RubyでLinuxデスクトップアプリケーションを作成する

• コンボボックスをドラッグします ウィジェットセクションからグリッドの4行目の2列目まで。
• IDを設定します priority_combo_boxへ 。
• 共通 [プロパティ]セクションのタブで、ウィジェットの間隔>展開>水平を確認します チェックボックスをオンにして、右側のスイッチをオンにします。これにより、親（グリッド）のサイズが変更されるたびにウィジェットを水平方向に拡張できます。
• このウィジェットはドロップダウン要素です。ウィンドウクラス内に表示されたときにユーザーが選択できる値を入力します。

• Drag a Button Box from the Widget section to the second column of the last row of the grid.
• In the pop-up window, select 2 items.
• 一般 tab of the Properties section, set the Box Attributes> Orientation property to Horizontal 。
• 一般 tab of the Properties section, set the Box Attributes> Spacing property to 10 。
• In the Common tab of the Properties section, set the Widget Spacing> Alignment> Horizontal to Center 。
• Again, our code won't alter this widget, but you can give it a descriptive ID for readability. I named mine actions_box 。

• Drag two Button widgets and place one in each box of the button box widget we added in the previous step.
• Set their ID properties to cancel_button and save_button , respectively.
• 一般 tab of the Properties window, set their Button Content> Label with option image property to Cancel and Save , respectively.

The window is ready. Save the file under resources/ui/new_item_window.ui 。

It's time to port it into our application.

Implement the new item window class

Before implementing the new class, we must update our GResource description file (resources/gresources.xml ) to obtain the new resource:

<?xml version="1.0" encoding="UTF-8"?>

<gresources>

  <gresource prefix="/com/iridakos/gtk-todo">

    <file preprocess="xml-stripblanks">ui/application_window.ui</file>

    <file preprocess="xml-stripblanks">ui/new_item_window.ui</file>

  </gresource>

</gresources>

Now we can create the new window class. Create a file under application/ui/todo named new_item_window.rb and set its contents as follows:

module Todo

  class NewItemWindow < Gtk::Window

    # Register the class in the GLib world

    type_register



    class << self

      def init

        # Set the template from the resources binary

        set_template resource: '/com/iridakos/gtk-todo/ui/new_item_window.ui'

      end

    end



    def initialize(application)

      super application: application

    end

  end

end

There's nothing special here. We just changed the template resource to point to the correct file of our resources.

We have to change the add_new_item_button code that executes on the clicked signal to show the new item window. We'll go ahead and change that code in application_window.rb to this:

add_new_item_button.signal_connect 'clicked' do |button|

  new_item_window = NewItemWindow.new(application)

  new_item_window.present

end

Let's see what we have done. Start the application and click on the Add new item ボタン。 Tadaa!

But nothing happens when we press the buttons. Let's fix that.

First, we'll bind the UI widgets in the Todo::NewItemWindow class.

Change the init method to this:

def init

  # Set the template from the resources binary

  set_template resource: '/com/iridakos/gtk-todo/ui/new_item_window.ui'



  # Bind the window's widgets

  bind_template_child 'id_value_label'

  bind_template_child 'title_text_entry'

  bind_template_child 'notes_text_view'

  bind_template_child 'priority_combo_box'

  bind_template_child 'cancel_button'

  bind_template_child 'save_button'

end

This window will be shown when either creating or editing a ToDo item, so the new_item_window naming is not very valid. We'll refactor that later.

For now, we will update the window's initialize method to require one extra parameter for the Todo::Item to be created or edited. We can then set a more meaningful window title and change the child widgets to reflect the current item.

We'll change the initialize method to this:

def initialize(application, item)

  super application: application

  set_title "ToDo item #{item.id} - #{item.is_new? ? 'Create' : 'Edit' } Mode"



  id_value_label.text = item.id

  title_text_entry.text = item.title if item.title

  notes_text_view.buffer.text = item.notes if item.notes



  # Configure the combo box

  model = Gtk::ListStore.new(String)

  Todo::Item::PRIORITIES.each do |priority|

    iterator = model.append

    iterator[0] = priority

  end



  priority_combo_box.model = model

  renderer = Gtk::CellRendererText.new

  priority_combo_box.pack_start(renderer, true)

  priority_combo_box.set_attributes(renderer, "text" => 0)



  priority_combo_box.set_active(Todo::Item::PRIORITIES.index(item.priority)) if item.priority

end

Then we'll add the constant PRIORITIES in the application/models/item.rb file just below the PROPERTIES constant:

PRIORITIES = ['high', 'medium', 'normal', 'low'].freeze

What did we do here?

• We set the window's title to a string containing the current item's ID and the mode (depending on whether the item is being created or edited).
• We set the id_value_label text to display the current item's ID.
• We set the title_text_entry text to display the current item's title.
• We set the notes_text_view text to display the current item's notes.
• We created a model for the priority_combo_box whose entries are going to have only one String 価値。 At first sight, a Gtk::ListStore model might look a little confusing. Here's how it works.
  • Suppose we want to display in a combo box a list of country codes and their respective country names.
  • We would create a Gtk::ListStore defining that its entries would consist of two string values:one for the country code and one for the country name. Thus we would initialize the ListStore as: 
    

    model = Gtk::ListStore.new(String, String)

  • To fill the model with data, we would do something like the following (make sure you don't miss the comments in the snippet): 
    

    [['gr', 'Greece'], ['jp','Japan'], ['nl', 'Netherlands']].each do |country_pair|
    
      entry = model.append
    
      # Each entry has two string positions since that's how we initialized the Gtk::ListStore
    
      # Store the country code in position 0
    
      entry[0] = country_pair[0]
    
      # Store the country name in position 1
    
      entry[1] = country_pair[1]
    
    end

  • We also configured the combo box to render two text columns/cells (again, make sure you don't miss the comments in the snippet): 
    

    country_code_renderer = Gtk::CellRendererText.new
    
    # Add the first renderer
    
    combo.pack_start(country_code_renderer, true)
    
    # Use the value in index 0 of each model entry a.k.a. the country code
    
    combo.set_attributes(country_code_renderer, 'text' => 0)
    
    
    
    country_name_renderer = Gtk::CellRendererText.new
    
    # Add the second renderer
    
    combo.pack_start(country_name_renderer, true)
    
    # Use the value in index 1 of each model entry a.k.a. the country name
    
    combo.set_attributes(country_name_renderer, 'text' => 1)

  • I hope that made it a little clearer.
• We added a simple text renderer in the combo box and instructed it to display the only value of each model's entry (a.k.a., position 0 ）。 Imagine that our model is something like [['high'],['medium'],['normal'],['low']] and 0 is the first element of each sub-array. I will stop with the model-combo-text-renderer explanations now…

Configure the user data path

Remember that when initializing a new Todo::Item (not an existing one), we had to define a :user_data_path in which it would be saved. We are going to resolve this path when the application starts and make it accessible from all the widgets.

All we have to do is check if the .gtk-todo-tutorial path exists inside the user's home ~ ディレクトリ。 If not, we will create it. Then we'll set this as an instance variable of the application. All widgets have access to the application instance. So, all widgets have access to this user path variable.

Change the application/application.rb file to this:

module ToDo

  class Application < Gtk::Application

    attr_reader :user_data_path



    def initialize

      super 'com.iridakos.gtk-todo', Gio::ApplicationFlags::FLAGS_NONE



      @user_data_path = File.expand_path('~/.gtk-todo-tutorial')

      unless File.directory?(@user_data_path)

        puts "First run. Creating user's application path: #{@user_data_path}"

        FileUtils.mkdir_p(@user_data_path)

      end



      signal_connect :activate do |application|

        window = Todo::ApplicationWindow.new(application)

        window.present

      end

    end

  end

end

One last thing we need to do before testing what we have done so far is to instantiate the Todo::NewItemWindow when the add_new_item_button is clicked complying with the changes we made. In other words, change the code in application_window.rb to this:

add_new_item_button.signal_connect 'clicked' do |button|

  new_item_window = NewItemWindow.new(application, Todo::Item.new(user_data_path: application.user_data_path))

  new_item_window.present

end

Start the application and click on the Add new item ボタン。 Tadaa! (Note the - Create mode part in the title).

Cancel item creation/update

To close the Todo::NewItemWindow window when a user clicks the cancel_button , we only have to add this to the window's initialize method:

cancel_button.signal_connect 'clicked' do |button|

  close

end

close is an instance method of the Gtk::Window class that closes the window.

Save the item

Saving an item involves two steps:

• Update the item's properties based on the widgets' values.
• Call the save! method on the Todo::Item instance.

Again, our code will be placed in the initialize method of the Todo::NewItemWindow ：

save_button.signal_connect 'clicked' do |button|

  item.title = title_text_entry.text

  item.notes = notes_text_view.buffer.text

  item.priority = priority_combo_box.active_iter.get_value(0) if priority_combo_box.active_iter

  item.save!

  close

end

Once again, the window closes after saving the item.

Let's try that out.

Now, by pressing Save and navigating to our ~/.gtk-todo-tutorial folder, we should see a file. Mine had the following contents:

{

        "id": "3d635839-66d0-4ce6-af31-e81b47b3e585",

        "title": "Optimize the priorities model creation",

        "notes": "It doesn't have to be initialized upon each window creation.",

        "priority": "high",

        "filename": "/home/iridakos/.gtk-todo-tutorial/3d635839-66d0-4ce6-af31-e81b47b3e585.json",

        "creation_datetime": "2018-01-25 18:09:51 +0200"

}

Don't forget to try out the Cancel button as well.

View ToDo items

The Todo::ApplicationWindow contains only one button. It's time to change that.

We want the window to have Add new item on the top and a list below with all of our ToDo items. We'll add a Gtk::ListBox to our design that can contain any number of rows.

Update the application window

• Open the resources/ui/application_window.ui file in Glade.
• Nothing happens if we drag a List Box widget from the Widget section directly on the window.それは正常です。 First, we have to split the window into two parts:one for the button and one for the list box. Bear with me.
• Right-click on the new_item_window in the Hierarchy section and select Add parent> Box 。
• In the pop-up window, set 2 for the number of items.
• The orientation of the box is already vertical, so we are fine.

• Now, drag a List Box and place it on the free area of the previously added box.
• Set its ID property to todo_items_list_box 。
• Set its Selection mode to None since we won't provide that functionality.

Design the ToDo item list box row

Each row of the list box we created in the previous step will be more complex than a row of text. Each will contain widgets that allow the user to expand an item's notes and to delete or edit the item.

• Create a new project in Glade, as we did for the new_item_window.ui 。 Save it under resources/ui/todo_item_list_box_row.ui 。
• Unfortunately (at least in my version of Glade), there is no List Box Row widget in the Widget section. So, we'll add one as the top-level widget of our project in a kinda hackish way.
• Drag a List Box from the Widget section to the Design area.
• Inside the Hierarchy section, right-click on the List Box and select Add Row

• In the Hierarchy section, right-click on the newly added List Box Row nested under the List Box and select Remove parent 。 There it is! The List Box Row is the top-level widget of the project now.

• Check the widget's Composite property and set its name to TodoItemListBoxRow 。
• Drag a Box from the Widget section to the Design area inside our List Box Row 。
• Set 2 items in the pop-up window.
• Set its ID property to main_box 。

• Drag another Box from the Widget section to the first row of the previously added box.
• Set 2 items in the pop-up window.
• Set its ID property to todo_item_top_box 。
• Set its Orientation property to Horizontal 。
• Set its Spacing (General tab) property to 10 。

• Drag a Label from the Widget section to the first column of the todo_item_top_box 。
• Set its ID property to todo_item_title_label 。
• Set its Alignment and Padding> Alignment> Horizontal property to 0.00 。
• In the Common tab of the Properties section, check the Widget Spacing> Expand> Horizontal checkbox and turn on the switch next to it so the label will expand to the available space.

• Drag a Button from the Widget section to the second column of the todo_item_top_box 。
• Set its ID property to details_button 。
• Check the Button Content> Label with optional image radio and type ... (three dots).

• Drag a Revealer widget from the Widget section to the second row of the main_box 。
• Turn off the Reveal Child switch in the General tab.
• Set its ID property to todo_item_details_revealer 。
• Set its Transition type property to Slide Down 。

• Drag a Box from the Widget section to the reveal space.
• Set its items to 2 in the pop-up window.
• Set its ID property to details_box 。
• In the Common tab, set its Widget Spacing> Margins> Top property to 10 。

• Drag a Button Box from the Widget section to the first row of the details_box 。
• Set its ID property to todo_item_action_box 。
• Set its Layout style property to expand 。

• Drag Button widgets to the first and second columns of the todo_item_action_box 。
• Set their ID properties to delete_button and edit_button , respectively.
• Set their Button Content> Label with optional image properties to Delete and Edit , respectively.

• Drag a Viewport widget from the Widget section to the second row of the details_box 。
• Set its ID property to todo_action_notes_viewport 。
• Drag a Text View widget from the Widget section to the todo_action_notes_viewport that we just added.
• Set its ID to todo_item_notes_text_view 。
• Uncheck its Editable property in the General tab of the Properties section.

Create the ToDo item list-box row class

Now we will create the class reflecting the UI of the list-box row we just created.

First we have to update our GResource description file to include the newly created design. Change the resources/gresources.xml file as follows:

<?xml version="1.0" encoding="UTF-8"?>

<gresources>

  <gresource prefix="/com/iridakos/gtk-todo">

    <file preprocess="xml-stripblanks">ui/application_window.ui</file>

    <file preprocess="xml-stripblanks">ui/new_item_window.ui</file>

    <file preprocess="xml-stripblanks">ui/todo_item_list_box_row.ui</file>

  </gresource>

</gresources>

Create a file named item_list_box_row.rb inside the application/ui folder and add the following:

module Todo

  class ItemListBoxRow < Gtk::ListBoxRow

    type_register



    class << self

      def init

        set_template resource: '/com/iridakos/gtk-todo/ui/todo_item_list_box_row.ui'

      end

    end



    def initialize(item)

      super()

    end

  end

end

We will not bind any children at the moment.

When starting the application, we have to search for files in the :user_data_path , and we must create a Todo::Item instance for each file. For each instance, we must also add a new Todo::ItemListBoxRow to the Todo::ApplicationWindow 's todo_items_list_box list box. One thing at a time.

First, let's bind the todo_items_list_box in the Todo::ApplicationWindow class. Change the init method as follows:

def init

  # Set the template from the resources binary

  set_template resource: '/com/iridakos/gtk-todo/ui/application_window.ui'



  bind_template_child 'add_new_item_button'

  bind_template_child 'todo_items_list_box'

end

Next, we'll add an instance method in the same class that will be responsible to load the ToDo list items in the related list box. Add this code in Todo::ApplicationWindow ：

def load_todo_items

  todo_items_list_box.children.each { |child| todo_items_list_box.remove child }



  json_files = Dir[File.join(File.expand_path(application.user_data_path), '*.json')]

  items = json_files.map{ |filename| Todo::Item.new(filename: filename) }



  items.each do |item|

    todo_items_list_box.add Todo::ItemListBoxRow.new(item)

  end

end

Then we'll call this method at the end of the initialize method:

def initialize(application)

  super application: application



  set_title 'GTK+ Simple ToDo'



  add_new_item_button.signal_connect 'clicked' do |button|

    new_item_window = NewItemWindow.new(application, Todo::Item.new(user_data_path: application.user_data_path))

    new_item_window.present

  end



  load_todo_items

end

注： We must first empty the list box of its current children rows then refill it. This way, we will call this method after saving a Todo::Item via the signal_connect of the save_button of the Todo::NewItemWindow , and the parent application window will be reloaded! Here's the updated code (in application/ui/new_item_window.rb ）：

save_button.signal_connect 'clicked' do |button|

  item.title = title_text_entry.text

  item.notes = notes_text_view.buffer.text

  item.priority = priority_combo_box.active_iter.get_value(0) if priority_combo_box.active_iter

  item.save!



  close



  # Locate the application window

  application_window = application.windows.find { |w| w.is_a? Todo::ApplicationWindow }

  application_window.load_todo_items

end

Previously, we used this code:

json_files = Dir[File.join(File.expand_path(application.user_data_path), '*.json')]

to find the names of all the files in the application-user data path with a JSON extension.

Let's see what we've created. Start the application and try adding a new ToDo item. After pressing the Save button, you should see the parent Todo::ApplicationWindow automatically updated with the new item!

What's left is to complete the functionality of the Todo::ItemListBoxRow 。

First, we will bind the widgets. Change the init method of the Todo::ItemListBoxRow class as follows:

def init

  set_template resource: '/com/iridakos/gtk-todo/ui/todo_item_list_box_row.ui'



  bind_template_child 'details_button'

  bind_template_child 'todo_item_title_label'

  bind_template_child 'todo_item_details_revealer'

  bind_template_child 'todo_item_notes_text_view'

  bind_template_child 'delete_button'

  bind_template_child 'edit_button'

end

Then, we'll set up the widgets based on the item of each row.

def initialize(item)

  super()



  todo_item_title_label.text = item.title || ''



  todo_item_notes_text_view.buffer.text = item.notes



  details_button.signal_connect 'clicked' do

    todo_item_details_revealer.set_reveal_child !todo_item_details_revealer.reveal_child?

  end



  delete_button.signal_connect 'clicked' do

    item.delete!



    # Locate the application window

    application_window = application.windows.find { |w| w.is_a? Todo::ApplicationWindow }

    application_window.load_todo_items

  end



  edit_button.signal_connect 'clicked' do

    new_item_window = NewItemWindow.new(application, item)

    new_item_window.present

  end

end



def application

  parent = self.parent

  parent = parent.parent while !parent.is_a? Gtk::Window

  parent.application

end

• As you can see, when the details_button is clicked, we instruct the todo_item_details_revealer to swap the visibility of its contents.
• After deleting an item, we find the application's Todo::ApplicationWindow to call its load_todo_items , as we did after saving an item.
• When clicking to edit a button, we create a new instance of the Todo::NewItemWindow passing an item as the current item. Works like a charm!
• Finally, to reach the application parent of a list-box row, we defined a simple instance method application that navigates through the widget's parents until it reaches a window from which it can obtain the application object.

Save and run the application. There it is!

This has been a really long tutorial and, even though there are so many items that we haven't covered, I think we better end it here.

Long post, cat photo.

Useful links

• This tutorial's code
• A set of bindings for the GNOME-2.x libraries to use from Ruby
• Gtk3 tutorial for Ruby based on the official C version
• GTK+ 3 Reference Manual

This was originally published on Lazarus Lazaridis's blog, iridakos.com, and is republished with permission.