Implement scrollbar

Author: aycabta

lib/reline.rb

@@ -24,7 +24,7 @@ def match?(key)
     end
   end
   CursorPos = Struct.new(:x, :y)
-  DialogRenderInfo = Struct.new(:pos, :contents, :pointer, :bg_color, :width, :height, keyword_init: true)
+  DialogRenderInfo = Struct.new(:pos, :contents, :pointer, :bg_color, :width, :height, :scrollbar, keyword_init: true)
 
   class Core
     ATTR_READER_NAMES = %i(
@@ -228,7 +228,7 @@ def get_screen_size
         context.clear
         context.push(cursor_pos_to_render, result, pointer, dialog)
       end
-      DialogRenderInfo.new(pos: cursor_pos_to_render, contents: result, pointer: pointer, height: 15)
+      DialogRenderInfo.new(pos: cursor_pos_to_render, contents: result, pointer: pointer, scrollbar: true, height: 15)
     }
     Reline::DEFAULT_DIALOG_CONTEXT = Array.new
 

lib/reline/line_editor.rb

@@ -661,6 +661,13 @@ def add_dialog_proc(name, p, context = nil)
     reset_dialog(dialog, old_dialog)
     move_cursor_down(dialog.vertical_offset)
     Reline::IOGate.move_cursor_column(dialog.column)
+    if dialog_render_info.scrollbar and dialog_render_info.contents.size > height
+      bar_max_height = height * 2
+      moving_distance = (dialog_render_info.contents.size - height) * 2
+      position_ratio = dialog.scroll_top.zero? ? 0.0 : ((dialog.scroll_top * 2).to_f / moving_distance)
+      bar_height = (bar_max_height * ((dialog.contents.size * 2).to_f / (dialog_render_info.contents.size * 2))).floor.to_i
+      position = ((bar_max_height - bar_height) * position_ratio).floor.to_i
+    end
     dialog.contents.each_with_index do |item, i|
       if i == pointer
         bg_color = '45'
@@ -672,10 +679,22 @@ def add_dialog_proc(name, p, context = nil)
         end
       end
       str = padding_space_with_escape_sequences(Reline::Unicode.take_range(item, 0, dialog.width), dialog.width)
+      if dialog_render_info.scrollbar and dialog_render_info.contents.size > height
+        if position <= (i * 2) and (i * 2) <= (position + bar_height)
+          str += '█'
+        elsif position <= (i * 2) and (i * 2 - 1) <= (position + bar_height)
+          str += '▀'
+        elsif position <= (i * 2 + 1) and (i * 2) <= (position + bar_height)
+          str += '▄'
+        else
+          str += ' '
+        end
+      end
       @output.write "\e[#{bg_color}m#{str}\e[49m"
       Reline::IOGate.move_cursor_column(dialog.column)
       move_cursor_down(1) if i < (dialog.contents.size - 1)
     end
+    dialog.width += 1 if dialog_render_info.scrollbar and dialog_render_info.contents.size > height
     Reline::IOGate.move_cursor_column(cursor_column)
     move_cursor_up(dialog.vertical_offset + dialog.contents.size - 1)
     Reline::IOGate.show_cursor