test-text-viewer/src/window.py

# window.py
#
# Copyright 2024 Benjamin Burkhardt
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
# SPDX-License-Identifier: GPL-3.0-or-later

from gi.repository import Adw, Gtk, Gio, GLib  # Adw is Adwaita and GTK GTK :)
                                               # Gio is needed for actions etc.
                                               # and GLib for saving the file!

@Gtk.Template(resource_path='/com/example/textviewer/window.ui')
class TextViewerWindow(Adw.ApplicationWindow):
    __gtype_name__ = 'TextViewerWindow'

    main_text_view = Gtk.Template.Child()
    open_button = Gtk.Template.Child()
    cursor_pos_text = Gtk.Template.Child()
    toast_overlay = Gtk.Template.Child()

    def __init__(self, **kwargs):
        super().__init__(**kwargs)

        open_action = Gio.SimpleAction(name="open")
        open_action.connect("activate", self.open_file_dialog_action)
        self.add_action(open_action)

        save_action = Gio.SimpleAction(name="save-as")
        save_action.connect("activate", self.save_file_dialog_action)
        self.add_action(save_action)


        buffer = self.main_text_view.get_buffer()
        buffer.connect("notify::cursor-position", self.update_cursor_position)

        self.settings = Gio.Settings(schema_id="com.example.textviewer")
        self.settings.bind("window-width", self, "default-width",
                           Gio.SettingsBindFlags.DEFAULT)
        self.settings.bind("window-height", self, "default-height",
                           Gio.SettingsBindFlags.DEFAULT)
        self.settings.bind("window-maximized", self, "maximized",
                           Gio.SettingsBindFlags.DEFAULT)
        # Gio.Settings.bind method takes
        # 1. the key defined in the settings scheme to bind to
        # 2. the object which owns the property to bind the setting key to
        # 3. property: the property, e.g. default-width as defined in the XML!
        # 4. flags: BindFlags.DEFAULT means it's a kind of bidirectional rw bound



    def open_file_dialog_action(self, action, _):
        native = Gtk.FileDialog()
        native.open(self, None, self.on_open_response)

    def on_open_response(self, dialog, result):
        try:
            file = dialog.open_finish(result)
        except:  # if the user dismisses the dialog, a GError/sth else is raised
            return
        # If the user selected a file...
        if file is not None:
            # ... open it
            self.open_file(file)

    def open_file(self, file):
        file.load_contents_async(None, self.open_file_complete)

    def open_file_complete(self, file, result):
        info = file.query_info("standard::display-name", Gio.FileQueryInfoFlags.NONE)
        if info:
            display_name = info.get_attribute_string("standard::display-name")
        else:
            display_name = file.get_basename()

        contents = file.load_contents_finish(result)
        if not contents[0]:
            path = file.peek_path()
            print(f"Unable to open {path}: {contents[1]}")
            self.toast_overlay.add_toast(Adw.Toast(title=f"Unable to open “{display_name}”"))

        try:
            text = contents[1].decode('utf-8')
        except UnicodeError as err:
            path = file.peek_path()
            print(f"Unable to load the contents of {path}: the file is not encoded with UTF-8")
            self.toast_overlay.add_toast(Adw.Toast(title=f"Invalid encoding for {display_name}"))
            return


        self.set_title(display_name)

        buffer = self.main_text_view.get_buffer()
        buffer.set_text(text)
        start = buffer.get_start_iter()
        buffer.place_cursor(start)

    def update_cursor_position(self, buffer, _):
        # Retrieve the value of the "cursor-position" property
        cursor_pos = buffer.props.cursor_position
        # Construct the text iterator for the position of the cursor
        iter = buffer.get_iter_at_offset(cursor_pos)
        line = iter.get_line() + 1
        column = iter.get_line_offset() + 1
        # Set the new contents of the label
        self.cursor_pos_text.set_text(f"Ln {line}, Col {column}")

    def save_file_dialog_action(self, action, _):
        native = Gtk.FileDialog()
        native.save(self, None, self.on_save_response)

    def on_save_response(self, dialog, result):
        try:
            file = dialog.save_finish(result)
        except:  # if the user dismisses the dialog, a GError/sth else is raised
            return
        if file is not None:
            self.save_file(file)

    def save_file(self, file):
        buffer = self.main_text_view.get_buffer()

        # Retrieve the iterator at the start of the buffer
        start = buffer.get_start_iter()
        # Retrieve the iterator at the end of the buffer
        end = buffer.get_end_iter()
        # Retrieve all the visible text between the two bounds
        text = buffer.get_text(start, end, False)

        # If there is nothing to save, return early
        if not text:
            return

        bytes = GLib.Bytes.new(text.encode('utf-8'))

        # Start the asynchronous operation to save the data into the file
        file.replace_contents_bytes_async(bytes,
                                          None,
                                          False,
                                          Gio.FileCreateFlags.NONE,
                                          None,
                                          self.save_file_complete)

    def save_file_complete(self, file, result):
        res = file.replace_contents_finish(result)
        info = file.query_info("standard::display-name",
                               Gio.FileQueryInfoFlags.NONE)
        if info:
            display_name = info.get_attribute_string("standard::display-name")
        else:
            display_name = file.get_basename()
        if not res:
            print(f"Unable to save {display_name}")
            self.toast_overlay.add_toast(Adw.Toast(title=f"Unable to save {display_name}"))
        else:
            self.toast_overlay.add_toast(Adw.Toast(title=f"Saved to {display_name}"))

        self.set_title(display_name)