Saving The Content To A File

In this lesson you will learn how to add a menu entry with a key shortcut, ask the user to select a file for saving the Gtk::TextBuffer contents, and save a file.

Add the “Save As” menu item

1. Open the UI definition file for your window and find the primary_menu menu definition at the bottom of the file
2. Remove the “Preferences” menu item, as we are not going to need it
3. In place of the removed menu item, add the definition of the Save As menu item:

<menu id="primary_menu">
  <section>
    <item>
      <attribute name="label" translatable="yes">_Save as...</attribute>
      <attribute name="action">win.save-as</attribute>
    </item>
    <item>
      <attribute name="label" translatable="yes">_Keyboard Shortcuts</attribute>
      <attribute name="action">win.show-help-overlay</attribute>
    </item>
    <item>
      <attribute name="label" translatable="yes">_About {{name}}</attribute>
      <attribute name="action">app.about</attribute>
    </item>
  </section>
</menu>

The “Save as” menu item is bound to the win.save-as action; this means that activating the menu item will activate the save-as action registered on the Text::Viewer::Window window.

Add the “Save As” action

1. Open the window.cr file, and find the class constructor of the Text::Viewer::Window widget
2. Create the save-as action, connect a callback to its activate signal, and add the action to the window

    def initialize
      super()

      @header_bar = Adw::HeaderBar.cast(template_child("header_bar"))
      @main_text_view = Gtk::TextView.cast(template_child("main_text_view"))
      @open_button = Gtk::Button.cast(template_child("open_button"))
      @cursor_pos = Gtk::Label.cast(template_child("cursor_pos"))

      open_action = Gio::SimpleAction.new("open", nil)
      open_action.activate_signal.connect do
        self.open_file_dialog
      end
      self.add_action open_action

      save_action = Gio::SimpleAction.new("save-as", nil)
      save_action.activate_signal.connect do
        self.save_file_dialog
      end
      self.add_action save_action

      @main_text_view.buffer.notify_signal["cursor-position"].connect do
        buffer = @main_text_view.buffer
        cursor_position = buffer.cursor_position
        iter = buffer.iter_at_offset(cursor_position)
        @cursor_pos.label = "Ln #{iter.line}, Col #{iter.line_offset}"
      end
    end

Select a file

1. In the activate callback method for the save-as action, create a file selection dialog using the Gtk::FileChooserAction::Save action, and connect to its response signal

    private def save_file_dialog
      filechooser = Gtk::FileChooserNative.new("Save File As", nil, Gtk::FileChooserAction::Save, "_Save", "_Cancel")
      filechooser.transient_for = self
      filechooser.response_signal.connect do |response|
      end

      filechooser.show
    end

2. In the method, retrieve the Gio::File for the location selected by the user, and call the save_file method

    private def save_file_dialog
      filechooser = Gtk::FileChooserNative.new("Save File As", nil, Gtk::FileChooserAction::Save, "_Save", "_Cancel")
      filechooser.transient_for = self
      filechooser.response_signal.connect do |response|
        if Gtk::ResponseType.from_value(response) == Gtk::ResponseType::Accept
          self.save_file(filechooser.file)
        end
      end

      filechooser.show
    end

Save the contents of the text buffer

In the save_file method, retrieve the contents of the Gtk::TextBuffer using the start and end Gtk::TextIter as the bounds of the buffer, then save it to the Gio::File's Path using Crystal's File IO

    private def save_file(file : Gio::File?)
      return if file.nil?

      file_path = file.not_nil!.path.not_nil!
      File.open(file_path, "w") do |file_io|
        buffer = @main_text_view.buffer

        # Retrieve the iterator at the start of the buffer
        start_iter = buffer.start_iter

        # Retrieve the iterator at the end of the buffer
        end_iter = buffer.end_iter

        # Retrieve all the visible text between the two bounds
        text = buffer.text(start_iter, end_iter, false)
        return if text.size == 0

        file_io.print(text)
      end
    end

Add a key shortcut for the “Save As” action

1. Open the text-viewer.cr source file and find the constructor for the Text::Viewer::App class
2. Add Ctrl + Shift + S as the accelerator shortcut for the win.save-as action

  #...
  class App < Adw::Application
    def initialize
      #...

      self.set_accels_for_action("app.quit", {"<primary>q"})
      self.set_accels_for_action("win.open", {"<Ctrl>o"})
      self.set_accels_for_action("win.save-as", {"<Ctrl><Shift>s"})

      #...
    end
    #...

Add the “Save As” shortcut to the Keyboard Shortcuts help

1. Find the help-overlay.ui file in the sources directory
2. Find the GtkShortcutsGroup definition
3. Add a new GtkShortcutsShortcut definition for the win.save action in the shortcuts group

<object class="GtkShortcutsGroup">
  <property name="title" translatable="yes" context="shortcut window">General</property>
  <child>
    <object class="GtkShortcutsShortcut">
      <property name="title" translatable="yes" context="shortcut window">Open</property>
      <property name="action-name">win.open</property>
    </object>
  </child>
  <child>
    <object class="GtkShortcutsShortcut">
      <property name="title" translatable="yes" context="shortcut window">Save As</property>
      <property name="action-name">win.save-as</property>
    </object>
  </child>

At the end of this lesson, you should be able to:

• select the “Save As” menu item from the primary menu
• select a file from a dialog
• save the contents of the text viewer in the selected file