devpad

name	devpad
description	A C++17/Qt6 code editor built with QScintilla syntax highlighting and QTermWidget embedded terminal. Use for contributing to or customizing Devpad's source code, build system, themes, snippets, translations, and configuration.
triggers	["Edit any file under src/, tests/, CMakeLists.txt, or resources/","Build, test, or package Devpad (CMake, Flatpak)","Add or modify themes, color schemes, QSS styling","Add or modify snippets (JSON format)","Add or modify translations (TS files under i18n/)","Add new languages, lexers, or syntax highlighting","Add new managers, dialogs, panels, or widgets"]

Devpad Skill

A C++/Qt6 code editor with QScintilla syntax highlighting, QTermWidget embedded terminal, project panel, split views, session management, and 7 built-in themes.

License: GPL-2.0-only
Copyright: 2026 Semagsoft

When This Skill Applies

Use this skill when working with:

• Source code in src/ — any .cpp or .h file
• Build system — CMakeLists.txt, Flatpak config (flatpak/com.semagsoft.Devpad.yml)
• Tests — tests/*.cpp, GTest + QtTest framework
• Themes — src/theme.*, src/themeapplier.*, resources/color-schemes/, resources/theme.qss
• Snippets — src/snippet.*, src/managers/snippetmanager.*, resources/snippets/default.json
• Translations — i18n/devpad_*.ts
• Resources — resources/resources.qrc, icons, sounds
• CI — .github/workflows/ci.yml

Architecture

Directory Layout

Devpad/
├── .clang-format          # LLVM style, Allman braces, 4-space indent, 150 col limit
├── .clang-tidy            # modernize, performance, bugprone checks as errors
├── .editorconfig          # 4-space indent, LF, UTF-8
├── CMakeLists.txt         # CMake 3.23+, C++17, Qt6, qtermwidget6, QScintilla
├── flatpak/
│   └── com.semagsoft.Devpad.yml
├── i18n/
│   ├── devpad_de.ts
│   ├── devpad_es.ts
│   └── devpad_fr.ts
├── resources/
│   ├── resources.qrc
│   ├── theme.qss             # QSS template with %placeholder% tokens
│   ├── color-schemes/        # 6 .colorscheme files
│   ├── icons/                # SVG icons by category
│   ├── snippets/
│   │   └── default.json      # VS Code-format snippet definitions
│   └── sounds/
├── src/
│   ├── main.cpp              # Entry point, CLI args (files, folders, --transfer)
│   ├── mainwindow.h/cpp      # Main window, owns all managers/panels
│   ├── codeeditor.h/cpp      # QsciScintilla subclass: editor core
│   ├── editorcontroller.h/cpp# Save/load/close coordination, backup restore
│   ├── theme.h/cpp           # ThemeId enum, ThemeColors struct, 7 themes
│   ├── themeapplier.h/cpp    # Applies theme: QPalette + QSS template substitution
│   ├── languageinfo.h/cpp    # Language → QsciLexer mapping
│   ├── keywords.h/cpp        # Keyword lists per language for auto-completion
│   ├── encodingutils.h/cpp   # BOM detection, encoding conversion
│   ├── snippet.h/cpp         # Snippet data model + VS Code-format body parser
│   ├── logger.h/cpp          # File-based logging
│   ├── defaultsyntax.h       # Default syntax constant
│   ├── appstrings.h          # Centralized UI string literals
│   ├── managers/
│   │   ├── actionmanager.*       # QAction registry, keyboard shortcuts
│   │   ├── backupmanager.*       # Auto-save backups + crash recovery
│   │   ├── encodingmanager.*     # Populates encoding menu/combo
│   │   ├── externaltoolmanager.* # External tool execution
│   │   ├── filemanager.*         # File read/write with conflict detection
│   │   ├── filewatchermanager.*  # QFileSystemWatcher for external changes
│   │   ├── printmanager.*        # Print + print preview with highlighting
│   │   ├── remotefileservice.*   # HTTP(S) file download
│   │   ├── searchmanager.*       # Find/replace/find-in-files coordination
│   │   ├── sessionmanager.*      # Tab/project persistence across launches
│   │   ├── settingsmanager.*     # QSettings wrapper (singleton, cached)
│   │   ├── snippetmanager.*      # Snippet loading + auto-completion
│   │   └── tabmanager.*          # QTabWidget wrapper, editor tracking
│   ├── dialogs/
│   │   ├── aboutdialog.*         # About dialog
│   │   ├── dialogsettings.h      # QDialog geometry persistence helper
│   │   ├── externaltoolsdialog.* # External tools editor dialog
│   │   ├── finddialog.*          # Find text dialog
│   │   ├── findinfilesdialog.*   # Find in files dialog
│   │   ├── optionsdialog.*       # Settings/options dialog
│   │   └── replacedialog.*       # Find & replace dialog
│   ├── panels/
│   │   ├── projectpanel.*    # File tree sidebar with icons, filter, recent
│   │   ├── terminalpanel.*   # QTermWidget wrapper (docked or tab)
│   │   └── splitview.*       # Split editor views (horizontal/vertical)
│   └── widgets/
│       └── themepreviewwidget.*  # Live theme preview in Options dialog
└── tests/
    ├── main.cpp                 # QApplication + GTest main
    ├── test_appstrings.cpp
    ├── test_backupmanager.cpp
    ├── test_codeeditor.cpp
    ├── test_editorcontroller.cpp
    ├── test_encodingutils.cpp
    ├── test_filemanager.cpp
    ├── test_keywords.cpp
    ├── test_languageinfo.cpp
    ├── test_logger.cpp
    ├── test_mainwindow.cpp
    ├── test_remotefileservice.cpp
    ├── test_searchmanager.cpp
    ├── test_sessionmanager.cpp
    ├── test_settingsmanager.cpp
    ├── test_snippet.cpp
    ├── test_snippetmanager.cpp
    ├── test_tabmanager.cpp
    ├── test_theme.cpp
    └── test_themeapplier.cpp

Dependency Graph

main.cpp
  └── MainWindow (QMainWindow)
        ├── EditorController  →  FileManager, TabManager, FileWatcherManager, ActionManager
        ├── ActionManager     →  all QActions, keyboard shortcuts
        ├── SessionManager    →  persist/restore tabs + project folder
        ├── ThemeApplier      →  ThemeColors → QPalette + QSS
        ├── EncodingManager   →  encoding menu/combo
        ├── PrintManager      →  QPrinter + print preview
        ├── SearchManager     →  FindDialog, ReplaceDialog
        ├── ExternalToolManager
        ├── RemoteFileService
        ├── SnippetManager
        ├── FileWatcherManager
        ├── TabManager (QTabWidget)
        │     └── CodeEditor (QsciScintilla)  ←  snippet.h, theme.h
        ├── ProjectPanel (QDockWidget)
        ├── TerminalPanel (QDockWidget / QTabWidget tab)
        └── SplitView

All managers are singletons or parented to MainWindow. The EditorController is the primary coordinator for file I/O. SettingsManager is a true singleton (SettingsManager::instance()).

Build System

Dependencies

Package	Purpose
Qt6 Core, Gui, Widgets	Base framework
Qt6 PrintSupport	Print + Print Preview
Qt6 Multimedia	Sound effects
Qt6 Network	Remote file download
Qt6 LinguistTools	TS compilation
qtermwidget6	Embedded terminal
QScintilla (qt6)	Syntax highlighting
CMake 3.23+	Build system
C++17 compiler	g++ or clang++

Building

# Debug
cmake -S . -B build -DCMAKE_BUILD_TYPE=Debug
cmake --build build -j$(getconf _NPROCESSORS_ONLN)

# Release
cmake -S . -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build -j$(getconf _NPROCESSORS_ONLN)

# With tests
cmake -S . -B build -DCMAKE_BUILD_TYPE=Debug -DBUILD_TESTS=ON
cmake --build build -j$(getconf _NPROCESSORS_ONLN)

# Install system-wide
cmake --install build

Flatpak Build

From flatpak/com.semagsoft.Devpad.yml:

cd flatpak
flatpak-builder --force-clean build-dir com.semagsoft.Devpad.yml
flatpak-builder --run build-dir com.semagsoft.Devpad.yml Devpad

The Flatpak manifest:

• Uses org.kde.Platform runtime (6.8)
• Builds qtermwidget from source (git tag 2.1.0)
• Builds qscintilla from source archive (2.14.1)
• Builds Devpad with -DBUILD_TESTS=OFF

Coding Conventions

Formatting (enforced by .clang-format)

• LLVM-based style
• Allman braces (breakBeforeBraces: Allman)
• 4-space indent, no tabs
• Column limit: 150
• Pointer/reference: left-aligned (int* p, int& r)
• Includes: regrouped (local "" before system <>)

Naming

• Classes: PascalCase (CodeEditor, SettingsManager)
• Methods/Variables: camelCase (currentEditor(), m_tabWidget)
• Member variables: m_ prefix (m_fileName, m_snippetActive)
• Constants/Enums: PascalCase (ThemeId::Light, BOOKMARK_MARGIN)
• Signals/Slots: camelCase (fileSaved(), onTabChanged())

Includes

// Own header first
#include "codeeditor.h"

// Then project headers
#include "settingsmanager.h"
#include "theme.h"

// Then Qt headers
#include <QApplication>
#include <QPalette>

// Then system headers
#include <array>
#include <mutex>

Conventions

• Q_OBJECT macro in every QObject-derived class
• override keyword on all overridden virtual methods
• explicit on single-arg constructors
• Forward-declare classes in headers where possible
• Use Q_DISABLE_COPY for singleton classes
• constexpr over #define for constants
• Structured bindings and const auto& for iteration

Clang-Tidy (.clang-tidy)

• Enabled: clang-diagnostic-*, clang-analyzer-*, modernize-*, performance-*, readability-*, bugprone-*
• Warnings as errors: modernize-*, performance-*, bugprone-*
• Disabled: trailing return type, identifier length, magic numbers

Testing

Framework

• Google Test (GTest) with QtTest integration
• System GTest preferred; falls back to FetchContent from GitHub (tag v1.14.0)
• BUILD_TESTS=ON enables tests
• Test entry point: tests/main.cpp (creates QApplication)

Running Tests

cmake -S . -B build -DCMAKE_BUILD_TYPE=Debug -DBUILD_TESTS=ON
cmake --build build -j$(getconf _NPROCESSORS_ONLN)
ctest --test-dir build --output-on-failure

Test Patterns

• File: tests/test_<Component>.cpp
• Naming: TEST(ComponentName, TestCaseName)
• Pattern: instantiate component, call methods, assert with EXPECT_EQ, EXPECT_TRUE, etc.
• Each test file tests one component class

Adding a New Test

1. Create tests/test_newcomponent.cpp
2. Add source to TEST_SOURCES in CMakeLists.txt
3. Implement test cases
4. Run with ctest

Theme System

Architecture

ThemeId (enum)
  │
  ▼
getThemeColors(ThemeId) → ThemeColors
  │
  ├── resolve() → computes 23 derived color fields from 19 core values
  │
  ├── getThemePalette(ThemeColors) → QPalette
  │
  ├── buildStyleSheet(ThemeColors) → QSS string
  │     Reads resources/theme.qss, replaces %placeholder% tokens
  │
  └── ThemeApplier::applyTheme(QMainWindow*)
        Sets QPalette + styleSheet on QApplication + window

ThemeId Enum (src/theme.h)

enum class ThemeId {
    Light = 0,
    Dark = 1,
    System = 2,
    Nord = 3,
    SolarizedLight = 4,
    Monokai = 5,
    GruvboxDark = 6
};

ThemeColors Struct (src/theme.h)

• 19 core fields: background, foreground, surfaceBg/Fg, accent, border, caret, lineHighlight, marginBg/Fg, foldMarginBg/Alt, comment, keyword, string, number, operator_, function, preprocessor
• 23 derived fields (computed by resolve()): toolbarBg/Fg, menuBg/Fg, statusbarBg/Fg, tabBg, tabBgActive, tabFg, tabFgActive, tabBorder, scrollbarBg/Handle/HandleHover, selectionBg/Fg, matchedBraceBg/Fg, dialogBg/Fg, inputBg/Fg, buttonBg/Fg, groupboxBg/Fg, checkboxIndicator, separator

QSS Template (resources/theme.qss)

Uses %placeholder% tokens like %background%, %foreground%, %menuBg%, etc. The ThemeApplier reads the file and substitutes each token with the hex color from the resolved ThemeColors.

Color Scheme Files (resources/color-schemes/)

Scintilla-specific color scheme files for editor syntax colors. One per theme:

• DevpadLight.colorscheme
• DevpadDark.colorscheme
• DevpadGruvboxDark.colorscheme
• DevpadMonokai.colorscheme
• DevpadNord.colorscheme
• DevpadSolarizedLight.colorscheme

Adding a New Theme

1. Add entry to ThemeId enum in src/theme.h
2. Add color values in getThemeColors() in src/theme.cpp
3. Add a .colorscheme file in resources/color-schemes/
4. Register the theme in themeDisplayName() and isThemeDark() in src/theme.cpp
5. (Optional) Add accent color support in SettingsManager

Snippet System

Format

Snippets are stored in VS Code-compatible JSON format in resources/snippets/default.json:

{
  "Snippet Name": {
    "prefix": "trigger",
    "body": ["line 1", "line 2 with ${1:default}"],
    "description": "What this snippet does",
    "scope": "cpp,javascript,python"
  }
}

• prefix: What the user types to trigger auto-completion
• body: Array of lines (joined with \n at expansion)
• scope: Comma-separated language names where this snippet is available
• Tab stops: ${1}, ${2}, ${1:defaultValue}, $0 (final cursor position)
• Mirrors: Same tab stop number in multiple places (e.g., ${1:name} in header guard)

Tab Stop System (src/snippet.h)

struct Snippet {
    QString name;
    QString prefix;
    QString description;
    QStringList body;
    QStringList scope;

    struct TabStop {
        int number;
        QList<int> positions;  // positions in expanded text
        QString defaultValue;
        int length;
    };

    struct ExpandedSnippet {
        QString text;
        QList<TabStop> tabStops;
    };

    ExpandedSnippet expand() const;
};

Snippet Manager (src/managers/snippetmanager.h)

• Loads resources/snippets/default.json at startup
• Loads user snippets from config directory
• Methods: snippetsForLanguage(), snippetsByPrefix(), snippetByName()
• Singleton access via SnippetManager::instance()

CodeEditor Snippet Integration

• insertSnippet(const Snippet&) — expands and inserts, enters snippet mode
• Tab/Shift+Tab navigates between tab stops
• Visual indicators using Scintilla indicators (indicator ID 21)
• Auto-completion integration via registerSnippetAutoCompletion()

Adding Snippets

1. Edit resources/snippets/default.json or create a new file
2. Define snippet with prefix, body lines, scope
3. Rebuild — snippets are loaded at startup via SnippetManager::loadBuiltIn()
4. User snippets are loaded from ~/.local/share/devpad/snippets/

i18n / Translation Workflow

File Layout

• i18n/devpad_de.ts — German
• i18n/devpad_es.ts — Spanish
• i18n/devpad_fr.ts — French

Build Integration

qt_add_translations(Devpad
    TS_FILES ${TS_FILES}
    QM_FILES_OUTPUT_VARIABLE qm_files
)

TS files are automatically compiled to .qm during build.

Updating Translations

# Extract strings from source into TS files
lupdate src/ -ts i18n/devpad_de.ts i18n/devpad_es.ts i18n/devpad_fr.ts

# Translate... (edit TS files manually or with Qt Linguist)

# Compile to QM (done automatically by CMake, or manually):
lrelease i18n/devpad_de.ts i18n/devpad_es.ts i18n/devpad_fr.ts

Adding a New Language

1. Create i18n/devpad_<lang>.ts
2. Add to TS_FILES in CMakeLists.txt
3. Run lupdate to populate strings
4. Translate and rebuild

Key Workflows

Adding a New Manager

1. Create src/managers/newmanager.h and src/managers/newmanager.cpp
2. Add source files to Devpad_lib in CMakeLists.txt
3. Forward-declare in mainwindow.h
4. Create instance in MainWindow::setupUI() or constructor
5. Connect signals/slots in MainWindow::connectActions()

Adding a New Dialog

1. Create files in src/dialogs/ (e.g., newdialog.h, newdialog.cpp)
2. Add to Devpad_lib in CMakeLists.txt
3. Inherit from QDialog
4. Use dialogsettings.h for geometry persistence if needed
5. Open from MainWindow slot via action in ActionManager

Adding a New Language

1. Add keywords to src/keywords.cpp → keywordsForLanguage()
2. Add lexer mapping to src/languageinfo.cpp → createLexer()
3. Add extension→language mapping in SettingsManager::extensionMap()
4. Add file name→language mapping in SettingsManager::fileNameMap()

Adding a New File Type Icon

1. Add SVG to resources/icons/File/
2. Update resources/resources.qrc if needed
3. Register in ProjectPanel or relevant icon provider

Working with Encoding

• encodingutils.h/cpp provides BOM detection (detectBom) and encoding conversion
• FileManager::loadFile()/saveFile() accept optional encoding parameter
• Supported: UTF-8, UTF-16 LE/BE, UTF-32 LE/BE, ISO-8859-1, System
• EncodingManager populates the status bar encoding combo

External File Change Detection

• FileWatcherManager wraps QFileSystemWatcher
• Signals fileModifiedExternally(filePath) to MainWindow
• MainWindow shows reload dialog via EditorController::promptBackupRestore()

Auto-Save & Backup

• BackupManager saves to ~/.local/share/devpad/backups/
• EditorController::autoSave() called by QTimer (configurable interval)
• On startup, SessionManager checks for backups newer than saved files
• EditorController::promptBackupRestore() offers restore dialog