convert to PNG from PDF

Gemfile

@@ -7,7 +7,7 @@ gem 'rails', '~> 5.0.0'
 gem 'bcrypt','~>3.1.11'
 
 gem 'devise'
-
+gem 'rmagick', '~> 4.1', '>= 4.1.2'
 gem 'will_paginate',   '~> 3.1.0'
 gem 'bootstrap-will_paginate', '~> 0.0.10'
 gem 'font-awesome-rails'

Gemfile.lock

@@ -184,6 +184,7 @@ GEM
     responders (2.4.1)
       actionpack (>= 4.2.0, < 6.0)
       railties (>= 4.2.0, < 6.0)
+    rmagick (4.1.2)
     rubyzip (2.0.0)
     sablon (0.3.2)
       nokogiri (>= 1.8.5)
@@ -272,6 +273,7 @@ DEPENDENCIES
   prawn-table
   rack-mini-profiler!
   rails (~> 5.0.0)
+  rmagick (~> 4.1, >= 4.1.2)
   sablon
   sass-rails (~> 5.0)
   spring

app/controllers/samples_controller.rb

+require 'RMagick'
 class SamplesController < ApplicationController
+  include SamplesHelper
    before_action :authenticate_user!
    before_action :correct_user,   only: :destroy
    before_action :set_sample, only: [:show, :edit, :update, :destroy,:update_status]
@@ -85,14 +87,27 @@ class SamplesController < ApplicationController
       @sample = current_user.samples.find(params[:id])
       @user = @sample && @sample.user
     end
-     respond_to do |format|
-       format.html
-       format.js
-       format.pdf do
-         pdf = SamplePdf.new(@sample,operator?,@user)
-         send_data pdf.render, filename: "sample_#{@sample.id}.pdf",
-                               type:"application/pdf",
-                               disposition: "inline"
+    file_type = params["format"]
+    if file_type == 'pdf'
+      respond_to do |format|
+        format.html
+        format.js
+        format.pdf do
+          pdf = SamplePdf.new(@sample,operator?,@user)
+          send_data pdf.render, filename: "sample_#{@sample.id}.pdf",
+                                type:"application/pdf",
+                                disposition: "inline"
+        end
+      end
+    end
+    if file_type == 'png'
+      respond_to do |format|
+        format.html
+        format.js
+        format.png do
+          pdf = SamplePdf.new(@sample,operator?,@user)
+          send_image(pdf)
+        end
       end
     end
   end
@@ -137,6 +152,13 @@ class SamplesController < ApplicationController
      flash[:success]= "Sending e-mail to user"
   end
 
+  def send_image(pdf)
+    pdf_file_name = "sample_#{@sample.id}.pdf"
+    png_file_name = "sample_#{@sample.id}.png"
+    result = pdf_to_png(pdf, pdf_file_name, png_file_name)
+    send_data result.to_blob, filename: png_file_name, type: "image/png" , disposition: "inline"
+  end
+
   private
 
   def sample_params

app/helpers/samples_helper.rb

@@ -30,4 +30,23 @@ module SamplesHelper
      s.abs.round(2)
    end
 
+  def pdf_to_png(pdf, pdf_file_name, png_file_name)
+    pdf.render_file(pdf_file_name)
+    images = Magick::ImageList.new(pdf_file_name) do
+      self.density = 400
+      self.quality = 100
+      self.format  = "PNG"
+    end
+    File.delete(pdf_file_name)
+    images.each_with_index do |a, i|
+      a.format = 'PNG'
+    end
+    result = images.montage do |m|
+      m.tile = 1
+      m.geometry = "1024x1024+10+5"
+      m.background_color = "white"
+    end
+    result.format = "PNG"
+    result
+  end
 end

app/mailers/user_mailer.rb

 class UserMailer < ApplicationMailer
+  include SamplesHelper
   default from: 'notifications@example.com'
   respond_to? :pdf
   def measured_email(user,sample)
    @sample = sample
    @user = user
-
-    attachments["report.pdf"] =[SamplePdf.new(@sample,@user).render]
-
+   pdf = SamplePdf.new(@sample,@user)
+   pdf_file_name = "report.pdf"
+   png_file_name = "report.png"
+   attachments[pdf_file_name] =[pdf.render]
+   png = pdf_to_png(pdf, pdf_file_name, png_file_name)
+   attachments[png_file_name] = {:mime_type => 'image/png', :content => png.to_blob }
    mail to: @user.email, subject: "Your sample has been measured", from: "elemental_analysis@ioc.kit.edu"
  end
 

app/views/samples/_show.html.erb

@@ -142,4 +142,4 @@ $(document).ready(function(){
   </div>
 <%end%>
 <br>
-<p><%=link_to "Download PDF", sample_path(@sample, format: "pdf"), target: "_blank" %><p>
+<p><%=link_to "Download PDF", sample_path(@sample, format: "pdf"), target: "_blank" %>&nbsp;<%=link_to "Download PNG", sample_path(@sample, format: "png"), target: "_blank" %><p>