Merge pull request #54 from petergoldstein/feature/add_rise_and_leading

Add rise to the set of text state operator helpers

lib/pdf/core/text.rb

@@ -252,6 +252,22 @@ def horizontal_text_scaling(amount = nil, &block)
         end
       end
 
+      # Move the baseline up or down from its default location.
+      # Positive values move the baseline up, negative values
+      # move it down, and a zero value resets the baseline to
+      # its default location.
+      def rise(amount = nil, &block)
+        if amount.nil?
+          return defined?(@rise) && @rise || 0
+        end
+
+        if rise == amount
+          yield
+        else
+          wrap_and_restore_rise(amount, &block)
+        end
+      end
+
       def add_text_content(text, x, y, options)
         chunks = font.encode_text(text, options)
 
@@ -316,6 +332,10 @@ def wrap_and_restore_character_spacing(block_value)
         end
       end
 
+      def update_character_spacing_state
+        add_content "\n#{PDF::Core.real(character_spacing)} Tc"
+      end
+
       def wrap_and_restore_word_spacing(block_value)
         original_value = word_spacing
         @word_spacing = block_value
@@ -328,6 +348,10 @@ def wrap_and_restore_word_spacing(block_value)
         end
       end
 
+      def update_word_spacing_state
+        add_content "\n#{PDF::Core.real(word_spacing)} Tw"
+      end
+
       def wrap_and_restore_horizontal_text_scaling(block_value)
         original_value = horizontal_text_scaling
         @horizontal_text_scaling = block_value
@@ -340,20 +364,24 @@ def wrap_and_restore_horizontal_text_scaling(block_value)
         end
       end
 
-      def update_character_spacing_state
-        update_real_text_state(character_spacing, 'Tc')
-      end
-
-      def update_word_spacing_state
-        update_real_text_state(word_spacing, 'Tw')
+      def update_horizontal_text_scaling_state
+        add_content "\n#{PDF::Core.real(horizontal_text_scaling)} Tz"
       end
 
-      def update_horizontal_text_scaling_state
-        update_real_text_state(horizontal_text_scaling, 'Tz')
+      def wrap_and_restore_rise(block_value)
+        original_value = rise
+        @rise = block_value
+        update_rise_state
+        begin
+          yield
+        ensure
+          @rise = original_value
+          update_rise_state
+        end
       end
 
-      def update_real_text_state(amount, operator)
-        add_content "\n#{PDF::Core.real(amount)} #{operator}"
+      def update_rise_state
+        add_content "\n#{PDF::Core.real(rise)} Ts"
       end
     end
   end

spec/pdf/core/text_spec.rb

@@ -236,6 +236,56 @@ def font_size
     end
   end
 
+  describe '#rise' do
+    describe 'called without argument' do
+      let(:result) { mock.rise }
+
+      it 'functions as accessor' do
+        expect(result).to eq(0)
+      end
+    end
+
+    describe 'called with argument' do
+      context 'when the block does not raise an error' do
+        before do
+          mock.rise(2.3) do
+            mock.add_content('TEST')
+          end
+        end
+
+        it 'resets rise to original value' do
+          expect(mock.rise).to eq(0)
+        end
+
+        it 'outputs correct PDF content' do
+          expect(mock.text).to eq("\n2.3 TsTEST\n0.0 Ts")
+        end
+      end
+
+      context 'when the block raises an error' do
+        let(:error_message) { SecureRandom.hex(5) }
+
+        # rubocop:disable RSpec/ExpectInHook
+        before do
+          expect do
+            mock.rise(5) do
+              raise StandardError, error_message
+            end
+          end.to raise_error StandardError, error_message
+        end
+        # rubocop:enable RSpec/ExpectInHook
+
+        it 'resets rise to original value' do
+          expect(mock.rise).to eq(0)
+        end
+
+        it 'outputs correct PDF content' do
+          expect(mock.text).to eq("\n5.0 Ts\n0.0 Ts")
+        end
+      end
+    end
+  end
+
   describe '#add_text_content' do
     it 'handles frozen strings' do
       expect { mock.add_text_content 'text', 0, 0, {} }