,7 +21,8 @@ <h2>Table features</h2>
     <tr><th style="width: 1cm;">No</th><th>Description</th><th style="width: 25%;">State</th></tr>
     <tr><td>1</td><td>Headers and custom widths are supported</td><td>Done</td></tr>
     <tr><td>2</td><td><table><tr><td>subtables</td><td>so</td></tr><tr><td>very</td><td>crazy</td></tr></table></td><td>Done</td></tr>
-    <tr><td>1</td><td>Even lists <ol><li>one</li><li>two</li></ol></td><td>Check</td></tr>
+    <tr><td>3</td><td>Even lists <ol><li>one</li><li>two</li></ol></td><td>Check</td></tr>
+    <tr><td>4</td><td>and Images: <img src="https://github.com/puzzle/prawn-markup/blob/master/spec/fixtures/logo.png?raw=true" style="width: 50px;"></td><td>Yieha</td></tr>
   </table>
   This table has text underneath
 </div>
@@ -40,5 +41,6 @@ <h3>Ordered</h3>
 </ol>
 
 <h2>So far</h2>
+<img src="https://github.com/puzzle/prawn-markup/blob/master/spec/fixtures/logo.png?raw=true" style="width: 100%;">
 <p>and thanks for all the fish</p>
 <iframe src="http://codez.ch"></iframe>

spec/prawn/markup/processor/headings_spec.rb

@@ -38,7 +38,7 @@
       processor.parse('<h1>hello</h1><h2>world</h2><p>bla</p><h5>earthlings</h5><div>blu</div><h2>universe</h2><p>bli</p>')
       expect(text.strings).to eq(%w[hello world bla earthlings blu universe bli])
       # values copied from visually controlled run
-      expect(top_positions).to eq([720, 666, 646, 620, 605, 562, 542])
+      expect(top_positions).to eq([720, 666, 641, 620, 605, 562, 537])
     end
   end
 

spec/prawn/markup/processor/images_spec.rb

@@ -4,25 +4,38 @@
 RSpec.describe Prawn::Markup::Processor::Tables do
   include_context 'pdf_helpers'
 
+  LOGO_DIMENSION = [100, 38].freeze
+
   it 'renders an image on own line' do
     processor.parse("hello <img src=\"#{encode_image('logo.png')}\" style=\"width: 50mm;\"> world")
 
-    orig_img_dimension = [100, 38]
-    scaled_height = 50.mm * 38 / 100
-    gap = doc.font.line_gap + doc.font.descender
+    scaled_height = 50.mm * LOGO_DIMENSION.last / LOGO_DIMENSION.first
     expect(text.strings).to eq(%w[hello world])
     expect(left_positions).to eq([left, left])
-    expect(top_positions).to eq([top, top - line - scaled_height - gap].map(&:round))
+    expect(top_positions).to eq([top, top - line - scaled_height - p_gap].map(&:round))
   end
 
   it 'renders placeholder for unknown format' do
     processor.parse('hello <img src="data:image/bmp;bla,foobar"> world')
 
-    expect(text.strings).to eq(['hello ', '[unsupported image]', 'world'])
+    expect(text.strings).to eq(['hello', '[unsupported image]', 'world'])
     expect(left_positions).to eq([left, left, left])
     expect(top_positions).to eq([top, top - line, top - 2 * line].map(&:round))
   end
 
+  it 'renders image for remote src' do
+    processor.parse('<p>hello</p><p><img src="https://github.com/puzzle/prawn-markup/blob/master/spec/fixtures/logo.png?raw=true"></p><p>world</p>')
+
+    expect(text.strings).to eq(['hello', 'world'])
+    expect(left_positions).to eq([left, left])
+    expect(top_positions).to eq([top, top - line - LOGO_DIMENSION.last - p_gap - 5].map(&:round))
+  end
+
+  it 'renders unsupported image for remote src' do
+    processor.parse('<p>hello</p><p><img src="https://upload.wikimedia.org/wikipedia/commons/2/2c/Rotating_earth_%28large%29.gif"></p><p>world</p>')
+    expect(text.strings).to eq(['hello', '[unsupported image]', 'world'])
+  end
+
   it 'renders nothing for iframes' do
     processor.parse('hello <iframe src="http://vimeo.com/42" /> world')
 
@@ -40,4 +53,16 @@
       expect(top_positions).to eq([top, *([top - line] * 3), top - 2 * line].map(&:round))
     end
   end
+
+  context 'with custom loader' do
+    let(:options) { { image: { loader: ->(src) { "spec/fixtures/#{src}" } } } }
+
+    it 'render image with custom loader' do
+      processor.parse('<p>hello</p><img src="logo.png"><p>world</p>')
+
+      expect(left_positions).to eq([left, left])
+      expect(top_positions).to eq([top, top - line - LOGO_DIMENSION.last - p_gap - 5].map(&:round))
+    end
+
+  end
 end

spec/prawn/markup/showcase_spec.rb

@@ -7,9 +7,9 @@
   it 'renders showcase' do
     html = File.read('spec/fixtures/showcase.html')
     doc.markup_options = {
-      heading1: { margin_top: 30, margin_bottom: 5 },
-      heading2: { margin_top: 24, margin_bottom: 4 },
-      heading3: { margin_top: 20, margin_bottom: 3 },
+      heading1: { margin_top: 30, margin_bottom: 15 },
+      heading2: { margin_top: 24, margin_bottom: 10 },
+      heading3: { margin_top: 20, margin_bottom: 5 },
       table: {
         header: { background_color: 'DDDDDD', style: :italic }
       },