Notepad

A WordPad-like rich text editor built with C++ and Qt 6.

Build

cmake -S . -B build && cmake --build build

Set the working directory to the project root so that data/images/ and data/words.txt resolve correctly. In CLion: Run > Edit Configurations > Working Directory → $ProjectFileDir$.

Features

File

Action	Shortcut
New	—
Open	Ctrl+O
Open Readme	Ctrl+Shift+R
Save	Ctrl+S
Save As	—

Open Readme loads Readme.md from the working directory and automatically enables the Markdown preview panel.

Edit

Action	Shortcut
Undo / Redo	Ctrl+Z / Ctrl+Y
Cut / Copy / Paste	Ctrl+X / Ctrl+C / Ctrl+V
Select All	Ctrl+A
Insert Symbol	Ctrl+Shift+S

Insert Symbol opens a table of 50 special characters grouped by category: typography, math, currency, arrows, and marks. Single click inserts and keeps the dialog open; double click inserts and closes.

Format

Bold / Italic / Underline — toolbar buttons and Ctrl+B / Ctrl+I / Ctrl+U.

Font — opens QFontDialog; applies to selection or whole document.

Text Color — opens QColorDialog; applies to selection.

Highlight — applies a background color to selected text. Five preset colors (Yellow, Green, Cyan, Pink, Orange), a custom color picker, and a clear option. The H toolbar button applies the last used color.

Text Case — five transforms applied to selection or whole document:

• To Uppercase
• To Lowercase
• Capitalize Words
• Sentence Case
• Swap Case

Search

Find / Replace (Ctrl+F) — find next, replace one, replace all, optional case-sensitive matching.

Tools

Word Frequency — counts every word in the document and shows a sorted table.

Text Statistics — shows characters (total and without spaces), words, sentences, paragraphs, average word length, and the most frequent word.

Check Spelling — re-runs the spell-check highlight pass over the whole document.

View

Zoom In / Out / Reset — Ctrl++ / Ctrl+- / Ctrl+0.

Markdown Preview (Ctrl+Shift+M) — splits the window: editor on the left, rendered Markdown on the right. Updates live as you type. Uses Qt 6's built-in setMarkdown() — no external libraries required.

Spell Checker

Loaded from data/words.txt at startup (370 105 English words). Misspelled words are underlined in red as you type. Right-clicking a misspelled word shows up to five suggestions.

Status Bar

Displays word count, line count, and current cursor position (line and column) in real time.

Exception Handling

File errors are caught and shown in a QMessageBox::critical dialog:

• file_not_found_exception — path does not exist
• file_read_exception — file cannot be opened for reading
• file_write_exception — file cannot be opened for writing

All three inherit from notepad_exception, which inherits from std::runtime_error.

Project Structure

.
├── main.cpp
├── main_window.h
├── main_window.cpp
├── text_transform.h
├── notepad_exception.h
├── spell_checker.h
├── spell_checker_highlighter.h
├── text_statistics_dialog.h
├── symbol_insert_dialog.h
├── find_replace_dialog.ui
├── word_frequency_dialog.ui
└── data/
    ├── words.txt
    └── images/
        ├── bold.svg
        ├── italic.svg
        └── underline.svg

Implementation Notes

text_transform is an abstract base class with a pure virtual apply() method. Each of the five case transforms is a concrete subclass. The main window stores them as std::vector<std::unique_ptr<text_transform>> and iterates over them to build the Text Case menu dynamically.

spell_checker stores the word list in std::set<std::string> for O(log n) lookup. Suggestions are generated using Norvig-style edit distance 1: deletions, transpositions, replacements, and insertions.

spell_checker_highlighter extends QSyntaxHighlighter and underlines unrecognized words using QTextCharFormat::SpellCheckUnderline.

text_statistics_dialog and symbol_insert_dialog are self-contained header-only QDialog subclasses.

Markdown preview uses QSplitter to divide the window and QTextEdit::setMarkdown() to render. The preview panel updates on every textChanged signal when visible.